x2 cnc controller ?'s

[maxboostbusa]

Ok I bought a X2 and a Hobbycnc controller from a guy and have been working on getting the necessary items together to begin the CNC conversion. I recently found out that the controller I got wasnt for a mill exactly, it would work but it lacks the following features. No home or limit switches supported, only full and half step and only rated at 2A current. How big of a problem would this be? Would I be pretty much better off just buying a new controller? Thanks in advance for any and all information and opinions.

[hoss2006]

I think you can still get enough power from that board.
It's no doubt a unipolar driver ( bipolar will give more power from the same motor)
They seem to be sold out of 305 oz/in (unipolar rating) 2A steppers though.
Hooked up to a bipolar board, you'd get 425 oz/in from those motors.
305 is plenty though.
You can add a second parallel port and breakout board to get plenty of pins
for limit switches, relays etc.(about $40)
1/2 step mode will give a decent accuracy and smoothness for the motors so that would be OK too.
A xylotex bipolar board would run you about $155-185 but has pins for switches.

[maxboostbusa]

Thanks Hoss. What do you consider decent accuracy?

[hoss2006]

A 200 step/rev stepper (1.8 degree per step, pretty typical)
A .200 pitch ballscrew (5 revs per inch)

200 x 5 = 1000 steps/inch (full step mode)
1000 x 2 = 2000 steps/inch (1/2 step mode)
1.000 inch divided by 2000 steps = .0005 axis movement per step.
Use a 2 to 1 timing pulley ratio (like on my Z axis) = .00025 per step.
More than enough accuracy for any of these little mills.
Hoss

[maxboostbusa]

Sounds like a breakout board would be a cheaper alternative to buying another controller altogether. I am probibly going to go with the 305's for the X and Y axis and would like to step up to something larger for the Z like a 425 but it appears that they will pull over 2A so I may have to use a belt or gear drive setup so as to not strain the stepper to badly. I tried to look at your site and it appears to be down again I couldnt remember if you used a direct drive on your Z axis or not. I think adding a counter balance like you have installed would help the stepper out some also. If you have any other ideas please feel free to shoot them my way.

Ok I got your site up now and see you do infact use a pulley setup on the Z axis. I would assume I would have to reduce it even further than yours is to use a 305.

[hoss2006]

I use 495 oz/in on the Z now because of the extra weight from the articulating head.
I used a 269 oz/in with the stock X2 with little trouble.
Keling has a 425 oz/in (bipolar rating, 305 unipolar) motor that has 8 wires and 2A for $54.
Check #8 on this page.
An air spring would help the Z axis and would be easier to install than a counter balance.