Ghosting / Shadows with PicLaser

[Flashsolutions]

I am getting ghosting or shadows on every image I try to process.

This appears to only be a problem with the picengrave software because I can get excellent results in Inkscape plugins and a simple free web based program (http://nebarnix.com/lmg2gco/) that incidentally is many times faster than piclaser.

The fact that all of the other software I use produces no ghosting, I think this excludes my hardware as I have used the same parameters and source files and get no ghosting in the other software solutions.

I have tried reducing/increasing speeds and laser power, scan directions, running from the SD card, and many many combinations of settings in piclaser but the ghosting is consistent and appears as two images, one slightly smaller than the other.

I took the gcode that piclaser generated and edited it to change all of the M106 S commands to Z so that I could look at the gcode visually in a program such as Camotics and the ghosting does not appear in the visual representation.

It appears that many others have had this problem and many have tried to solve it by tinkering with their hardware. I don't think my hardware is the issue here. It produces excellent quality with several other software solutions and it is only the piclaser software that is giving this result.

Now, since looking at the visuals of the modified GCODE does not reveal anything, I wonder if maybe piclaser activates the laser in both forward and reverse paths while other solutions may only activate the laser in one direction only.

By the way, I have tried horizontal, and 45 degree and the same ghosting is present in both.

Only the J-tech option produces code that runs on my controller which is an Arduino Mega 2650 running Marlin firmware driving a RAMPS 1.4 board.

IMG_0531.JPG (292.56 KiB) Viewed 10609 times

Using an inkscape extension to process a vector graphic there is no ghosting.

IMG_0529.JPG (248.59 KiB) Viewed 10609 times

I have created simple test patterns such as a text on white image for testing. Piclaser burns two copies yet appears only once in the visual when I change the M106 commands to Z and only once if I run it thru the web based solution mentioned above.

[Picengravertoo]

As I explained before in our email conversation, others has experienced the ghosting issue also. In every case the issue was not our image to gcode programs. The gcode is generated properly. Did you read though those posts I linked to find where your problem may be at your end?

I just generated the gcode from your image with all the suggestions I made to you in our email conversations. The only difference is, I used our EmBlaser running grbl 9g firmware to do the laser engraving and did not add the M106 or M107 commands. The comment characters & file extension is different also. Here are the settings I used.

CaptureLarry.JPG (45.08 KiB) Viewed 10600 times

I used different Start & End Comment Characters, different file extension and no M106 & M107 commands. The gcode generates the same based on the Blacks & Whites in the image as you have done.

Here is the preview in Mach3 with Z axis depth commands instead. No ghosting.

CaptureLarry1.JPG (41.36 KiB) Viewed 10600 times

This is the results of your image engraved with our EmBlaser using the PicLaser settings above to generate the gcode. No Ghosting.

Larry.jpg (477.4 KiB) Viewed 10600 times

Snippet of the gcode from the file.

S0
G1 X6.858 Y34.5948
S0
G1 X7.0104 Y34.4424
S0
G1 X7.1628 Y34.29
S0
G1 X7.3152 Y34.1376
S0
G1 X7.4676 Y33.9852
S0
G1 X7.62 Y33.8328
S255
G1 X7.7724 Y33.6804
S255
G1 X7.9248 Y33.528
S255
G1 X8.0772 Y33.3756
S255
G1 X8.2296 Y33.2232
S255
G1 X8.382 Y33.0708
S255
G1 X8.5344 Y32.9184
S255
G1 X8.6868 Y32.766
S255
G1 X8.8392 Y32.6136
S255
G1 X8.9916 Y32.4612
S255
G1 X9.144 Y32.3088
S255
G1 X9.2964 Y32.1564

What is causing the ghosting is your machine and/or controller software and/or firmware. You refused to except my recommendations with the image and PicLaser settings I gave you, so it will be impossible to convince you that your conclusion is incorrect.

BTW, are you using the ; for the Start & End Comments?

[Flashsolutions]

Contrary to your suggestion that I did not follow your previous suggestions, I have done all those things and more trying to isolate this.

Yes, I used start and end comments of ( and ) and yes I used various pixel resolutions.

I did not use as high a feed rate as in your capture, and my Laser off command is 'M106 S0' and Laser Control Command is 'M106 S'. No of passes I used was 1. I documented that previously.

I have tried Left 45, Vertical, and Horizontal and all of these still produce the ghosting. That was one of the solutions reported in the forum, but did not have any affect for me.

Testing different combinations of settings etc takes an enormous amount of time. I have reduced my test images to bare bones so that I can observe the effects of the various changes.

I did not use your PreCode commands, but I will give that a try next.

And yes, I did read thru the forum and solutions of those who reported ghosting, such as one person who switched computers and fixed his problem, but that is not a solution I have at my disposal. Most of the other posts concentrated on tightening belts and other hardware approaches, but I have used my machine for CNC cutting and laser cutting/engraving with other software with absolutely no problems so if it is hardware, I would expect to see some semenlance of the problem with those software.

The ghosting is as consistent as can be. If it were loose belts or drive train issues, it would not be this consistent.

In order to try to eliminate as much as I could, I did however try putting GCODE on an SD card and running it from there to eliminate the computer and USB sender from the equation. It did not make any difference. I tried a number of different images. Each and every one have the same ghosting present.

Certainly, it could be a controller issue, but all of the other image to GCODE software I have tried work just fine and do not cause ghosting.

I know you use a GRBL controller. Have you or anyone on here used Repetier controllers? Others seem to experience the ghosting in various degrees from what I can tell from the forum posts, so maybe you ought not to be so closed mind to the fact that your software may play a part in it. I would not be this blunt if it were not for the fact that other image to gcode solutions I have tried do not exhibit the problems that your software introduces.

I am a programmer too and I know how we don't like to think that our own software has issues and are first to blame the users, but it does come back to bite us from time to time. If you have not tested your software in other environments, you can't say for certain that there are no bugs or issues with your code.

On the other hand, It may well be a controller issue of some sort. But until I can determine something, anything, that makes any impact on the problem, I am left searching for answers.

I am using the standard setup for 3D printers. An Arduino Mega 2650 loaded with Marlin firmware driving a RAMPS 1.4 board for the stepper drivers and such. My computer is running Windows 7 with the Repetier Host/Server for the GUI.

It would interesting to know if any other of your users are using this combination.

[Flashsolutions]

Okay, I used your settings and it worked, at least on the first test image I put it to. I wonder if it was the PreCode commands that made a difference?

I also made some changes to my controller to use M42 as the laser trigger, so my Laser On and Off are slightly different now.

Now to try some more complicated images and then eliminate the variables one by one to see what really fixed it.

Screen Shot 2016-07-28 at 6.57.22 PM.png (32.99 KiB) Viewed 10582 times

[Flashsolutions]

Okay, spoke too soon. Ghosting is still there. I ran two copies using PicLaser and one using lmg2gcode. Piclaser has shadows. img2gcode does not.

Same hardware, just different software. The piclaser quality is crap compared to lmg2gcode and lmg2gcode renders many times faster. The problem with lmg2gcode is that it reverses the image. I am working on the code to flip it the right direction since it was open source.

See attached images.

[Picengravertoo]

It would interesting to know if any other of your users are using this combination.

From what I understand, Jay at J-Tech Photonics is running the same controller setup as you are.

https://www.youtube.com/watch?v=-DyqshA7Jn4

There are only 3-4 (including you) users that we know of claimed Ghosting issues, but your the only one that has not let us know if it has been resolved.

Have you figured out what is causing the ghosting with your setup yet? Even your example using that other program looks terrible, so there is definately a problem at your end.

If no resolve yet, can you give us more information on your machine and laser? Maybe we can help you figure it out.

[Flashsolutions]

After many many hours of work, I have resolved the problem and am now printing flawlessly!

It seems the version of Marlin firmware I was using was at fault. I suspect it was doing some kind of interpolation. It only showed up running your GCODE, but I could find nothing wrong with the GCODE.

I tried to use Repetier firmware, but it failed miserably at doing lasers. I built a CNC Shield for use with GRBL, but really did not want to rework all my wiring so I decided to try another version of Marlin, one that was designed for Laser cutters on 3D printers. It is not perfect by any means and still has some issues, but it does have a lot of options for Lasers.

The new Marlin firmware failed to compile with the latest libraries for Ramps 1.4 and I had to fix a bunch of duplicate defines before I could get it to load. Then the limit switch code would not work with inverted logic (normally closed) limit switches, so I had to rewire my limit switches. Another bug requires running an M92 command to initialize the steps/axis before you can start printing the first time. But that is easy enough to include in the startup code in the Repetier GUI.

Once all that was done, I ran the Cardinal Baseball file thru PicLaser with new settings to correspond to the Marlin requirements. I am now using M3 to turn the laser on and off. the ';' is the comment character. Feed Rates and other parameters all work as expected.

So bottom line, you were correct. It was a hardware issue not your code. I may fork a branch on Github for the changes I made to the Marlin code. If anyone is having problems running the Ramps 1.4 with Marlin firmware on an Arduino Mega, I would be happy to provide them a copy of my files.

[Picengravertoo]

Thank you for letting us know this has been resolved. It will help others with ghosting issues.