Re: TV Lift

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"E. Lee Dickinson" <lee@xxxxxxxxxxxxxxxxxxxxx> wrote in >
> "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>
> > How's your TV lift coming?

<stuff snipped>

> The second is the one you asked about, my projector lift.  It worked
> beautifully for a month, before the motor burnt out. Pics of that online
> too. This was a very, very DIY project. It moutned up in my bedroom
ceiling,
> where I used an X10 appliance module to raise and lower both the
home-built
> lift and the store-bought roll down screen.
>
> As I said, the motor burnt up. Also, I occasionally had to reach up and
> adjust the projector after it "landed."  I'm going to re-build the thing
> with drawer slides as guides, and an off-the-shelf linear actuator. I
> believe you mentioned these same two items when you were talking about
your
> dog bowl lift. :)

Yeah, there are a lot of ways to do lifting.  I had been looking at linear
actuators and threaded rod lift screws and all sorts of stuff.  The power
window systems in cars that I have worked on used a threaded rod with a
scissor-jack like assembly to lift and lower the window.  I've looked at
cable lift designs, where you build a framework and lift the weight, in this
cae the dog food bowl tray, like an elevator in a shaft.  Many of the
writeups of home-built lift systems end up like yours - too much torque
required of the motor, which burns out as a result.

Norm Abrams' device was a wooden box within another box with only enough
space between them to accomodate the slides.  I can't remember what he used
but I've got some really slippery tack-bottomed Teflon ones that I think
will work.  I have been tempted to used the ball bearing telescoping drawer
guide assemblies at each of the four corners and a large 3/8 or 1/2"
threaded rod as the lift screw.  Trouble is I can't find any drawer kits
that are 3' long.

> When building mechanical things, I reference Gordon McComb's "Robot
> Builder's Bonanza" and Edwin Wise's "Animatronics: A guide to animated
> holiday displays."

Thanks.  I'll see if I can find them.

> The lift, as I said, worked well for a while. Getting the limit switches
> adjusted was tough. The real problem I had was, when I cut into my
ceiling,
> discovering my ceiling joists are not straight or parallel.  I built the
> projector lift as a 14.5" square. Had to use my Stanley 18oz Fine
Adjustment
> Tool and repatch some drywall. Measure twice, etc.....

That's just such a bitch to find things out of square like that.   My
problems are small compared to working to conceal a lift like yours in the
ceiling.  I have a small area of kitchen floor space flanked by cabinets in
which to build my lift.

> The new version will be put off to this summer, when business is rolling
> along a little better. But I'll post some more pics then.

Great.  Thanks for the insights.  My biggest problem is how to make sure it
lifts evenly and doesn't spew dog water and kibble all over the floor.
Norm's box within a box design would pretty much insure that things stay
level but I just don't know if I can power it and limit it properly.

--
Bobby G.