Electronic piston ?

Question

Hi, for my GCSE DT courswork I need to make a piece of wood move outwards from a cupboard. I thought that there was such a thing as an electric pistion, but it seems not.
I did some research on wikipedia and found a linear motor. I found this, (http://www.zaber.com/products/product_group.php?group=T-LLS)

However this is too much money for me,or my school, so I either need a cheaper alternative or an easy(ish) way of making my own.

The sizes and weights are the same as the link above, Thanks.

Answer 1

You are referring to a linear actuator, which as you discovered can be alittle pricey. If you can accept a larger sized mechanism you can make your own...

Check out one of my favorite on-line parts suppliers. (All Electronics Corp)

I would suggest using drawer slides to support the shelf and give you a low friction sliding surface. To operate it I would suggest a small gear head motor which will have a low rpm and deliver a large torque.

To move the shelf you can do one of the following:

1.) Make a lead screw using a lenght of threaded rod which the motor will spin via a coupling(sample shown on link). The turning of teh lead screw will drive a nut along the lenght of threaded rod. The shelf is attached to the nut. The lead screw also has the advantage of further reducing the speed of operation and can handle a large weight

2.) Have the motor drive a friction wheel which is in contact with the botto of the shelf

3.) Have a motor drive a COG belt that is attached to shelf
or use a Rack & Pinion gear

4.) Use string and pulleys and fabricat a small windlass. The motor would then pull the string along to either extend or retract the shelf