Speed Control or Countershaft for Flexispeed Lathe?

[Ian S CParticipant @iansc]

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

[john carruthersParticipant @johncarruthers46255]

Hi James, mine came with a 3 step pulley and countershaft, works fine.
http://www.model-engineer.co.uk/wp-content/uploads/sites/4/images/member_albums/144829/594062.jpg

[James AlfordParticipant @jamesalford67616]

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.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by James Alford on 06/04/2015 09:01:06:

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.

.

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.

.

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 06/04/2015 09:17:58:.

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

… This clearly shows the manufacturer's countershaft.

.

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

MichaelG.

[john carruthersParticipant @johncarruthers46255]

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 06/04/2015 09:17:58:

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

.

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.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 06/04/2015 13:53:25:

… My little Jason lathe seems fine, using XL250 timing belts turned inside-out

.

Silly typo

That should, of course read XL025

i.e. 1/4" wide.

MichaelG.

[John McNamaraParticipant @johnmcnamara74883]

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by john carruthers on 06/04/2015 09:48:13:

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

.

John,

That is delightful.

MichaelG.

[James AlfordParticipant @jamesalford67616]

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.

[Ian S CParticipant @iansc]

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

[James AlfordParticipant @jamesalford67616]

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.

[Ian S CParticipant @iansc]

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

[BazyleParticipant @bazyle]

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

[James AlfordParticipant @jamesalford67616]

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

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