.

Delrin.??

I posted this only yesterday. **LINK**

Nick

We used to use tufnol on larger dp gears or nylatron on smaller ones.

Tufnol is excellent if you use the right grade in the correct grain orientation. Allegedly stronger and better able to cope with shock loads than delrin or nylon. But ideally needs proper attention to lubrication for long life. Delrin and nylon are, up to a point, happy run dry if kept clean.

Chocolate fireguard time if you use wrong grade and / or wrong grain orientation with Tufnol.

Clive.

Tufnol is surprisingly strong if the correct material is used (Woven sheet for gears, not rod which is rolled). I once had a vintage sports/racing car that used a Tufnol gear for the camshaft drive, admittedly the works racing team used a steel gear as they were not concerned with the noise but failures were very rare.

However these days I would use acetal (Delrin).

Russell.

Tufnol gears are/were used to a great extent on printing presses, the ideal lubricant happened to be printing ink.

Ian S C

One problem with the specialised plastics is locating them in small quantities at a reasonable price.

All plastics have rocketed up in price over the last few years. Tufnol used to be available for pence. I have seen works offices thrown up in a corner of the shop and sheeted in with tufnol sheet it was that cheap but now a piece of 1M x 300mm 10mm Whale Tufnol which is what is used for gears is over £100.

The cheaper grade is paper based and the dearer is fabric based.

I can only assume they are using £20 notes for the paper grade and Armani for the fabric grade.

Good for electrically insulating standoffs, knobs, handles and anything that doesn't need to be metallic. Rather like wood but without quite the same directional weakness. Machines nicely and polishes up with a bit of oil to show the colour textures. The phenolic smell isn't entirely pleasant but it's not particularly hazardous.

Some ideas and data here.

The rod is made by rolling up a sheet of paper or cloth in the resin, before hardening it. This means the layers are like the rings of a tree, so a gear will have the weak direction (between the layers) running across the teeth, making it easy to lose teeth. Gears made from flat sheets have the weak layers aligned so they only have to cope with forces trying to 'spilt' the gear – an unlikely situation in normal use.

I've not used them before but small quantities are available here…

**LINK**

HTH

Jon

I have several nylon gears in my Harrison L5 changegear set and when i needed one of them for cutting the thread in the backplate for a new chuck I was a bit worried if it would stand the load from cutting a 1.5 " X 6 TPI thread in cast iron but it did it fine , dont know if it would have done it if it had been a tufnol gear though , and a bonus is the geartrain runs a lot quieter with a plastic gear in it because as anybody with a Harrison knows the steel gears can ring a quite a bit at higher speeds.

regards Geoff

Edited By Kettrinboy on 21/03/2017 18:03:38