Conversion cheap manual milling table to CNC

[abasir]

The original table had very significant backlash and very difficult to move due to the way the leadscrew is attached to the 'holding' plate. I decided to capture the leadscrew using two skate bearings and flexible coupler. No noticeable backlash now, very smooth move eventhough the 8TPI leadscrew is directly coupled to the stepper (2.3V @ 1.75A - 6wires)
Photos below... all done in one afternoon...

[H500]

How did you eliminate the backlash between the lead screw and the nut?

[abasir]

Originally Posted by H500 How did you eliminate the backlash between the lead screw and the nut?

The original leadscrew and nut had no noticeable backlash. The main cause for significant system backlash was from the way the leadscrew was attached to the table.

If you can see in the picture #1, the original leadscrew was attached to the table using a metal plate. One the thread side, it had a dowel(?) pin and the other side was the handle. If you press the handle very tight against the plate, backlash is zero BUT it is almost impossible to turn.

BTW, I'm yet to get a dial gauge to measure but if backlash is still unmanageable, I'll try potting it using 'Milliput' epoxy to see how it goes

[abasir]

The final setup...

[rippersoft]

Very brilliant stuff!! I had wondered if someone would/could/did a conversion like this. What is the torque rating for the stepper motors?

[abasir]

Originally Posted by rippersoft Very brilliant stuff!! I had wondered if someone would/could/did a conversion like this. What is the torque rating for the stepper motors?

Motors are from scrap dot matrix printers... rated: 4.2V @1.75A, I would guest somewhere around 100-120oz/in.

[yukonho]

Any word on how well this is working?
colin

[abasir]

It's working fine.
Have not tried aluminum milling but MDF and acrylic cut with no problem. Backlash is about 0.002" in both X and Y axis but that's something I can live with
Currently, I could rapid to about 50ipm with no loss step.