LaserUser.com Forum (formerly RDWorksLab)

David Borneman wrote: Sun Jul 11, 2021

Jeffrey Aley wrote: Sun Jul 11, 2021 Interesting problem. How often does it happen (one in ten times, one in a hundred...) ? You'll want to have this info to determine if the problem is improving or getting worse when you make analog changes.

You have a large (and presumably heavy) gantry. So my hypothesis is that the programmed acceleration is a bit too high. Try reducing it a bit and see what happens. Reduce both the Idle Acc and the Max Acc. You may wish to also reduce the Idle Speed. These are all accessed in the upper-right corner of RDWorks under the USER tab, and the Processing radio button.

Remember to first READ the values from the laser, then SAVE the original values to a file. Make your experimental changes, and then WRITE the values back to the laser. By the way, on my screen, the OPEN, SAVE, READ, ... buttons were not visible. There's a boundary between the USER area and the Laser Work area below it. I had to move the boundary down in order to see the buttons.

Screen pics are available upon request.

Regards,

-Jeff

Not sure how to quantify how often it happens. Enough to cause me problems lol... but not on every sheet I cut. Once every 8 hours of operation maybe?

For the Acc numbers, we are using default values set by the seller. We actually did tinker with these way back in Feb, but doing so broke something (lol) so we had them connect and reset everything to their defaults. And to be honest I have no idea what all those values do... which is another reason I have not touched them. (I do have a lot to learn!)

Hmm. There are a couple of challenges. First, it'll take a long time (a few days of production) to determine if the problem is improved or fixed. Second, the changes that I propose WILL slow down your production, and time is money. If it were a problem that occurred every time, I'd do an experiment where we'd reduce the speeds and accelerations by half. But in your case, that's not an affordable experiment.

So here's what I propose: go to the User tab in RDWorks as shown. If necessary, drag the line (green arrow) downwards to reveal the Open, Save, Read, Write buttons.

Then press the READ button. This will read the current parameters from the laser. Now press SAVE. This will save the current parameters to a file. You can use this to restore the laser in case we mess up a setting somewhere.
Now you can make modifications. The three I recommend reducing are Idle Speed, Idle Acc, and Max Acc.

Idle Speed - this is the speed that the laser head moves when the laser beam is off. You probably notice that the head moves slowly while cutting, and then zooms to the starting point of the next cut. It is this latter speed that we're adjusting.

Idle Acc - this is the corresponding acceleration. There's no way for a kilogram of Y-axis gantry to instantly start moving at [Idle Speed]. If the controller tried to do so, the motor would slip, and then the controller wouldn't know the true location of the Y-axis gantry. So the controller starts off slowly and ramps up the speed until it is at [Idle Speed]. This acceleration rate is programmed in Idle Acc.

Max Acc - I think this is the acceleration for when the laser is actually turned on. I don't see any reason why this would need to be a different value from [Idle Acc].

Experiment 1: Reduce the two accelerations by 10%. Do not change Idle Speed. Press the WRITE button to send the new values to the laser. Then run your production and see if there's any improvement. The impact to your production throughput should be relatively small.

Experiment 2: If no improvement from Experiment 1, also reduce the Idle Speed by 10%. This will impact your production throughput by < 10% because the speed while the laser beam is on is unaffected. I'm guessing maybe 5 - 7% impact to throughput time.

If both experiments fail, you can press the OPEN button to load the file you saved, and then WRITE that back to the laser, thus setting things back to the way they were before the experiments.

Good luck!

-Jeff

Jeffrey Aley wrote: Mon Jul 12, 2021 <snip>

Good luck!

-Jeff

Awesome. Something I have not tried

I just made those changes... so ya it may take a while before I know anything. My 2 Acc values were not the same btw... the Idle Acc. was set to 1000, while the max acc was set to 800... strange? To keep it simple I changed them to 900 and 700 respectfully (down 100 each).

Should I change the Max to be the same as the Idle Acc? Or leave them as they are?

David Borneman wrote: Mon Jul 12, 2021
I just made those changes... so ya it may take a while before I know anything. My 2 Acc values were not the same btw... the Idle Acc. was set to 1000, while the max acc was set to 800... strange? To keep it simple I changed them to 900 and 700 respectfully (down 100 each).

Should I change the Max to be the same as the Idle Acc? Or leave them as they are?

900 and 700 are a good experiment. I hope it will help solve your problem!

-Jeff