bridgeport clone w/ballscrews- now i need steppers and drivers

[lkasdorf]

So, I have this decent Bridgeport clone with x & y & quill ballscrews. It is in good shape and has a LubeSite automatic oiler. It has an ancient Bandit controller which is not working right and 3 big DC servos.

I'm looking for opinions on a good low cost approach for getting this making chips again. I am a hobbyist and am very comfortable with DIY electronics, wiring, etc. I really like what I have seen of Mach3, and I'd like to use that. I have spare PC's lying around that will ruin it.

The existing servos indicate a stall torque of 400 oz/in. I'm thinking for my purposes, big steppers will be fine. I see nema42 steppers rated at over 4000 oz/in. I think the servos are geared down, and maybe the 400 oz/in is the rating of the motor before the gear reduction?

I'm thinking that if I get pretty much the biggest steppers that will fit, and associated driver, it will work fine and not stall/slip when actually cutting.

If you search for nema42 stepper on ebay, you will encounter a 3 axis setup with 4120 oz/in steppers, drivers, and break out board. Price is < $1500. This seems like a decent approach to me, although it is all Chinese. It is all no-name. I'd rather use Gecko, ideally.

What approach would you take?

[vidio1]

I'm curious why you want to replace the servos with steppers. If they are in working order large drives will run you $180-$259 each depending on brand, encoders if needed are $25-$100 each, once again brand specific, and a BOB ~$100. You stand to save $500 or more.