Actuator idea - (pole climber)

i have been looking at pole climbing robots that use a wheel and motor

if you look at this video you can see something that will climb a threaded bar



add a motor and we have motion

this could make a very cheap linear actuator

i think the parts may not be that resistant to wear - however they are so cheap they should be easy to replace

the gear wheel could be made from brass so they become the part that wears (like a car lift)

-------------------------------------------------------------------------------------

the other idea i have is a sprocket that climbs up and down a chain

i have not seen a linear actuator using a chain - has anyone built one ?

Yes, see here for a working DIY build of a chain-driven linear actuator: http://bffsimulation.com/linear-act.php
On this page you can see a wooden rig that includes these actuators: http://bffsimulation.com/platform2.php
And for 14.95 British pounds, you can even download a construction plan with all measures and datasheet of the used motors.

I once also built a similar actuator. You can find some pictures here and some more detailed information including videos here.
So it did work, but I discontinued this approach right after this feasibility study. The reason was that I learned that I don't need that much rod travel for my 2DOF simulator. So a worm gear motor with a simple lever on its axis is still sufficient for me.

IMHO the gear ratio is too low of the design seen in the video, that said we would need motors with gears to get it working. By reason of this it is not recommended, better you go the actuator route as @SeatTime or @SilentChill did.

thats a neat idea doing a prototype in wood - how well did it work ? were you able to measure the load it could lift ?

I have the plans for this actuator, looks as though it has some serious lifting power.

Open up the zip file and you can see a "Load Test" on this actuator.

wow that thing has some grunt !

what spec is the motor and the gearbox ?

According to the site is is an MY7712NZ - 24V DC 200W motor.
Gearing according to the plans is 17:1 - ~200rpm at load, 391mm/s. 52kg lifting force at rated power output.

Linky: https://www.motiondynamics.com.au/1...ve-geared-motor-200w-21-256-rpm-7.5-45nm.html

I never used this actuator and I also did not perform a load test. After the initial tests you see in the videos, I stopped working on it. I guess it would have worked, but I decided to return to the approach with a simple lever mounted to the motor axis. Until now this is absolutely sufficient for me.

But if I will ever decide to build linear actuators again, I will definitely follow the ballscrew approach that is applied in most of the recent builds. In my opinion this one has turned out to be the best in regards to multiple important aspects, like e. g. backlash, efficiency, and size (diameter).