e-Bay DIY kit

[bvsnowman]

I'm another first timer. Not new to CNC as in plasma, no experience re a CNC router. Want to purchase a small unit to get started, I'm thinking a 24"x36". Found what looks like a well built kit by a Phoenix company on e-Bay, $3,000.00 plus $285.00 shipping. You assemble and add your own computer and router. Is anyone acquainted with this company (don't have name) and their reputation as well as the quality of the CNC package? Here are a few excerts from their advertisement. Your opinions would be most appreciated..
J.Snow

Easily Adapted for Routing, Engraving, Plasma or Laser Cutting. This Machine Frame is Approximately 30" Wide x 48" Long, with an 8" Z-Axis Travel and is approximately 24"x 36" inside the frame... It is exactly the same as my assembled machines, but you do the assembly. I Have modified the X-Axis support system to include a THIRD SUPPORT RAIL with an extra set of recirculating follower bearings as shown in the photos. This Auction includes Four Motor Driver Modules, an M2 Breakout Board from Bob Campbell Designs and a 20-Amp Power Supply. You supply only the computer and your router of choice. The motors included with this machine are 500 Oz-Inches.

[Torchhead]

I would ask:

What is the max velocity of the system? The leadscrews look like 10 TPI or greater. Given the motors will spin about 600 RPM tops with 48VDC you could expect a top speed of less than 60 IPM.

How good is the instruction manual (a copy before you buy would be a plus). If you can't follow the manual then assembly and tuning will be a challenge.

The motor mounts look like they may not have support bearings (can't see from the photos) between the motor and lead screws. Puts strain on the motor bearings they are not designed for.

It certainly looks like it's well build and worth the 3 G's but precision alignment on this kind of machine is critical and that is hard to see in a photo.

I'm not sure I would shell out 3 grand until I had feedback from other builders.

Alignment and tuning on a dual drive system is critical and the instructions need to cover that.

20A power supply at 48VDC (960 watts) is way overkill for four 3A rated steppers. A 10A supply is completely adequate. While bigger supplies may make you feel better they serve no real engineering purpose, won't last longer or give your machine more speed or torque and just take up more room.

The third rail is nifty but looks like it was added to correct for torsional twist under routing loads and that tall motor and Z travel.

It's not a bad deal if in the end you have a machine you can get running reliably and without major hassles.

Tom Caudle
www.CandCNC.com