Making blocks/sheaves out of Delrin

[castaway]

I am in need of some big sheaves (approx 100mm wheels) and was thinking about using Delrin for both the wheels and the cheeks of the blocks.

The material is reasonably available on Ebay in both round bar and sheet. I don't have access to a lathe which of course would be ideal, but was wondering if any of the engineers out there would have any input / guidance etc. on working with this material.

Tufnol appears to be another suitable material but a bit more expensive.

Of course if anyone knows where I could buy ready made wheels, something over 65mm, I would be very happy to hear...has to be fairly cheap.

Thanks and regards,

Nick

 

[PetiteFleur]

Tufnol will be much harder wearing, and take higher loads. Delrin is softer and can deform if a large load is left on for a long period. Not quite sure how you will make the sheaves - they do really need to be turned to get a decent round bottom groove for the rope. You could try Lewmar for ready made sheaves - but I suspect they may be expensive - they only show spare sheaves for their 'T' track cars, which probably aren't large enough diameter.

 

[DownWest]

Look at www.plasticsonline.co.uk I have just bought both Delrin/Acetal and Tufnol from them. The Tuf was for winches at 100mm dia. They do round from 150mm.long up. But you need a lathe (or friend with) The sheet Tufnol is much cheaper and good for cheeks
Andrew
I did once make some sheeves on a pilar drill, not ideal but worked.
Ishould get this right first time, not by editing....
You can cut circles with hole cutters (the bimetal steel ones are best) and grouve the edge spinning the disc on an electric drill with a round file/rasp, rough but works. Delrin can be cut with a hack saw and filed, not as easily as Tufnol but possible.
Not sure about the deformability of Delrin under load, but it is common in blocks.--A

 

[PuffTheMagicDragon]

I do have a lathe (and other machine tools), however, I do not think that it is worth the hassle of my turning 'normal' sheaves. The material is not exactly cheap and there is a lot of wastage. Therefore I buy them ready-made.
I have only made 'specials', parts that were not readily available off the shelf.
I don't think that you should find much difficulty in sourcing ready-made: we can even find them here! /forums/images/graemlins/grin.gif

 

[DownWest]

Your right about the waste, About 950grms of Tufnol 100mm dia. bar ended up as 450grms of winch drum and a lot of smelly turnings. But nobody sells a winch like it.
Andrew

 

[rogerthebodger]

Why make when already available here
and here

Both have agents in the UK.

 

[pyrojames]

Classic Marina in Woodbridge do tufnol sheaves. I got some 80 mm ones from them some time ago.