Has anyone used this cnc kit?

[cruzin]

Im shopping for a cnc kit for a bridgeport series 1 with j head. I found this ebay seller of a kit and was wondering if anyone has used the parts on a mill cnc? thanks for any insight.
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

3 PCS Nema 42 Stepper Motor with 1588oz-in holding torque,

3 PCS Stepper Motor Driver DM2HB78M, 24-80VDC, 7.0A, 300 Microstep,

3 PCS 200W,24VDC Power Supply,

1PC Breakout Board & 1 Parallel Cable for free offering

[jthornton]

That might be a fair kit for some hobby application, but not enough power for a full sized knee mill. You also need to change the acme screws out and fit ball screws or your wasting your money IMHO. You might visit the EMC2 wiki site and see what others have done to convert machines to CNC control.

John

[HimyKabibble]

With a 24V/200W power supply, it will be a real dog. That's barely enough current to run a single motor to full torque, and the low voltage will severely limit max RPM, which will already be limited by the NEMA42 motors. You'd be better off with smaller, NEMA34 motors, a higher voltage/higher current power supply, and perhaps timing belt reducers. And running a machine the size of a BP on leadscrews will require a LOT of torque, due to the very high friction. Ballscrews would be well worth the money.

Regards,
Ray L.

[cruzin]

thanks for input folks. how many oz motors would a bridgeport require?

[TarHeelTom]

I have a Series I CNC. I'm not an expert, by any means. I'm using the original stepper motors, each of which is about the size of a fire hydrant.

Seems that you need about a 72 volt, 7 amp power supply to run these. The Gecko 203V driver does a fine job.

My machine was "#47" in a production shop, so has probably led a quite active life. I setup a video camera and a cheap dial indicator (0.001") and wrote some simple G code to move the table back and forth rapidly. I can detect some backlash, but it's way less than I can measure, and probably less than 0.0001".

There are two benefits to using ball screws. One is far less torque required to move the table, the other is far less backlash.

Tom

[ichudov]

I agree that this kit is for small benchtop mills, at best.

For comparison, my Bridgeport Interact CNC mill has servo motors on X, Y and Z that take 145 volts and up to 30 peak amps (15 running amps). Do the math, they could produce about 2.8 HP each.

After converting this mill to EMC2 due to a dead controller, I ended up making a 72v, 20A continuous power supply from a toroid transformer.

This seems to be very adequate for what I need from this mill, however, it mean that the performance is a bit below its full potential. Personally, am fine with that.

I would say, that anything significantly below 800 watts would make you feel that your machine is underperforming.

[mactec54]

cruzin

This is ideal, but cost is more AC servo system, from Dmm Techonolgy

Motion Control Products - DMM Technology

[Kelinginc]

Originally Posted by TarHeelTom I have a Series I CNC. I'm not an expert, by any means. I'm using the original stepper motors, each of which is about the size of a fire hydrant. Seems that you need about a 72 volt, 7 amp power supply to run these. The Gecko 203V driver does a fine job. My machine was "#47" in a production shop, so has probably led a quite active life. I setup a video camera and a cheap dial indicator (0.001") and wrote some simple G code to move the table back and forth rapidly. I can detect some backlash, but it's way less than I can measure, and probably less than 0.0001". There are two benefits to using ball screws. One is far less torque required to move the table, the other is far less backlash. Tom

We have some customers using this kit
Page Title

NEMA 34 1200 oz-in Steppper Motors 3 Axis CNC Kit

A:3 PCS KL-9082, 24V-90V, 8.2A Bipolar Driver or G201X, G203 updated

B: 3 PCS NEMA 34-1200 oz-in Stepper Motors

C: 1 PCS KL-7220, 72V(No load), Max 20A,Unregulated Power
Supply, 110V/220V

D:1 PCS C10 Breakout board, E-Stop or Limit Switch can be wired

E: 5V Power Supply for Breakout Board

http://www.kelinginc.net

[cruzin]

thanks for all the input and ideas and links for kits. I really appreciate the help.