Newbie with 3040 machine

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19-05-2017
Rwoolley

Newbie with 3040 machine

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.
19-05-2017
Neale

Re: Newbie with 3040 machine

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?
20-05-2017
Rwoolley

Re: Newbie with 3040 machine

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.
20-05-2017
Neale

Re: Newbie with 3040 machine

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?
21-05-2017
Rwoolley

Re: Newbie with 3040 machine

Quote:

Originally Posted by 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?

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.
21-05-2017
cropwell

Re: Newbie with 3040 machine

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
21-05-2017
Rwoolley

Re: Newbie with 3040 machine

Quote:

Originally Posted by 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.htmlf

Cheers,

Rob

Thanks for your input Rob, I have explored the two link since you kindly posted,nothing in there rings any bells unfortunately.
As said previously the controller is marked prt-e750 and I've been unable to find anything on the web pertaining to it.
The driver cards are marked TX 14207 on the etch and the driver chip is a Toshiba tb6560ahq, the spec sheet for this device has pins for high/low current so I'll have to trace out pins to the relevant switches on the board. The stepper motor windings measure only 1.1ohm, there are no markings to identify the motors so I'm unsure if the motors can handle a higher current.
21-05-2017
Clive S

Re: Newbie with 3040 machine

Quote:

The stepper motor windings measure only 1.1ohm, there are no markings to identify the motors so I'm unsure if the motors can handle a higher current.

I would not worry about the steppers as they will be happy to at least 50C in other words if you can still keep your hands on them they are fine.
21-05-2017
Rwoolley

Re: Newbie with 3040 machine

Quote:

Originally Posted by Clive S

I would not worry about the steppers as they will be happy to at least 50C in other words if you can still keep your hands on them they are fine.

I thought to eliminate the PC just in case from a Dell motherboard to an Asus motherboard. This was due to a diagnostic within Mach3 that tests the pulse frequency in the PC. Mach3 said this pulse frequency was too high and whatever I did with settings didn't seem to change it. The change in motherboard - problems have disappeared! I'm running some g-code but have yet to set up the motors properly. Things are looking positive at the moment.....