Lathe in a Box

[Andy_HParticipant @andy_h]

This 2015 thread drew my attention to the wonderfully neat "lathe in a box" Link

The part of this solution I am particularly interested in is the belt-less method used for the motor to drive the countershaft.

Curious if anyone has experience of using a setup like this and if so how eefective you find it.

The photos in the above link are quite small and not too clear when zoomed but….

It looks like a plywood ring has been screwed to the outer surface of the original drive pulley. That seems very easy to fabricate but I reckon it needs to be truly concentric to the pulley and with a even internal surface to avoid inducing annoying vibration.

I'm less clear on the motor drive side of this setup. Looks like a rubber wrapped brass boss attached to the motor shaft – a bit like a over-sized version of pinch roller found in cassette players! Any suggestions on how to make this (assuming such a component is not available?) or, more to the point, what to use?

Andy

[Andy_HParticipant @andy_h]

[DC31kParticipant @dc31k]

Posted by Andy_H on 27/08/2023 14:13:08:

That seems very easy to fabricate but I reckon it needs to be truly concentric to the pulley and with a even internal surface to avoid inducing annoying vibration.

Looks like a rubber wrapped brass boss attached to the motor shaft – a bit like a over-sized version of pinch roller found in cassette players! Any suggestions on how to make this…

Make the motor 'pulley' first. Any old bit of hardwood would do. Drill and tap so it can be secured to the motor shaft. Shape roughly circular with hand tools. Mount on motor. Switch on. Apply sandpaper glued to a flat board until the pulley is round and smooth.

Glue sandpaper, rough side out to finished pulley. Switch on and apply to rough finished plywood disk on countershaft. Rotate countershaft slowly. Once plywood is finished round, concentric and smooth, remove sandpaper from motor pulley and replace with rubber.

A smart person would size the motor pulley so something like a slice of mountain bike inner tube fits it snugly.

[Andy_HParticipant @andy_h]

Posted by DC31k on 27/08/2023 15:17:50:

A smart person would size the motor pulley so something like a slice of mountain bike inner tube fits it snugly.

Thanks for the suggestion. My badly worded question was aimed at the rubber covering on the motor disc. The inner tube slice is an interesting idea but I'm wondering if that would be think enough and robust enough. But the idea has led me to look at large bore reinforced rubber hose.

Also, for the wooden boss on the motor shaft I'm thinking of boring that out and gluing a couple of shaft collars into the hole. Thinking this may be a more secure (safe) way of fixing to the shaft rather than relying on a screw through the wood – which could result in the wood splitting when under load?

As for the countershaft side of things. I am now thinking of using two rings bolted together with the pulley sandwiched between them. This would avoid ruining the original pulley buy drilling holes through the rim.

Main hesitation still is whether the whole setup would be effective so would still be interested to hear if anyone has used this method

Andy

[peak4Participant @peak4]

I've not tried that, but assuming finances allow, how about an internally toothed gear such as these, along with the appropriate spur gear(s) on the motor.
https://www.hpcgears.com/n/products/6.internal_gears/internal_gears.php

Bill

Edited By peak4 on 28/08/2023 20:31:41

[An OtherParticipant @another21905]

I don't know if they are still obtainable, but would a hard rubber doorstop be suitable for the drive pulley? – I,m thinking of the slightly conical things about 3cm high x 3cm diameter.

[Andy_HParticipant @andy_h]

Posted by An Other on 29/08/2023 09:15:08:

I don't know if they are still obtainable, but would a hard rubber doorstop be suitable for the drive pulley? – I,m thinking of the slightly conical things about 3cm high x 3cm diameter.

That's a good idea.

Looks like this may be perfect as it's 50mm diameter, and also straight sided rather than conical. I'd have to remove some material from the centre to fir the boss on the shaft.

I'm guessing rubber is not very machinable (more of a hole-saw job) – or am I wrong?

Andy

[Grindstone CowboyParticipant @grindstonecowboy]

Popping it in the freezer for a day might help stiffen it up enough to be more easy to machine. Of course, you're then fighting the fact that it's warming up as you go, so work fast

Rob

[Michael GilliganParticipant @michaelgilligan61133]

I would probably look at skateboard wheels … some of them are modestly priced, and it would be easier to machine a new core than to machine rubber.

MichaelG.

.

No connection with these people [they probably wouldn’t have me] … but here is an indicative range:

https://www.skatehut.co.uk/skateboards/skateboard-wheels?productListFilters=&productListPgNo=1

Edited By Michael Gilligan on 29/08/2023 17:47:37

[Andy_HParticipant @andy_h]

Posted by Michael Gilligan on 29/08/2023 17:43:40:

I would probably look at skateboard wheels … some of them are modestly priced, and it would be easier to machine a new core than to machine rubber.

MichaelG.

.

No connection with these people [they probably wouldn’t have me] … but here is an indicative range:

**LINK**

Edited By Michael Gilligan on 29/08/2023 17:47:37

That looked like an interesting suggestion but having looked into more detail it seems these are all made of plastic materials and I am thinking this would not provide the required degree of friction for driving the countershaft wheel.

My current idea is to use one of the larger and "chunkier" Rubber ferrules for a walking stick which has a solid parallel sided Rubber section on the end. Unfortunately the diameter of that section is 15mm less than I really wanted but can compensate for that by adjusting the diameter of the countershaft wheel.

Andy

[Michael GilliganParticipant @michaelgilligan61133]

You might want to look a little deeper, Andy: **LINK**

https://www.slamcity.com/pages/hard-skateboard-wheels-vs-soft-skateboard-wheels

… or maybe not

MichaelG.

[Andy_HParticipant @andy_h]

Posted by Michael Gilligan on 01/09/2023 21:19:41:

You might want to look a little deeper, Andy: **LINK**

https://www.slamcity.com/pages/hard-skateboard-wheels-vs-soft-skateboard-wheels

… or maybe not

MichaelG.

I take that back! Thanks, that link gives a good explanation of the hardness numbers that had previously mystified me.

Andy

[Michael GilliganParticipant @michaelgilligan61133]

You’re welcome, Andy

I shall be very interested to see how you get on, if you decide to use them.

MichaelG.

[Author]

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