holders of bearing holders?

goldenchicken II wrote:
*With an ID of 40 mm (equal as the bearing's OD) I believed the shaft
collars couldn't be tightened so much that they prevent the axle from
rotating freely ... *


Although the inner radius is 40mm the two parts do not make a complete
circle, if you put both parts together and measured the distance from
wall to wall you would measure around 37mm. To explain without drawing a
picture imagine they made a single collar ID 40mm and then cut it in
half with a 3mm wide saw blade.

This clearance means you can easily overtighten & crush a bearing.

So far I have either ignored the lip or brazed on the outside only, this
makes it much easier to align the wheel during assembly. On my first
frame I did suffer from a little slippage hence adding a lip.


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keg wrote:
*Although the inner radius is 40mm the two parts do not make a
complete circle, if you put both parts together and measured the
distance from wall to wall you would measure around 37mm. *


That does sound a bit discouraging. On my 36" wheel (which is what I
plan to build the frame around) it is hard to find out how hard to
tighten the bearing holders. The heavy wheel is not a sensitive
indicator and it is easy to overtighten, I have noticed.


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Would this work?

Instead of welding/brazing the frame tubes directly onto the upper
bearing holder you weld them onto a 3 mm steel plate which you use for
bolting a (stock) bearing and its house (plummer block type). Such
housings can be found in aluminium or polymer. The bolts could perhaps
be of QR type.

The benefit would be having a proper bearing housing that is not giving
any slip or flexing. Haven't found a suitable one yet though.


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keg wrote:
*Although the inner radius is 40mm the two parts do not make a
complete circle, if you put both parts together and measured the
distance from wall to wall you would measure around 37mm. To explain
without drawing a picture imagine they made a single collar ID 40mm
and then cut it in half with a 3mm wide saw blade.

This clearance means you can easily overtighten & crush a bearing.
*



I found the illustration for you ;-)

The inner diameter of this collar is 40 mm when 's' is 2 mm. I believe
you would be able to fine tune this measurement with help of washers so
that tightened the clamp provides a sufficient hold without deforming
the bearing.

And, why not put some red lockite on the lower part of the collar?

All to avoid the trouble of making a lip ...


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keg wrote:
*Although the inner radius is 40mm the two parts do not make a
complete circle, if you put both parts together and measured the
distance from wall to wall you would measure around 37mm. To explain
without drawing a picture imagine they made a single collar ID 40mm
and then cut it in half with a 3mm wide saw blade.

This clearance means you can easily overtighten & crush a bearing.
*



I found the illustration for you ;-)

The inner diameter of this collar is 40 mm when 's' is 2 mm. I believe
you would be able to fine tune this measurement with help of washers so
that tightened the clamp provides a sufficient hold without deforming
the bearing.

And, why not put some red lockite on the lower part of the collar?

All to avoid the trouble of making a lip ...


+----------------------------------------------------------------+
| Attachment filename: wns.png |
|Download attachment: http://www.unicyclist.com/attachment/347379|
+----------------------------------------------------------------+

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goldenchicken II wrote:
I believe you would be able to fine tune this measurement with help of
washers so that tightened the clamp provides a sufficient hold without
deforming the bearing.


I would think you could do a machined collar like that up very tightly
indeed before it would deform the bearing, as the case of the bearing is
supported almost all the way round. The cheap pressed bearing holders
are quite bendy and really only grip the bearing at two points (top and
bottom) so the middle could spread quite easily.

Do people who are using machined bearing holders/collars get much
problem with deformed bearings from overtightening?


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rob.northcott wrote:
*I would think you could do a machined collar like that up very
tightly indeed before it would deform the bearing, *


I am not sure I agree with you. Take another look at the illustration.
The bearing that goes into that collar has a 40 mm diameter. This is the
same diameter as the opening of the collar -as long as the distance
between upper and lower half is 2 mm (where the bolt holes are placed)-.
If you tighten the parts so they go against each other the hole is no
longer circular and the diameter will be less then 40 mm.

So depending on how strong the collar is and how much porridge you ate
as a child, you could squeeze that bearing inside the collar to be oval.
Placing washers on the bolts between the two collar parts might be a way
to adjust the squeeze to perfection ...


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goldenchicken II wrote:
*I am not sure I agree with you. Take another look at the
illustration. The bearing that goes into that collar has a 40 mm
diameter. This is the same diameter as the opening of the collar -as
long as the distance between upper and lower half is 2 mm (where the
bolt holes are placed)-. If you tighten the parts so they go against
each other the hole is no longer circular and the diameter will be
less then 40 mm.

So depending on how strong the collar is and how much porridge you ate
as a child, you could squeeze that bearing inside the collar to be
oval. Placing washers on the bolts between the two collar parts might
be a way to adjust the squeeze to perfection ... *
I sincerely doubt that would be a problem; I doubt that you could
actually deform the bearing by hand with that holder.

That said, a while ago I came up with 40 ft-inches (same number as
cranks, different units) as a reasonable torque for the bearing
holders.

This comment applies only to the nearly-completely circular type, not
the main-cap type of bearing holder.


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