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some help please

Posted: Sun Feb 18, 2018 3:28 pm
by Mukka_Meck
Has a little problem with settings with J pic convert.

I have 393.7 steps and feed 2250 and accleration 350 metric dimensions. us 3-3

China 450nm laser 2500mw pwm/ttl i use pwm

If I use -0.6477, the pic drops the converts and loses where it is, but I go down to -0.23, so it does not drop. Why is it like that?

Engraving settings 1600 mm / min. pixel size 0.1800. power mode min -0.003 and max -0.23.

Re: some help please

Posted: Sun Feb 18, 2018 6:43 pm
by Picengravertoo
Where are you zeroing the PicConvert's axis? At the lowest voltage? The PicConvert is 8bit, so you can not go out of the 0 to -.6477 range in the gcode, or it will be loosing steps constantly when executing commands for the black & white shades (max step travel distance). Also, you need to experiment with the Step & Dir. pulse in Motor Tuning. 3-3 worked the best on our Mach3 CNC, but it may not on yours.

Re: some help please

Posted: Mon Feb 19, 2018 3:14 am
by Mukka_Meck
When I start the machine, I enter Z2 G0 to go to 0 volts, then I zero Z axis, then I test M3 to see if the laser is off after I test Z-0.01 to see that the laser works. It's my startup cyckel.

In the beginning I had the settings Z0 and Z-0,6477 in picengrave 6+, but then I lost that step, now I have Z-0.03 min and max Z-0.23 and then it works well.

Re: some help please

Posted: Mon Feb 19, 2018 8:09 am
by Picengravertoo
The key to get successful grayscale engraving results is to use as much of the PWM range as possible. Theoretically, your only using 1/3 of your Laser's power range with a Min Z-0.03 and max -Z0.23. That is only a possible 1/3 of the shade range you can burn.

Do you have a way to monitor the PWM voltage? I use an Analog Modulation laser driver and monitor the output voltage with a 0-5v analog voltage meter. One of these.

https://www.amazon.com/uxcell-Rectangle ... tage+meter

If you have one, wire it into the analog voltage side on the PicConvert board so you know what voltage range you are getting. Generate a small gcode file with the full range, or slightly less to see if it returns back to your Z axis zero place at the end of the file each time. I would experiment with the step & dir pulse setting to find out what works best for your machine not to lose any steps. If you have not already, set the X,Y & Z at the same velocity & accels. The accels should be set at the highest value possible to where none of them lose any steps.

Re: some help please

Posted: Mon Feb 19, 2018 2:50 pm
by Mukka_Meck
I've tested a lot of different settings and do not know what to try more, when I make a frame around the picture then works with -0.6477 but when it starts engrave it starts to drop steps and everything is getting burned / black all the time. Is a wooden router and it works well, have made a new mach3 profile and put the pic converter on the z axis only. Try more settings. Have a leafboy usb control card. has 2.5D engraved with the machine and it works well.

Re: some help please

Posted: Mon Feb 19, 2018 3:24 pm
by Picengravertoo
I'm wondering if your the step & direction pin voltage is borderline too low for the PicConvert. Can you measure the voltage on those two pins when your jogging that axis?

Re: some help please

Posted: Tue Feb 20, 2018 2:05 pm
by Mukka_Meck
I have measured now and on step it was 0.8 and dir 4.75, the laser pwm signal 4.75 at full power. feed pic converted with 12.9.

Re: some help please

Posted: Tue Feb 20, 2018 3:37 pm
by Picengravertoo
That looks OK. The Step is at a frequency, so it will be low when jogging. Try selecting this in Ports & Pins and restart Mach3.

Capture.JPG
Capture.JPG (10.35 KiB) Viewed 6955 times


it will double the pulse width. You may have to experiment with the Step & Dir pulse settings again.

Re: some help please

Posted: Sat Feb 24, 2018 11:04 am
by Mukka_Meck
I tried sherline but no difference, changed to 100khz and put 3-3 us and put the acceleration to 250 on all axles, now it's a bit better, laser engraved in 2000 mm / min, you see a little light stretch on the image on me, eyes on google girl where good but dark stretches there.

Re: some help please

Posted: Sat Feb 24, 2018 12:41 pm
by Picengravertoo
I run Mach3 at 25khz on both of our laser engravers. I don't know what else to suggest, other than contacting J-Tech as they may have some suggestions for you to try.