LacL have you tried the lockdown version as Hoss suggested?
Last edited by Mad Welder; 04-14-2012 at 08:33 AM. Reason: typo
@Fixittt, I tried with sherline mode and also tried increasing the pulse widths. No change.
@Fastest1, if by "Mach optimization steps" you mean windows optimization steps, then yes I did.
I just scrapped Windows 7 and installed XP after a clean format. No change but I restored MACH from a backup so it may be the problem is in the config setup, but what? I will try a clean config next time.
Do you guys know if its OK to ground the stepper PSU power gnd to the same ground as the LPT port and C11 card or do I need to keep the stepper PSU isolated? Right now I suspect the heatsink on the 203s is grounding the power gnd to the case and the C11 and LPT port is also grounded to the case. I asked gecko if this is safe but never got a response from them on this.
What should I do? Should I rewire all the electronics, buy a USB smooth stepper and scrap the LPT port, get a new mobo...get a new hobby? LOL
The MPG is an LPT type that I converted to USB. I could not get mach to recognize the 2nd LPT port so I wrote a plugin for it. It is able to bypass the max speed as a result. It's basically a bug in the plugin I need to fix and I have disabled the plugin just in case.If this is the case, then whenever you execute a rapid move (G00 in code) you will almost certainly lose steps. Your rapid speed is set too high and your MPG max speed should never exceed the machine rapid speed.
Remember, I'm not getting any lost steps when I use G00 or G01 moves in MDI, only when I cut the part from a gcode file.
Right now I'm thinking of programming a microchip to count the pulses coming out of the LPT port. This will at least tell me if the problem is either software/OS related or with the stepper card/drivers.
I take it as you seem software proficient that you found the correct numbered address from your device manager in XP for your LPT MPG and this then you have to physically input into to the LPT 2 in Mach as it doesn’t recognise a third party LPT address automatically only the PC’s physical hardware…..
and some advice here too DON’T get the USB Smooth Stepper get the Eithernet (ESS) version as speaking from experience electrical noise and “the dreaded ground loop bug” are intermittent bugs from the USB SS and these have been addressed and eliminated from the ESS…..
are we still chasing the part being smaller?
Has the spindle been trammed in? If the tool is not straight up and down then that will cause undersizing.
As for the MPG, try setting your velocity to 800 mm a min or lower and see if you loose any steps anywhere. creap up untill you can make it loose steps, then back it down 20%
I would suspect that it may also be the LPT to USB conversion that may be causing you grief.
A smooth stepper will give you 2 ports to play with. and can eliminate the possibility of a printer port that can be causing you problems. Also kernel speed, use the lowest kernel speed you can.
Hmm. didn't read everything, but having JUST set up my lathe, a couple observations:
1. Check mechanical backlash - that throws all kinds of stuff off.
2. With a dial indicator, check that your requested moves match the physical moves and adjust if not. at the end of the move, move back to zero and see how close you are.
3. This is most important in this scenario: cut your max speeds and accel WAY down. I'll bet money they are set too high for the hardware you have, especially the accel.
4. Confirm cutter compensation in software
I just finished installing a new mobo, CPU, clean config in mach and I'm right back to the same problem.
MDI moves always perfect and return to zero! I cut a 3" square and its about 0.045" smaller. I tried a 1" square and its about 0.015" smaller. Running these at 6 ipm and accel set to 5.
Drivertest says my PC is excellent.
I really don't want to sink another $200 into a Ethernet controller only to find out I still have the same problem. Why oh why didn't I just go for a turnkey solution?
your 3" and 1" squares are giving you the exact same minus discrepancy's i.e. 0.015" is 1/3rd of 0.045" and I know you're aware of this too but have you used or changed your measurement tool yet and are you using the same measuring tool to calibrate your axis in Mach’s axis calibration? not sure if this is relevant but your getting an exact amount each time so there's a simple logical solution here if you were getting differing measurements I wouldn't have suggested this....
I doubt this is being caused by your computer or any of the electronics attached to it. I believe continuing in that direction is taking you further on a wild goose chase.
Have you watched Hoss's axis calibration tutorial? It may help if you calibrate your machine over a larger area.
http://www.youtube.com/watch?v=ZAQHNYSYR2I&feature=player_embedded]G0704 Axis Calibration.wmv - YouTube
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
Hey Jeff, glad to see you around, I miss out phone conversations!
As to the problem at hand, I have a feeling the issue is not going to be one thing, but a combo of a couple smaller issues that add up.
First off, is spindle tramming. If your spindle is not square then the endmill will cut larger then its diameter. If its off front to back and left to right, then it will cut even larger.
Next is run out. If you have runout, then the endmill will cut larger then its diameter.
Next is backlash. We all know what backlash is.....
one other thing I have noticed with the xylotex 269 motors mostly is stepper shaft end play. So if you direct connect to the stepper, you may want to check the shaft endplay as well.
Also is your part to small in X and Y and Z or is it just one axis that is off? Im willing to bet that its at least 2. X and Y