Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Hydrops on November 13, 2014, 08:29:46 AM
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Reposting here hoping somone can help me
Hi
I have a problem with the configuration of mach 3 and laser.
CNC Machine is a heiz 720T, this http://goo.gl/z2THoM laser kit is from J Tech Photonics using latest version of mach 3
I have managed to get it working with the db25 dual breakout board connecting pin 17 and 25 to laser board and making output to #3 and M3 Command on mach and creating a new profile in mach 3 for laser
My doubts are :
How can I stop the Z axis from moving without disabling it in ports config in mach 3 ?
After testing the laser I notice that it is burning too much especially near the edges of the drawing is there some setting to correct this ? I have tried to increase height and speed but problem remains.
Can someone please help me ?
Thank you
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Hi Hydrops,
Basically, if your Gcode does not contain any Z axis moves then the Z axis should not move – simple as that really.
Perhaps use a text editor with ‘search and replace’ to delete any Z axis commands from your Gcode??
If you attach a picture, or two, of the excessive burn near the edges of the drawing this may give us a better understanding of the cause of the problem.
Tweakie.
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Hi Tweakie,
thank you very much for replying
I use vectric aspire, is there any way I can do this besides deleting all z commands ?
I am considering buying pic engrave pro laser, do you know if this progam eliminates the z commands, which I thought it would but just to be sure.
I would prefer a program that I don't have to do text editing
Regarding the photos of the excesive burn, I will take some later and post here.
Just to have an idea, what stepover should I be doing for laser engraving ? In this case I created a tool in aspire with .2mm for the laser
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Hi Hydrops,
1) The easiest way is to modify the Vectric post processor to include the M10/M11 commands and remove the Z axis commands. If it's any help to you, one of my modified post processors is here http://hobbymaro.puhasoft.hu/Tweakie/Laser.zip
2) John's PicLaser software allows the choice of axis letter for the laser trigger. With TTL work you just use the axis direction signal and with Greyscale work the actual axis position (either detected electronically with step/direction controlled electronic potentiometer or mechanically with rotary encoder - but there are other options).
3) A stepover of 0.15 to 0.2 mm is usually about right.
Tweakie.
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Your step-over (Pixel Resolution in PicEngrave) for raster engraving images should be based on your focal point burn line. If this is set too small, overlapping of the burn lines will occur and detail will be lost and if it's set to high, un-burn lines will appear in your engraving. The smaller the focal point is, the finer image reproduction detail that can be achieved and gives a more intense burning power so you can engrave at a higher feedrate.
As Tweakie stated, you can set to a different axis letter other then Z and use another axis direction pin to TTL engrave using a Dithered image. PEP will generate Dithered images and allows A,B, & C axis letters also. There is another option in PEP that will allow you to use a Variable Feedrate (X,Y & F) to get shading using a TTL or CW Laser Diode drivers, but this requires a very good heat sink on your Laser Diode because it will run at full power for long periods of time. However, it does give excellent 8bit shading results.
Jeff
www.picengrave.com
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Thank you both very much for the replies
I will post a photo of the burned sample soon as I'm not near the machine right now
Tweakie, I downloaded the file where should I put this file ? Is it a script to open in mach 3 ?
As you guys said I would prefer to assign other axis but Z to control the laser and I would prefer a method where I don't have to edit every gcode file I load into mach 3.
Sorry for dumb question but what is TTL ?
Jeff, do you have a link where I can read more about the variable feedrate ? Regarding the heatsink I have the mist hose installed on the machine which can also spray air only, can this be used to cool the diode ?
And by what I understand in PEP it is easy to assign other axis than Z, is this correct ?
Thank you for your patience, I'm having quite a hard time understanding and getting this stright
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TTL is a type of modulation input which is 0v is laser off and 5v is laser on so you can pulse the laser. J-tech's TTL laser driver will also except a 5v max PWM signal to turn the laser on and off (pulse) at a very fast frequency.
The info is on our web site about the Variable Feed Rate in PDF links in the PEP page. You can also download the Demo from there. http://www.picengrave.com/PicEngraver%20Pro%204%20+%20Laser.htm
There is a fan avaliable for the LD heat sink on J-Tech's web site. Not only will it cool the heat sink, it will also blow the smoke away when engraving. It will also help to keep contaminates from collecting on the lens. http://jtechphotonics.com/?product_cat=accessories
If you do use the VFR code, do not set the driver at no more then 1.7a. That is the maximum recommended amp input for the 9mm Nichia 445nm LD.
Jeff
www.picengrave.com
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I will read the pdf now.
regarding the fan I already brught with the kit, in fact it's got 2, one for the laser and one for the laser circuit board.
Can the M10/M11 commands that Tweakie refered to be implemented with PEP and do you have a tutorial explaining how to do it ?
Thank you very much
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Not at this time will PEP generate the M10/M11 commands.
Jeff
www.picengrave.com
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So, if I understand right PEP will only work with Z axis for laser control, is that it?
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It will work with Z, A, B, C or F.
www.picengrave.com
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Ok
let me go through the pdf and check the program.
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Thank you both very much for the replies
I will post a photo of the burned sample soon as I'm not near the machine right now
Tweakie, I downloaded the file where should I put this file ? Is it a script to open in mach 3 ?
As you guys said I would prefer to assign other axis but Z to control the laser and I would prefer a method where I don't have to edit every gcode file I load into mach 3.
Hi Hydrops,
The file I linked is a Vectric post processor - you need to study the Vectric documentation which will tell you how post processors are used to modify the generated Gcode so you do not have to carry out any subsequent editing etc.
Hope this helps.
Tweakie.
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Thank you very much Tweakie
will let you guys know how it goes.
Best regards
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Thank you both very much for the replies
I will post a photo of the burned sample soon as I'm not near the machine right now
Tweakie, I downloaded the file where should I put this file ? Is it a script to open in mach 3 ?
As you guys said I would prefer to assign other axis but Z to control the laser and I would prefer a method where I don't have to edit every gcode file I load into mach 3.
Hi Hydrops,
The file I linked is a Vectric post processor - you need to study the Vectric documentation which will tell you how post processors are used to modify the generated Gcode so you do not have to carry out any subsequent editing etc.
Hope this helps.
Tweakie.
Tweakie, is this file for aspire ?
I put it in PP folder and when I try to choose it in aspire it's not showing, and I also notice there's no other file there with the .pst extension
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Hi Hydrops,
Sorry, my mistake - try this one... ;)
Tweakie.
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Thank you very much Tweakie,
will let you know later how it goes as I'm not near the machine right now.
Regards
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Tweakie,
Regarding this pp file, is it metric or imperial ? My Mach 3 and vectric are metric if it makes a difference.
and can you tell me approximate values for height and feed settings for this laser ?
Regards
Hydro
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Hi Hydrops,
The pp is for Metric units (G21).
Height is unimportant as the pp does not create any Z axis moves only X and Y (with M11P1 for G01,G02,G03 ... moves and M10P1 for G00 moves).
Feed setting depends on many factors so perhaps use F600 (or whatever you think will be right) as a starting point (it's easy enough to edit the final Gcode as required).
Tweakie.
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Hi Tweakie
I understand that with this pp file the Z axis will be static, but isn't there a distance to observe between the laser and the job to be done ?
Pardon my ignorance but what feedrate in mm/sec equals F600 ?
And regarding this PP file you sent me, is there anything else I need to do in Mach3 or Vectric or just use it as pp for the job ?
I have read the PP manual from aspire but don't really understand it tbh.
Thank you very much for your patience, really grateful
Hydro
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Hi Hydro,
I understand that with this pp file the Z axis will be static, but isn't there a distance to observe between the laser and the job to be done ?
The distance between the laser and the work relates to your 'focal length'. This distance is set so that the laser's focal point (smallest dot size) is flush with the surface of the work.
Pardon my ignorance but what feedrate in mm/sec equals F600 ?
F600 = 600 mm/min = 10 mm/sec
And regarding this PP file you sent me, is there anything else I need to do in Mach3 or Vectric or just use it as pp for the job ?
Just select it (within Vectric) as and when required to produce a laser related Gcode toolpath. Nothing else needs to be done except configuring Output#1 within Mach3 so it becomes your laser trigger.
I have read the PP manual from aspire but don't really understand it tbh.
I think that once you have 'hands-on' experience it will all become a lot more understandable.
Tweakie.
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Finally got it run,
thank you very much Tweakie, without you I wouldn't have made it, very grateful indeed.
Will post some pics as soon as I upload them to pc.
One question though, I want to save Z axis height as a template is there a way to do it in mach 3 ?
Now that its focused I'd like to keep this height as default because there will be jobs done with different thickness where I'll adjust Z axis height to focus laser and I want to be able to always return it to default
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Hi Hydro,
I am pleased to hear you have it all running.
Assuming you have home switches you can reference all home then apply the offset to position all axes to the desired position – the Mach3 manual has details of how this is achieved. http://www.machsupport.com/help-learning/product-manuals/
Having said that, I find the easiest (and quickest) way is to make a mechanical template (the dimension between the Z axis and surface of the work) then just use this to set the focus with relation to different thicknesses of work.
Tweakie.
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Hi Tweakie
I have managed to ref all home but that's not exactly what I meant as the Z axis seems to go to a pre established height. I would like to to make a mechanucal template but can't find no mention of it in the manual, can you please point me to it
Regarding the laser it seems it won't engrave properly on plywood but it works flawlessly on mahogany. I tried on plywood wivarious feedrate and stepover settings and on slower feedrate ie. about 5mm sec it engraves better but leaves blank spots with nothing engraved as on faster feedrate it kind of stutters on the engraving but seems to not be leaving blank spots, really strange. Same thing happened on pine wood, can it be because these are brighter woods ?
On mahogany its perfect even on feedrate of 1000 or more, check images
Does this mean that I can't use the laser to engrave on plywood ?
Regards
Hydro
(http://i54.photobucket.com/albums/g110/Tuareg_photos/P1015581.jpg)
(http://i54.photobucket.com/albums/g110/Tuareg_photos/P1015578.jpg)
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It also engraves very well on mdf
(http://i54.photobucket.com/albums/g110/Tuareg_photos/P1015583.jpg)
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Hi Hydro,
I think some materials just laser engrave better than others and you need to continue, as you are doing, finding what works and what does not work quite so well. Your MDF example is excellent - keep up the good work my friend.
Tweakie.
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Hi Tweakie
thank you
Is it normal that the laser engraves badly on pine or plywood ?
Regards
Hydro
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Is it normal that the laser engraves badly on pine or plywood ?
No, not really but it depends on so many factors - laser power, feed-rate, moisture content of material, laser wavelength, etc., etc.
Tweakie.