Speed Control or Countershaft for Flexispeed Lathe?

For a variety of reasons, mainly being busy rebuilding the kitchen and now the workshop, I have yet to set up this lathe. I have been looking for a set of suitable pulleys to make up a countershaft, but still like the idea of electronic control if affordable and practicable.

I have seen these on E-bay and wonder whether anyone can suggest whether either would be suitable for a single phase, capacitor start AC motor of 120 watts?

**LINK**

or

**LINK**

Thank you.

James.

Hi James,
The simple aswer is no and no. Single phase induction motors are not suitable for speed control. I did see a design in the "Elektor" magazine once that claimed to work but I would not reccomend it. The solution is a 3 phase motor with a VFD or a permanent magnet or shunt DC motor with a suitable PWM speed controller or brushless DC motor with a suitable speed controller.

Les.

When you make up a counter shaft, as well as the 3 pulleys to the lathe, it's worth while putting a 2 or 3 speed pulley from the motor to the counter shaft, that along with the back gear gives you 12 speeds, and if you work it right, your low speed could be 30 rpm or less, just don't go for excess speed at the top end. Use HSS tools, be prepared to run a bit slower, and the wee lathe will work to the maximum it can handle.

Ian S C

Thank you both for your replies.

Les: that is pretty much what I had expected, but it was worth checking, especially at the low price of the two controllers.

Ian: a good idea about the additional speeds. I shall see what I can find in the way of pulleys.

Regards,

James.

I'm still a believer in mechanical speed control, the main reason for electronic speed control on small to medium bench lathes is for cost reasons, it's much cheaper to build a lathe without gears than it is to make a back geared, belt head, or a gear head lathe.

Ian S C

Hi James, mine came with a 3 step pulley and countershaft, works fine.
http://www.model-engineer.co.uk/sites/7/images/member_albums/144829/594062.jpg

John,

May I ask what size the pulleys are on your set up? I have been looking for some myself, but cannot find anything suitable, unless I am being obtuse.

If I understand correctly, ideally, the countershaft pulleys should be as close as possible to the size of the headstock pulleys. Assuming that I have measured them correctly (to the base of the pulley groove), my headstock pulleys are 22mm, 35mm and 48mm. The pulleys that I can find are all much larger than this, meaning that I need an enormous (or so it seems) pulley on the other end of the countershaft to slow the machine back down.

Can any one suggest a supplier of smaller pulleys, or does someone with a lathe fancy earning a few bob making some? If, on the other hand, I have measured the wrong part of the pulley, and they are measured from the outside edge, not the bottom of the groove, I shall start looking again.

Regards,

James.

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James,

It's worth having a close look at the 1948 Advert. on lathes.co.uk

... This clearly shows the manufacturer's countershaft.

Yes, it's best to have a matching set of pulleys for the secondary belt.

As I mentioned earlier: for a more compact primary reduction, I would go for Poly-Vee.

MichaelG.

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P.S. ... Pulleys are usually measured at their 'effective diameter' [i.e. where the belt mkes contact].

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Also: Look at the very tidy installation used by Cowells.

MichaelG.

The pulleys on mine came with the machine, they are 2 x 12mm wide V with root diameters of 47mm, 34mm, and 22mm. The lay shaft just runs in a pair of Picador standards.The motor is a 1/3 HP with a 35 dia pulley driving the layshaft with a 135mm dia pulley. I have now rigged the motor on an overhead bracket so the weight of the motor tensions the belt but it's easy to swap speeds. It also prevents the weight of the motor twisting the bed by hanging off the back as per the recomended set up. I believe the drive set came from Flexispeed originally? but Chronos do a range of similar pulleys etc.

https://dl.dropboxusercontent.com/u/95073912/fm%20pulleys.JPG

Here's a neat idea; Lathe in a Box....
https://sites.google.com/site/flexispeedlatheinabox/

Edited By john carruthers on 06/04/2015 09:54:35

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James,

Thinking about this a little further:

On a machine the size of the Flexispeed; flat pulleys would probably adequate for the primary drive [unless you are planning to work it very hard]. ... My little Jason lathe seems fine, using XL250 timing belts turned inside-out

MichaelG.

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Silly typo

That should, of course read XL025

i.e. 1/4" wide.

MichaelG.

Hi James

A while back I acquired a rather old Colechester with flat belt pulleys and no countershaft, I could not find a three step cone pulley that matched the lathe ratios. Anyway I had acquired a variable speed motor and drive and decided to fit that. I did have a cast iron pulley that when bored out would fit over the middle step on the headstock pulley, it was a double V pulley for A section belts. to attach it was drilled and tapped for a couple of M6 grub screws set in the middle of the V's.

Wedge link belting was used making it unnecessary to dismantle the head for a belt change although I never had to do it, the Red reinforced plastic (Not rubber that perishes if oil gets on it) lasted for years.

You could do the same thing with a polly V pulley (Ring) you made yourself Allow extra width for the grubscrews or Loctite or shrink it it on.

A simple countershaft frame was welded up with off the shelf plumber block bearings was made to fit
The headstock casting required the belts to be near vertical. the motor was connected to the countershaft behind the lathe similar to the way Myford did it.

Gee I loved that setup...

The variable speed allowed me to speed through the cut then slow down and creep up to a shoulder when screw cutting.

It also allows you to change the speed slightly without stopping to stop chattering resonance that sometimes occurs when turning.

You can also speed up as you move towards the centre of a large disk without stopping. reducing the bad finish you get in the centre because the speed is too slow for the small diameter in the middle of the disk while correct for the outer edge. Some CNC lathes do this automatically.

Regards
John

Edited By John McNamara on 06/04/2015 15:38:20

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John,

That is delightful.

MichaelG.

Thank you all for the helpful replies, without which I would porbably have wasted a fair bit of money. My main problem with using pulleys was finding a stepped pulley small enough. However, a friend now has a lathe up and running that I can borrow to turn up a suitable stepped pulley for the Flexispeed.

Fingers crossed and watch this space. I shall post some pictures once I have it sorted out.

Regards,

James.

One of the pulleys on a home built scroll saw I have is made of wood, and seems to have stood up to a fair amount of use, it's about 6" diameter, and has an A section belt. For a smaller pulley I think metal would be better, but wood could be used for quite a large pulley. Have a look at some of the home brew machines in old "Popular Mechanics" magazines or books.

Ian S C

Ian,

That's a good point about wood. I have just realised that I have a large slab of butcher's block oak workshop left over from doing the kitchen recently. I wonder whether that would hold up?

Regards,

James.

Should do, use either stainless or brass scews / bolts, and fittings, the tannin in the oak tends to rust steel. Apart from the mess it makes, it can be machined in the lathe, and on the mill, just think of it as a metal, use a HSS tool very sharp.

Ian S C

I bought a nice little motor + countershaft on impulse without really looking at it and later found the 3 speed pulley is built up from lots of ply. Works fine as the hole is long enough to avoid wobble. On a large dia or single pulley I would recommend a metal bush and perhaps welded flange. Ply or even mdf varnished might be better than real wood in this case to avoid warp later on.

Edited By Bazyle on 09/04/2015 13:30:45

A litle update of this: I have almost finished making a stepped pulley using my friend's lathe, with sizes to match the headstock pulley. I have also bought an 8 inch second-hand pulley and plan to pick up a 2 inch pulley for the motor.

By my reckoning, this should give a range of speeds from 35rpm, with the backgear, up a maximum of 610rpm.

The alternative pulleys I have considered would give a range from 65rpm up to 1,230rpm, which I felt was too high.

I have also sorted out a shaft and located plummer blocks to fit. Next step: clear the bench.

Regards,

James.

Edited By James Alford on 01/05/2015 08:01:22

Edited By James Alford on 01/05/2015 08:01:57