Need Help!- Acceleration and Velocity vs stalling.

[Drools]

I'm only able to get an Acceleration of 10 and a Velocity of about 50 from my setup before the motors stall. I hate it when the system stalls in the middle of drilling holes for a PCB, Swiss cheese...
Anyway I'm using the avrstmd.com (1/10 micro stepping) drivers, 1/2-10 lead screws, 270oz Tormach steppers and a 40VDC@6Amp unregulated Power Supply. Should I expect more from the system or is this what others with a similar setup are getting?
I asked a similar question in the "General Electronics" section but it has not generated a response.
Thanks for the help.

[ger21]

I'm not familiar with your machine, do you have some pics or info?

My Z axis uses 1/2-10, 250 oz motors and a Xylotex at 24V. I have almost the exact same settings, although for very detailed 3D work I have to lower the accel to 5. But at 40V, I would think you should get more, unless the screws are whipping. Maybe not higher accel, but at least a higher top speed.

1/2-10 is not the best for top speed, but I've seen people get 100ipm out of it with a HobbyCNC drive.

[Zygoat]

how much does it WEIGH?

[lunchtrayrider]

what are your computer specs and software?

[Drools]

Here is my machine.
My computer is a IBM small form factor (SFF) Think Centre, P4 3.6, 2GB ram. I upgraded to this computer from an AMD 1600+ with 1GB ram which did the same.
The OS is a stripped down Windows XP Pro. At first I thought it was my linear rails so I changed them to the carriages from Ahren. Then I thought it might be my power supply see this thread.
I'm still not 100% sure it is not the PS but before I go replacing the current one I would like to get some feed-back from the pros on here. I have an e-mail into the designer of the drivers but he has yet to reply. At this point I'm looking at the drivers but I do not have a substitute to try.

[Crevice Reamer]

Hi Drools.

Do you have the driver set to supply full Amps to the steppers?

CR.

[jsheerin]

You can check out the mechanicals by disconnected pieces and trying to move things by hand. For instance, disconnect your lead screws and push all your axes around. They should all move easily at all locations. Reconnect your screws and turn them by hand. They should be easy to turn, although sometimes it does take a bit of usage for the delrin nuts to loosen up a bit. If you feel binding anywhere, that is a problem.

[Drools]

Funny you should mention that CR because originally when bench testing the system before installing I had the current set to .6A and forgor to change it. I was actually able to route some PCBs at that setting but when I started milling some UHMW plastic things started to get interesting and it was at that point I realized my error and bumped the current limiting on the drivers up to 2.8A, so at the moment they are set to 2.8Amps.
I do not think the X or Y axis is very heavy compared to other 80/20 builds.

[Crevice Reamer]

How long are the screws?

CR.

[Drools]

Screws Are.
X=36"
Y=24"
Z=12"

[jsheerin]

I simulated your situation really fast using a 282oz*in motor - you should have plenty of force available below 100ipm at 5in/s/s acceleration if your gantry is below 100pounds (or whatever weight/axis combination you want to look at). I would not try to go much faster than that though.

I'm not familiar with your controller, but if you only stall after motion starts (as opposed to right when motion starts), you might be having mid band resonance problems. A drive like a Gecko G540 could help that. Otherwise I'd look for mechanical issues. Or at least rule out the mechanical issues as it's pretty easy to do.

[lunchtrayrider]

are you running mach3?