My Setup - Plasmacam DHC 4x4, Hypertherm Powermax 1000 w/ T60 Torch, 40amp Fine Cut Consumables w/smaller swirl ring, 11 gauge (.120") Mild Cold Rolled Steel Plate, Plenty of clean dry air.
Bottom Line before i give the history run down is that i can never get the z-axis to come back to the same position. If i zero out the z-axis, send the gantry home, then come back to the same position, the z-axis position readout shows a different point and when I re-zero at the exact same spot (within a thousandths or two), the z-axis position changes by 10's of thousandths at least every time. If I pause the cut while not cutting (checking pierce height), its different every time at the same place on the metal surface, and when I'm cutting and pause (checking for cut height) its different every time. Make Sense?
It started with chasing my height control issues in an effort to extend consumable life and improve cut quality. Been running the machine for a year now and it seems that some days i can cut all day with great success and other days it cuts like hell with no change in setup or settings. Finally trying to get a handle on it. I first found that my grating was warped and causing a headache when the torch came down to touch the metal before the cut. The spring action in the metal made it inconsistent so i often burned up a tip when piercing while touching the metal. Fixed that with new grating (nice and rigid and shiny!
Then while I was trying to dial in exact Arc Voltage Shift (AVS) set points to give me the proper cutting height based on the Hypertherm manual for my consumable setup, I found that often times when I tried to zero the z-axis, set the AVS, Pierce Height, Cut Height, at least one or two settings would be 'Out of Range' and it would force them to change to values I didn't want. With the 11 gauge metal and zeroing out on the surface, my z-shift was about .780-.950 depending on which Country Song was playing on the radio at that particular time it felt like. Sometimes it would go over 1 and force itself to a different number but then i would re-initialize and it would often come back within the range I put above.
I then noticed while changing my consumables out to be fresh that the z-axis motor seemed loose. So i pulled the whole thing apart to check and to clean (first time pulling this assembly apart). I noticed the z-axis motor sits on a plate that appears to 'teetering' on the end points like it is meant to do that. Did Plasmacam intend for this 'teetering' action? I have pictures of what I'm talking about and why it appears that the Pcam came with this intended to not sit flat and tight. Anyway, I cleaned the rollers and the rails (some hard gunk appeared to have been formed at the limits). When i put it all back together, the z-axis had much more travel than it used to! I always heard the 'grinding' when it would go to the top or bottom but many people have said (including Pcam reps) that it is normal to hear some chatter. I'm worried that the gunk prevented the movement and the motor chewed itself up. Could this be the case?
Like I said before, sometimes the machine works great, sometimes it doesn't so I know it's not 100% bad. Just intermittent. If anyone has run into this problem I am all ears to what may be causing my problem. Thank you all, you have been a great help in the past.
... I have learn to stand right there with my hand on the STOP button!
