Drive belt for small Lorch

I have a length of round leather belt from a sewing machine - it joins by means of a staple which goes "clink" everytime it hits a pulley if that's of interest!

Steve

There is a definite knack to joining the polyurethane belt together, but once you get it, it works well.

It is important to ensure that the ends of the belt are thoroughly heated before joining. When you press the ends to the hot knife, push them together until you raise a burr about 1/16"-2mm high and then hold everything still for about 20 seconds. That ensures that the material has reached melting point all the way through. When you join the ends together, the pressure must be kept on for 3-5 minutes and the joint must not be tilted at all during this time. Do all that and you should see the two burs on the ends of the belt fuse together all the way to the outside edges. Give the belt 10-15 minutes to reach room temperature before trimming the burrs. When you trim off the burrs, you shouldn't see any cracks or splits anywhere.

If you succeed, the join should be as strong as the parent belt. If not, keep trying until the belt is too short to use and then carry on with it as a practice piece!

Other than that, you could always machine new pulleys for a poly V belt, but the polyurethane round belts do work, eventually :-)

Mark Rand RTFM

Peatol/Taig),

everything.

It took me quite a while to get the technique for joining plastic belts, but I can now make joints that last for years. The problem is that a knife cools too quickly, so the temptation is always to heat it to too high a temperature, charring the end of the belt, but not really melting to a significant depth.

You need to use a thick blade of brass or steel at a lower temperature so that the plastic only just goes sticky on contact. Hold the belt ends on the hot metal for 15 seconds or more so that the heat penetrates for a millimetre, then push the hot ends together and hold them for a few minutes until cool. The mushroom around the joint can be smeared flat with hot metal, then trimmed when cool with a sharp knife.

Cliff Coggin Kent UK

here's a better picture

cheers,

Rod

Nigel Cliffe wrote:

Sorry, seem to have lost my first reply. The gist was that I use the hollow type of of tubing with the ally joiner for an overhead drive and it gives smooth power transmission.

Rod

Rod wrote:

You can buy round leather belt from Clockspares of Dereham; it is less harsh on the Lorch pulleys than the plastic stuff (especially if you have bakelite pulleys). I prefer to join it with superglue (the stuff which uses a primer which you paint on one surface works best) and this provides silent drive withoug the "clink".

I use the same method on my 4" Centre Height Lorch Schmidt lathe with a 2m long 1/4" dia round leather belt; just superglue on the joint and it has lasted for several years.

Alan

If a suitable size, an "O-ring" seal should work. I use them for my Unimat lathe.

Don Young (USA)

Thanks for the replies, some good ideas to think about in there.

The ideas for fusing the belts are more precise than the "heat it and push" information we had before. Might also be worth asking Bond-a-Band for a price on a dozen made up belts (they say "any quantity" on their site...)

Not sure if the jointed hollow belts will come small enough for this application, the belt in question must be only 2 or 3mm section.

I couldn't find any belts on Clockspares website, but guess a phone call might reveal the part.

- Nigel

I use a piece of very clean 1/4" brass and it works perfectly.

At Upton Hall I've seen such belting used on a Boley F1 lathe. It had an annoying habit of going "ping" (maybe the pulley dia is really a bit too small for the length of the joiner). I prefer the stuff you heat join to that stuff. You can always dismantle the headstock if you want the belt off, good excuse to clean and oil the bearings.

If you give them a ring they should be able to find it; it was < 5 pounds a metre and came in 3 size, 1/8", 3/16" and 1/4". You probably want the smallest. 3/16" is too big for my WW 8mm lathe.

Alan

I have a 102 year old Boley Standard watchmakers lathe. The best solution I have found, is to use the spring belts used for 16 MM movie projectors. Most camera repair firms stock them. I have been using the same belt since 1975! My lathe has an ebony step pulley. The staple in leather sewing machine belts can do serious damage to the pulley.

Steve R.

Just following up and closing the thread (should anyone be interested!).

Friend has persisted with the poly-belt, and joining with heat. Some of the ideas here have helped with heating technique and the belt seems to be holding up now.

So, fingers crossed and the Lorch is back in action. Thanks for the various suggestions.

- Nigel