In article 1104243020.895023.178950
@z14g2000cwz.googlegroups.com,
says...
I am looking to make a couple of tables that raise and lower. Each
would have a handle at one end, which when turned lifts or lowers the
top. The proposal is to use 2 screws linked to the handle shaft by a 2
pairs of miter gears.

I am having trouble finding an econmical source for suitable miter
gears. They do not need to be high quality or extremely large, but
need to accept/have up to a 3/4" diameter bore. They could even be a
strong plastic. Anyone have a suggestion where I could find something
suitable; preferrably in Canada?



Boston Gear makes nylon bevel gears in a limited range of
sizes. For example, a GP1632Y is a 16DP, 32T gear with 1-
1/4 dia hub. Motion Industries shows them in stock at
around $6US each.

Someone else mentioned car jacks as a source, and trailer
tongue jacks are another. You may also be able to use the
nut and screw, or the whole jack.

Don't forget that a two-screw lift isn't very stable. If
your load is small or is always centered you're probably
OK. A more stable arrangement for eccentric loads (other
than 3 screws in a triangle) would be a scissors lift (see
Southworth lift tables) or a parallelogram arrangement.
Each has advantages and drawbacks.

Ned Simmons