Long threaded rods?

I’m trying to build a 3D printer but there is free play in the gears. I tried rack and pinion gears and bevel gears. I wish that the company that makes the Vex Robotics Kit sells threaded rods and nuts with flanges.

try looking around home depot, they usually have stuff like that…just make sure its the right stuff

I used 1/4" threaded rods from the local hardware store for my Bionic Arm shown in the Gallery. Using a single Vex Motor and gearing reduction it can easily lift over five pounds.


tswift1, How do you attach parts to the nuts that move up and down the threaded rod?

I used three 1/4" stainless steel hex nuts soldered to Vex angle rails using high temperature silver solder and a butane torch. The nuts were held in place along the Vex rail using vice grips and kept in alignment during the welding process by having a section of threaded rod screwed through each of the three hex nuts as you can see in this photo.


Recently I purchased short threaded rod connectors at the hardware store, which can replace the hex nuts for more accurate linear movements and stronger welds. Another idea is to just attach them to rails using steel brackets or steel hose clamps.

The Bionic Arm lifts the weights slowly using the Vex motor and reduction gears, but could easily be adapted to each axis of your 3D printer to allow for very precise positioning.

I find your idea of a DIY Vex 3D printer excellent! How are you going to extrude the 3D “ink”?

You can run a standard Vex square axle through a #8-32 die and thread the axle. I used it on my scissor lift and it worked great.

On the other hand, the vex motors don’t move a nut down an 8-32 shaft very fast.