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Castings

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AdrianR09/03/2019 12:28:31
49 forum posts

I don't have a specific project in mind, but I am wondering about castings. How much they cost, and how the price compares to the kit suppliers.

I understand pattern making is a real art and no doubt expensive to pay for, so assume I make my own patterns.

Iron would be my first choice, but I have also been considering Aluminium.

Anyone had castings made?

JasonB09/03/2019 13:09:24
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It's a bit like how long is a piece of string, cost of a small 3£ flywheel casting maybe £10-12, 6" scale traction engine cylinder £900.

If you are getting your own done then some foundries will charge per job, others by weight of finished casting with rates for each material.

It would cost a lot to have someone make traditional patterns, may be cheaper if they can be 3D printed provided you can do teh CAD, again really depends on the specific part. I have all teh woodworking machines so happy to make traditional but now I have the CNC mill may also us ethat for curvy work.

Edited By JasonB on 09/03/2019 13:12:08

Brian H09/03/2019 15:21:30
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1040 forum posts
83 photos

Hello Adrian, as Jason says, difficult to price without knowing exactly what you want.

You could have a look at the prices of castings on suppliers websites e.g. Reeves, Blackgates and Polly Models, That will give you some idea.

Don't dismiss making your own patterns although It would pay you to find a foundry to see what they advise on draught angles and cores.

Many foundries carry standard cores which saves making your own coreboxes and will also advise on materials.

Some years ago I made these patterns;

patterns.jpg

They were for a 3" traction engine and were made from MDF and wood from a DIY shop.They were painted with cans of car paint and caused much comment at the foundry because most patterns are just varnished rather than being finished in the correct colours.

The fillets were produced using car body filler and a ball bearing glued onto a piece of tube.

The cores prints were sized to suit their standard cores, at their suggestion and they were mostly cast in a cast iron alloy called Mehanite because some items would need iron rivets hammering in and Meehanite is less brittle that normal C.I.

Hope that helps,

Brian

Edited By Brian H on 09/03/2019 15:25:58

geoff walker 109/03/2019 15:23:12
274 forum posts
116 photos

Hi Adrian,

It's true what you say pattern making is a real art and very complex patterns are best left to the experts.

However simple pattern making is not that difficult but having said that you would need reasonably good woodworking skills and equipment. That is assuming you make them from wood with mahogany being a good choice for most patterns.

I would suggest you do some basic reading on sand casting and pattern making. An old school metalwork book would be a good choice, explains the processes but in a simple straightforward way.

If you do decide on a project do some simple sketches of your idea, post them on here a see what response you get. I've done a lot of pattern making so providing I don't miss your post I certainly will respond.

Good luck Geoff

Chris Evans 609/03/2019 16:02:28
1359 forum posts

I get a few castings done mainly for my old motorcycles. A couple of years ago I made a new cross slide for my lathe. This was just a simple polystyrene pattern burnt out of the sandbox prior to pouring the iron and ideal for a one off. Most times though it is simple wooden patterns, just make sure you have around 3 degrees of draft taper to get them out of the sand. Good foundries here in the West Midlands for iron and aluminium.

AdrianR09/03/2019 16:51:59
49 forum posts

I did a bit of lead and Aluminium sand casting when I was a teenager. So I know the very basics, enough to know I don't know enough.

I built my boy a furnace and he got into it more than I did. He did brass too, then tried for Iron and melted the refractory. I might try and get it off my ex wife and resurrect it.

I have been reading back issues of MEW and some very old books. These mention casting suppliers that have long since gone.

It does sound like it may just be cheaper to buy stock CI and cut most of it away.

JasonB09/03/2019 17:09:03
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The last ones that were cast from my patterns did not work out any cheaper than buying CI bar, just saved time machining away metal.

Got some in the summer from someone else's patterns and the foundry they used was charging £10kg for iron which may give you a ball park figure, the run was for a few hundread Kg though they were not the best of castings.

Peter Tucker09/03/2019 17:48:29
174 forum posts

Hi Adrian,

If you are going to make the patterns you may as well go the hole hog and do the casting yourself.

Peter.

Emgee09/03/2019 18:32:03
1040 forum posts
197 photos

It's a big jump from making your patterns to casting same in iron, best IMO to use a foundry.

Emgee

Andrew Tinsley09/03/2019 19:42:56
833 forum posts

I didn't know there were standard colours for patterns. Where do I find the details please?

Andrew.

JasonB09/03/2019 19:45:21
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14864 forum posts
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You could start by putting "Foundry pattern colours" into Google.

Brian Oldford09/03/2019 19:51:14
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465 forum posts
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Posted by Andrew Tinsley on 09/03/2019 19:42:56:

I didn't know there were standard colours for patterns. Where do I find the details please?

Andrew.

When patterns were predominately wood most pattern-shops used: -

Red - As cast

Yellow - To be machined

Black - Core-prints

Green - Chilled

Although some hobbyists would find automotive rattle-can finishes satisfactory a pattern that is needing to be used many times over is best coated in the proper pattern-coat.

Nowadays, with the advent of air-set moulding sand orientation of the pattern in the sand isn't so critical so denoting machined surfaces isn't carried out so often.

DMB09/03/2019 21:12:54
865 forum posts

About 40 years ago, I had some iron castings made at Haven Foundry in Newhaven, Sussex. They have long since gone. Whilst there, I saw a lot of professionally made patterns painted in red and yellow. Yellow was about the shade of primrose flowers and the "red" looked a sort of orange-ish shade. Nothing like as dark as in the picture above.

John

Brian H09/03/2019 22:36:19
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1040 forum posts
83 photos

I believe that there is (or was) a British Standard for the colours used on patterns and the paint was cellulose, normally very thick and appled by brush.

The paint I used was a job lot of spray cans at a car boot sale, hence the less than perfect shade but the foundry knew what the colours represented.

The patterns were only intended to be used once and so were made with the cheapest materials.

It's very satisfying producing your own patterns and I would recommend it to anyone.

Brian

Edited By Brian H on 09/03/2019 22:36:47

The Novice Engineer09/03/2019 23:37:01
44 forum posts
20 photos

I have done some Aluminium casting of small items , upto 600g . I used a 3 Kg electric furnace [3kg is weight of gold it will take !] that I picked up from e-bay a few years ago.

It takes about 45 -60 min to getup to temperature ~ 750C and melt the aluminium, the process can be speeded up by preheating the scrap with a gas torch.

My source of Aluminium is old cast items , eg chair bases, car engine pistons , hard drive chassis etc ... , tin cans , extruded sections and foil are not good they produce a lot of slag and pour like treacle and is a soft alloy that is horrible to machine.!

I use oil bonded sand in home made wooden cope and drag moulding boxes, this is a find sand that gives a good finish.

Pattens are made of MDF , 3D printed, or if its simple Polystyrene that is burnt out at the pour ...outside ! for good reason ...it smokes and stinks.

Have a look with google for more information ...there's loads out there , Back yard foundry etc ...

As Brian said ...its a satisfying process.

Steve

 

Edited By The Novice Engineer on 09/03/2019 23:39:40

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