Grant Erwin wrote:
mlcorson wrote:
I need to construct something that will slide occasionally
inside a 2.5"x1/4" steel tube. I want to use a 2"x1/4 to
fit inside a 2.5"x1/4" Do they fit? [...]
I doubt it. Such tubes are welded, and there is a
weld bead on the inside, and [...]

What I recommend is to carefully fit pads of 1/4" steel
inside e.g. 3" square tube, just to make a rim around the
inside edge. This can be ground to fit over the bead, and
welded on the end, and the pad can be filed or
otherwise shaped to just fit e.g. a 2" square tube. The
inner member should have a similar pad put on its innermost
end, but on the outside. This will make it ride straight,
and will keep it from ever coming out. [...]

Sounds like you put in pads on 4 sides of each piece, 8 pads
total. Also like there could be an assembly problem if the
outer tube is closed on the other end. With 3 pads arranged
at A, B, and C as below (where = represents a pad, with A and
B fastened inside the outer tube, and C on the outside of the
inner tube) you could insert the inner tube until pad C hits
pad B, then tip the end up to pass B. Vice versa to remove.
.. B
.. ---=-----------
.. -----------= C
.. ------------
.. A =--------------
This is for tube walls vertical and horizontal, ie, where the
vertical cross-section of a horizontal run of tube is a square.
With a diamond cross-section (ie, tube rotated 45 degrees)
this idea would work ok with 6 pads.
-jiw