When I finish cutting a job I like to check to see if the ply cut all the way through. If it didn’t I’ll make another pass to finish the job. The problem if I bump the laser head the next cut, if needed, won’t align.
Here’s what I do now. If there is graving involved I’ll turn that off and set the cutting passes to one. Then I start the laser and quickly pause the laser to lock in in place.
That works but I was wondering if there is a button I’m missing to do this in just one step.
BTW, I do have the laser set to current position when I start a job
What i do is raise the material just a little above the honeycomb. Even just a couple of pennies will work. That way after the cut is made it drops down. If it doesn’t drop i know it wasn’t cut all the way through. That also makes the cut a little cleaner and tends to eliminate small spots in the cut line that may not cut all the way through because of material inconsistency
I can only say how I do it, I use absolute coordinates, and position my material in a way that I can pick it up and put it back to its exact last position.
Practically speaking, I have aligned my work bed so that it fits exactly to the geometry of my laser, i.e. 0:0 is in the home position and all material is positioned in this position with a 90 degree corner. Works perfectly - here.
Setting the GRBL $1 parameter to 255 will keep the stepper motors powered continuously, which should lock the laser head in position firmly enough to resist casual bumps.
You can also set the Finish Position to park the laser head out of the way at the end of a job.
However, as other folks have noted, repeatability requires putting the material back in exactly the same location. Fixtures and fences will become your friends forever.
Repeatability also depends on accurate homing when the controller starts up, so that two runs of the same job start from exactly the same position. If the machine homes inaccurately or not at all, fixing that is the first step.
If you use absolute coordinates, it does not matter that you move your laser head. The machine/job always starts in exactly the same place and if you have placed the material as mentioned in the same position, i.e. for example with the same corner of the material in the same corner as 0:0, then it works fine. In the preview window you can afterwards decide from where the laser should resume the task.
If just bumping the head moves its position then you really do need to Check $1=255 in machine settings, as previously suggested to keep the motors powered, so they stay locked between jobs.
It should take more than a bump with fingers to move the head if the motors are still powered! with $1=255
Moving the laser by bumping it, the programme will not have any idea where the actual position of your laser is until it is re homed, and even then still unreliable with unlocked motors to hold its position references to the software.
I discovered (not mine) some controllers do not conform to this rule. We were never able to find the magic number to keep the power on to hold the motors in place.
I peg down my material so the head returns to 0,0 at the end of the pass - if I can not lift out the material then it might need another cut.
I use pegs, not my deign - I think there were on this forum somewhere, and this holds the sheet in place. I use this for perspex - cut first with the film on so I do not get the slight heat marks a cut makes then I remove the top film, the piece usually come out of the pegged sheet at this point, then I can return the piece to the exact same place so that the engraving can be done.
Also good if I am engraving on both sides of something.