Author Topic: Engine from castings?  (Read 3834 times)

Offline kvom

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Engine from castings?
« on: July 20, 2009, 09:11:07 AM »
I've now fabricated 2 engines from bar stock and am wondering if I ought to try one from castings in the future.  Aside from the ST quality issues Bogs talks about in his rebuild thread, what are the pros/cons? 

Offline sbwhart

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Re: Engine from castings?
« Reply #1 on: July 20, 2009, 09:29:57 AM »
Hi

I made a beam engine from castings also quite a lot of the bits for my loco build are from casting

Certainly in the UK the bigest problem is the quality of casting we seem to get lumbered with. In the case of the beam engine I had to return quite a few of the casting as they were unmachinable it was a similar case with the loco castings. .:- not enough materiel, too much material, Material in the wrong place, Blow holes etc etc. I've got to the point where I'll avoid castings as much as I can.

Another big problem with casting is you have to take great care how you machine them up, the first thing you need to do is clean them up measure them carfully all over and work out the best machining sequence to get where you want to go, you need recognise and machine a good datum feature first.

Working from bar stock you lose some of the features and details you get with castings (twidly bits) but with ingenuity its suprising what you can get with cleaver fabrication.

Hope this helps

Stew
A little bit of clearance never got in the road
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Location:- Crewe Cheshire

bogstandard

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Re: Engine from castings?
« Reply #2 on: July 20, 2009, 01:49:15 PM »
Kirk,

If you want to try castings, then I would, if at all possible, try to get one that is mainly bronze. They will be a bit (or a lot) more expensive, but they do tend to have much cleaner and closer tolerance castings. Ali and cast iron can be almost any shape and size.
I used to make IC engines from ali castings, and on average, I would machine up around 30% of the engine from bar stock, purely because the castings were so bad and couldn't be used. Wrong size, large inclusions, blowholes, unmachineable material, you name it, you can get it in a casting.

Try a small kit at first, so if you do mess it up, then not so much to hide under the bench.

As Stew has mentioned, the main thing is find your datum, then work from there. Every casting in the kit will need to have the datum found. Get it wrong on your first cut, and you will either be doing a rescue job, or buying a new bit. Just take it very steady and triple check everything.


John

Offline rleete

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Re: Engine from castings?
« Reply #3 on: July 20, 2009, 02:32:32 PM »
I'd suggest a PM Research 3A horizontal engine.  Simple, and fairly decent castings from what I've seen.

Aluminum: http://www.pmresearchinc.com/store/product.php?productid=3086&cat=4&page=1

Bronze/iron: http://www.pmresearchinc.com/store/product.php?productid=3087&cat=4&page=1


I intend to try to make one  similar out of bar stock one of these days.
Creating scrap, one part at a time

Offline Mike K

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Re: Engine from castings?
« Reply #4 on: July 20, 2009, 06:12:07 PM »
Also, a PM 2A.  That was my first engine.  I'm almost done and if you need any tips I can help you out.

Mike