Re: [ATM] From mirror support to the frame

["Alan K. Henderson" <alankh@ev1.net>]

The aluminum tubing at the hardware stores is typically 1" diameter with a
.065" wall. Online Metals has tubing twice that thick. It also has
rectangular tubing; a 1.5x0.75 tube (with the long side vertical) would
support a heavier load without bending than a 1x1 tube.

The cell design (http://users3.ev1.net/~alankh/Cell4.gif) has plenty of
bracing for when the scope is pointed at horizon. But when facing up, the
full weight of the 50-pound mirror falls on the two center bars in the
diagram (where the 6-point flotation is mounted) and on the two vertical
sections where a collimation bolt is supported on each end. What
diameter/thickness of aluminum tubing would work?

I could make the tailgate out of aluminum as well, Since threading for
collimation bolts is often provided by a steel nut welded to the tailgate at
each of the collimation holes, I'd need to know if steel can be welded to
aluminum.

Alan

> if you don't mind the price, which is not very expensive but is not the
> cheapest either, try http://www.onlinemetals.com
> You can find there from stainless steel to titanium , to all types of
> aluminum alloys. They carry a large diversity of shapes and sizes.
>
> best regards,
> matt tudor
>
> -----Original Message-----
> From: Alan K. Henderson <alankh@ev1.net>
> To: atm@atmlist.net <atm@atmlist.net>
> Date: Saturday, July 16, 2005 7:51 PM
> Subject: [ATM] From mirror support to the frame
>
>
> >
> >Now for the frame. One-inch steel tubing would be sturdy enough for the
> >50-pound mirror, but steel is heavy, and this design uses about 13 feet
of
> >it. (Not counting the tailgate.)  I would like to use aluminum, but the
> >stuff available at Ace Hardware or Home Depot isn't strong enough. Where
> can
> >I find a heavier-duty variety of square aluminum tubing?
> >
> >Alan K. Henderson


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