Re: [ATM] Ball bearing for triangles

["A. Suijkerbuijk" <a.suykerbuyk@wxs.nl>]

Hi Peter,

What I mean is that it is not slippery, it damages easily. When you turn a
nut on a bolt, it can get stuck by a slight damage.

Regards,
Adrie Suijkerbuijk

----- Original Message ----- 
From: "Peter" <peter@kitgear.com>
To: "A. Suijkerbuijk" <a.suykerbuyk@wxs.nl>; "Raphaël GUINAMARD"
<rguinamard@infonie.fr>; "ATM Group" <ATM@atmlist.net>
Sent: Friday, September 03, 2004 12:03 AM
Subject: RE: [ATM] Ball bearing for triangles


> Hi Adrie,
>
> Please explain what you mean about stainless freezes easily?? Stainless
has
> 1/2 the thermal expansion coeff of aluminum.
>
> Thanks,
>
> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net]On Behalf
> Of A. Suijkerbuijk
> Sent: Thursday, September 02, 2004 2:17 PM
> To: Raphaël GUINAMARD; ATM Group
> Subject: Re: [ATM] Ball bearing for triangles
>
>
> Bonjour Rafael,
>
> You could drill holes in the triangles to restore the original centers of
> gravity. However I wonder if stainless steel is the best material for
> bearings. This stuff "freezes" easily. Bolts and nuts out of stainless
steel
> need much play and even then you can have problems.Perhaps the use of
> aluminum would be better.
> Interesting to read about "heating the aluminum layers". I understand that
> in this case both sides of the mirror have a aluminum coating? Normally
the
> back side of the mirror cools most, since the aluminum avoids radiation.
>
> Regards,
> Adrie Suijkerbuijk
> ----- Original Message -----
> From: "Raphaël GUINAMARD" <rguinamard@infonie.fr>
> To: "ATM Group" <ATM@atmlist.net>
> Sent: Wednesday, September 01, 2004 10:07 PM
> Subject: [ATM] Ball bearing for triangles
>
>
> > First of all, I apologie for my poor technical english...
> >
> > I have a 24" f/3.3 dob.
> > My mirror is very fine (40mm) an I have built a 27 point mirror cell (9
> > small triangles on 3 big triangles).
> > For the "rotation" of the big triangles I have used a carriage bolt that
I
> > have drilled so that the collimation bolt could pass though, and I have
> > beveled the bottom part of my triangle so that the spherical part of the
> > bolt could fit in it.
> > I have put only a very very small amount of grease.
> > My big triangles are quite heavy (6 mm stainless steel) and my problem
is
> > that there is friction and my triangles needs each approx 300 g of
force
> to
> > be really in the same plane.
> > I think this could deform a little bit my miror because I see some
> spherical
> > aberration in the star test.
> > My question : does anyone has example of using bearing to support the
big
> > triangle (close picture, reference where I could find the bearings) ?
> > I've seen Bruce Sayre page
> > (http://www.foothill.net/~sayre/22-in.%20binocular.htm) but I can't get
in
> > touch with him to have more details .
> > Thanks for your help
> >
> > _______________________________________________
> > ATM mailing list http://www.atmlist.net/
> >
>
>
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>
>


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