Linear Actuators

[JamesTerm]

Originally Posted by Jared

http://www.mcmaster.com/#fast-travel-acme-nuts/=syswre
We used nuts identical to the ones at the top of that page. All the half inch multi start lead screws and their nuts can be purchased from amazon.com for a lot less. IIRC, they were from nook industries. To connect the nut to the sprocket, used a 14 tooth sprocket from McMaster, removed the hub and put a clearance hole for the lead screw.

To transfer the torque, we cut a small (0.1 thick?) groove about .25" deep on the diameter of the nut. We left behind part of the sprocket's hub, and it fit into this groove. There were also 2 4-40's that went into holes we tapped in the nut.

Thanks for reply as it has inspired my to try an experiment with 3D printing just to see how far I can push the envelope in that direction using nothing more than the VEX motor, which has about 9 inch-pounds of torque on the higher setting. In this picture I want to create a lead screw which encases itself within a cylinder casing, and the motor can drive a printed nut that is fused with a gear that is compatible with Vex gears. The pitch on the screw is going to be very large like one revolution per inch, and I may be able to have multiple helix (e.g. 2 or 4) cut grooves for the screw. I'm not sure yet of the optimal geometry of the groove profile, but I'll study the acme angles... This will end up being able to push weak load (probably less than 9 pounds) that has a quick time probably 2-4 seconds for full range motion. Since the Vex motor turns less than 2 revolutions per second the friction should be minimal... although ABS material does have a high melting point. This is probably a few months out to complete, but I'd like to share this experiment to see what people think about it and any advise on how to make it actually work.

Thanks again... wish me luck!