Thanks Mark. Took me a while to understand how your
bearing system works: when extended, the bearings on
the female and male are on top of each other so there
is no clearance.

I was going to suggest building up small ramps with
epoxy, on both sides of the plastic band.

If you have rounded insides of the beams you can
compression-fit the bands in these grooves inside the
female.
You might also be able to weld the strips together, in
a groove around the male beam.

But it appears that there are glues that sticks to
UHMW:
http://www.garlandmfg.com/plastics/bonding.html
PSA backed UHMW strips:
http://www.garlandmfg.com/plastics/pstape.html

here is a forum page with a discussion of the subject:
http://bbs.homeshopmachinist.net/Forum1/HTML/009217.html
Here is a page with lots of slippery tape, teflon and
UHMW amongst others:
http://www.cshyde.com/tapecat.htm

Sigurd

>Hi Sigurd,

Both the male and female beams have a band of epoxy
glue at the ends and 400mm from the ends, the bearing
thickness being half the clearance. This way when the
bearings are not aligned there is plenty of clearance
for telescoping. This is important if you want an easy
telescoping boat.

Yes I did consider plastic bearings but plastic
bearings of half the thickness of the clearance (like
the epoxy bearings) become too thin to screw onto the
beams and I don't know of any glue that sticks to
UHMW-PE (though there may be). If you use plastic
bearings of full thickness on the ends only you lose
the telescoping clearance with the added problem of
the bearings preventing the beams from coming fully
apart (and assembly impossible).

The epoxy bearings worked well and are easy to make. I
only used bearing pads on the bottom angled faces and
not on the top. As it turned out they don't need to
be tight when the beams are extended. We tried sailing
the boat at folded width which meant the bearings
weren't aligned and despite plenty of clearance the
beams didn't rattle around at all, even in rough
water.

I agree plastic bearings would be a good solution if a
way to fix them could be found.

Cheers,
Mark




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