"Winston" wrote in message
...
David Lesher wrote:
... I agree the umph of most door openers, but how much CAN they
lift?
Approximately 'Not Enough'.

The springs counterbalance the weight of the door. When you pull the cord to
disconnect the door it should move easily up or down at any position.

With the pipe, I think I could anchor it with a arm from the house; that
would
provide some stability.

We have a good supply of thickwall ~1.5" sq tube, as seen on stuff here
http://2.ly/p9sp
Square tube is stronger and easier to work with.
--Winston

My platform stacker uses cam followers rolling on rectangular tubing.
http://baileynet.com/index.php?page=...m=cam+follower

The upright rails on my sawmill are channel cutoffs that weren't long enough
to use for horizontal track.
https://picasaweb.google.com/KB1DAL/...53006429714322
The wheel frame rests on the two horizontal square tubes whose open ends are
visible below it, one behind the idler pulley. When the wheel frame is off
they protrude like forklift forks, ready to support a basket of firewood.

The back ends are welded to four vertical plates, one on each side of each
channel, like an L lying dead on its back. The rollers that resist the
cantilevered weight on the arms are bolted between the plates and ride on
the outside of the channel flanges. It required fairly simple welding and
machining to build.

Two 3/8-16 threaded rods raise and lower the head. Bicycle chain barely
visible above the top bar keeps them synchronized. The screws are slow and
inefficient to raise the head between logs, with a battery drill, though not
bad to lower it by 24 or 32 16th of an inch for each new plank.

My third vertical track, the only one left out in the rain, is part of my TV
antenna.
https://picasaweb.google.com/KB1DAL/...51829689947138

The rails are aluminum U extrusions such as might frame a sliding shower
door. The slide that holds the rotator base is simply a rectangular steel
plate that fits loosely between the U's, [===].

Everything exposed to the weather is PT wood, aluminum, galvy, stainless,
brass or plastic. None of these were available cheaply in the shapes I
needed for load-bearing structural members like on the sawmill, and only
stainless bolts for axles for the bearings and pulleys. The cam followers
have removed the paint they roll over on the platform stacker so I spray it
with LPS3 when I put it away and wipe off the wind-blown grit before the
next use. It's protected from rain but not humidity or dust.

That's why I suggested a removeable jib crane made from fairly cheap
ready-made commercial components.

jsw