holders of bearing holders?

Good question. Twice I've sawed them off a damaged frame to use in my
new ones. But I'd like to get some as well.

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goldenchicken II said:

*Here perhaps?

http://www.staffordmfg.com/ *

Or 'McMaster-Carr' (http://www.mcmaster.com/)

The shaft collar is the more common option for a DIY machined bearing
holder. George Barnes uses a machined shaft collar for his frames. DM
used a shaft collar for the Vortex frame. They're not ideal cause
they're a little heavy for what you need and some can be a bit thin
where the bolt head is countersunk meaning that there can be very little
metal supporting the area under the bolt head. Depends on the make of
the shaft collar.

Here's a thread that talks about 'bearing holders'
(http://tinyurl.com/3w6n3).

Steve Howard has also used shaft collars for his steel unicycles.
Here's one thread where he talks about his 'stainless steel muni
project' (http://tinyurl.com/d2paw). Steve's gallery has pictures of
the shaft collar being machined but the gallery is down right now so I
can't link you there. Steve's main gallery page is at
http://www.unicyclist.com/gallery/showard

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In the UK I use Farnell for some personal orders. As I can't read
Swedish I don't know if this option is available to you but here is a
link to a 40mm 2pc collar:

http://tinyurl.com/bkhcm

It seems very easy to buy shaft collars over the web in the US, and
other metal items, but very difficult in the UK.

Regards

Keith

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Thanks for all the good links. Through them I managed to find a dealer
even in my home town!

I wonder why people have found it necessary to bore out a lip preventing
the frame to slip radially on the bearing surface. These collars seem to
be made for industrial use - won't they clamp tight enough not to slip
without a lip?

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goldenchicken II said:

*I wonder why people have found it necessary to bore out a lip
preventing the frame to slip radially on the bearing surface. These
collars seem to be made for industrial use - won't they clamp tight
enough not to slip without a lip? *

You don't want to clamp it down too tight as that will make the bearings
move less freely and will also wear out the bearings quicker.

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I haven't measured the torque used however I tighten them with a ball
ended allen key (screwdriver style handle) and I doubt it is any higher
than with the standard pressed bearing holders.

Saying that I generally braze a small lip of steel on the outside of the
shaft collars, this is easier for me than getting undersized collars and
boaring out to leave a lip.

Keith

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Gilby said:

*You don't want to clamp it down too tight as that will make the
bearings move less freely and will also wear out the bearings quicker.
Though that's probably less of an issue with good machined bearing
holders. *

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 ...

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keg said:

*I haven't measured the torque used however I tighten them with a ball
ended allen key (screwdriver style handle) and I doubt it is any
higher than with the standard pressed bearing holders.

Saying that I generally braze a small lip of steel on the outside of
the shaft collars, this is easier for me than getting undersized
collars and boaring out to leave a lip.

Keith *

The brazing solution did cross my mind but then I suppose you've got to
find a collar that is not too wide, just a fraction wider than the
bearings.

So you think it is enough having a lip only on one side (the outside)?

I saw that some collars have grooves on the inside. Find a ball bearing
with similar grooves on the outside and we could pip the lips ...

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goldenchicken II said:

*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 said:

*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.

+----------------------------------------------------------------+
| Attachment filename: unibearing.gif |
|Download attachment: http://www.unicyclist.com/attachment/346784|
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keg said:

*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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keg said:

*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 said:

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 said:

*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 said:

*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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