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Which material for change gears?

shapeaholic

Stainless
Joined
Oct 14, 2003
Location
Kemptville Ontario, Canada
I'm thinking of making a set of metric change gears for my hendey lathe.
These gears will not be used heavily so I think ease of machining would be the primary concern.
I was thinking either 12L14, or Dura-bar.

What does the collective brain think would be the most appropriate?
 
I am not sure what size lathe you have but for smaller lathes it is easy to print them on a 3D printer. Mr Pete tried a set on a 10” atlas lathe and I have printed some for my 9x20. I will probably make a few for my 13x40 eventually as well. If I ever get really bored I would like to try casting a couple in aluminum or brass (or a combination of the two)


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A very good material for gears is canvas reinforced phenolic. It is strong, quiet and easy to machine (though dusty if machined dry and needs dust collection). In fact some machine tools, lathes, for example, do have phenolic gears in the gearbox.
 
Cut mine out of moly filled nylon 66, cuts like butter. Thats for a 11" harrison. Plenty strong enough too, yet hopefully if theres ever a big oh fuck, they will strip.

Going nylon they run really quiet too and don't realy need any lube which makes them clean to mess with. IMHO metal is not needed for this job at all, unless your on some strange lathe with really narrow gears. The harisons i cut are 5/8" wide, which is kinda massive over kill for the power they transmit!
 
A very good material for gears is canvas reinforced phenolic. It is strong, quiet and easy to machine (though dusty if machined dry and needs dust collection). In fact some machine tools, lathes, for example, do have phenolic gears in the gearbox.

Yes but cut a round blank from a sheet The round stock of that stuf has the fibers orientated wrong Teeth break of in a instant

Peter
 
The original print calls for cold rolled steal per "Hendeyman" himself. Thats what i made mine from and some plate for the larger. And its what i already had
 
Yes but cut a round blank from a sheet The round stock of that stuf has the fibers orientated wrong Teeth break of in a instant

Peter

I am not sure what material you do have in mind. I've cut dozens, maybe hundreds, gears in canvas reinforces phenolic, many out of material cut out from a plate. The canvas in the stock is arranged in many layers creating a random pattern of fibres that is very strong. Here is one of two identical gears I made some 30 years ago as a replacement for a damaged nylon gear in a milling machine power feed. During milling the force on the gear is considerable and I've made two just in case I need to replace it again (the gears are cut together, so it is the same effort to make two). Well, in all those years the installed gear is just fine and I will leave the spare for my grandson :)
Peter, it is possible that we talking about different material or the stuff I was buying 40 years ago is not available today.

gear-phenolic.jpg
 
Looks like the phenolic grade C I make for Ammco bull gears Matra. The mating pinion is steel.

For the few transposing gears I've made I followed the material the original change wheels were made of but used continuos cast malleable iron, also known as durabar I guess. Since the standard change wheels never wear out it stands to reason the better cast material, which gears are seldom used normally, will outlast the lathe.
As mentioned also, as long as you make sure no chips get into a phenolic gear running with a steel gear they seem to last forever too.
 
A very good material for gears is canvas reinforced phenolic. It is strong, quiet and easy to machine (though dusty if machined dry and needs dust collection). In fact some machine tools, lathes, for example, do have phenolic gears in the gearbox.

and do break easily if any interference ......
 
Looks like the phenolic grade C I make for Ammco bull gears Matra. The mating pinion is steel.

For the few transposing gears I've made I followed the material the original change wheels were made of but used continuos cast malleable iron, also known as durabar I guess. Since the standard change wheels never wear out it stands to reason the better cast material, which gears are seldom used normally, will outlast the lathe.
As mentioned also, as long as you make sure no chips get into a phenolic gear running with a steel gear they seem to last forever too.

Yes, Phenolic C (C for canvas filled) is the right material, though there is a wide range in quality. I cannot remember who was my original supplier as I do have a large stock bough decades ago, but the right material is not that brittle at all. This gear was made for the "Type 70 Servo Feed" (Servo Products, Altadena, CA) mill power feed. This was working daily for some 25 years - though much less in the last 5.
Years ago I have made many similar gears for small gearboxes used on hand-cranked generators; never had a failure.

Type 70 servo feed.jpg
 
Harrison M300 one of the main drive gears is something like Bakelite. It is designed to shred if the machine is stalled saving all the precision metal gears. First made around 1971 and still made that way AFAIK.
Atlas was known to use Zamac for the gears for the same reason.
 
I am not sure what material you do have in mind. I've cut dozens, maybe hundreds, gears in canvas reinforces phenolic, many out of material cut out from a plate. The canvas in the stock is arranged in many layers creating a random pattern of fibres that is very strong. Here is one of two identical gears I made some 30 years ago as a replacement for a damaged nylon gear in a milling machine power feed. During milling the force on the gear is considerable and I've made two just in case I need to replace it again (the gears are cut together, so it is the same effort to make two). Well, in all those years the installed gear is just fine and I will leave the spare for my grandson :)
Peter, it is possible that we talking about different material or the stuff I was buying 40 years ago is not available today.

View attachment 255812

he stuf is also available in round stock That is fabricated by winding impregnated cloth to round stock
That gives no fiber orientated on the radius of the gear

hardweefsel_staf.jpg


This then
Peter
 








 
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