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Bob UK
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Posted From: 94.197.122.79
Posted on Saturday, 17 January, 2015 - 12:18 pm:   Edit PostDelete PostView Post/Check IP

Plastics tend to been seen as inferior or cheap. But without them we would be using ceramic and wood instead. Both nice materials but not always the best for the job.

Plastics have 3 distinct types, thermoset and thermoplastic and resins like glass fibre wwhich is exothermic.

The column covers are thermoset and wiring insulation is thermoplastic.
Note that although the column cover doesn't bend and wiring does, it can be the otherwise round. There are thermosets that are soft.

Tufnol. This thermoset plastic is very useful and it machines and files like soft metal. If holds threads well. It is an ideal replacement for Bakerlite.

Tufnol makes good low torque gears like found in wiper motors. Also is good for electrical stuff.
There are different grades and makes because the patent has lapsed. With Tufnol and brass high quality fuse box and distribution boards can be made just like older RRs.

Urethane is of particular interest in the light of a comment by Richard Treacy about compliant bushed cars.

My car being a 74 is compliant. The bushes are 40 years old.
I guess this applies to most Shadows.
Sooner or later they are going need changing. Mine seem ok but how do you actually test them. The best I can think of is a visual and measurement. A crowbar will show a broken on though.
Urethane is used by race guys for suspension bushes. It comes in round solid bar and it easy to turn and drill. The centre hole is usually bushed with stainless steel tube.
I have made a few. Most designs are two top hats from either side with a single SS tube. Sometimes fat washer either side. Water lubricates them. Hence SS only --- important mild steel will rust and rip the Bush up.

In the case of compliant bushes nothing swivels so the design is very much easier.

I imagine two top hats a accurate length of SS tube and 1/4 thick SS washers to make sure that the subframe cannot fall off.

There are many grades from so soft that it comes in 2 part liquid and it's moulded, to hard stuff for car suspension. The one I use is blue in colour and quite hard.

The problem is that which one is best. I have no idea and the maths is very complex.

Also on tee one topics Bill Coburn changed some and it not for the faint hearted, because it's possible that the whole subframe May have to come out should a bush refuse to come out. Rear wheel brgs are easier.

Screw driver handles can be turned into other things (not suspension bushes) such as insulated spacers.

I made two plastic rollers for a van sliding door from a screw driver handle. The rollers were not available separately and the assembly was 150. Took 30 mins to make. The cheap amber handles are not very good also not oil proof.

(Message approved by david_gore)

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