Gibson Crankpin slop

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petermeyer
Posts: 307
Joined: Tue Oct 01, 2013 10:06 am

Gibson Crankpin slop

Postby petermeyer » Sat Feb 06, 2021 3:52 pm

Apologies if this has been covered before. I was close to finally running out Gibson crankpins, so I ordered some more from Wizard. When I came to fit some, I noticed that the holes in the bush were larger than my much earlier version which meant they were looser on the screw. This could result in the rods moving once in place. On the photo I hope the difference is visible, the 3 bushes to the right are new, the one on the left is an ancient one. The other thing is a random nut. Has the spec changed? is this anything I should be worried about?

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Tim V
Posts: 2865
Joined: Tue Jul 29, 2008 4:40 pm

Re: Gibson Crankpin slop

Postby Tim V » Sat Feb 06, 2021 4:13 pm

A known problem. You will never get reliable running with sloppy bushes(!).

Options:
1. Wrap PTFE tape around the pins.
2. Try another make of crankpins.
3. (my method, but I do have a lathe) make your own!
Tim V
(Not all railways in Somerset went to Dorset)

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steamraiser
Posts: 557
Joined: Thu Dec 31, 2009 4:49 pm

Re: Gibson Crankpin slop

Postby steamraiser » Sat Feb 06, 2021 5:03 pm

I wonder if they are old stock.
I have noticed quite an improvement in the tolerances and quality of the crank pins and bushes since Collin took over.
I suggest you return them to Wizard models as the bushes should be a good fit on the crank pin.

Gordon A

Simon Moore

Re: Gibson Crankpin slop

Postby Simon Moore » Sun Feb 07, 2021 7:39 am

I have never had this problem with gibson crankpins myself so i am wondering if you got a duff batch. Whilst i like gibson crankpins i have since started to use ultrascale ones which are worth the extra cost.

Might be worth sending them back if they are duff.

davebradwell
Posts: 1173
Joined: Fri Jan 18, 2019 3:48 pm

Re: Gibson Crankpin slop

Postby davebradwell » Sun Feb 07, 2021 9:32 am

The real issue here is that you're chasing a different problem every time yu put the thing together. If the bush moves to the side then it's a quartering error, outwards and you're after a mysterious crank-throw difference. Get rid of them asap and get some more from Colin.

A very long time ago I had some Sharman bushes which were eccentric - you could see that the hole was off-centre - and it took a while to work out what was going on. There'll be some of these lurking in a forgotten drawer somewhere.

This is all a reminder, of course, to mark all the working components of a chassis so they always go back in the same place in the same orientation.

DaveB


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