Re: ATM problem with mirror cell

["A. Suykerbuyk" <asuyker@wxs.nl>]

Hi Jan,

Welding a nut on both sides of a steel tube is possible, however it will be
impossible to turn a bolt in them. The reason is a certain change of
dimensions,
caused by the heat of the welding process. You will have to use a tap after
welding.
Another solution is to weld two nuts together (and use a tap after welding).

Adrie Suijkerbuijk.
-----Oorspronkelijk bericht-----
Van: Jan van Gastel <jhm.van.gastel@mdw.vu.nl>
Aan: ATM <atm@shore.net>
Datum: woensdag 2 augustus 2000 19:06
Onderwerp: ATM problem with mirror cell


>
>For my 20" I have a 18 points cell: three bars, with two triangles on each
>bar as usual. The (1/3 inch diameter) bolts connecting the bars to the
>tailgate are the collimation bolts, also as usual.
>
>When I had the tailgate made, I was afraid that the collimation bolts
>wouldn't have enough grip in the threads in the square tube walls (the
>rungs), so I had a nut welded on top of each of the three mounting holes,
>instead of threading the tubewalls. And now the problem: The welded nut
>construction leads to 3 mm (1/8 inch) of play at the heigth of the top of
>the mirror, due to the movement of the bolt in the nut. So the top of the
>mirror can move 1.5 mm (measured from the center) in each direction. I have
>been thinking to solve the problem with another nut, at the other (bottom)
>side of the tailgate to lock the collimation bolts when collimating is
done.
>But I think the collimation will be gone then , because the collimation
bolt
>will change possition when the locknut is fastened. And it will give al
lot
>of movement of the supportpoints under the mirror, when I use a sling. When
>I use silicone blobs there will be too much strees on the mirror I think,
>because the mirror will try to hold the cell construction together.
>
>So I think there is no other solution then welding another nut against the
>bottom rungs with the holes, at the opposite side of the holes of the
>collimation bolts, so that each collimation bolt will be held by two nuts,
>about 25 mm from each other.
>
>Does this make sense or is there an other (hopelfully easier) solution?
>Jan van Gastel
>http://www.geocities.com/janvangastel/
>
>
>