"Alex" wrote in message
...
What is the optimal solution for this problem than?
I guess thousands of people before me encountered this problem before and
successfully(at least some of them) solved it.



"Mitch" wrote in message
...
How about using a spring washer of some sort (cone or wave type) in the
assembly to help you control the compression better? I would try this
in
conjunction with an elastic stop nut (nylock).

Your Delrin washers may cold flow after awhile and get thinner though,
which
might make it difficult to keep the compression constant.
--
Cheers,

--Mitch



"Alex" wrote in message
m...

I am using a swing arm for my home made device.
It was inspired by the swing arm lamp like this one
http://www.lightspc.com/img/g-2518.jpg

My swing arm is made of 3/8 square steel tubes and Delrin plates.
Tubes
are
attached to Delrin plates by 10-32 bolts.
I use steel washers against Delrin. That should give me low friction.

The problem I have is that it's hard to control bolts tightness. If
it's
not
tight enough the whole swing arm has a significant "play"
If you tight it to much it's hard to move due to high friction.

Is there a good solution for this problem?

BTW: what should I use to make sure bolts are not getting loose?
Retainer
nuts, lock washers, jamming nuts?

Thanks,
Alex


Alex,
The belleville washers others have suggested are a good option. A few
things to know. They come in different spring rates, by varying the
thickness. They also can be stacked. When stacking two with the cones the
same way the spring rate will double. Flip one over so the cones are
opposite and the travel doubles while the spring rate is cut in half. This
will keep a more constant pressure over a greater range of wear. You want
to use them with a flat washer against the delrin as the brake surface.
That way the bellevilles won't dig in and the tension will stay constant for
a very long time. Use the Nylon licking nut to keep the nut from working
loose.

Gary H. Lucas