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    Thread: FAQ

    1. Moderator yellowslc's Avatar
      Join Date
      Aug 29th, 2000
      03-01-2005 12:05 PM #1
      Please post FAQ information in this thread.
      How To's
      I will edit as they come in.

    2. 03-02-2005 02:27 PM #2
      Make your own short shifter (Applies to MK II)
      The intermediate lever that attaches to the relay shaft...
      (Engine compartment, near firewall (that thing with the little ball on it) that is moved by the shifting rod)
      If you unbolt the lever and weld a longer peice on it (with a hole for the selector rod bushing...) there you go! Short shift.
      Take a look at any short shift kit out there for these cars, you'll see what I mean.
      p.s. Good Idea not to re-use bushing. Shifter repair kits are cheap.

    3. Banned
      Join Date
      Jun 24th, 2004
      04-11-2005 12:00 PM #4
      stay away from that exploited racing guy. he's f'd me and many others over there is a big hubbub about it on h-t right now.

    4. 04-11-2005 12:27 PM #5
      Yea, I have been following all the drama. That guy is a moron. I took his link off my post.

    5. 04-17-2005 05:37 AM #6
      Duty cycles are only rated at the machine fully cranked(heat setting at max). Although I think 220v machines are the answer(do NOT buy a 110v tig), a "big" 110v mig is an excellent beginner friendly machine that will be capable of quite a bit(especially automotive).
      Stick/tig is a constant CURRENT(consistant/same amperage) process. Be ready for a decent sized breaker in the house! On the other hand, Wire feed(mig/fcaw) is a constant VOLTAGE process.
      General shielding gas guidlines- As kimosullivan said, consult your local supplier...but I have been mis guided by them before.
      Argon- An inert gas(tasteless odorless, does not react to any other element, etc) 100% argon is what you want to run in your TIG about 98% of the time.
      co2 Carbon dioxide(duh). This can be used as a straight sheilding gas for mig/FCAW welding. It is one of the cheapest gases you can buy. It provides a hotter heat affected zone and helps with undercutting(gouging at the edge of the weld). Some downsides are the dull grey color it leaves on your weld.
      Helium Ball parks around the price of argon, but provides a concentrated, hotter weld area(A good gas where co2 cannot be used, like aluminum, stainless, etc). This gas is also helpful with overhead and incline welding due to its light weight.
      Mixes/selecting a gas There are endless amounts of mixes out there. There are a few more gases available as well. But there are some basic guidlines to when you pick a mix/gas:
      TIG mixes/gases/thoughts-As noted earlier, if you are running a TIG, you are obviously(98%) running pure argon. There are a few mixes that people have been known to run, but for the most part, argon is your answer. It will weld Ti, stainless, exotics, mild steel etc. Another option is 100% helium, though. If you do not have a machine with a high freq unit and AC(alternating current), you can still weld aluminum with helium gas. You can weld on DCEN. This is a very tricky process, but I have personally seen VERY good results. Try to keep that trick on 1/8" and above, as it runs very hot. Also, if you want ripples doing that, you NEED a pulser.
      MIG mixes/gases/thoughts This is where the gas selection starts getting crucial. You can go from a 100 dollar mix to a down 20 dollar bottle of co2. The amount of mixes are endless, but for the most part, a few mixes have been "proven". The most popular mix is referred to as 75/25, which is 75%argon, 25% co2. If you are cheap, and have a small welder, I would recommend a higher %age of co2, as you will create a hotter puddle. When welding aluminum with mig, stick with pure argon(or helium if you REALLY want to pour some heat to it). When it comes to MIG stainless, be sure to keep your co percentange 2% or under(none is fine). I personally recommend a 96%helium, 2%argon, 2% co2. Helium with stainless helps keep you from getting a "ropey"(cold looking) weld, as it has a higher ionization potential and thus "concentrates" the heat(more or less). pure argon and stainless steel typically do not work well together, unless you have a large machine. I would not recommend pure argon on mild steel. Although it works, you have no gas aiding undercut.
      The information below is stolen from KimoSullivan
      What is MIG/TIG/Stick?
      Gas metal arc welding (GMAW) is the "correct" name for MIG, metal inert gas, and is also known as wire feed, and by several trades names like Airco-matic and Miller-matic. It is a semiautomatic welding process: the welder controls the movement of the torch or gun, and the machine controls the wire speed. An electric arc is established between a consumable, solid, bare metal electrode, aka wire, and the work pieces to be welded. Most GMAW machines with have two control knobs, one for power and one for wire speed. More power gives more heat, more wire speed gives less heat. GMAW is generally regarded as the easiest welding process to learn: just pull the trigger and go. GMAW is a gas shielded process, you will need a tank of gas from your welding supply store.
      Gas tungsten arc welding (GTAW) is the "correct" name for TIG, tungsten inert gas, and the trade name Heli-arc. It is a manual welding process: the welder controls the movement of the torch and how much filler metal is added. An electric arc is established between a non-consumable tungsten electrode and the work pieces to be welded. Filler metal is added by had with solid, uncoated wire rods. Most GTAW machines with have enough controls to scare off a novice, including a thumb wheel or foot pedal (like a sewing machine) to control the power. GTAW is generally regarded as the most difficult welding process to learn: you need to move both hands and often a foot to control it. GTAW is a gas shielded process, you will need a tank of gas from your welding supply store.
      Shielded metal arc welding (SMAW) is known as stick. It used flux coated solid electrodes. The arc is established between the electrode and the base metal. The flux burns to provide atmospheric shielding for the molten metal to prevent contamination. This is probably the least expensive process for a home user. It is also probably the least useful, being better suited for structural and pipeline construction. If you want to build a turbo exhaust manifold, SMAW will work. It's not good for thin stuff.
      Flux core arc welding (FCAW) is known as flux core or wire feed. It's basically a combination of GMAW and SMAW. The electrode wire is hollow and filled with flux. Sometimes it is gas shielded (FCAW-S). It can be a cheap way to get around needing a bottle of shielding gas for GMAW. It is designed for outdoor structural fabrication where a shielding gas would blow away in the wind. If you wouldn't weld your project with SMAW, I wouldn't recommend FCAW. It's generally not good for thing stuff either.
      Can I MIG/TIG/Stick Aluminum/Stainless/Mild Steel?
      All three processes will work on all three materials. If you have the power supply and materials needed for them is another story. Stick is best left to mild steel and is good for stainless work outdoors. Mig requires a short torch cable or a gun with the wire spool on board for aluminum. TIG for aluminum needs to have AC, to clean off the oxides, and an arc start/high frequency to get things going.
      What shielding gas/filler metal should I use?
      Consult your local welding supplier for specific recommendation about particular projects.
      What machine should I buy?
      I recommend staying with the major brands, Miller, Lincoln, and ESAB. It you get a TIG machine, get one with AC and arc start, since you will eventually get the desire to weld aluminum. Look at the prices and features of the new models and then see if there are any deals on used welders. Look for a duty cycle of 60%. That means you can weld for six minutes out of every ten. Avoid Matco, Snap-on, Craftsman, etc with 20% duty cycles. Also, stay away from any 120V machines. Get your garage wired for 230V, or plug it into the dryer outlet when your spouse isn't watching. Engine driven machines are a possibility for the home user who is also considering getting a portable generator. If you travel to racing events and want power tools in the pits, go for it.
      How can I learn to weld?
      Try your local community college. For a little money you get to learn from experience instead of trial and error. You get to use someone elses machines and consumables. Plus the scheduled class time might motivate you to quit being so lazy and practice. If you truly live in BFE, there are plenty of good books to get you started and then practice, practice, practice.

      Modified by cnbrown at 11:24 PM 4-17-2005

    6. Member vr6Cop's Avatar
      Join Date
      Jun 1st, 2000
      Music City
      12-06-2005 05:17 PM #7
      Carbon fiber, kevlar, fiberglass, resins, etc.
      Suppliers and several good how-to's on molds, etc.
      Cheers, Adrian
      726 bottles of beer on the wall.

    7. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      12-12-2005 02:24 PM #8
      Types of fasteners
      SAE Fasteners:
      Grade 2 - bolt head has no markings
      - Low carbon steel, used in what is often referred to as "hardware" quality fasteners. Miniumum tensile strength of 74 ksi.
      - Carbon level in this steel is too low to accept heat treatment, low strength and hardness.
      - Acceptable for nonmechanical applications
      - Heads do not carry any grade marking although some manufacturers may include company identification on the head. Traceability for this grade is not required.
      Grade 5 - bolt head has three dashes along the radius, one every 120 degrees
      - Medium carbon steel, minimum tensile strength of 120 ksi.
      - Heat treated, quenched, tempered. Used mostly in automotive body and other moderate strength applications.
      - THREE radial lines on head (extending outward from the center) = Grade 5.
      Grade 8 - bolt head as six dashes along a radius, one every 60 degrees
      - Highest standard, 150 ksi minimum TS. Carbon steel.
      - Strong, meeting needs for flywheels, universal joints, transmission mounts and cases, motor supports, front end suspensions, etc.
      - Identified by SIX radial lines on the head.
      - Not to be confused with Grade 8.2 bolts. Grade 8.2 bolts are low carbon, boron, martensitic (i.e., brittle) steel with similar strength and hardness, but not at higher temperatures. Heat treated and tempered Grade 8 bolts are better for service at elevated temperatures.
      Stainless Steel Facts
      Stainless steel (SS) is classified as "stainless" because the iron (Fe) contains a minimum of 10.5% (by weight) of corrosion-resisting chromium (Cr). Depending on the alloy, stainless steels may also contain nickel and trace amounts of other elements.
      SS fasteners are recommended for chemical, marine, and other special, rugged environments where corrosion is an issue. SS is also used in human implants, as the corrosion resistance of SS is such that it is generally biocompatible. Due to its weight, however, titanium alloys are sometimes used in place of SS.
      The corrosion resistance of SS comes from a chromium oxide layer at the surface which offers protection to the bulk metal. Much like a patina finish on a hot rod, once the oxide layer is uniform it will remain that way for a considerable amount of time, and it is generally self healing. Since the Cr is alloyed with the steel, the oxide layer forms on any free surface, thus resisting extended corrosion.
      A common SS fastener is made of 18-8 stainless, a chromium-nickel steel alloy (18% Cr, 8% Ni... thus the "18-8"). Generally non-magnetic, these fasteners have a minimum tensile strength of about 85,000 psi (85 ksi).
      18-8 SS is an austenitic stainless steel, meaning that it has a high content of a stabilized high temperature phase in its microstructure. Most austenitic steels contain nickel and are not hardenable by heat treatment because of the volume fraction of the austenitic phase. Martensitic stainless steels contain 12-20% Cr and are magentic and hardenable. Martensites phases in steels form upon quenching (cooling rapidly) from high temperature. Common martensitic SSs are Type 410 and 416. Ferritic alloys are also Cr SS alloys. They exhibit some magnetism, but are not hardenable by heat treatment. Type 430 is a common ferritic alloy.
      Comparison of Metric to SAE Grades
      Metric Class / SAE Grade -- Metric/SAE Tensile Strength (ksi)
      8.8 / 5 -- 120.35 / 120
      10.9 / 8 -- 150.8 / 150
      12.9 / na -- 176.9 / na
      Metric Strengths
      Metric Class -- Strength (ksi/MPa)
      8.8 -- 120.35 / 830
      9.8 -- 130.6 / 900
      10.9 -- 150.95 / 1040
      12.9 -- 176.9 / 1220
      Metallurgical Terms and Processes
      Slow cooling after holding a specimen at elevated temperature for an extended period of time.
      Case Hardening
      Heating a steel such that the outer layer is hardened, usually with a nitrogen- or carbon-rich atmosphere.
      "Flexiblity". A specimen in tensile testing will resist yielding by permitting a certain level of stretching. The gauge section, or section of the specimen experiencing the greatest stress, will stretch (elongate) and shrink (sometimes called "necking"). Measuring the % Elongation (%E) and the % Reduction in Area (%RA) will give a measure of ductility.
      Measurement of a specimens resistance to indentation by a standard tip. The tip is a rounded or pointed tip. The depth and cross-sectional size of the indentation are measured and compared to the standard.
      Force per unit area. In tensile and compression testing, the load is the value measured.
      SAE = load is measured in pounds per square inch (psi). Since most tensile strengths extend into the thousands, values are often given in kilopounds per square inch, or "ksi".
      Metric = Newtons per square meter, or Pascals (Pa). Values usually reach the millions of Pascals, so tensile values are often given in Mega Pascals (MPa).
      SAE = Threads/inch.
      Metric = distance between threads.
      For SAE, the pitch of one thread is the distance that a nut would advance on a bolt when turned one full turn.
      For metric fasteners, the pitch is the distance from the crest of one thread to the adjacent thread, expressed in millimeters.
      Yield Strength (YS)
      In tension testing, the yield strength is the load (in psi) where the specimen begins permanent deformation, i.e., the stretching cannot be reversed. Generally, the specimen will breach the threshold from elastic to inelastic yielding when the yield strength is met or exceeded.
      Tensile Strength (TS)
      Load (psi) where the specimen fails in tensile testing. Sometimes called Ultimate Tensile Strength (UTS).

      Modified by DHill at 1:25 PM 12-12-2005

    8. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      12-12-2005 02:28 PM #9
      (this is just as much for my own personal edification as well as anyone who is interested)
      Alloying Aluminum
      Strength is increased by the addition of magnesium (up to about 7% by weight) and also additions of zinc, copper, and/or silicon in conjunction with Mg.
      High temp strength is achieved by adding up to 4wt% Cu and/or nickel, manganese, or iron (none of these latter elements are added above 1wt% - they are heavy alloying elements as well).
      Chemical and Corrosion resistance is obtained with the addition of Mg, Mn, or a combination of Mg and Si.
      Machinability is greatly improved by the addition of lead and bismuth up to 0.6 wt% each.
      Grain refinement (which often leads to better strength in castings) is obtained via the addition of titanium and boron in very small amounts. Solid Ti and borides in the melt pool provide a greater nucleation site density during solidification, thus creating more nucleation sites per unit volume, thus reducing grain size. Chromium and zirconium (up to 0.1wt%) will also refine grains, along with iron and manganese.
      Homogeneity in casting is achieved by adding up to 13 wt% of Si. Dimensional stability at high temperature is achieved by adding as much as 25 wt% Si, leading to a fiber reinforced metal composite. This is often used in the fabrication of aluminum PISTONS.
      Major Alloying Elements and Aluminum Series Designation for Wrought Alloys
      1xxx >99% Al
      2xxx Cu
      3xxx Mn
      4xxx Si
      5xxx Mg
      6xxx Mg and Si
      7xxx Zn
      8xxx "Other"
      9xxx Unused as of now
      Four digits are used to identify wrought aluminum and its alloys. The alloy group is identified by the first digit. Modifications of the original alloy and impurity limits are indicated by the second digit. In the case of the 1xxx group, the last two digits indicate the minimum aluminum percentage. For the 2xxx through 8xxx groups, the last two digits serve to further identify individual aluminum alloys. For experimental alloys, a prefix capital "X" is added, i.e., X2037.
      CastingsFor castings, a different standard is used, i.e., xxx.x.
      1xx.x 99% Aluminum or more
      2xx.x Cu
      3xx.x Si + Cu or Mg
      4xx.x Si
      5xx.x Mg
      7xx.x Zn
      8xx.x Sn
      9xx.x Other
      6xx.x Unused
      Wrought Alloy Designations

      1xxx - Pure Al
      Ex. 1100 (99% pure Al), 1050 (99.5% pure), 1350 (99.5%), 1175 (99.75%).
      Some used for electrical applications, like 1350. Not ideal for strength. Better for corrosion resistance, high formability, and conductivity.
      2xxx - Al-Cu Alloys
      Ex. 2014, 2024, 2219.
      Heat treatable alloys, good for strength, especially at high temps. Good toughness (i.e., good for fracture-critical applications). Good weldability. Usually painted to improve corrosion resistance, as it isn't all that great otherwise. 2024 is used in aircraft, 2014 is used in automotive body applications - bolted or riveted. 2219 and 2048 show good weldability and are thus ideal for aerospace. 2195 includes lithium as an alloying element, shows good strength and weldability, and also sees usage in aerospace. 2124 and 2149 have good fracture toughness and are used in aircraft. 2011, 2017, and 2117 are widely used for fasteners and screw-machine stock.
      3xxx - Al-Si alloys
      Ex. 3003, 3004, 3105.
      Strain hardenable alloys have excellent corrosion resistance, reasonable weldability, brazability, and solderability. Alloys 3004 and 3104 are widely known and used (out of all Al alloys) because they are used in beverage cans. 3003 is used in cooking utensils, chemical equipment, and builder's hardware. 3105 is used in roofing and siding. A lot of the 3xxx series is used in sheet and tubular form.
      4xxx - Al-Mg alloys
      Ex. 4032, 4043.
      4032 is medium to high strength and heat treatable used principally for forgings. 4043, on the other hand, is widely used as a filler for GMA welding 6xxx alloys. 4043 is also used in structural and automotive applications. High Si content leads to better molten flow in molds and during welding. Also used for cladding and brazing.

      5xxx - Al-Mg Alloys
      Ex. 5052, 5083, 5086, 5183, 5754.
      Strain hardenable, moderately high strength, excellent corrosion resistance (even in salt water), high toughness even at cryogenic temps. Readily welded and therefore find a wide range of applications in construction of bridges, storage tanks, pressure vessels, cryogenic tank systems, and marine applications. 5052, 5086, 5083 are work horses for structural applications, and strength increases with increasing Mg content. 5182 is used in beverage can end caps, 5754 is used in automotive bodies and frames, 5252, 5457, and 5657 are used for bright automotive trim applications (very polishable).
      6xxx - Al-Mg-Si Alloys
      Ex. 6061, 6063, 6111.
      Heat treatable, moderately high strength, excellent corrosion resistance. Readily welded. Exturdable as well! First choice for architectural and structural members where unusual strength or stiffness (high modulus) is required. Alloy 6063 is widely used in aluminum bridge structures and automotive space frames. 6061 has better strength than 6063, and is used in truck and marine frames, railroad cars, and pipelines. 6066-T6 is used in high strength forgings, 6111 is used in automotive panels with high dent resistance, and 6201 is used in high strength conductive wire.

      7xxx - Al-Zn Alloys
      Ex. 7005, 7050, 7075, 7475.
      Heat treatable and provide highest strengths of all aluminum alloys. 7150 and 7475 have controlled impurity levels to maximize the combination of strength and fracture toughness. The aircraft industry uses a lot of 7-series alloys, though they are not generally very weldable. Usually they are used in riveted construction. Corrosion resistance is not as high as 5xxx or 6xxx alloys, so 7xxx alloys are usually coated.

      8xxx - Al + other elements
      Ex. 8017, 8090.
      Use alloying elements such as Fe, Ni, and Li. Fe and Ni provide strength with little loss in conductivity such as in the 8017 alloy (which is used in conductive applications). Li provides a high modulus in aerospace applications.
      Source: Aluminum: Technology, Applications, and Environment. A Profile of a Modern Metal. 6th Ed. Dietrich G. Altenpohl. The Minerals, Metals, and Materials Society (TMS). 1998. ISBN #: 0-87339-406-2
      Basic Designations
      F -- As Fabricated - No special control has been performed to the heat treatment or strain hardening after the shaping process such as casting, hot working, or cold working.
      O -- Annealed - This is the lowest strength, highest ductility temper
      H -- Strain Hardened - (applied to wrought products only) Used for products that have been strengthened by strain hardening, with or without subsequent heat treatment. The designation is followed by two or more numbers as discussed below.
      W -- Solution Heat Treated - This is seldom encountered because it is an unstable temper that applies only to alloys that spontaneously age at ambient temperature after heat treatment.
      T -- Solution Heat Treated - Used for products that have been strengthened by heat treatment, with or without subsequent strain hardening. The designation is followed by one or more numbers as discussed below.

      T Temper Codes

      T1 - Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition.
      T2 - Cooled from an elevated temperature shaping process, cold worked, and naturally aged to a substantially stable condition.
      T3 - Solution heat treated, cold worked, and naturally aged to a substantially stable condition.
      T4 - Solution heat treated, and naturally aged to a substantially stable condition.
      T5 - Cooled from an elevated temperature shaping process then artificially aged.
      T6 - Solution heat treated then artificially aged.
      T7 - Solution heat treated then and overaged/stabilized.
      T8 - Solution heat treated, cold worked, then artificially aged.
      T9 - Solution heat treated, artificially aged, then cold worked.
      T10 - Cooled from an elevated temperature shaping process, cold worked, then artificially aged.
      Additional digits may be used after the first T temper digit to indicate subsequent stress relieving by processes such as stretching, compressing, or a combination of the two.
      H Temper Strain Hardening Codes
      H1 - Strain hardened only
      H2 - Strain hardened and partially annealed
      H3 - Strain hardened and stabilized
      H4 - Strain hardened and lacquered or painted. This assumes that thermal affects from the coating process affect the strain hardening; not encountered often.
      The second digits (required) after the first H temper digit indicates the level of strain hardening and is based on the minimum ultimate tensile strength obtained. The third digit (optional) is a variation of the two digit temper.

      Also, see

      Modified by DHill at 10:43 AM 5-16-2007

      Modified by DHill at 10:45 AM 5-16-2007

    9. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      12-15-2005 04:25 PM #10
      Myths and Truths about TIG welding:

    10. 06-03-2006 05:12 PM #11
      Here is some more info about SAE and Metric fasteners:
      SAE Grade Classifications
      SAE Grade No 1
      Size range: 1/4 to 1-1/2 in
      Min Proof Strength: 33 kpsi
      Min Tensile Strength: 60 kpsi
      Min Yeild Strength: 36 kpsi
      Material: Low Carbon Steel
      Head Mark: None
      SAE Grade No 2
      Size range: 1/4 to 3/4 in
      Min Proof Strength: 55 kpsi
      Min Tensile Strength: 74 kpsi
      Min Yeild Strength: 57 kpsi
      Material: Medium Carbon Steel
      Head Mark: None
      Size range: 7/8 to 1-1/2 in
      Min Proof Strength: 33 kpsi
      Min Tensile Strength: 60 kpsi
      Min Yeild Strength: 36 kpsi
      Material: Low Carbon Steel
      Head Mark: None

      SAE Grade No 4
      Size range: 1/4 to 1-1/2 in
      Min Proof Strength: 65 kpsi
      Min Tensile Strength: 115 kpsi
      Min Yeild Strength: 100 kpsi
      Material: Medium Carbon Steel, Cold-drawn
      Head Mark: None
      SAE Grade No 5
      Size range: 1/4 to 1 in
      Min Proof Strength: 85 kpsi
      Min Tensile Strength: 120 kpsi
      Min Yeild Strength: 92 kpsi
      Material: Medium Carbon Steel, Quenched & Tempered
      Head Mark: 3 marks, equally spaced every 120°
      Size range: 1-1/8 to 1-1/2 in
      Min Proof Strength: 74 kpsi
      Min Tensile Strength: 105 kpsi
      Min Yeild Strength: 81 kpsi
      Material: Medium Carbon Steel, Quenched & Tempered
      Head Mark: 3 marks, equally spaced every 120°
      SAE Grade No 5.2
      Size range: 1/4 to 1 in
      Min Proof Strength: 85 kpsi
      Min Tensile Strength: 120 kpsi
      Min Yeild Strength: 92 kpsi
      Material: Low Carbon Martensite, Quenched & Tempered
      Head Mark: 3 marks, sequentially equally spaced at 60°
      SAE Grade No 7
      Size range: 1/4 to 1-1/2 in
      Min Proof Strength: 105 kpsi
      Min Tensile Strength: 133 kpsi
      Min Yeild Strength: 115 kpsi
      Material: Medium Carbon Alloy Steel, Quenched & Tempered
      Head Mark: 5 marks, equally spaced at 72°
      SAE Grade No 8
      Size range: 1/4 to 1-1/2 in
      Min Proof Strength: 120 kpsi
      Min Tensile Strength: 150 kpsi
      Min Yeild Strength: 130 kpsi
      Material: Medium Carbon Alloy Steel, Quenched & Tempered
      Head Mark: 6 marks, equally spaced at 60°
      SAE Grade No 8.2
      Size range: 1/4 to 1 in
      Min Proof Strength: 120 kpsi
      Min Tensile Strength: 150 kpsi
      Min Yeild Strength: 130 kpsi
      Material: Low Carbon Martensite, Quenched & Tempered
      Head Mark: 6 marks, sequentially equally spaced at 30°
      Selected SAE Sizes
      8-36 UNF
      Nom. Dia.: 0.1640 in
      Tensile Stress Area: 0.01474 sq. in.
      8-32 UNC
      Nom. Dia.: 0.1640 in
      Tensile Stress Area: 0.0140 sq. in.
      10-32 UNF
      Nom. Dia.: 0.1900 in
      Tensile Stress Area: 0.0200 sq. in.
      10-24 UNC
      Nom. Dia.: 0.1900 in
      Tensile Stress Area: 0.0175 sq. in.
      1/4-28 UNF
      Tensile Stress Area: 0.0364 sq. in.
      1/4-20 UNC
      Tensile Stress Area: 0.0318 sq. in.
      5/16-24 UNF
      Tensile Stress Area: 0.0580 sq. in.
      5/16-18 UNC
      Tensile Stress Area: 0.0524 sq. in.
      3/8-24 UNF
      Tensile Stress Area: 0.0878 sq. in.
      3/8-16 UNC
      Tensile Stress Area: 0.0775 sq. in.
      7/16-20 UNF
      Tensile Stress Area: 0.1187 sq. in.
      7/16-14 UNC
      Tensile Stress Area: 0.1063 sq. in.
      1/2-20 UNF
      Tensile Stress Area: 0.1599 sq. in.
      1/2-13 UNC
      Tensile Stress Area: 0.1419 sq. in.
      9/16-18 UNF
      Tensile Stress Area: 0.203 sq. in.
      9/16-12 UNC
      Tensile Stress Area: 0.182 sq. in.
      5/8-18 UNF
      Tensile Stress Area: 0.256 sq. in.
      5/8-11 UNC
      Tensile Stress Area: 0.226 sq. in.
      3/4-16 UNF
      Tensile Stress Area: 0.373 sq. in.
      3/4-10 UNC
      Tensile Stress Area: 0.334 sq. in.
      Metric Classifications
      Metric Class 4.6
      Size range: M5 to M36
      Min Proof Strength: 225 MPa
      Min Tensile Strength: 400 MPa
      Min Yeild Strength: 240 MPa
      Material: Low Carbon Steel
      Head Mark: 4.6
      Metric Class 4.8
      Size range: M1.6 to M16
      Min Proof Strength: 310 MPa
      Min Tensile Strength: 420 MPa
      Min Yeild Strength: 340 MPa
      Material: Low Carbon Steel
      Head Mark: 4.8
      Metric Class 5.8
      Size range: M5 to M24
      Min Proof Strength: 380 MPa
      Min Tensile Strength: 520 MPa
      Min Yeild Strength: 420 MPa
      Material: Low Carbon Steel
      Head Mark: 5.8
      Metric Class 8.8
      Size range: M16 to M36
      Min Proof Strength: 600 MPa
      Min Tensile Strength: 830 MPa
      Min Yeild Strength: 660 MPa
      Material: Medium Carbon Steel, Quenched & Tempered
      Head Mark: 8.8
      Metric Class 9.8
      Size range: M1.6 to M16
      Min Proof Strength: 650 MPa
      Min Tensile Strength: 900 MPa
      Min Yeild Strength: 720 MPa
      Material: Medium Carbon Steel, Quenched & Tempered
      Head Mark: 9.8
      Metric Class 10.9
      Size range: M5 to M36
      Min Proof Strength: 830 MPa
      Min Tensile Strength: 1040 MPa
      Min Yeild Strength: 940 MPa
      Material: Low Carbon Martensite, Quenched & Tempered
      Head Mark: 10.9
      Metric Class 12.9
      Size range: M1.6 to M36
      Min Proof Strength: 970 MPa
      Min Tensile Strength: 1220 MPa
      Min Yeild Strength: 1100 MPa
      Material: Alloy Steel, Quenched & Tempered
      Head Mark: 12.9
      Selected Metric Sizes
      Tensile Stress Area: 8.78 sq. mm
      Tensile Stress Area: 14.2 sq. mm
      Tensile Stress Area: 20.1 sq. mm
      Tensile Stress Area: 39.2 sq. mm
      Tensile Stress Area: 36.6 sq. mm
      Tensile Stress Area: 61.2 sq. mm
      Tensile Stress Area: 58.0 sq. mm
      Tensile Stress Area: 92.1 sq. mm
      Tensile Stress Area: 84.3 sq. mm
      Tensile Stress Area: 125 sq. mm
      Tensile Stress Area: 115 sq. mm
      Tensile Stress Area: 167 sq. mm
      Tensile Stress Area: 157 sq. mm
      Tensile Stress Area: 272 sq. mm
      Tensile Stress Area: 245 sq. mm
      Another useful bit of info is calculating the required torque to properly preload a fastener. This varies quite a bit for every application but a general guideline for non-permanent, lubricated fasteners (this applies to most automotive fab applications) is:
      For SAE fasteners:
      Torque (ft-lbs) = 12.5 x (Proof Strength in kpsi) x (Tensile Stress Area in square inches) x (Nominal Major Diameter in inches)
      Torque (in-lbs) = 150 x (Proof Strength in kpsi) x (Tensile Stress Area in square inches) x (Nominal Major Diameter in inches)

      For Metric Fasteners:
      Torque (N-m) = 0.00015 x (Proof Strength in MPa) x (Tensile Stress Area in square mm) x (Nominal Major Diameter in mm)
      Torque (N-cm) = 0.015 x (Proof Strength in MPa) x (Tensile Stress Area in square mm) x (Nominal Major Diameter in mm)

      Useful Conversions:
      1 ft-lb = 1.356 N-m
      1 N-m = 0.738 ft-lb
      1 ft-lb = 12 in-lbs
      1 N-m = 100 N-cm

    11. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      06-20-2006 10:00 AM #12
      Air Compressor INFO!!!
      In general:
      Belt drive > direct drive
      High CFM > low CFM (10 CFM and higher is good)
      220 V > 110 V
      low RPM > high RPM
      Dual stage > single stage
      Oiled > oiless
      Here's the price breakdown:
      $100 - $200: Low CFM, light duty, nailers only, maybe impact wrenches, fill tires, direct drive, oilless, 110 V
      $200 - $300: Medium CFM, nailers, impact wrenches, direct drive, some oiled, some not, 110 V
      $300 - $500: Medium to high CFM, nailers, impact wrenchs, maybe hammers or nibblers, some belt drive, 110/220 V, oilless or oiled
      $500 - $700: Approaching 10 CFM and up, most air tools, maybe sanders and sand blasting (pushing it), usually 220 V, 3-5 HP, belt drive, oiled, fast motors at 3450 RPM and compressor runs hot at 1200 RPM, usually single stage
      $700 and up: Greater than 10 CFM, any air tool, light duty sand blasting, 220V single phase and some 440 V 3 phase, single or dual stage belt drive, oiled, look for 5 HP, low RPM.
      I bought an Ingersoll Rand SS3L3 from about a year ago and have learned a lot about it. I can run a DA sander no problem with it - it keeps up just fine. Here are the specs:
      Quote, originally posted by IR SS3L3 Air Compressor »
      Ingersoll Rand Electric Stationary Air Compressor
      3 HP, 10.3 CFM At 135 PSI, 230 Volt, Model# SS3L3

      The inlet and outlet holes in the compressor pump are NPT fittings. I think the inlet is 1/4" NPT and the exhaust is 3/8" NPT. All the holes into the tank at 1/2" NPT with the exception of the drain valve, which is 1/4" NPT. The drain valve is useless - a weak stop-**** sh*tty thing that is completely inaccessible. I finally fixed that last week (6/8/2006).
      My review of the compressor is quoted at the bottom of this page (from Amazon).
      I am also in the process of making a web page devoted to the process of building and customizing my air compressor. You can see it here:
      As of this writing there isn't much there, but recently I upgraded the drain valve and bought a dryer and regulator. Some day I would like to add an intercooler with a pre-inlet condensor to catch most of the moisture before it goes into the tank. I will document it on that page.
      I'm drawing up plans for a sand blasting cabinet and I'm thinking my 3L3 won't take it. The 3L3 is rated at 3 HP, but this rating is peak HP. When running it is more like ~1.5. This is a typical rating system. The 3L3 is a 220V system and costs about $560. Its a good value for a stout home shop compressor. IR also makes the SS5L5 which is rated at a peak 5 HP and sells for ~$120 more.
      How much should I spend?
      My recommendation is that you buy as much as you can afford, because after you start using some tools you'll want to use more. It just happens that way - you get used to running the compressor and then you eventually start pushing its limits and then you wish you had a bigger one.
      Belt Drive or Direct Drive?
      Belt driven is better than direct driven. All of the ~30 gal 1-2 hp compressors from Sears are direct drive and very noisy. They will run any impact wrench, nail gun, or similar tool that does not require extended air flow, but you will see their limits the first time you try to use a grinder or sander or any continuous-running tool. My brother-in-law built a fence in his yard, and we set up all the posts and then used a nail gun to put up the boards, and his poor 30 gal. direct drive compresor was running all day as we were shooting a lot of nails.
      110V or 220V?
      Another thing to consider is your power consumption. 110V or 220V? I run my IR off my dryer outlet in my basement, but if you don't have a 220V outlet handy then it will change your requirements. I have seen a 2.5 hp 110V 60 gal. compressor, but only once and it was a brand I did not recognize. It was ~$400 and flowed about 8-9 CFM at 90 psi. I was ready to buy it but it sold. I'm glad I went for 220V instead. At 220V you will be drawing less current and the motor won't be working as hard as a 110V motor with the same power rating. I have read that the rule of thumb for HP on 220V motors is that it takes ~4 to 4.5 A of current for 1 HP, so if your 220V circuit is 30A you might get away with a 5 HP motor but if the load suddenly increases (such as during start up) you might flip breakers.
      What CFM do I want? How much power?
      Things to check are the motor and pump ratings. If it says 2 HP, is it a split-phase motor? Most motors, in order to prevent them from overloading your circuit, are split phase. When they start up the current draw is greatest, which corresponds to the peak HP. During continuous running the power is less, usually about half the peak rating. So an advertised 2HP is rarely that much - more like 1HP. Also, the CFM rating is usually biased - it is based on the displacement of the compressor. If you turn the crank on a compressor with the head off, you look at the bore and stroke and find that volume. Then, at a given RPM for the crank speed, that volume is filled, expelled, and replaced x many times per minute, and that is your CFM rating. This calculation is fine if you aren't actually compressing any air - but under compression the air heats up, the density decreases, and the CFM rating goes down. Depending on how efficient the system is (i.e., how hard is the motor working to run the compressor, how fast is the compressor running, etc.), the system can get very hot and your CFM rating starts to fall off. Thus a 11 CFM "free air" compressor will never put that out at 90 psi - it might be more like 8 CFM, maybe even less.
      Is efficiency really that much of a concern?
      In the case of the 30 gal. direct drive compressors, those motors are working hard to drive the tiny compressor, so they are not very efficient. Take your HP rating, divide by two. Take your peak CFM rating, and assume the actual rating is between %60-70 of that in the best case.
      My 3L3 runs really hot. The motor turns at 3450 RPM. The ratio of pulleys makes the compressor run at 1250 RPM. These are typical values but are on the high side. A better scenario is a motor running at 1200 RPM and the compressor running at a lazy 750 RPM. Instead of "WAAAHHHHHHH!" your compressor should be going "chuggachuggachuggachuggachugga..." and the head is only warm to the touch. You don't want it working too hard - find a unit with an oversized electric motor that isn't working too hard to drive the compressor. A quiet compressor chugging along will last a lot longer than a compressor designed barely within its limits.
      Where can I buy a compressor?
      Check out I plan on buying a new compressor (just the pump) from here and matching it to a true 5 HP motor if I can find one that will not trip my breakers. The prices here are very good and they guy runs a good business.
      I bought my IR from Northern Tool. Shipping was free and it arrived without too much trouble. Sears now carries IR compressors so one might be able to find them there too. In addition to the SS5L5 and SS3L3 models, IR makes a beefier Type 30 series that is more heavy duty and is just over $1k.

      Quote, originally posted by Review of IR SS3L3 Compressor »
      This is the first air compressor that I have ever owned, so it was a learning experience from the start.
      It is recommended that you purchase the IR SS3L3 startup kit as the compressor is delivered to you without any oil in it. In some cases the warranty is not valid unless you have purchased the startup kit.
      One thing I immediately noticed was that the pressure switch was flimsy. When I plugged in the compressor to test it out, I found that the motor continued to run even as the gauge on the tank passed 130 psi. As it creeped closer to 135 psi (the limit printed on the tank), I pulled the plug. I ordered a new switch from Ingersoll Rand for ~ $35 and this fixed the problem. Perhaps I could have made a warranty claim, but it was easier to order the switch as there is an authorized IR dealer nearby and I had the switch within 2 days.
      I ran the compressor off and on for several months without any major issues. I used it for several things... a little bit of die grinding, I rotated the tires on my car using the impact wrench and air ratchet, I used it to blow dust off my work bench and check the air in my tires on a routine basis. I bought the compressor because I have several project cars, and I would like to begin the serious work of restoring them. Recently, I have been looking at plans for a sandblasting cabinet, and I am starting to doubt that this compressor will stand up to the task of sand blasting for extended periods. Things I have learned about the compressor since its purchase that have led me to this conclusion:
      1. This unit uses a 3 HP "split phase" motor, which can be run on a standard 30A 230V household outlet - it draws about 15A during continuous duty. (I swap between my compressor and my dryer on the only 230V outlet in my house). The motor does not output a true 3 HP at all times. At startup the motor may approach its 3 peak horsepower, but during normal operation it may only be outputting half that power, so in truth it is essentially a 1.5 HP motor. This borderline false advertising is similar to peak and RMS power ratings in audio amplifiers, though it is fairly standard operating procedure to rate motors in this fashion.
      2. The motor runs at 3450 RPM. Though it is quieter than a direct drive unit like the 30 gallon compressors sold at most hardware stores, 3450 RPM is still quite fast. With the pulley ratios, the compressor crank spins at 1200 RPM. Heavier duty systems might have the AC motor running at 1200-1750 RPM with the compressor running at ~700 RPM or less, resulting in a much quieter setup. If I could do it over, I would consider a slower, beefier unit with a true power rating that runs at a slower, more quiet speed.
      3. There is apparently no available rebuild kit for the compressor itself, according to the local IR dealer, though they do sell gaskets and the oiling kit. It is a very simple design, consisting of essentially three parts; a cylinder head, cylinder block, and crankcase. It is a two cylinder, single stage compressor. The "valves" in the head are what I believe are called "reed valves", which are simply spring loaded "fingers" that cover holes in the cylinder head, and they move with the blowing/sucking of air as the pistons move in the cylinders (no mechanical actuation of the valves). The pistons are aluminum, and though I measured, I don't remember the diameter... something on the order of 60 mm. The rods are also aluminum, and there are no rod bearings. The crankshaft is cast iron machined at the journals, and the aluminum rods rotate on the crank without any rod bearings. The crankcase does not have a removeable oil pan, and the cylinder block bolts to the crankcase. I was somewhat disappointed to discover the absence of rod bearings and the use of aluminum rods.
      4. The compressor can run fairly hot, especially when pressurizing the tank from zero pressure. I would like to add an intercooler in line to the tank as the compressed air is quite hot, and I think the compressor itself could use some more cooling. I bought some copper to fab up a larger heat sink for the compressor housing, though I haven't made it yet. I think this will make the unit run much cooler, and therefore extend its life. The flywheel on the compressor is designed to move air over the unit, but I still think the design needs improvement.
      5. There is a flimsy drain valve in the bottom of the tank that is difficult to access. I have not yet installed a regulator and filter in the system, and I haven't checked how much condensation has collected in the tank. I would like to replace this drain valve, if possible, though I have been putting this off simply because I don't want to lay down on the floor and fiddle with it.
      6. I have made several trips to the hardware store to find the correct fittings to get the unit running properly, though most fittings were readily available. It seems to me that a lot of the fittings on the system are kind of cheap, though I am used to the Swagelok fittings that I use at work, which are expensive and well worth the price. Copper tubing is used to route compressed air from the compressor to the tank, and I think some improvements could be made there, as well.
      IR sells the SS5L5, which uses the same 60 gallon tank, but a 5 HP split phase 3450 RPM motor running a different two piston single stage compressor. For someone considering more power, this unit is still quite affordable, but it will still have some of the drawbacks of this system. It turns out that 5 HP is about the most one can get out of a 30A single phase 230V household circuit without flipping breakers.
      My biggest complaints are the use of the split phase motor, the relatively cheap design of the compressor (aluminum rods and lack of rod bearings), the flimsy pressure switch, and the cheap fittings used all over the machine. I will continue to use this unit for some time, but I am already considering either building my own low RPM, true 4-5 HP air compressor from various parts suppliers, or just purchasing a new one from a company like Eaton Compressor. Ingersoll Rand makes the Type 30 series which is a step above the SS series, and I have considered these units as well, but I would almost feel safer building the unit on my own so that I know exactly what is going into it.
      For someone that needs something better than the cheap 30 gallon direct drive units sold at most hardware stores, this unit is more than adequate. However, if you are considering something for medium-heavy duty, you might want to consider something with a little more quality, and therefore more cost. Like houses, I think good advice for someone looking to buy an air compressor is "buy the most you can afford". I for one like the idea of a compressor running at a quiet 750 RPM at a mere 73 dBa, as opposed to my high revving 1200 RPM SS3L3.
      And as a final note, I will say that IR has excellent customer support. With authorized IR dealers all over the country, getting parts (like gaskets, pressure switches, and oiling kits) is pretty painless.

      Modified by DHill at 9:00 AM 12-11-2007

    12. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      05-16-2007 12:06 PM #13
      AN and NPT Fittings
      AN" Thread Sizes
      AN sizes, originally developed for use by the U.S. Armed forces ("A" for army and "N" for navy), describe the outside diameter (O.D.) of tubing in 1/16-inch increments. For example, an AN 2 fitting will fit a tube with an O.D. of 2/16", or 1/8", while an AN 8 fitting will fit a tube with an O.D. of 8/16", or 1/2". Because the actual thickness of tube walls can vary from brand to brand, the inside diameter of a tube is not used as a reference. You will also find the dash (-) symbol or the word "dash" itself used in conjunction with AN sizes. A "dash six" fitting translates to AN-6. Each AN fitting has an established thread sizing. The following chart shows the relationship between AN size, tube O.D., and SAE thread size:
      "NPT" Thread Sizes
      NPT sizes (National Pipe Taper) are the most commonly used fitting sizes for general plumbing, piping, and tubing use; not quite as popular as AN for automotive use, but still very common. While AN fittings depend on the outside diameter of a tube for sizing, NPT fittings depend on the interior diameter (I.D.) of the fitting itself. The following chart shows the each size's thread-per-inch count, the I.D. of the fitting, and the AN fitting size with the closest-matching I.D.(inside dimension).

    13. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      08-16-2007 02:13 PM #14
      What Welder Should I Buy?
      The typical welder is DC, adequate for most steels, and operates on 110V power. Your basic MIG meets these requirements. The Hobart Handler 140, for instance, is a great basic MIG welder with about as much power as you can get with 110V.
      TIG Welders
      DC TIG
      Most TIG welders under $1000 are DC only. This means it is best for steel and will work on stainless. No aluminum. Options for DC only TIG welders include the Miller Maxstar, generic eBay solid state TIG welders/plasma cutter multi-machines, and the Lincoln Invertec V160. The latter can operate on 110V and might sell for $1300 new. Any TIG welder that is new and sells for less than $1300 is likely to be DC only. the more expensive Miller CST DC welders have more power but are hard to find for less than $1300 used. For that price, you can get AC too.
      AC TIG Welders
      Aluminum has a high conductivity and lower melting point than steel, and is also sensitive to the atmosphere while welding. Therefore, one must control the arc with aluminum to avoid excessive heat and subsequent burn through, melting, and oxidation. An AC TIG welder allows the operator to tune the polarity of the electrode and work piece. Current can then be tuned to spend more time on the work piece or more time on the electrode. This is accomplished by adjusting the duty cycle on the square wave for the welding power supply.
      Concerning the eBay generic welders (usually called CT####)... they are using solid state power supplies which are lightweight. Most of these TIG welders are DC and go for way cheap (< $700). They advertise them as plasma cutters as well which I assume means they have a high pressure regulator on the gas inlet, allowing you to run low pressure Ar/CO2 whatever for welding, then compressed air for plasma cutting. Presumably you need a different gun for plasma cutting (?) which I doubt they supply. Some new models have AC capability now and still sell for less than $800. These welders have no name recognition whatsoever so the information about them is limited.
      I had some email conversations with one of the eBay solid state welder sellers about a year ago. I learned a few things from him. The power supply is basically a huge transistor with a monster heat sink - nothing wrong with that as this is the typical way to trade heat for power. The fabrication of the electronics is subcontracted to Chinese factories. Most people will scoff at that. The only quality issue to worry about there is how the electronics are rated. They might take a transistor off the line, power it up, and see what the efficiency curve looks like. Some will be lower than others. This is all normal. But in the end, somebody has to decide how to rate that transistor. Tolerance might not be so good so you might get a transistor rated for lower power output, and they just compensate by putting a bigger fan and bigger heat sink on it. Nothing new - Compaq has been doing this for years. Your AMD Duron chip in your PC is really only as fast as the fan and heat sink allow.
      Recommended welders for home/shop use with AC capability
      $1000 - $1500
      Miller Econotig, Hobart Tigmate - same machine, sells for anywhere from $1350-1500 new. Cheapest new AC/DC Tig welder you can get. Options include foot control or finger tip control. Don't spend more than you have to - look around. Its not really worth buying a used one for more than ~$900 since a new one is only a few hundred bucks more. These machines would be adequate for making stainless exhaust manifolds or aluminum intake manifolds, methinks.
      Miller Syncrowave 180SD (used) - usually sells for about $1300 plus shipping. Less than that with all accessories is a good price.
      Lincoln Precision TIG 185 (used) - sells for about the same used.
      Miller Syncrowave 200SD, Lincoln Precision TIG 225 - new replacements for the 18x models. Expect new prices around $1800 and up, depending on accessories such as cart, foot pedal, etc. Used ones pop up occassionally for $1500-$1600.
      These have DC and AC capability, operate on 220V, and use big transformers with variable voltage and frequency output to control your arc. They are also frickin’ heavy, which means they are expensive to ship unless your seller has a good shipping deal. But these are great machines. A Syncrowave 180SD would be ideal for the home shop guy who has a serious hobby, I think.
      ESAB Heliarc 161 - these little solid state machines weigh 28 lbs. and sell for about $1900 new. These are a great bang for your buck. You will rarely find one used, sometimes a factory refurb will pop up. If you find one for less than $1900 new with included accessories, grab it!
      $2000 - $2500
      ThermalArc ArcMaster 185 - Beautiful machine, sells for about $2250 and good luck finding one used. Solid state. Weighs about 40 lbs.
      $2500 - up
      Miller Dynasty 200DX - sells for about $2650 new. If you find one for less than $2200 new, grab it. Solid state, ultra adjustable, lightweight.

    14. Member DHill's Avatar
      Join Date
      Jan 8th, 2002
      98 Jetta GLX (sold), 2012 Silverado, 2012 Honda CRV, 61 Impala
      08-21-2007 03:31 PM #15
      What materials to use for my custom exhaust headers?
      A few major issues with exhaust design considerations are high temperature service, corrosion, cost, and weight.
      Cast iron works great because its cheap and can be cast in sufficient thickness so that generalized corrosion is never a worry. But it's heavy and doesn't keep the heat required for some applications. Most of the time cast iron is adequate, as can be seen by the success of the Kinetic Motorsports or the ATP cast iron exhaust manifolds for the 12v VR6, or any OEM exhaust system for that matter.
      Stainless steel is great because less material can be used, so there is a small weight savings. However, stainless steel is expensive which is why it's rarely seen on OEM exhaust systems. In addition, some stainless steels are subject to sensitization, or embrittlement of the metal due to high temperature service (typically above ~425 deg C).
      Sensitization, more succinctly, is related to the breakdown of the chrome-oxide layer on the stainless steel which is what makes it "stainless" in the fist place. Without the Cr, the oxide layer cannot form and the steel in that area is just like any other steel - susceptible to corrosion. Therefore, when austenitic stainless steels such as the 300 series are heated and held above 425 C for some time, the Cr in the steel combines with the carbon and forms chrome carbides, especially at the grain boundaries in the metal. Since the Cr is now bound up with C, the areas around the chrome carbide precipitates are depleted in Cr (it had to come from somewhere...). As a result, the stainless steel corrodes rapidly in these Cr-depleted regions while the rest of it is fine, and this results in cracking and eventual failure after extended thermal cycling and/or mechanical loading. Thus, sensitization is a bad thing.
      How do you combat sensitization? You put other stuff in the steel, such as titanium (Ti) or niobium (Nb) and even nitrogen (N) to stabilze both Cr and C to prevent the formation of chrome carbides. You also limit the C content. Steels with an "L" designation (3xxL) indicate a carbon content of 0.03% by weight or less.
      Finally, since sensitization is a thermal issue, welding stainless steels can lead to Cr depletion in the heat affected zone (HAZ). Thus it is encouraged that the heat be concentrated at the weld with a minimal HAZ. Rapid cooling after the weld will reduce the time at high temperature and thus limit formation of Cr carbides. In the worst case scenario, the entire piece can be solutionized (heated and held) above 1035 C followed by quenching (cooled rapidly, such as via dropping in water). Heating to 1035 C gives the carbides plenty of thermal energy to diffuse and dissociate into the matrix, and cooling rapdily prevents them from having enough time to reform.
      In general, the best steels for exhaust headers are listed below, from highest preference to lowest preference. Incidentally, this order also corresponds to cost.
      1. 321 and 347 stainless steel - used for applications where heat must be contained in the header, such as turbo applications or tight engine compartments like Indy cars
      2. 316L - highly corrosion resistant because of Cr, Ni, and Mo. Has low C (0.03%) and resists sensitization a bit more than 304. Stainless steels will pit in chloride rich environments (pitting is accelerated, localized corrosion starting with micron-sized defects that grow into bigger problems) and are more susceptible at even higher temperatures. However, 316L resists this moreso than other alloys and thus 316L is the material of choice for marine exhaust systems.
      3. 304L - again, low C content (0.03) is good for resistance to sensitization. Common for NA exhaust header applications. Cheaper than the rest. Corrosion resistance is mostly due to Cr and a little bit of Ni but no other fancy elements.
      4. 304 = only difference from 304L is 0.08 C content. It is therefore more subject to sensitization than the other metals.

      321 = 0.08 C, 2.0 Mn, 1.0 Si, 17.0-19.0 Cr, 9.0-12.0 Ni, 0.045 P, 0.03 S, 0.4% Ti (minimum 5 times the C content to stabilize Cr-C precipitates).
      347 = 0.08 C, 2.0 Mn, 1.0 Si, 17.0-19.0 Cr, 9.0-13.0 Cr, 0.045 P, 0.03 S, 0.8 Nb (minimum 10 times the C content to stabilize Cr-C precipitates).
      316 = 0.08 C, 2.0 Mn, 1.0 Si, 16.0-18.0 Cr, 10.0-14.0 Ni, 0.045 P, 0.03 S, 2.0-3.0 Mo (316L is the same except it has 0.03 C)
      304 = 0.08 C, 2.0 Mn, 1.00 Si, 18.0-20.0 Cr, 8.0-10.5 Ni, 0.045 P, 0.03 S (304L is same but with 0.03 C).

      More details can be found at Burns Stainless or in Metals Handbook published by ASM International.

    15. Member kimosullivan's Avatar
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      Aug 12th, 2002
      Las Cruces, NM
      '10 Eos Komfort, '96 GTI 2.0, '70 Ghia vert
      08-22-2008 10:17 PM #17
      Quote, originally posted by cnbrown &raquo;
      Duty cycles are only rated at the machine fully cranked(heat setting at max). Although I think 220v machines are the answer(do NOT buy a 110v tig), a "big" 110v mig is an excellent beginner friendly machine that will be capable of quite a bit(especially automotive).

      More about welder duty cycles since it has come up recently in another post:
      Duty cycle is a measure of how much welding the machine can do versus how much time it needs to spend cooling down. It is rated on a ten (10) minute period. That is a machine with a 60% duty cycle (at a given power output level) can have the arc on for six minutes at a time and then must cool down for 4 minutes. Most machines will have a temperature sensor in the transformer to prevent melt down.
      Duty cycle varies with power output. The hotter you run the arc, the faster the transformer heats up, and the longer it needs to cool. A "professional" level machine should have 60% duty cycle at it's nominal output. For example, a Powcon 300ST (yes, I know it's an auld skool reference) has 60% duty cycle at 300 amps.
      "Hobbiest" or "amateur" machines will often have the same nominal and maximum power output. It makes it sound bigger. For example, the Miller Maxstar 150S, has 30% at 150A, and 100% at 100A.
      The data plate by the power cord on the back of the case should show this information. It will generally list the duty cycle at maximum output (as low as 20% depending on the machine) and the current/voltage for 100% duty cycle. Dual voltage (120/230V) may list this for each input voltage.
      Engine driven welders should have 100% duty cycle, since when the arc is off, you're probably using some other power tools plugged into the generator outlets.
      Unless you are a highly experienced fabricator with a helper (or a robot), you probably cannot weld more than 6 minutes out of 10. Additionally, autobody and exhaust work will not use the maximum power of most machines. Manifolds and frames may require you to pause if you get the smallest of 230V machines.
      I do not recommend any 120V machines. I also warn against less than a "180". You will eventually want to do bigger projects than these sizes of welders can handle.

    16. 12-11-2008 04:39 PM #18 has all the things you need, including their fasteners page, which is hard to find, so here is the direct link:

    17. Member Bearvr6's Avatar
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      96 Golf 4dr Vr6, 88 GLI Vr6,MK4 GTI 24V & B5.5 Wagon AWD
      11-30-2009 06:16 PM #19
      IM'd you about this, im trying to find a post or put up one about conversion on a Mk4 dash into a mk3 ive seen it in cars lots of time but cant find a post on it so i can get some info or help. If you or any one can help me that would be great, cause i dont wanna start cutting and making mistakes to have to do it all over again! [IMG]http://**********************/smile/emthup.gif[/IMG]

    18. Member VR6ix's Avatar
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      Woodsticks, Onterrible, Eh.
      My other VW is a WVW-W TDI, and the other one is a Vento
      10-27-2010 09:59 AM #20
      I use this stuff all the time at work:

      Tapping and Clearance Hole Table:

      Hardware Giants:

    19. Member GTijoejoe's Avatar
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      Oct 6th, 2001
      '06 Evo Mr, '13 CBR500r, '14 Accord 4dr, '15 Civic Si
      12-17-2011 05:46 PM #21
      I think we should add to the supplier list, I use them many times, decent prices excellent fast shipping.
      2.0T+034efi+meth = 300+whp = Part out PM me for anything

    20. Member bmxdarcy's Avatar
      Join Date
      Mar 7th, 2006
      Hotel Hopper
      '96 GTI, '03 TDI, DeluxeBMX
      06-24-2013 12:16 PM #22
      I have a few suppliers I like as well

      Abrasives Pretty reasonable prices and a few different warehouses. Any issues they've been very speedy about correcting.

      Exhaust Fab Weld els and Stainless Tubing
      Colombia River Mandrel Bends Some of these are "crushed" from the clamp in their bender, but it's the ultimate for selection. They have different radii and 1D on many sizes. Great prices if you buy enough, the shipping can be expensive, however. These guys have some pre-bent complete exhaust systems for mk2s and mk3s. The prices are awesome, haven't put one together yet but I have one I'm going to try here soon.

      Burns is awesome for some of your more exotic designs, tapered horns, Inconel and the like. Otherwise I feel like the prices are way too high.

      Plumbing Very easy to search catalog of AN plumbing
      Last edited by bmxdarcy; 06-24-2013 at 12:22 PM.

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