telescopic tubing
 

I'm in the early stages of designing a piece of furniture that has a
single column suspened from the ceiling. It must adjust vertically
carry ~100 #'s ecentrically and have as little play as possible and be
inexpensive to make. I'm thinking of using 2.5" x 2.5" x .125" square
tube female & 2" x 2" x .125" male. My local steel providers don't
provide anything with closer tolerances how do i take up the slack. I
remember seeing a piece of weight lifting equipment use a kind of
teflon tape as a type of anti friction / shim. Any ideas would be
appreciated. www.ironworkx.com

telescopic tubing
 

Vittorio wrote:
I'm in the early stages of designing a piece of furniture that has a
single column suspened from the ceiling. It must adjust vertically
carry ~100 #'s ecentrically and have as little play as possible and be
inexpensive to make. I'm thinking of using 2.5" x 2.5" x .125" square
tube female & 2" x 2" x .125" male. My local steel providers don't
provide anything with closer tolerances how do i take up the slack. I
remember seeing a piece of weight lifting equipment use a kind of
teflon tape as a type of anti friction / shim. Any ideas would be
appreciated. www.ironworkx.com

How do you plan to connect this to the ceiling?
Do you mean hundreds of pounds of side forces?

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
Get off a shot FAST, this upsets him long enough to let you make your
second shot perfect. -- Robert A Heinlein.

telescopic tubing
 

As you are finding out, the regular grades of square tubing are not very
good at telescoping. The sizes don't match and the tube usually has an
inside weld flash the size of mount Everest. Some tube manufacturers
make a range of 'telescoping' tube. These are sized to give good fits,
have the flash removed on the inside as well as the outside, and have
matched corner radius. Not commonly stocked by the local suppliers but it
is available. Plan on getting quite a bit of it at one time.

Your other choice is to weld .120 (or perhaps .104" for some extra
clearance) pads on the outside of the small tube, inside of the large tube
(one end of each tube). You can cut a grove to accomodate the flash. The
assembly must be done from the end opposite the telescoping end. This
might be a safety factor in your case or make it impossible to take apart.

I'd suggest using the pads for you prototype and early production. If you
get to any volume, switch to the telescoping tube.

cheers.

Vittorio wrote:

I'm in the early stages of designing a piece of furniture that has a
single column suspened from the ceiling. It must adjust vertically
carry ~100 #'s ecentrically and have as little play as possible and be
inexpensive to make. I'm thinking of using 2.5" x 2.5" x .125" square
tube female & 2" x 2" x .125" male. My local steel providers don't
provide anything with closer tolerances how do i take up the slack. I
remember seeing a piece of weight lifting equipment use a kind of
teflon tape as a type of anti friction / shim. Any ideas would be
appreciated. www.ironworkx.com

telescopic tubing
 

"Vittorio" wrote in message
om...
I'm in the early stages of designing a piece of furniture that has a
single column suspened from the ceiling. It must adjust vertically
carry ~100 #'s ecentrically and have as little play as possible and be
inexpensive to make. I'm thinking of using 2.5" x 2.5" x .125" square
tube female & 2" x 2" x .125" male. My local steel providers don't
provide anything with closer tolerances how do i take up the slack. I
remember seeing a piece of weight lifting equipment use a kind of
teflon tape as a type of anti friction / shim. Any ideas would be
appreciated. www.ironworkx.com

Teflon tape:
http://www.usplastic.com/catalog/pro...Teflon%AE+Tape