On Wed Aug 20 19:41:43 2025 John B. wrote:
On Wed, 20 Aug 2025 19:35:19 -0500, AMuzi <am@yellowjersey.org> wrote:
On 8/20/2025 4:54 PM, Jeff Liebermann wrote:
On Wed, 20 Aug 2025 15:49:49 -0500, AMuzi <am@yellowjersey.org> wrote:
On 8/20/2025 1:37 PM, Jeff Liebermann wrote:
On Wed, 20 Aug 2025 12:11:52 -0500, AMuzi <am@yellowjersey.org> wrote: >>>>
On 8/20/2025 12:02 PM, Jeff Liebermann wrote:
On Wed, 20 Aug 2025 08:50:11 -0500, AMuzi <am@yellowjersey.org> wrote: >>>>>>
Locktite has several products to fill excessive
shaft/bearing clearance and some can be very effective, just
not always:
https://www.henkel-adhesives.com/uk/en/applications/all-applications/how-to/retaining-with-loctite-retaining-compounds.html
Maybe. I followed the above link to Loctite 648. The specs indicate >>>>>> a maximum gap fill of 0.15mm (0.006in) which might work with the >>>>>> 0.005in gap:
<https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_6480.html>
<https://www.henkel-adhesives.com/uk/en/applications/all-applications/how-to/retaining-with-loctite-retaining-compounds.html>
<https://dm.henkel-dam.com/is/content/henkel/product-information-sheet-loctite-648-anaerobic-retaining-compound>
The gap also needs to be air tight (anerobic). To remove it requires >>>>>> 250C (482F) heat which might be a problem for the bearing lubricant. I >>>>>> couldn't find a suitable solvent.
Right, typical specs for that whole series. Pressing the
shaft and sleeve together makes an anaerobic fit so that's
not a problem in practice.
Good.
Loctite release temperature doesn't affect steel at all (but
can't be done nondestructively around paint. Or carbon
layups!). If you plan to re use a bearing (who does that?)
just pop out the seals and flush/fill.
I've had the problem of anaerobic glue taking forever to harden when >>>> fixing old sewing machines. My solution was to remove the oxygen
with:
<https://www.google.com/search?udm=2&q=oxygen%20absorber>
and embalm the joint with package shrink wrap:
<https://www.google.com/search?q=package%20shrink%20wrap&udm=2>
The package wrap is then shrunk in place with a common heat gun,
displacing all the air:
<https://www.google.com/search?q=heat%20gun&udm=2>
The hardening time went from about 8 hrs to a few minutes.
Different crank system but typical bearing with seal & tool
shown here:
http://www.yellowjersey.org/photosfromthepast/wfd25q.jpg
Hmmm... I wonder if just wrapping the crank with aluminum foil and
then gluing the foil in place will work? I just measured some
Reynolds Wrap "heavy duty" foil at exactly 0.001in thick. (I have
other foil thicknesses available but I don't want to open the boxes). >>>> Four or five wraps of this foil should might work for a 0.005in gap. >>>> To keep it from wrinkling or moving, a few drops of cyanoacrylate
(super glue) adhesive.
Gone for a free lunch and a service call. To be continued, assuming I >>>> survive.
As with any very thin shim, I strongly doubt a 0.001
anything can be installed intact in this or similar application.
I had the same doubt about 0.001in thin shims. I've been playing with
the "heavy duty" Reynolds Wrap aluminum foil. I think it will
survive. If you have installation problems, use one or two layers of
foil instead of 4 or 5, and fill the gap with some kind of expanding
glue:
<https://www.hippoproducts.co.uk/product-details/hippo-expanding-glue/>
I'll see if I can find something similar that's sold in USA. Also,
some aluminum foil that's thicker than 0.001in.
tempered steel shim stock is a commodity. As are feeler
gauges if you only need a short length.
pick a thickness.
https://www.mscdirect.com/product/details/32019895
https://shop.awggases.com/flat-length-steel-feeler-gauges-0-0025-in-12-in-length
Is this a Shimano two part BB, threaded or press fit? I've had a
number of threaded BB's, no press fit (which seems like a poor design)
so my first effort to solve the question would be, "What does Shimano
say about the problem?"
Press fit into a properly designed and executed frame is fine. A bearinhg is press fit into a threaded sleeve.
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