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The complete guide on casting parts

388K views 692 replies 112 participants last post by  Brian.G. 
#1 ·
Vw parts of course!
Said Id throw this up for the craic, some of you may be interested in the process so I might as well share given the fact that I took pics of the progress and build as I went.
First off, this line of work is next near impossible get info on so alot of it I had to design up myself and choose the suitable materials too along the way.
Casting is now a dying trade and fully automated around the world in controlled environments.
While Im sure nobody will go to the trouble I have here it may rise some interest as to whats involved, the process, materials, procedures, mould making, melting, design, etc.
I had to do this to figure out a few things I needed to know for my bigger smelter Ill be using to melt the alloy for the cylinder head Im designing.
Using this smaller smelter less heat up times, gas, and raw materials can be used in order to get the feel for molten alloy in general.
Plus, its a bit easier than winding up my bigger smelter which can melt approx 9litres of alloy at a time, where as this one can do 1.25 litres.
Im going to be using this to make a few parts I have in mind for a while, DTH throttle bodies and a few trick intake manifolds being just some of the stuff.
Casting is a pretty simple process, but the finished item all depends on the quality of the mould the metal is poured into.
The main mould types ill be using will be of the sand variety, meaning, you make your pattern part you want in timber(Iroko) and you then strike both your sand mould halves off this pattern. The part shape is then formed in the sand and you can pour in your alloy, that way, ending up with the timber pattern shape, just thats its now alloy.
Its a bit more complex than that but Ill try my best to explain all as I go.
Pattern making is what Im good at as my main ''skill'' is cabinetmaking so making very complex accurate pattern parts is not a problem.

Its important to note that this is not the cylinder head thread, this will be covered in another thread on Club Gti
Ok, so onto the first step of a long road, and that is the smelter itself.
A smelter is basically just a round oven where the crucible is placed in order to melt the charge inside it.
The smelter must be well insulated as the heat inside is in excess of 700 degrees.
The smelter is powered by plan ordinary gas you get for your cooker.
Its all pretty basic, now onto the build...
For the body of the smelter something round is needed, you could use a large diameter pipe but I used a gas cylinder, the walls are 3mm steel and there tough by nature.
I filled it with water to expel any gas still left inside.

Next up, off comes the top with my favourite tool[LOL]


A second ring is then cut off the main body to for a locating ring for lid.

The ring is then split and welded to lid around the outside.

The lid now fits snug back onto main body again.

The lid is turned over and I welded some wire lattice in there to hold in the refractory material a bit better.

The refractory mix consists of,
Perlite
Cement
Sand
Fireclay
Perlite is a natural volcanic material, it is a natural insulator.
Cement is standard cement.
Sand is normal sharp sand.
Fireclay is the cement fire bricks are made from, kinda like normal cement but with a better heat resistance tolerance.

Mixed up

First the base is poured, approx 80mm high.

Then, I wrapped up a bit of Formica to form the inner circle.

Pouring the walls.

Done and tamped.

Onto the lid
A bit of pipe is placed into where the valve was in order to form a vent hole up through the lining. The pipe is removed when lining is set.

Thats the smelter pretty much done now, so next up, onto the crucible.
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The crucible is the cup used to place the metal in that is to be melted.
This is used from start to finish, that is, the raw unmelted alloy is placed in this and stays in here until it melts, the crucible is then removed from the smelter and the alloy poured from it directly into the mould.
So, the material needed for the crucible has to be picked with care, depending on what you are melting, what the part is for, and what properties the finished part has to have all reflect on the crucible material choice.
If poor crucible materials are used some material from the crucible walls can leech out into the molten alloy and effect the alloys properties.
In this case Ill be using stainless steel >316. Its ok for small parts and doesent really have any bad quality's that will effect the final part.
However for the cylinder head, I will be using a pure graphite crucible, graphite poses no threat on the final part qualities, be it strength, structure, or machinable properties.
Obviously On such parts as throttle body's, intakes, and the like, the final properties can afford to be altered a tiny bit as there is no work on these parts as such, and machining of parts is minimal, so, stainless is a perfect choice for crucible material.

The Crucible manufacture.
I got a bit of pipe approx 250mm long with a wall thickness of 5mm, to this I welded a base plate in 6mm.
Rods used are also 316 s/s.

Next, a 'V' is cut for spout

The spout is constructed from two pieces cut to triangle shapes


Spout tacked in place

Finish weld



Next, a ring is needed at the rear in order to tilt vessel in order to pour alloy

Pins are welded to the sides to catch crucible with the pouring tongs



I gave the whole thing a quick sandblast after to remove any oxides or ****.


Sandblasting really works in lifting any dirt or general dirt, a close up of one weld shows surface finish.

It may appear an over kill looking at the scale of the plate thickness, welding, ring, spout, sizes etc, but keep in mind this isent a milk jug and has to with stand very tough conditions for may cycles.

Thats the crucible done, next up the burner tube.
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#152 ·
Re: (turbinepowered)

Quote, originally posted by turbinepowered »
Are you at all worried about porosity of the castings?

Im not really to be honest, the degassing operation when melting reduces not only hydrogen but oxides as well, that coupled with good stout risers, sprues, and vents help a lot. On bigger castings more precautions have to be taken but on small stuff its really not an issue. So far when machining I haven't come on any pits, pores, or voids so so far so good. I did come on a few when cutting up the alloy block mind you, small bubbles, maybe 1mm in diameter here and there. I dont know if this answers your question?
From what Ive seen with my own from working them, drilling/tapping/cutting/milling, they dont differ from oem castings at this point.
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@ Quintin@USRT, you picked a bad time to start reading

@ frechem, no mis-haps or failures as yet, so I aint hiding anything, it would be pretty easy spot if I did though as a new part would differ slightly from one if I did screw up due to the uniqueness of each part. If something does go wrong for whatever reason Ill post that up too, I believe mistakes are great teachers, so Ill share as with the rest of the stuff http://****************.com/smile/emthup.gif
More later this eve,
Brian.
 
#153 ·
I cut the flange bit off a spare pump case to get a better idea of where the inlet and outlets need to be>


Rotors fitted, inlet/outlet shape is very clear>


Bit too close of a close-up...


Inlet drilled to 16mm, it meets the first drilling below it>

Bit of porting with the 12mm carbide ball, handcleaner works good to stop it clogging, or wd40 if its a small job like this>


Poor picture...

Quick check>

Drilling the outlet, 12mm hole fitted here, Ill be opening it up to scribed line>

Ported it, and moved to the dremel to get into the corners>

Like so! >

Top view, bit of fettling to do yet but almost done on this one, the other one (cast section) will be the very same. Picture of the tap there too, for the fittings>

Brian.
 
#154 ·
FV-QR

http://****************.com/smile/emthup.gif
I may have missed this, but how are you going to seal up the brass throttle plate in the aluminium housing? Is the PTFE strip good enough or is there something else? I've always wondered about this aspect of slide throttles tbh.
 
#155 ·
Re: FV-QR (MikkiJayne)

Quote, originally posted by MikkiJayne »
http://****************.com/smile/emthup.gif
I may have missed this, but how are you going to seal up the brass throttle plate in the aluminium housing? Is the PTFE strip good enough or is there something else? I've always wondered about this aspect of slide throttles tbh.


Yup, ptfe is bonded to underside of throttle plate, and that sides in tracks, and has a nice bit of pressure on it too at idle to help it seal. Air will have to take a long route to actually get past it if you know what I mean. By which time the engine will need more air at that stage anyway. I do expect a bit to go by but Im hoping and wont stop until I see a 900-1000(cam) idle speed. Looking at how its all fitting I dont see any problems, I hope

Moar!>
Got the second one done(ported) the same as the first>

Tapped the inlets/outlets>

The cast taps real good>



All pinned for a quick look at things>

Drilling holes to 8mm and counter-boring the lower hole>





Time to dowel them together for boring the mainshaft pilot hole, Ill be reaming this, and also cutting a large counter-bore in the first section for bearings and oil seal,
The spring pins>
These are spring steel and almost impossible to cut up in this state, so a quick run with the blow torch to red and let cool naturally anneals it back to semi soft again, making it easy cut.


Counter-bored the 8mm holes to 10mm for the dowels/positioners

Heated the cut pieces again to cherry red and quenched them in water, this makes them attain there 'spring' again,

Tapped in,

Section placed on,

Sharp tap,

Two more tapped in,

You can see how they now locate casing,

Another intact casing tapped onto them, and an oil oil pump drive spindle...

Ball bearing held into factory centre drilled hole with some grease, fitted spindle down into casing(its the fit for hole!) as above and gave it a tap, the ball left an indent where the shaft centre will now have to be drilled, tomorrow hopefully...


Brian
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#157 ·
Thanks for the shot of the router table, I was always trying to slid the vice in my vertical drill press - what a pain. I have a router table - but it would be hard to do what your doing. Your way makes allot more since with a router. I was thinking the router was stationary like my table.
Guess what tool I'm building next.
About how big & thick is the Plexiglas.

So simple
 
#158 ·
Re: (RRSB_1971)

Quote, originally posted by RRSB_1971 »
Thanks for the shot of the router table, I was always trying to slid the vice in my vertical drill press - what a pain. I have a router table - but it would be hard to do what your doing. Your way makes allot more since with a router. I was thinking the router was stationary like my table.
Guess what tool I'm building next.
About how big & thick is the Plexiglas.

So simple

Ah its about 14mm I think, around 5/8 approx. Its tufnol too. I find it the best way to do stuff like this, make sure your two sleighs/battens are exact your leaving it down on and away you go, you can even screw a batten to the plastic and run it off sleighs to give you parallel machining, a mill would do this in a second and I should prob really use mine instead, but I get a kick outa doing it this way
Alloy cuts like cheese
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Boring update...>
Got the main shaft holes bored...
Pilot drilling,

Reaming,


You can see the finish the reamer leaves,

Compared to the drill bit...

Stacked to check clearances,

Checked holes for squareness in respect to shaft and rotors using a small bit of lapping paste between rotor and section, its a very fine grinding paste much like valve grinding paste used for jobs like these, a couple of turns of the rotor highlights a circle an etched and that it is indeed square/ok,

Did this with all sections,

The oil grooves milled to oil rotor/section interface, also done on the two section,

And the oil drilling from outlet to end hole where the shaft spins, I thought this was the best place to tap it from as the pipe up to tank will always be full of oil even after shutdown so the bearing should always be wet even if the car is sitting for a while, again, also done on the centre section. The same pipe up will also seal the rotors with this same back feed/head pressure so they'll never run dry or not pump on startup. There will always be a small amount of oil in the pipe to run back and keep things wet.

Stacked and all spins free.

Ive to cut two more oil grooves yet, and also drill out the end section for the bearings/oil seals. I can then lock the rotors to shaft, bolt the lot together and machine the base where it sits onto the mounting bracket.
Getting there slowly...
Brian.
http://****************.com/smile/emthup.gif
 
#159 ·
Well its nice to have this place back!! You may have noticed I changed my profile name at this time also. I prefer it this way from now on as it is my 'real' name after all. Nothing has changed otherwise. I have the change noted in my profile also. This does mean Im back to 0 on the post count but that doesn't bother me a bit.

More stuff>

Scored these on ebay last week, I got them for around 2.50each, cheaper than hydraulic fittings at the time on there! They're m18x1.5 one end, and an -8 the other. There also alloy, anodized black.







Screwed in temporary, Ive to face off the cast yet under hex portion on fitting...







I had an insane job trying to find bearings with a 14mm bore but I got them in the end, these are open and not shielded as I intend oiling them from the pump itself, that also means that they need an oil seal, like your crank/cam oil seals so I had to get them too, funny enough, I had no bother finding oil seals for a 14mm shaft...







These have to be fitted/pressed into a counter-bore of course in the section itself. If I had the skimmer finished the boring set would be ideal for this job, but I haven't it finished yet so I had to come up with another plan to keep things moving, so here it is>

One old oil pump shaft, remember this is also 14mm,



Rotor driven off/removed,



You can see its a bit bigger in diameter than the rotor...



I cut off all but one tooth...



Grinding to cutter profile,



With shaft inserted and bearing dropped on I can see were my ballpark cutter diameter needs to be,



Checked and finished with the diamond hone, Im pretty used of making cutters for the spindle moulder so it was pretty quick grinding this,





With the oil shaft cut at the waisted section I can now mount it in the drill stand, drove on the rotor again,



Test, fits snug, and it should too! (reamed)



One turn by hand to check cutting angles are ok,



Mounted in the stand, went down approx 1mm to check diameter, I need it a bit smaller than bearing for a press fit, it actually came out at 25.750mm(I think)



Boring,



I got It bored to my depth but the memory card was full, I now need to counter bore the top section of hole for the oil seal, much the same plan as above.
 
#160 ·
Time for the oil seal counter-bore, the diameter of this was bigger than the rotors so I couldnt use them as a cutter, so I made a basic fly cutter using the same oil pump shaft/spindle as I did when boring the bearing housing,

Tapping shaft,



12.9 m8 bolt threads in, tip ground to cutter profile,











Bored,



Tip reground to form a lip at bottom of hole to provide seal there too as oil seal counterbore just hits m8 allen head counter-bore,



Done,



Snug press fit,



And the final bore on the bearing counter-bore to provide pressfit,



Brian.G
 
#162 ·
The HUGE problem with this thread, is that the more I see, the more things I can think of to make, and the fact that all your stuff is being made without expensive or complex equipment just makes it worse! Do you not know I have enough to do without giving me evil ideas?

Very inconsiderate......
 
#169 · (Edited)
Secondgen
Im going to anodise to protect a little more yes. Heat treating is no good once the part sees more than 130 degrees c for a period of time, which this will internally(It should anyway after a hard rip)

Turbinepowered, Im not sure, I always hated alloy sumps for breakage reasons, since this will be up a little more and the fact all my Mk2s always run standard ride height I may cast it, but Im not sure, I originally thought of making it from 316 stainless, no rock would crack or go through that. I need to decide on that one yet.

MikkiJayne, its pretty basic stuff really, I think? Maybe its not, I cant tell whats 'normal stuff to be at' anymore...

Moar>

FINALLY got the bolts i wanted(got 4), I could have used threaded bar, but its a bit agricultural i feel. These are tidier but a bit harder got than I had expected...



They fit the counterbores fairly snug,





They end just flush at rear of pump. I could have tapped end section but Im going to sink a steel nut in there instead, doing it this way made boring the sections easier as they were all done in one drilling operation.



Counterbored>



Nut points marked>







Dremel





In,





Mocked it up to see if it all lines with shaft inserted, thankfully it does spin free with bearing pressed in also and everything in place,







And on its side showing the bases of sections where I can now mill them flat the fact its all bolted together, the pulleys Im using are off an AHW 1.4 16v engine, the bigger sprocket is off the camshaft, and the smaller the crank pulley, I reamed the bigger one to 14mm so All I need do is lock it on there. Ive to groove shaft for a circlip between bearings, and also lock rotors to shaft, drill one more oil way, mill and tap the base for mounting to bracket, clean them all up do a final assemble, strip them all again and I think Im going to clear anodise all parts to save them a bit. Not too bad really, sounds a lot, but its handy enough.
I also have to make up two shoulders on the crank pulley to keep belt on there.




Updates regular again now that Ive all the bits I need for the next few weeks,

Brian.
 
#170 ·
I will hazard a guess that you have some way of anodising the parts at home that will be equally impressive as everything else you have done so far?

(and no, to 99.9999999% of people including, I suspect, most of us on here what you are able to do with limited tools and resources is not "normal" - its verging on black magic! :D)
 
#171 ·
Unfortunately, cast aluminium doesn't anodize very well, it has something to do with the crystalline structure of the metal and the other elements that are alloyed into the aluminium to improve it's casting properties such as fluidity etc.

But you're right about Brian, his resourcefulness and skills do border on freakish. However, I do understand what he's talking about when he says he's not sure what normal stuff is. I'm always amazed at the whole world of possibilities that open up when you learn a new skill, like casting or welding, what once seemed freakish suddenly becomes doable and after a little practice, seems normal.
 
#172 · (Edited)
I put in the last two pictures above that I somehow forgot yesterday...

@MikkiJayne, yes Ill be anodising them here of course!!!!! Point taken on the 'normal' stuff!!

@ABA Scirocco, Lm25 anodises just fine and its the 2nd best casting alloy to do so with(I verified this to be sure with a few guys in Hong Kong as I was unsure). The problem lies on if you try dye it after you anodise, it dyes patchy and speckled because of the silicon. But That wont bother me, because Ill just be clear anodising, which I believe leaves it more or less the same stone/sliver/grey colour. I wont know until I do it on a test bit first though.
I still feel though that there is no need to treat these for wear issues but I will all the same for external protection if nothing else. Lm25 has a good bit of silicon for its great antiwear properties as is.
I cant agree with you more on the above, once you start doing stuff you cant stop.......building an entire engine seems very possible at the minute to be honest, pistons, rods, block the works...hmmmmmm...I may need to cheat and use the bridgeport for some parts but its very doable I feel.
 
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