Fenner Powertwist v belts

[Simon CollierParticipant @simoncollier74340]

The belt on my Hercus lathe is delaminating and turning into a tar like goo. I intend to replace it with the type of link belt in the title, the red ones. I have read all posts on link belts I could find and unsurprisingly, opinions differ. Any advice or opinions please? I don't want to dismantle the shafts to fit a normal belt as I would have to learn how first and I have enough to do.

[Simon CollierParticipant @simoncollier74340]

[John HaineParticipant @johnhaine32865]

They are excellent. But get the proper Fenner type, and make sure it's the right size. Though expensive, RS are a good source.

[Simon Williams 3Participant @simonwilliams3]

Seems like a no brainer, though I don't like them. The massed opinion seems to be positive as far as I have read on here, but all those sharp edges and catch points whizzing round give me the willies. But so long as it is adequately guarded it will be OK.

I've seen stuff on the forum about how these link belts reduce vibration, though I can't see that myself. Unless of course the original style belt was set in its shape from having been stood for too long. Nothing that isn't cured by spending the money and buying a new one. If the link feature saves time and aggro in dismantling the head stock it's a done deal.

HTH Simon

[Paul LousickParticipant @paullousick59116]

Dismanlling the spindle on a Hercus/Southbend lathe is not difficult. Lots of instructions and videos on Google.

Paul

[Mike PooleParticipant @mikepoole82104]

It seems an often quoted observation that link belts are smooth but I wonder if this comes from replacing a belt that is in poor condition and fitting a new v belt would also improve the smoothness of the machine.

Mike

[RobboParticipant @robbo]

I have found that fitting a link belt to the motor to countershaft drive on my Mk1 Super 7B has reduced vibration.

There was a slight misalignment of the motor pulley/countershaft pulley which made using the high speed range a nightmare and also caused the motor pulley to come loose (which then increased the vibration).

The link belt solved all this.

However on the countershaft to spindle drive the link belt needed more careful tensioning than the old Vee belt to avoid slipping.

The Boxford Model A that is also lurking about has a link belt drive as standard from countershaft to spindle, as it is easier to fit than a Vee belt. That works fine, but is the old fashioned type with metal pins in the links.

[Mark RandParticipant @markrand96270]

They're better than a clapped out belt and sometimes easier to fit in an emergency. That's all.

They aren't as smooth as a new V belt, can't cope with small pulleys as well as a standard or -X belt. They need more tension than the standard belt and are more expensive than the standard belt.

Learn how to fit the correct belt and you will be better off.

Yes, I have used them. That's how I know…

[Simon CollierParticipant @simoncollier74340]

Thanks for replies. I must check the pulleys as I remember from the specs that the minimum is 80 mm. I did have a look at videos but there are many variations. I would have to find one like mine. It is an ARL with roller bearings on the spindle. I do have the Hercus book showing the parts. The old ruined belt works fine, but I mostly use this lathe for small brass steam fittings, so it is hardly working.

[brickyParticipant @bricky]

I was advised by Myfords 40 years ago to reduce vibration, to use a Brammer link belt on my Mk 1 S7.The belt worked.The fibre belts with metal studs were difficult to connect so many years later when the T link belts were availiable I fitted one,this belt slipped quite often and eventually I refited the original fibre Brammer and had no more slippage.Expensive but better in my experiance than the plastic belts.

Frank

[Simon CollierParticipant @simoncollier74340]

Encouraged by Paul's comments above, and I remember that he has a Hercus himself, I decided to study up and remove the spindle. I watched several utube videos on Southbends, Atlas and finally found one doing a Hercus AR like my ARL, but he was finding his way and working it out as he went, so not a great teacher. Finally this afternoon after two days, I got the spindle out, but destroyed the front taper roller bearing. I used threaded rod and a spacer I made from steel pipe on the other lathe, as shown in some of the videos, but at some point the force must have been against the bearing and it was bent. It is still on the spindle and pushing it off will require another special tool to be made. At this point I really wish I had bought the link belt. It is obvious from the paint across joints that the spindle has never been removed before.

[HopperParticipant @hopper]

Sorry to hear about your troubles. What part of the bearing is "bent"? Sounds odd. Presumably the roller cage?

When you get a new belt, try the "cogged" V belts with notches cut out along the inside diameter. They bend better around small radiuses such as lathe pulleys and run smoother than the regular V belts.

 

Edited By Hopper on 29/08/2018 09:14:36

[Ian S CParticipant @iansc]

Use link belt, you'll never need to remove the spindle again, I had a similar sort of problem, and wrecked the front oil seal on my lathe.  I have Fenner Power Twist on the primary drive, motor to counter shaft, and a Chinese copy on the final drive, the only problem was that the cheap stuff needed a few hours running until it bedded in, until then it would n't take full load without slipping.

Ian S C

Edited By Ian S C on 29/08/2018 11:50:55

[Simon CollierParticipant @simoncollier74340]

I promise I won’t be removing it again assuming I can obtain the bearings and get it back together, which I expect to be at least as difficult. Yes, the roller cage was bent. It’s too depressing to take a picture of.

[HopperParticipant @hopper]

LOL, not to worry. Should be a readily available bearing if you take the old one, or the number off it, to your local quality bearing supplier. SKF are usually pretty good. if not, this guy sells Hercus parts **LINK**

Take your time reassembling it and it will be OK. Bearings are consumable items, made to be used and replaced.

But as you already have the spindle out, you might as well fit a good quality cogged V belt. You can fit a link type belt when that wears out in 20 years' time.

Edited By Hopper on 30/08/2018 03:04:34

[not done it yetParticipant @notdoneityet]

The spindle in my lathe would need to be removed to fit new V belts, so when they require replacing (if ever) I will fit linked belts. There would be no problem with ‘smoothness’, I would think, as it is a twin pulley drive.

[Simon CollierParticipant @simoncollier74340]

I've ordered the bearings and cones from CBC. I am fairly confident about replacing the cones. What I am worried about is reassembling the spindle, especially pushing the bull wheel onto its key within the confines of the headstock casting. The videos I was watching didn't show this bit to my great disappointment. I suppose I'll work it out. At least I can make tools on my other lathe.

[HopperParticipant @hopper]

A long piece of threaded rod through the centre of the spindle and suitable piece of pipe and big flat washer on the other end so you can tighten the nuts and draw the spindle into the pulley should work. Handy having the other lathe to make up any needed spacers etc for the operation.

It might help, too, to file small chamfers on the ends of the key and the keyway so its easier to get the key to go in the hole as you pull the spindle through the headstock and pulley.

 

Edited By Hopper on 30/08/2018 09:16:23

[Simon CollierParticipant @simoncollier74340]

I did that to get the spindle out so I'll work out a way to reverse the procedure. It was very hard indeed to get the Woodruff keys out, especially the bull gear one. I mashed it a little but filed the burrs off. When a tight fitting part has been in place since about 1974, it does not want to move! I think it should go back a lot easier. What's the bet that with all these worries, on assembly I forget to put the new belt over the pulleys? A bloke on U-tube did just that and there was much "railway esperanto".

[steamdaveParticipant @steamdave]

If using link belts, remember to install them in the correct orientation, as per pic:

Dave
The Emerald Isle

[Simon CollierParticipant @simoncollier74340]

I have finished the job and the lathe is back in service. I used a length of 12 mm threaded rod with various diameter lengths of pipe and tubes, some of which had to be cut and faced and one bored. The biggest headache was how to get out the old bearing outer race cones. There are two holes 180 degrees apart in the casting through to the cone seat so a pin punch can be used, but only a 3 mm pin would fit through the holes so I cut the shank of a 3 mm drill and used a 4lb hammer head, with my finger through the handle hole to hit the pin. There was precious little swing room in the spindle cavity, but I managed to get the front cone moving and turned up some longer pins to get it all the way out. The rear cone however was not going to move, especially as the backgear was in danger of being hit with the hammer. I tried to get a gear puller in behind the cone but it couldn't grab. Eventually I tried cutting a big washer into quarters and poking it in behind the cone where it could engage by just a mm or two. I then used a pusher. I thought I would have to screw the segments to the pusher, hence the holes, but friction sufficed, and after a couple of frustrating days trying to come up with a solution, the cone started to move.

[Simon CollierParticipant @simoncollier74340]

This shows the method, with a wheel spreading the force on the front inside casting. You can see one of the pin punch holes on the left side near the spanner.

[Simon CollierParticipant @simoncollier74340]

This is the damaged bearing that caused all the trouble. Ignorance resulting in the used of a too small spacer which was pushing against the roller cage.

[Simon CollierParticipant @simoncollier74340]

I had to find a large bit of pipe, a lathe faceplate, a spacer and a bit of tube the right diameter to bear against the bearing inner race in order to drive the front bearing onto its interference. For this, hammering on the spindle end, with a block of wood between, seemed the only way.

[Simon CollierParticipant @simoncollier74340]

The items needed for the job, not all of which worked, such as the puller.

Edited By Simon Collier on 18/09/2018 11:27:12

[Author]

Posts