Material for rudder bearings

rjp

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I'm looking for a source of flat sheet plastic material for making up some bearings/washers for my transom hung rudder. From my search of the YBW archives the preferred materials seem to be Delrin or UHMWPE. Anyone got any suggestions?
 
there was a lady who used to have a stall at jumbles around the solent area selling cylinders and blocks of these materials.
 
Almost any industrial plastic supplier will have what you want. Bear in mind 'Delrin'(nylon) absorbs water and swells slightly - not sure of the amount but bear this in mind when used as bearings etc. UHDPE is a cheaper sort of Teflon - slippery, so is ideal for washers etc, but also can absorb water(I think).
Depending on the thickness for washers, the white chopping boards used in the kitchen are I believe a form of UHDPE and are cheap! From memory they are about 6 - 8mm thick.
 
If you are not sure whether a plastic is water absorbent, soak it in water and then microwave it (be sure to include a cup or like of water in the microwave to save blowing it up).

If afterwards the plastic is warm/hot (careful!) it has absorbed water.

UHMWPE (Ultra High Molecular Weight Poly Ethylene) is supposed not to absorb water.
 
Delrin and nylon and completely different materials.

Nylon is very hydroscopic (absorbs water) and is not suitable for rudder bearings. Delrin is only slightly hydroscopic and is suitable, as is high or ultra high density polyethelene. Bear Brand Tufnol is also meant to be good.

Ian
 
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