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ianh1968 wrote:Discuss - As regards fitting a nice soft bronze bush to the taper...


Ian

Not meaning to sound rude or anything like that. But you don't really think soft bronze is used do you ? Bronze is a alloy, a alloy is a combination of more than one type of metal. It can be made from differing combinations and different metals to give different strengths, wear characteristics.

I went looking for the topic on Turbomini's and found it!

http://www.minifreunde.at/harry/links/flywheel.htm < the bush

the topic

http://www.turbominis.co.uk/forums/inde ... tid=474587

I genuinely think that the best thing you can do is to make the thinnest film of substance which acts as a lubricant and is not thick enough to deform or creep in any way. This has got to be copper.

I was thinking about Mark's suggestion of dipping the relevant part in CuSO4 solution....the iron buggering off with the SO4 and the Cu being left behind as a coating. I don't think you are going to get enough of a thickness for it to provide any meaningful level of lubrication. A better idea would be this....Ignore the flywheel and leave it as it is....get the mating surface very very very clean and polished and then wash with a volatile solvent.

The crank surface can be plated with the CuSO4 solution, a bit of copper pipe as the anode and it being rigged up to a car battery. a bit of insulating tape, or some vaseline would mask off the area...threads.

We are talking about the smallest gnats fanny thickness of copper, but it would provide an interface which would stop the steel surfaces locking. It would not deform/flow at all and would be the idea solution.

I am going to do this when I put the 1430 together.

Smiffy wrote:

ianh1968 wrote:Discuss - As regards fitting a nice soft bronze bush to the taper...


Ian

But you don't really think soft bronze is used do you ?
Bronze is a alloy, a alloy is a combination of more than one type of metal.

I'm a bit thick, me, I can't tell the difference between cheese and proper metal...

I made the assumption that if a steel locking washer can be soft, then it is
more than likely that some kind of bronze alloy would be even softer.

A very quick bit of research shows that a "hard steel" is typically 55-66
on the Rockwell C Scale.

Phosphor Bronze is 92-98 on the Rockwell B Scale.
92-98 Rockwell B equates approximately to 11-21 as Rockwell C.
On the face of it, 11-21 RHC vs 55-66 RHC would appear to be quite soft...

I am sure that there will be an expert amongst us that will be able to clarify
matters.

Ian

ianh1968 wrote:I'm a bit thick, me,

Wouldn't like to comment on that, I'd probably get a warning but I think your been a touch hard on yourself.

The whole point of the exercise is to use a metal which is different to the crank/flywheel. This is the real problem with the crank and flywheel and why they weld themselves together.