Topics

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General Mach Discussion / X axis missing steps after Y has moved a fixed amount!

« on: November 01, 2010, 01:31:24 PM »

Hi to all

I have this homemade plasma CNC that was working alright. Suddenly the x axis started to miss steps and then stopped alltogether. This now happens regularly but sometimes without stopping, only missing steps. I changed the motor, no good. I swapped over the X and Y drives but the same motor still has the problem. I changed the transistor in my buffer circuit, no good. I changed back to the motherboard LPT port instead of the auxiliary one that I had been using, no good. I installed KCAM software instead of Mach3, the same problem. I reinstalled Windows XP, no good. One consistent thing seems to happen though and that is when the y axis has moved about 25cm, the x axis starts to show this problem. Apart from calling in an exorcist, can anybody tell me what could be wrong that I haven't looked into yet.
Motors are 18 kg.cm chinese
Drives are chinese

Thanks guys
Bluebird

2

General Mach Discussion / Freeing the motor to avoid overheating

« on: February 26, 2010, 08:49:39 AM »

Hello all,

Can anyone tell me how to include code to make sure the motor stops being energized when standing idle or at the end of a job to avoid overheating the motors. How is it actually done hardwarewise. I mean what pin should be connected to the "free motor" screw terminal on the driver and where in the configuration can this pin be assigned.

Thank you
Bluebird

3

General Mach Discussion / Anomalies in the LPT signalling

« on: February 16, 2010, 09:02:22 AM »

Hi to all,

I am getting some unexpected results from the LPT port. I hope you will bear with me while I give a full explanation. I use the circuit attached to verify that I get the correct TTL signals from my LPT port pins. When I use a little software called LPTinterface.exe I get logical results, ie when I make say pin 2 high I get the LED in the circuit go off and when I make pin 2 low I get the LED lit up. The same happens on other pins up to 7 that I have tried. I have measured the current and the LPT can apparently supply as much as 35mA to the optocoupler at about 3.5Volts.
The problem starts when I use the Mach3 software. All the necessary configurations are done but when I try to jog in the x or y or z direction using the arrow keys, the LED toggles the first time I push the appropriate arrow key but the LED stays in the same condition indefinitely regardles of which arrow key I push next. This happens when the "low active" column is not ticked. 
On the other hand when the "low active" is ticked I sometimes get a very dimly lit LED for the pulses as long as the key is kept down. Can anyone tell me what is happening and how to overcome this problem. I have to add that when the pins are connected to a step motor driver it won't drive the motors unless I use a buffer circuit as an interface. Is there any reason why the LPT should be able
to drive the below circiut using the LPTinterface.exe but not when using Mach3?
I have increased the pulse duration to the max. of 25mS still with no improvement.
I will be grateful for any help.
Cheers Bluebirdiran