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Fork crown repair

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Old 02-11-13 | 08:31 AM
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Bikes: '73 Raleigh RRA, 1986 Trek 500 commuter

Fork crown repair

Due to a machine shop screw up (back in the '70s), my '73 Raleigh RRA fork has a crown race portion which was cut too small for an ISO Campy race (26.4mm). The fork crown measures ~25.96mm (according to my digital calipers). I either need to find a shop which can knurl this, or braze up the crown race portion and remachine it correctly.

Anyone on this board do this, or does anyone know of a shop in Chicago or burbs that can do either of these?

re: the original screw up; I had the fork replaced by the LBS because of an alignment issue with the original. The replacement must have been JIS size, as the Campy race would not fit on. The LBS was relatively new and didn't have a crown race cutter (NE Iowa).
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Old 02-11-13 | 03:23 PM
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Before you try to braze or knurl the fork crown race oversize, you might try finding some sheet-metal that is 0.2mm thick, use it to make a shim between the fork steertube race and the headset race.
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Old 02-11-13 | 05:24 PM
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I'd probably lay some brass then remachine. Depends on the filler used for the crown/steerer. Andy.
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Old 02-11-13 | 05:55 PM
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if knurling on a lathe would work, it would save the paint job if it is still good. Dunno if there is anyone in that area with a lathe, maybe check with Clockwork in Minneapolis ?
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Old 02-11-13 | 06:27 PM
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I checked with Chris Kvale in the twin cities and he will do it for a reasonable price (rebuild with silver and remachine). I've used shims for 35+ years, but I can only get those so tight, and figured it was time to fix it once and for all. Thanks for the suggestions.

EDIT: BTW, it was interesting to check with a few shops I know of down here. One, that has been in business for quite some time, had no idea what I was talking about I also sent an email to RRB Cycles, as Ron at least used to build custom frames, but no reply yet. I'm not originally from here, so other than Licktons, have never been to any of the bigger or old school Chicago shops and don't know much about them.

Last edited by Pars; 02-11-13 at 06:30 PM.
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Old 02-11-13 | 09:07 PM
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You might check with Owen Lloyd <olloyd1@gmail.com> South side of Chitown doing a collective frame shop thing and owns a shop. Andy.
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Old 02-12-13 | 08:17 AM
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+1 on knurling. With the right tool (not any knurler would work) it's a quick job on a lathe, with no effects on the paint. JA Stein has a nice tool exactly for that, but I doubt many shops have it. I've also tried shimming, it works but it's a pain.
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Old 02-14-13 | 09:27 AM
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Originally Posted by tuz
+1 on knurling. With the right tool (not any knurler would work) it's a quick job on a lathe, with no effects on the paint. JA Stein has a nice tool exactly for that, but I doubt many shops have it. I've also tried shimming, it works but it's a pain.
I agree - find someone with the Stein tool and it will take just a minute or two to do the job. If your local shop doesn't have one it would be worth the cost to send the fork off to have it done. No heat or finish damage and low cost is hard to beat.

I'd shy away from trying to shim it. That is a VERY thin shim and will tend to crumple up below the race as it's pressed down. This very well could make the race fit tightly on the crown race seat but not sit squarely down onto the crown. It's a tough row to hoe.

The Stein tool was designed for just this and works just as it should.

Good luck.

dave
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Old 02-14-13 | 10:41 AM
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For those not familar with the knurling tool it is $185 from one vendor, here's the link: https://www.universalcycles.com/search.php?q=stein+tool

and instructions: https://www.jastein.com/PDF/Stein%20K...nstruction.pdf
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Old 02-14-13 | 11:45 AM
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I guess I'll get a straight knurling wheel for my lathe. I suspect the crosshatched knurls would work just as well and Stein just went with straight because it's better for bench use, but why mess with success
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Old 02-14-13 | 12:35 PM
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Already sent off to Chris Kvale to be built up and remachined. If I could have found someone who could do the knurling I would have probably gone that route.

I would think crosshatched knurls would work better than straight (as the Stein tool does), but I might be missing something...
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Old 02-14-13 | 02:24 PM
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my concern would be depth of the knurl and how much damage to the knurls that putting the race on does. I suspect that straight knurls would be better for both of these issues
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Old 02-15-13 | 03:21 PM
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Originally Posted by unterhausen
if knurling on a lathe would work, it would save the paint job if it is still good. Dunno if there is anyone in that area with a lathe, maybe check with Clockwork in Minneapolis ?
Unterhausen; Joel started in Minneapolis, however a year or 2 ago he moved and is currently in the Milwaukee WI area I believe.
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