advice for a strong draw/counter pull

wayne mak wrote:
> I want a STRONG smooth slide. I was
> thinking of having 1" OD round rods inside the cabinet base that are hard
> mounted then having it outer sleeved with a 1" ++ ID tube that has a
> mounting point. What is a good clearance? What is a good material for the
> outer sleeve that will slide smooth on the steel rod?

What about sandwiching the rod (front and back on each side) between two
pieces of UMHW polyethylene? You could shape the inner sides of the two
pieces to match the rod, and as it gradually wears over time you could
tighten the two pieces together a bit.

Chris

wayne mak wrote:
> The frame of the island is made from 2"x2" ¼ angle iron and will be 52" x
> 32", what I want is a 12" x 50" (or about 50") pull out counter so you can
> sit at the island to eat or drink. I want a STRONG smooth slide. I was
> thinking of having 1" OD round rods inside the cabinet base that are hard
> mounted then having it outer sleeved with a 1" ++ ID tube that has a
> mounting point. What is a good clearance? What is a good material for the
> outer sleeve that will slide smooth on the steel rod? I could use bushings
> if needed. If there is such a beast out there that would be great.

Anything that heavy is unlikely to slide without a lot of effort, no
matter what material you use, I'd think. The other problem with your
telescoping-rods idea is that you can only support the rods at the back
of the case, not at the front, so the countertop will sag a lot.
(Unless you also put wheels under the front, which might be enough to
take the weight off it so it would slide ok too.)

I was taking apart an old typewriter recently, and came across a nice
simple way of doing strong smooth slides that might work pretty well for
this. The slides were made of a couple of pieces of angle iron (well,
ok, it wasn't really angle iron, but that's the idea) with the insides
machined smooth, facing each other to make a square with small gaps at
two corners, and then it had a couple of loose ball bearings that rolled
between them. The typewriter version was pretty tiny (about 3/16"
bearings), but it should work just as well if you scale it up.

I'd also be tempted to suggest some sort of system where you've got a
gear rolling on a rack at each end of the slide and an axle connecting
the two gears, so that it's always going to go in and out perfectly
straight. With something as wide and shallow as your shelf, I'd think
it would be pretty easy to get it cocked sideways and then it'll start
binding up good on the slides.

Though I haven't looked at it recently, I'd bet the McMaster-Carr online
catalog (www.mcmaster.com) has some machine slide components in it that
would be good for this sort of thing. They'll also have large ball
bearings, if you go that route.

- Brooks


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