Material for Lathe Gears

Ray C said:
My first guess would be to match the material with the gears it will mate with.
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Ray,
The stripped gears are between steel spindle gear and a "pot metal" gear. The original gears are made of the weird zinc alloy (similar to ones I had on my old Atlas 101 lathe). I don't think I can even find that alloy, and even if I could, I don't think it's very machinable.
Surprisingly, most other gears are made of cast iron with brazed bronze bushings, so it looks like the stripped gears were made to be sacrificial (as was mentioned in this thread).

Thank you
Yuriy

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Woffler said:
I have some laying around what bore do you need and how many teeth.
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Woffler,
I will need to take that assembly apart (still). I haven't figured out how it's held together :) I will let you know once I can measure the bore.

Thank you for the offer.
Yuriy
 
Pacer said:
--- so it really shouldnt matter much. I had to cut a complete change gear set of 10 gears and I had 4 from some grade of cast iron and the rest from scrap yard steel finds ("unknownium:)))
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Ah yes Unknownium and Unobtainium, the two elements that we could all live without. I too priced Brass for a small steam engine project and got my feelings hurt pretty quickly. I think for the flat pieces and the round stock I wanted it was over 100 bucks. It would have been a really beautifull specimen, but I couldn't afford the brass so I went with stainless and CR. The stainless turned out fair and the CR turned out very nicely once buffed and polished on a wheel with rouge. Turned out pretty good overall as an early project that I gave away as a Christmas present to a handicapped kid I used to know well. Brought him many hours of intense pleasure and he took it to heaven when he went...

Bob
 
I once saw an article in HSM (I think) where the guy made replacement lathe gears real easy:
1. Cut a strip of brass shim as wide as the gear and length maybe 3-4x the circumference of the gear he wanted to make.
2. Fed the brass shim in between 2 of the meshed gears so it produced a rack of teeth (presume there would need to be a bit of clearance between them)
3. Bent them into a circle and overlapped the teeth at the right place to produce the number of teeth that he wanted
4. Turned up a plywood blank (or any other material) so the ring of teeth just slipped on
5. Filled the space between the teeth and the blank with epoxy resin with rubber band from an inner tube over it to give the pressure to hold it in place
6. Trimmed the loose end with a Dremmel + cutoff wheel when the epoxy set.
All done
Said he had ones that had been used off and on for years and plywood was perfectly adequate.
Could get you out of a hole or make that special gear you need for an odd thread pitch etc, maybe even use the band to make a temporary epoxy repair to that gear with the tooth missing.
Rgds - jv
 
rowbare said:
Delrin is really good for feed gears. It is quite strong and machines nicely.

bob
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Bob,
I think I will have to go that route. I've measured the gears and they are "weird" to say the least. They come up either as Module 1.58 or 6.1 TPI, so I think my best bet would be to copy the buggered up gear as close as I can and call it good.

Thank you
Yuriy
 
ycroosh said:
Bob,
I think I will have to go that route. I've measured the gears and they are "weird" to say the least. They come up either as Module 1.58 or 6.1 TPI, so I think my best bet would be to copy the buggered up gear as close as I can and call it good.

Thank you
Yuriy
Click to expand...

Hi Yuriy, how are you working out the gear pitches? I would guess that the Jet would have 1.5mod gears, when you calculated did you add 2 to the tooth count to allow for the tooth addenda? The module or DP is calculated at the pitch line, roughly half way down the tooth faces - the tooth height (addendum) above the pitch is near as dammit the same as adding two more teeth's worth on the pitch diameter. If you measured the OD of a 40 tooth gear and divided by 40 instead of 42, you'd get a strange resulting gear pitch :)

Back to the original question, steel, cast-iron, brass, aluminium, Delrin, anything's better than no gears! Those pot-metal gears are probably Zamak / Mazak, a zinc recasting alloy nearly as strong as mild steel,

You might want to look up gear hobbing, the correct rack-form hob can cut any number of teeth, and they're pretty easy to make - http://homepage.ntlworld.com/peter_harrison/workshop/gearcutting/index.htm shows the process from calculations through making the hob and cutting the gears, nicely written up, too.

Dave H. (the other one)
 
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