Lathe Change Wheels

[David NobleParticipant @davidnoble71990]

I would like to buy some change wheels for the Mellor lathe that I am attempting to restore. As the Mellor lathe seems to be fairly rare, they are not immediately available, so, as a last resort I could make them but I wondered if anyone knew if there is another lathe with the same tooth form of 16D.P.

Many Thanks, David

[David NobleParticipant @davidnoble71990]

[EmgeeParticipant @emgee]

David

Colchester Bantam lathe uses 16DP gears.

Emgee

[ChrisLHParticipant @chrislh]

You also need to know Pressure Angle, 14.5 or 20 degrees, to get a satisfactory match.

[David George 1Participant @davidgeorge1]

Hi David you can buy these gears from HPC.

https://www.hpcgears.com/stampede/products/spur.gears/spur.gears.php

Worth a look.

David

[Lee RogersParticipant @leerogers95060]

Worth remembering that for fine cutting feeds you can use any set with the correct bore, with a bit of imagination you can compound 2 different sets on the same banjo.

[Martin ConnellyParticipant @martinconnelly55370]

Smart and Brown also use 16DP gears. Here is an original with one I made, 95 teeth.

Martin C

[not done it yetParticipant @notdoneityet]

We need some more detail. Most Raglan lathes used 16DP gearing. But they may not be the tooth count required, the correct width (spacers may help), or the bore/boss dimensions – and anything else that may be a limiting factor.

[David NobleParticipant @davidnoble71990]

Posted by not done it yet on 03/02/2023 12:20:53:

We need some more detail. Most Raglan lathes used 16DP gearing. But they may not be the tooth count required, the correct width (spacers may help), or the bore/boss dimensions – and anything else that may be a limiting factor.

Thanks everyone, I was prepared to modify the gears if they were from another make but more details are:-

16D.P. 14.5 deg p.a. 3/8" wide, 3/4" bore, 5/32" keyway.

I was hoping to buy these second hand as there are quite a lot that are missing and to buy new is looking quite pricey.

David

Edited By David Noble on 03/02/2023 12:45:52

[BazyleParticipant @bazyle]

Which gears do you already have? For an 8tpi leadscrew the 'best' set is 11 wheels in steps of 5 teeth from 30 to 65 plus 2×20 and 38 (to do 19tpi BSP only) plus a couple more to get you metric. However some lathes used steps of 3 and all sorts of odd ones which are not so elegant.
You could look at which threads you are actually likely to cut and just get the ones for that. Also they don't need to be particularly strong or precise (unless you are cutting a new leadscrew) so you can get away with plastic, thin aluminium and even hand file the teeth.
Perhaps not big enough to span the gap but it might be easier to get a mini-lathe set as they are the most common.

[David NobleParticipant @davidnoble71990]

Thanks Bazyle,

As you can see there seems to be quite a number needed as I only have 4 or 5.
maybe my best option is to buy a sheet of 8mm aluminium and make them.

David

[not done it yetParticipant @notdoneityet]

Posted by David Noble on 03/02/2023 12:45:22:

Posted by not done it yet on 03/02/2023 12:20:53:

We need some more detail. Most Raglan lathes used 16DP gearing. But they may not be the tooth count required, the correct width (spacers may help), or the bore/boss dimensions – and anything else that may be a limiting factor.

Thanks everyone, I was prepared to modify the gears if they were from another make but more details are:-

16D.P. 14.5 deg p.a. 3/8" wide, 3/4" bore, 5/32" keyway.

I was hoping to buy these second hand as there are quite a lot that are missing and to buy new is looking quite pricey.

David

Edited By David Noble on 03/02/2023 12:45:52

Raglan are 5/8” plain bore.

[Martin ConnellyParticipant @martinconnelly55370]

10mm alloy plate would be better than 8mm to be close to 3/8", you could turn the blanks down to 3/8" if required to be exact.

Martin C

[BazyleParticipant @bazyle]

Ah, looks looks you have a 4tpi leadscrew. I suggest you see whether you can modify the banjo or add an outrigger to enable 6 wheel trains. Then use a 2:1 starter pair eg 20 & 40 to make everything more 'standard' so you don't need the high count wheels.

[David George 1Participant @davidgeorge1]

David I have just made some gears from Acetal and they were easy to machine and seem to be very strong and stable. The machining and gear cutting was so easy compared to cast iron and a lot quieter running.

These are for a tumbler reverse.

David

[egaParticipant @ega]

You could also use Oilon (oil-filled nylon) which is self-lubricating.

[bernard towersParticipant @bernardtowers37738]

Acetal is the way to go, machines beautifully with a lovely finish and they run quietly.

[David NobleParticipant @davidnoble71990]

I hadn’t thought of Nylon/Acetol/Oilon great ideas, thank you.

David

[HuubParticipant @huub]

You can 3D print these gears, especially the large ones. You probably have to bore or ream the hole for the shaft.

It is the metal to metal contact that makes the noise. If you place a plastic gear between 2 metal gears, the gears run really quietly.

[David George 1Participant @davidgeorge1]

Having run my Acetal gears for over a month and having used them for rough cutting screw cutting and finnish milling they look just as new. I would not worry about having these gears again as long as there is no heat to damage them. They don't evan get warm on my lathe.

David

[David NobleParticipant @davidnoble71990]

Thanks for that David, I've bought a sheet of black acetal and made a 30 tooth and a 75 tooth gear as I wanted to cut a 10 tpi thread.They seem be performing well atm.

Many thanks, David

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