[dxf]

Hi all,
I'm new here, and wrote my initial post over at the Club House thread.

I'm designing my first CNC router table for wood work, to have a capacity of something like 24"x24"x6" and based on the JGRO design and plans. I have done some research and have made a preliminary selection of drive components:
- Unipolar stepper motors, (3) #57BYGH303, 3.6V / 2.3A / 1.8* per step / 208 oz-in holding torque (Webtronics.com)
- Microstepping drive, (3) Gecko G250
- Acme 1/2-10 2-start threaded rod (McMaster-Carr)
- Anti-backlash Acme nuts, couplings, etc. (Dumpster)

I will be building an (approx) 40v unregulated power supply per Bubba's microwave-oven transformer re-winding article here at CNCzone, to power the Gecko motor drives.

Can anyone advise this newbie on whether these components are appropriate and (at least somewhat) compatible for a wood-routing machine of this size?

Thanks,
dxf

[ger21]

Spend the extra money for the G540. It has 4 G250's in it, as well as a breakout board and additional features.

And go with bipolar motors, something like the Keling KL23H276-30-8A and wire it Bipolar parallel. You'll get much better high speed torque.

[dxf]

Gerry,
from my little research, I had come to understand that unipolar motors were better overall than bipolar - thanks for the advise.

dxf

[dustin1706]

+1 for the G540. Very easy to setup and has a ton of support online as it is so popular.

Have you checked out the kits at cncrouterparts? http://www.cncrouterparts.com/produc...products_id=74

Nothing wrong with building your own P/S, but their kits are nice for people starting from scratch and Ahren (the owner/operator) provides very good customer service!

[dxf]

I like the combination of the G540 drive and the Keling KL23H276 8-wire motors that I could configure in diferent modes if I want to experiment some for different speed/power/torque arrangements.

I have several junkboxes full of old stuff that I can use to throw together a motor power supply, so that's no problem.

Is it advisable to use the same size motor for the short Z axis travel, as for the X and Y axes?

Thanks,
dxf

[ger21]

The Z needs more power than most people think, so don't try to get away with a smaller motor there.

[dxf]

In the Z axis, what about using some sort of spring counterbalance arrangement to reduce some of the router motor's dead weight on the Z-axis leadscrew?

dxf

[ger21]

Not necessary on a machine the size your building, and probably more expensive than the $10 you'll save on a smaller motor, which would probably give poorer performance.
The Z needs more power than most people think, so don't try to get away with a smaller motor there.

Usually, at least once a week someone asks why there Z axis is losing position. For some reason, it never occurs to them that their Z axis is underpowered. 99% of the time, it is.