Jerky Motion (Mach3, ESS, PicConvert)

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6of1
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Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Tue Oct 02, 2018 4:42 pm

Parts involved:
CNCRouterParts 2448
Mach3
ESS
Jtech 4.2w Kit
Pic-Convert

I have everything setup and burning for the most part with the help of a member over at inventables community. At a low feed rate of 60 it isn't as noticeable. At 100ipm the machine gets very hurky jerky and this isnt a light machine, lol. It seems to jerk around as the laser fires on and off but I'm not sure. With my router a can cut with no problem at 100ipm or more and for the most part I used that profile in Mach3 to make my laser profile.

photos of settings to follow..

6of1
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Tue Oct 02, 2018 4:57 pm

Well I was going to include pics of my settings but the forum is telling me they are to big. What is the file size limit for new accounts?

The first pic is only 381kb

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Picengravertoo
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby Picengravertoo » Tue Oct 02, 2018 6:55 pm

Go ahead and attach your settings. I just increased the size limit.

6of1
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Tue Oct 02, 2018 9:15 pm

Thank you!
I am going to try updating my ESS Plugin in the morning to see if that has something to do with it. Attached are my current settings.
Attachments
image2.jpeg
image2.jpeg (373.19 KiB) Viewed 1559 times
image1.jpeg
image1.jpeg (317.16 KiB) Viewed 1559 times
image5.jpeg
image5.jpeg (381.35 KiB) Viewed 1559 times

6of1
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Tue Oct 02, 2018 9:16 pm

My X and Y (and A) motor settings are identical.
Attachments
image4.jpeg
image4.jpeg (320.88 KiB) Viewed 1558 times
image3.jpeg
image3.jpeg (332.03 KiB) Viewed 1558 times

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Picengravertoo
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby Picengravertoo » Tue Oct 02, 2018 9:39 pm

Your acceleration is low for running raster code. Since you are using the X,Y & C axis, all three will need to be increased and be the same value. Both of our Mach3 ball screw laser raster engraving machines are set at a 125 acceleration, but you will have to experiment with those settings.

In General Config, select the CV Dist Tolerance and set it at 1. Un-select the Stop CV on Angles. We have our LookAhead set at 200 lines. Your Pixel Resolution setting for the 4.2W should be around .0065" to .0075" depending on how small your laser's focal point is. We run our 3.8W at a 130 IPM feedrate with a 25%-30% Feed Rate Change on Poplar, but it will depend on the material your laser engraving on what feedrate you should run at.

6of1
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Wed Oct 03, 2018 9:26 am

If the pic upload issue was b/c you are conserving server space, feel free to delete them.

Picengravertoo wrote:
In General Config, select the CV Dist Tolerance and set it at 1. Un-select the Stop CV on Angles. We have our LookAhead set at 200 lines.


That did it! Thanks! I haven't played with the motor tuning yet though.

Picengravertoo wrote:
Your Pixel Resolution setting for the 4.2W should be around .0065" to .0075" depending on how small your laser's focal point is.


For my first run I had it set to 0.007 and I "think" I could see lines/skipped space.

Picengravertoo wrote:
We run our 3.8W at a 130 IPM feedrate with a 25%-30% Feed Rate Change


I admit I don't understand how the sausage is made but wouldn't fluctuation in the feed rate also cause it to be jerky vs solid and steady movement?

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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby Picengravertoo » Wed Oct 03, 2018 10:57 am

Your image attachment sizes are not an issue. They will help others that have a similar setup as you do.

The smaller the axis increment movements are (Pixel Resolution), it will be harder for the axis's to get up to full speed, especially at the accels your using and it will cause the jerkiness. If you use one of the 45 D angles, the burn lines will be closer together at the same Pixel Resolution setting than with the Horizontal or Vertical engraving angles.

Look at this Motor Tuning graph with an accel of 125 compared to yours at 30. Notice the ramping up and down angles are more abrupt at 125. You will need to experiment with that setting on your machine so your steppers do not lose any steps/positions.

Capture.JPG
Capture.JPG (46.72 KiB) Viewed 1522 times


The key is to move as fast as possible through the short incremental axis positions. It will actually smooth out the motion and the blended running feedrate will be closer to the set feedrate.

With slower accels/de-accels, you may see burnt spots in your laser engravings from the hesitations too. The Feed Rate Change will expand the burning shade range. It should not cause any jerky motion issues when the accels are set properly.

6of1
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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby 6of1 » Wed Oct 03, 2018 2:50 pm

I am now having some issues with areas of the burn that transition rapidly from dark to light (grill of a car). These spots are slowing the movement and look to be throwing off the laser. Over extends past the border, It corrects itself as seen in second one from bottom.
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image1sml.jpg
image1sml.jpg (320.89 KiB) Viewed 1505 times

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Re: Jerky Motion (Mach3, ESS, PicConvert)

Postby Picengravertoo » Wed Oct 03, 2018 2:58 pm

Have you made any changes to your X, Y & C accel settings?


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