weird cutting (Missed steps?????)
Pentium 4 3GigHz, 1 Gig RAM, 120meg HDrive,
Mach3
2 x Vexta 5 Phase UDX 5114 drives (X and Y axis)
1 Vexta CSD 5814 (Zaxis)
Y = 0.750" wide 0.200 pitch belt drive geared down 3:1
X = 0.750" 12 start acme thread with antibacklash polyacetal nut
Z = Thompson linear guide with ball screw
hey all.
I have finished building my 3rd router and I am having problems with the axis moving during a cut. If I cut a square then it comes out like a parallelogram but with the Y axis sides straight as they should be. I wasn't sure if I was losing steps because the cut length is the same, unless I lose steps right at the end of the cut length. Each line of cuts starts a little behind the previous one so it seems I am losing steps.
My last job finished about 80mm away from the zero point on the Y axis when homed after finishing and about 4mm off on the X and 1mm on the Z.
This is repeatable and was exactly the same after doing the job 5 times after zeroing.
I thought it was mechanical but everything is tight with no loose pulleys or belts and I double checked this as it seems to point to a mechanical fault.
I tried the following to see if it made any difference.
I separated the main power wires for the router from the motor wires and ran it overhead instead of next to all the stepper motor wires.
I put Ferrite cores over the motor wires and power wires.
I rewired the motor wires with twisted pair wires and grounded the shield on one end only.
I rewired the step and dir wires with shielded cable and grounded the shield.
I rerouted all the wires going to the motors.
I deselected the limit switches in Mach3 (I was getting a reset that I thought was being induced into the Home and Limit micro switches before I rewired with shielded cables).
I swapped the 2 UDX5114 drives for X and Y.
I set the lookahead in mach3 to 500
I connected to the internal parallel port 0x378 instead of the 2nd parallel port card.
I used another parallel port cable from the plasma cutter that I know works ok.
I cut at 50% of the cut rate = 50 ipm. (default 100 ipm)
I cut at 120% of the cut rate = 120 ipm
I still get the same results everytime.
It seems mechanical but I have ruled that out.
The first job I cut on the router was with the majority of the cutting done on the cross X axis with the step over on the long Y axis and it turned out ok. This new job was with the majority of the cutting on the long Y axis with the X axis used for the step over. I am trying to carve some designs on a table leg. i.e long and skinny.
Do you think it could be a software problem? I am thinking of using CNCpro but I will have to install Win98 for the DOS command line interface because I don't know if I can do that with WinXP Pro.
I hope I have explained the problem good enough for you to get a grip on what's happening.
Any suggestions?
ANY help will be soaked up with much enthusiasm.
Thanks in advance.
Richard
I am not completely useless.......I can always serve as a BAD example.