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[ewan]

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A car jack can be quite chunky. If you strip down a cheap workbech such as the one here: http://www.toolstation.com/index.html?code=12739http://www.toolstation.com/index.html?code=12739
Then you can take out the leadscrew assembly. I just brought one and did that this morning actually after seeing Alans format. A drill motor should have plenty of torque to lift a feather at the end of an assembly like the one Alans made, and at quite a speed. A windscreen wiper motor would work but would be horribly slow.
I pop some pictures of the assembly up this evening. As for mark Na when you get free money spend it, dont make a homemade one ... free money?

[Guest]

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Grant of BNG (british nuclear fuels)

[Guest]

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Anybody have any idea of the reduction inside a technobot wiper motor?

[Guest]

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And does anybody with good cad skills like to do me a drawing?

[robotic_ants]

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What do you want drawing and to what quality? ie.producing parts for milling or rough prototype.


Chris - http://www.featherweights.org/forum

[Guest]

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just a rough drawing please

[grant_ploughbot]

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Picture of my home-made actuator on profile. I also use 2 large springs from the motor bracket to the lifting arm either side of the bolts to help it start up easier with a few feathers on the end!

Hope it helps someone

[grant_ploughbot]

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http://images.ibsys.com/2003/1126/2665390_200X150.jpghttp://images.ibsys.com/2003/1126/2665390_200X150.jpg this is probably the best type of jack to use, they are easy to disasemble and the pitch of the thread is pretty good, but its probably better to add a gear reduction in unless your using a window wiper motor, then it will be fine.

[Guest]

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ok so is the silver circle the pivot grant on your home made thingy? do you have a pic of the entire construction?

[aliboy]

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Hi grant , In the pic on y our profile did you just make the entire thing buy yourself or did you dismanlte a car jack ?

[grant_ploughbot]

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Mark- The silver circle on the yellow lifter part is the pivot for the arm, but the silver bit on the motor/thread just joins the thread to the motor via pins and weld on the thread.

Alister-yes i made the whole thing myself, we used the car jack for the wiper motor on the pit as it is a much larger pitched thread and so would not give a large enough reduction on the gold motor and so it would be too fast and not lift enough. i just bought a length of toughned steel threaded bar(M8 although M10 is probably better for other lifters)

[Guest]

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So does it work like this-

The motor is fixed down put is allowed to pivot round. As the motor turns, the screw pulls the one side of the pivot down and the motor pivots up?

[grant_ploughbot]

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i think you have the rite idea but not too sure. The back end of the motor mount is held but able to pivot, the lifting arm pivots just above where the thread attatches. and so when the motor screws the thread in, the arm goes up, and the motor pivots slightly from the back.

[RogueTwoRobots]

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Ok, Im finally getting around to making my own linear actuator but Im wondering if anyone knows where I can get some hollow tube with walls about 2-3mm thick, and with a tapped 8mm thread down the inside hollow bit, so that a length of threaded rod can fit in it. Is it likely to be available in garden centre/DIY shops or is it something which may have to be custom made?

Many thanks,
Jamie

[grant_ploughbot]

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erm, i cant see that being sold on the shelf so it would most likely have to be custom made. what size thread are you looking at? and how long does the tube need to be?