I have run several tests to no avail trying to see why my called for depth is not what is carved. This is new for me on the EX controller. When I used mach this was not an issue. I am trying to run a depth of .25 and I am continually .02 deeper than it needs to be. In most cases this is not an issue but when I do inlays I need precision. I have zeroed using my touch plate and checked the top of the material with my bit and I am with .004 using a feeler guage. When I check the pocket its too deep.
How’s your workholding?
Also can you post the G code you ran?
The workholding is solid. I was using the airweights vacuum table this time. I have been having this issue since I switched to the EX controller and servos. Attached is the gcode I was using.
(attachments)
coke.cnc (159 KB)
I took a look at your code, if you zeroed to the top of your material you should be fine…
When you were running Mach were you using a different workholding solution?
I can’t imagine there would be any Z axis “drift” here (a probably that Mach actually had at times)
These new controllers really don’t do random stuff like that… Not that it’s not possible but I’d look to your workholding/mechanicals to see if anything isn’t right.
What I would do next time you run a job is this:
Set your Z zero to the top of the material. Then physically move your bit to Z zero over the material and double check that it’s correct. (sounds like you are already doing this)
Then run your job and check the depth. If it’s not correct put your bit into the area that is too deep and check your workholding… Cycle your vacuum on that AirWeights and see if you can get the material to move.
I have done multiple tests before today using the airweights and other methods. I have screwed and nailed things down and still get the same problem. I find it very odd that it is always around .02 off. To me if it was workholding where something was popping up, it would vary in spots
Is it only when you are cutting, or even when you just do a jog? Like if you put a dial indicator on and just jog up/down, does it move the programmed amount (like if you just type something in the MDI window)?
The problem is when I cut. The DRO reads the right depth but its not cutting to what it says. I have tried multiple calipers to see if that was the issue and they all read the same. I am stumped
Ok, let’s try and suss this out…
If you jog your Z axis and use your dial indicators to check how far it moves, does it move the exact amount you command it?
Next, it sounds like you’re using your touch plate to Z zero to the top of the material. You did mention that you were checking the Z zero, but just to be sure: After you Z zero to the top of your material are you putting the bit on top of the material before you start the cut? If so does the Z DRO read zero? or some other number…
And just to ask again… are you positive that your workholding is spot on? Have you tried with Airweights and with a more traditional hold down method? Have you tried different material to test on?
Have you checked your machine for any mechanical looseness? Perhaps some loose bolts on the Z axis, worn bearing blocks, anything that could allow the Z axis to get pulled or pushed during cutting loads? This one might be difficult to find, but if you can grab your spindle and pull it around to see if you can feel for anything that is loose that might be a good start.
I know this might present as the Z axis “drifting” but on this control it’s very unlikely that it’s just sending random extra step moves. Not impossible but something we’ve not seen.
The only other possibility could be lost Z steps, and that could be caused by feedrates that are way to high, or something sticky in your Z axis.
The DRO isn’t that important, its just telling you what it commanded to move. Its not a true measurement of anything.
What I was getting at is if you command a move in air (don’t even bother to turn on the spindle) - like if you mount your caliper to the spoilboard on one jaw, and some part of your Z axis on the other - say with an MDI command, and it moves the exact amount you comanded, then it is not the EX controller, or its settings. It means that there is something happening only due to the load of cutting. Mabye the workpiece is loose, maybe something mechanically loose (like the motor to ballscrew coupler) or something. However, if a simple jog move with no load also gives the same erroneous movement as when actually cutting, then you may have an issue with the controller, or possibly a setting like the steps per revolution isn’t exactly right for your machine.
I’m checking everything. Using flat material and even checking tram. Only thing I see if that my title front to back is off by .04 but not sure that would have an effect on depth. I ran 1/4 hole and I got the proper depth once and then the next hole wasn’t. It’s just very odd that it’s off the same amount.
Not sure what you mean here…
I was checking the spindle to see if there was a tramming issue. There is a slight tilt that amounts to .04 but that’s it. Nothing is loose and spoil board is flat.
Have you measured the Z axis backlash? I am wondering if upcut milling is pulling the axis down.
i’m not sure what that is so I would say I havent measured it. can you give me directions?