Author Topic: Anyone fancy a simple lathe job?  (Read 529 times)

Anyone fancy a simple lathe job?
« on: March 29, 2021, 07:53:18 pm »
A Moulton TSR has Oilite rear bushes, which get a hammering because of the undersized offset pivot.  Well, you don't expect British engineering to be perfect.

The bushes are quite cheap as generic parts:

https://simplybearings.co.uk/shop/p120577/AJ0812-08-Oil-Filled-Bronze-Flanged-Bush-1/2x3/4x1/2-inch/product_info.html

But, for some reason, Moulton took an off-the-shelf part and machined the flange a bit thinner.  Or had some made.  Whatever, the standard cheap bushes don't fit.  The problem with buying bushes from Moulton is that they only come as part of a £48 kit, and you have to buy a load of other stuff that doesn't wear.

I imagine Oilite bronze is about the easiest material to machine this side of cheese.  Anyone fancy a job for beer money or a reciprocal favour?
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Chris N

Re: Anyone fancy a simple lathe job?
« Reply #1 on: March 29, 2021, 07:58:59 pm »
I’ll give it a go, but it might not be as easy as you think. The impregnated porous material can be tricky, apparently.

LittleWheelsandBig

  • Whimsy Rider
Re: Anyone fancy a simple lathe job?
« Reply #2 on: March 29, 2021, 08:25:54 pm »
The TSR pivot arrangement allows a triple crankset to be used after decades of AM designing for single rings and riders wanting at least a double. Not long afterwards, component manufacturers killed off triple cranks...
Wheel meet again, don't know where, don't know when...

Re: Anyone fancy a simple lathe job?
« Reply #3 on: March 30, 2021, 10:28:03 am »
If you get stuck I can probably help out.

Bronzes can be difficult but oilite can be machined but needs a very sharp tool bit to avoid 'smearing' the bronze over the surface and closing up the pores.

Assume you would supply bearings and sketch.

Is there a method of supplying oil to the bearing in service i.e grease/oil nipple - could one/two be provided ?
I'm in Clevedon - North Zumerset

Richard.

Re: Anyone fancy a simple lathe job?
« Reply #4 on: March 30, 2021, 01:30:48 pm »
Yes, there is a grease nipple which seems to work correctly and purges both sides.  I also read about the problem of Oilite "smearing" if a blunt tool is used.  The part that needs thinning is a bearing surface for the "ears" of the frame so it does need to maintain its original porous nature.

This is the second set of bushes, as slope replaced them during his ownership, but that was because he didn't have a grease gun at the time - he then bought one and gave it to me when I bought the bike from him.  The current ones, which have been maintained, aren't worn yet but it would be good to be ready.

The TSR pivot makes the often-slated Brompton design look good.  The Brompton pivot is small, plasticky, and costs a lot to overhaul, but it will usually last for years of use and abuse.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

LittleWheelsandBig

  • Whimsy Rider
Re: Anyone fancy a simple lathe job?
« Reply #5 on: March 30, 2021, 02:04:54 pm »
If kept properly greased, both Brompton and TSR pivot bushes last well.
Wheel meet again, don't know where, don't know when...

Re: Anyone fancy a simple lathe job?
« Reply #6 on: March 30, 2021, 03:46:04 pm »
So you just need to take a skim off the 'top surface of the top hat' - that should be fairly easy.
Could even be a while you wait service !

I do need to (well would like to) replace the grease in my S3X one day ! and understand you need a special spanner to do it correctly ?

R.

Re: Anyone fancy a simple lathe job?
« Reply #7 on: March 30, 2021, 04:11:27 pm »
I have that spanner.

S3X hubs don't screw themselves together too hard, so it's an easy job.  There are no pingfuckits inside, either.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.