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Mach3 control and no continuous jog

Posted: Tue Aug 15, 2017 11:37 am
by George M
I built my CNC machine three years ago and love it.
I recently added a JTech 2.8 Diode Laser to it. I set it up to use PWM on the spindle. It does great on engraving vector images created by Vectric Aspire.
I just purchased PicLaser and am testing it with the Grey Scale image.

The problem is that I cannot get it to run in continuous jog mode. I will only run in step mode which makes it very slow and burns even when increasing the feed rate. At first I thought it may be because I'm using a pendant, but even when I deleted the .dll for the pendant it still would only run in step mode.

Any advise would be greatly appreciated.
George M

Re: Mach3 control and no continuous jog

Posted: Tue Aug 15, 2017 1:29 pm
by Picengravertoo
Hi George,

Mach3 can not run S command laser power files in real time. It delays on each line for the spindle spin up time. You need this to raster laser engrave grayscale images/photos with Mach3 & Z, A, B or C axis depth commands generated with PicLaser. ... rter-board

You can use it with your vector gcode files and any Dithered B&W image/logo gcode files generated with PicLaser too.


Re: Mach3 control and no continuous jog

Posted: Tue Aug 15, 2017 3:16 pm
by George M
Thanks Jeff,
I thought there was something wrong with my setup.
I actually have one of those boards on order. Hope it gets here soon. Just was excited about my new tools.

George M

Re: Mach3 control and no continuous jog

Posted: Tue Aug 22, 2017 3:02 pm
by George M
I'm bringing this discussion from JTech here per your email. First Let me set up my system:

DIY CNC Machine
Mach 3
JTech 2.8 Laser and Driver
JTech PicConver board
Using A axis for laser.

The problem that I was having (and emailed Jay about) was the laser turning off during the running of a program. I was able to trace that problem to a loose plug at the Driver. I have the laser driver and the PicConver board located on a sliding drawer so that I can bring it out to turn on and watch the LED's but then slide it in when doing standard CNC work. The plug was loose enough so that it would loose connection. I then cut the plug off and screwed to the terminlas and have not had the laser shut off prematurely since.
I do still have question on some setups though. I will listed them individually.

1. Attached are pictures of my set up screens and a test burn of the grey scale. On the grey scale even though it looks like it does go from 0 to 255 the progression does not seem gradual and even to me.
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2. In the instructions for seting up the laser axis (in my case that is A), it shows the Acceleration as 30 and the Velocity as 100.2. However I have also read in some forum that all the axis should have the same Acceleration. My movement axis all have an Acceleration of 300 and a Velocity of 200. Should the A axis also have those settings?

3. I also design and engrave using Vectric Aspire. That Post Processor that I downloaded from JTech uses S command to turn laser to full power. I have Outpout 1 assigned to Pin 17 with Spindle disabled. Do I need to enable the Spindle and also assign it to Pin 17 in order to do this?

4. What is the relationship between the size of the focus spot of the laser and the pixel resolution in PicLaser?

5. The Instructions for the PicConvert says before running a program to turn laser on to full power and then off and then set A to 000. If the PicConvert board is plugged in all the time is this still neccesary or just when I start up for the day? Can this be put into the .txt program.

6. Even though I am used to haveing the Z axis going negative to route deeper into the material I struggle to remember to use the negative to go darker. What changes in the Dir and Step do I need to do to use positive number - say 0001 to 0256?

7. When engraving a vector and even something from PicLaser (see attachment of grey scale), the laser dwells at the start of each vector and creates a burn spot. In the Spindle / General Parameters I do have all four boxes set as 0 secs.

1. Attached is a picture of my set up screens and a test burn of the grey scale. On the grey scale even though it looks like it does go from 0 to 255 the progresion does not seem gradual and even to me.

Thank you for taking the time to look this over. Even though I havent attempted to picture engraving yet, I think I'm getting close on the setup and understanding some of the complexity.

George M
EDIT Looks like I can only attach 3 pics. I will add other 2 in another post.

Re: Mach3 control and no continuous jog

Posted: Tue Aug 22, 2017 3:03 pm
by George M
Here's other pics
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6.jpg (94.06 KiB) Viewed 9297 times

Re: Mach3 control and no continuous jog

Posted: Tue Aug 22, 2017 4:11 pm
by George M
See if these are better. I'l remember about the Jpg.
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d.jpg (160.98 KiB) Viewed 9293 times

e.jpg (100.81 KiB) Viewed 9293 times

Re: Mach3 control and no continuous jog

Posted: Tue Aug 22, 2017 4:18 pm
by Picengravertoo
1. You need to get your laser's focal point as small as possible to get the finest detail when laser engraving photos. We use a 3" focal height with a 3 element glass lens and use a piece of black anodized aluminum to focus on. The black surface will not reflect the beam so it's easiest to see when it's the smallest. We then use a few dabs of hot melt glue between the lens thread and laser module/heat sink to secure the lens in place. It could move when engraving and cause undesirable results.

2. You need to set the velocity and accel the same as your X&Y axis, or the slowest axis will affect the others

3. Don't use S commands in Mach3. They will dwell because there for spindle speed in Mach3, not laser power. Edit your PP to use the PicConvert board and A axis depth commands. A0 to A-.0255. The J-Tech Vectric PP is for grbl, not Mach3.

4. The focal point determines the laser's burn line width. The Pixel Resolution setting in PicLaser sets the X&Y axis step over distance in the gcode file, so the laser's burn lines lay down next to each other without overlapping or leaving gaps between them. You will need to resize your image in the editor using Auto. The instructions are on Page 14 in the Tutorial that you can find with the Help button.

5. Every time you power up the PicConvert board, it will go to approximately 2.5v. I use negative A axis values to increase the laser power, so you will need to jog up the A axis to 0v, then zero the A axis. If you keep the PicConvert wall wart power supply plugged in, you should not have to do it every time unless it looses position and need to calibrate it to 0v again.

6. I recommend using negative A axis values to power up the laser higher to burn darker. Just think of the laser as a cutting bit. The laser can actually cut 3D reliefs in softer wood like Poplar. ... rave-pro-5

7. No 3 answered that question.

8, You have to get the focus, Pixel Resolution setting and feedrate just right to get the lower & upper shade range correct. Different each material it will require a trial & error period to get the settings just right.

We use a 3 for the step & dir pulse in Motor Tuning. Leave it at 5 if it does not give you any issues with the PicConvert board loosing steps/position.


Re: Mach3 control and no continuous jog

Posted: Tue Aug 22, 2017 4:46 pm
by George M
3. JTech has multiple Vetric PP including two for Mach 3.
MACH 3 – M11p1/M10p1 option

I have to leave now but will review the other feedback when I return

Re: Mach3 control and no continuous jog

Posted: Wed Aug 23, 2017 5:11 pm
by George M
Ok, I've been able to do some more testing using the grey scale.First some updates:

7. I think that is solved by using the Modified PP from Jtech. It uses the M11px and M10px commands which work with the board.
5. I added the following to the PreCode in PL.
Thats seem to get it reset correctly before each engraving.

I've attached a pic (hopefully you can see this one better) of four grey scales. Two with the Acc set to 30 as in the instructions, and two with the Acc set to 200 as my other axis are. I don't see any difference between them. What I am seeing is still the unevenness of the shading. It does not go consistently from 0 to 255. The bottom two rows are very similar, the middle rows are very similar, only the top two rows seem to give the gradual increase I would expect all through. Any suggestions on what is causing this?


Re: Mach3 control and no continuous jog

Posted: Wed Aug 23, 2017 5:53 pm
by Picengravertoo
Vector laser engraving with the M11Px & M10px commands will work better than using S commands.

Adding those commands to the PreCode will ensure the PicConvert DAC is calibrated each time, but you should include a G1 at the beginning of the first A axis command move and a Feedrate at the end of the same move. (F10?)

To bring the lighter shades darker, use a negative value in the PicLaser Minimum Laser Value also. Example: -.005 min and -.0255 Max.

The 30 accel recommendation in the instructions was for John's laser engraver when we consulted Jay with the development of the PicConvert board. Everyone's setup could be different. My servo CNC router's X,Y & A axis's are set at a 125 accel. Our Mini laser engraver with steppers, the X,Y, & A are set at a 80 accel. You won't be able to tell any difference until you laser engrave a grayscale photo. With the X&Y only making short incremental moves (.006") and the A axis could make an abrupt A.0000 (white) to -.0255 (black), it could leave burnt spots there because all three axis's will hesitate from the A axis accel.