Casting gear blanks from scrap aluminium

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Ike Turner
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Location: Victoria, Australia

Casting gear blanks from scrap aluminium

Post by Ike Turner »

I'm planning on casting some gear blanks to make change gears for my lathe; several of the gears had been lost by the previous owner and a commercial quote to make them floored me. I've been doing a little online research on cutting gears and have in mind a fairly simple setup to use an involute cutter on the lathe to do the gear cutting. I plan to use aluminium and research suggests that 2011 is the stuff to use. My question is, how, if at all, can one tell whether a particular scrap item might contain suitable quality material. I have a couple of old Range Rover gearbox cases that I'm thinking might be prepared to take one for the team; would they be likely to yield hard enough material for the job?
Oh, and if it's not already obvious- this will be the first time I have cast anything.
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ctwo
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Re: Casting gear blanks from scrap aluminium

Post by ctwo »

I was thinking of cold rolled steel, so this is an interesting question. Which material would be suitable for the purpose. I thought the originals were cast iron.
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Ike Turner
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Re: Casting gear blanks from scrap aluminium

Post by Ike Turner »

ctwo wrote:I was thinking of cold rolled steel, so this is an interesting question. Which material would be suitable for the purpose. I thought the originals were cast iron.
There's an interesting blog http://users.picknowl.com.au/~gloaming_ ... 5rev7.html where the guy has made change-gears from cast iron, aluminium and bronze, he swears by the longevity of the aluminium gears. I figure this would be realistic for me to do without a full-on foundry setup.
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Pipescs
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Re: Casting gear blanks from scrap aluminium

Post by Pipescs »

I would have no problem giving the Range Rover gear box aluminum a shot. Add a shot of copper to it for strength.

Pistons would probably be better though as they are generally made from a pretty tough alloy.

Make sure you allow for the shrinkage in you pattern with plenty extra to machine on the gear face.

As far as strength and longevity the gears will out last you unless it is a full production lathe.

Charlie Pipes
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Ike Turner
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Re: Casting gear blanks from scrap aluminium

Post by Ike Turner »

Thanks for that, I might see if I can pick up some worn-out or cracked pistons then, would also save having to cut the gearboxes into workable chunks. Should I still add some copper?
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Pipescs
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Re: Casting gear blanks from scrap aluminium

Post by Pipescs »

The copper Idea came from Fender who helped me last year. he just rolled up a piece of 12 ga copper wire into a ball and dropped it into the aluminum just prior to pouring.

Fender tells me this makes it tougher and easier to machine.
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Pipescs
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Re: Casting gear blanks from scrap aluminium

Post by Pipescs »

You did not mention the name of the lathe you are looking for the gears for. Also it would be good to mention the gears by teeth number you are missing.
Charlie Pipes
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Ike Turner
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Location: Victoria, Australia

Re: Casting gear blanks from scrap aluminium

Post by Ike Turner »

Pipescs wrote:You did not mention the name of the lathe you are looking for the gears for. Also it would be good to mention the gears by teeth number you are missing.
The lathe is a Kobe, I haven't been able to find out much about this company or the lathe itself, the attached photo is the best I have of it, taken during the cleanup and repaint process after I acquired the machine last year.
The change gears are 12dp and 1" thick with 1" centre bore. The missing ones are the 127 tooth metric transposing gear, plus 45, 50 and 60 teeth.
Attachments
Lathe 1.jpg
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ctwo
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Re: Casting gear blanks from scrap aluminium

Post by ctwo »

It looks like a gap bed with the gap removed and that area painted. Is that right? Do you have the gap?
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Ike Turner
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Re: Casting gear blanks from scrap aluminium

Post by Ike Turner »

The gap insert is actually in place in the photo, you can see the bolt recesses if you look closely. The insert does not fill the gap all the way up to the headstock. I'm not sure if the gap insert has ever been out. It will swing about a 9" radius over the carriage so I can't see myself needing to remove the insert too often.
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ctwo
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Re: Casting gear blanks from scrap aluminium

Post by ctwo »

I see it now, and after just a bit of thought realize that the gap wouldn't fill the entire gap. Thanks. That is a nice looking lathe.
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steamin10
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Re: Casting gear blanks from scrap aluminium

Post by steamin10 »

As far as material, once cast material is best cast again, not so much drawn stock. Prefer machine case or similar stock to ornamental aluminum which may be of marine grades for weather, but probably not if from the China Syndrome.

If the gears are 1 inch wide, dont sweat it. Brass would be my first choice for a blank, but some confidence can be handed to Aluminum as some lathes in the past for hobbiests had Zamac change gears, and they held up reasonably well over time for light duty. Zamac is a zinc aluminum compound more commonly(often incorrectly) known as pot metal. Its hardness is a benefit, but can be brittle, as you know.

Thsi is a good chance to carve a Wax master, sink it in plaster and cast the result for light cleanup. It could ease the tricky machining by many hours.

Good luck.
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