Newbie with 3040 machine

[Rwoolley]

Hello,
I'm new to cnc machining and the purchase of a 3040 is a taster.
Unfortunately it's come with a few problems, the loose gantry and abismal earthing has been sorted but there is a problem under Mach3 when jogging the three axis can stall and scream or with the acceleration and velocity low there is an intermittent loss of steps - this is felt with finger pressure on the hand wheel. I have tried numerous settings of the motor (tuning as per Mach3) but to no avail. I'm starting to think about PC interrupts as the cause, could be wrong but there is a something common that's causing the problem on all three axis.intrface card, PSU, parallel cable PC?

Any thoughts out there, any similar experiences? The controller is a prt-e750 and the pc is a dell optiflex 740 running win 7 with mach3 set to run it in The so environment.

[Neale]

Given the other problems, it might be that the guide rails are binding - badly set up in the factory or became misaligned in transit? Is it possible to disconnect the leadscrew nuts and move the slides by hand? Or even disconnect motors and try turning by hand?

[Rwoolley]

Thanks for your input. I've tried the rail adjustment and got nowhere so I took a motor off and the problem still exists, that is the motor exhibits the problem when free of the rail and screw. An idea that the PC may be a root cause made me buy a 2nd hand ASus system running XP. So I'll give that a try to see if that changes any symptoms. A problem with earthing found the supposed earth connection inside the spindle cable did not exist(!) although there was an earth wire connected on the socket inside the controller.

[Neale]

Do the stepper drivers have adjustable current settings? If so, are these appropriate? Too low and you will get missing steps or worse...

When you say that the motor exhibits the symptoms, do you mean that driving the motor even when it is not connected to the machine hardware still gives missing steps?

[Rwoolley]

Do the stepper drivers have adjustable current settings? If so, are these appropriate? Too low and you will get missing steps or worse...

When you say that the motor exhibits the symptoms, do you mean that driving the motor even when it is not connected to the machine hardware still gives missing steps?

Yes, problem exists when the motor is uncoupled and sitting in my hand I can feel the loss of steps intermittently.

I'm unsure of current settings as there is no information on the motors or the driver electronics.

[cropwell]

I don't know if this helps, http://www.china-cncrouter.com//down...7282452561.pdf I have had a quick look and the only info I see about motor current is that it is set at 1.8A.

You might have to open up the box to see what board is inside to find out how to check and set driver currents.

Here's a website that might have some thing of use :-
http://www.chinacnczone.com/en/china...czone_l49.html

Cheers,

Rob