I'm building a custom TV Lift. I'm thinking of using a motor with high
torque that drives a basic block-tackle pulley system. Without getting
into electical engineering and power: I was thinking of using either an old
cordless drill, or corded drill.
I'm just curious.. How come most cordless drills come with a switch that
lets you choose low speed/high torque, or high speed/low torque? Corded
drills don't usually have this. Is it simply because the 110v motors can
deliver more torque?
It would be cheaper and easier for me to use and old corded drill. But, a
cordless type has a more reasonable speed when switched on the high-torque
setting. And I imagine since it's geared, the higher RPM may be better for
the life of the motor.
Generally if the motor is same size, DC motor is more powerful than AC
motor. Also it's easier to control speed. Look at Diesel loco. which is
driven by DC motor. Small high tourque motor with low RPM.... You can
find one at RV shop. They use it for moving front stabilizer jacks
up/down. They are pretty strong.
They are 12V motors.
Well, I seem to have my terminology wrong then, I essentially am using a
windlass like this:
Bit I'll have
four pulleys, and one driving shaft, if that makes sense..
I'd thought about 4(or three) threaded rods and nuts, then a chain drive..
Would this take a while to lift though? It'll need to lift roughly 3' and
I don't want to have to wait 5 minutes for each lift ;) Although, that's
just being anal.
SINGER (sewing machine people) have an electric sewing machine
lift that sounds like it's right up your alley. I make cabinets
and use them often - haven't had one fail yet, abut five years.
Well, one failed, but they "adjusted" "stuff" and the motor never
reached the limit switches and burned out.
I can't find it right now, but ...
1. Try here; I couldn't be sure it's there because I
wouldn't accept the Flash download and the parts charts
2. Try calling a local Singer Service Center and ask
them about sourcing it for you.
3. Here are a couple links, mechanical and electric,
"sewing machine lift"
Sorry, have to run - more later; try google * see if ht
Yep, that's basically what I had in mind, but I'll probably build it to use
direct drive. Since I won't be using a gear ratio, like in this drawing, I
figured the block-tackle would help with less load on the motor..
It's not useless. It's needed because rope is being transferred from
one part of the axle to the other (note that the ends don't go to the
same side of the axle). And since the two parts have different diameters,
the pulley will be moved up or down (as well as laterally).
The time it takes to lift the set is going to be directly related
to your mechanical advantage, it doesn't matter how you derive that
The drawing shown with the windlass is a bit odd, since it looks like
both ends of the rope are winding around the axle, which makes the
pulley useless. What I was evisioning was skipping the pulley,
and replacing the hand-crank with an edge-driven wheel, of whatever
size it takes to get you the mechanical advantage you want.
Sort of like this: www.goedjn.com/sketch/windlass.gif
The GEARING multiplies torque.The motor turns the same RPMs for both
ranges,just the gearing changes,slower range multiples the torque more.
Corded motors have much more electric power available,thus they can use
more powerful motors.
Why don't you try a scissors type lift mechanism(like a scissors jack for a
compact car),you have less complexity,drive the screw with your motor.
Think hydraulic. One teeny-weenie hydraulic motor and piston can lift TONS.
I've seen hydraulic positioning motors, taken from old mainframe disk
drives, used to manipulate an elevator in a hay barn. Motor was about 1/3 hp
and it pushed 4000+ pounds up 16 feet.
'Course a piston that long was a search...
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