Shapeoko3 - Laser etching mod documented and posted

FargoPhil
Posts: 62
Joined: Wed May 20, 2015 2:40 pm

Re: Shapeoko3 - Laser etching mod documented and posted

Post by FargoPhil » Sun Oct 04, 2015 3:54 pm

Right on, thanks.

I've got the FlexMod P3 driver and have just about got it tuned up. My el-cheapo mulitmeter only goes to 200ma, so I'm not able to accurately set the output.

apspurgeon
Posts: 122
Joined: Mon Jun 08, 2015 9:18 am

Re: Shapeoko3 - Laser etching mod documented and posted

Post by apspurgeon » Mon Oct 05, 2015 6:28 am

OK, Never used a FlexMod P3 driver, but you MUST (did I say MUST) use a current control driver board with a laser or it will draw as much power as you can give it....until it destroys it'self. The Lasers I've used all come with a driver board

e.g
http://www.ebay.com/itm/12V-TTL-1W-2W-3 ... 4aebfa6bdb

Let me know how you get on

FargoPhil
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Joined: Wed May 20, 2015 2:40 pm

Re: Shapeoko3 - Laser etching mod documented and posted

Post by FargoPhil » Tue Oct 06, 2015 5:07 pm

The documentation gave an alternate way to set the output current, so I was able to get it up and running. The laser doesn't get hot at all, but the transistor on the driver board does. I didn't check the rest of the grbl controller board, probably should do that.

I used the trial version of pic engrave to generate gcode, and sent via universal gcode sender. The first image I attempted was just black and white (no gray). That seemed to be fine. The second image I attempted was an actual grayscale picture. Not so fine. The machine isn't moving nearly as fast as the feedrate, so it's just burning everything black.

I believe there to be a couple of issues there.

First, UGS isn't quite up to the job of dealing with big gcode. I have some optimizations I implemented to make the file load faster (preprocessing actually). When I get time to clean them up a bit, I'll submit a pull request.

Second, when actually sending with UGS, the machine will pause intermittently (every couple seconds.) Those pauses don't shut the laser off of course, so there are random burns all over the place. I believe that's due to garbage collection, likely related to scrolling the output window. I've got a couple of ideas for things to tune up there. Of course the next step will be to try a different gcode sender.

Third, I'm suspicious that grbl doesn't like the gcode all that much. It's a ton of sub-millimeter movements with different spindle speeds. I am going to try and adjust the acceleration, but it seems like something else must be going on. The machine head is supposed to be moving smoothly in a straight line, so I'd be kind of surprised if the issue is acceleration.

apspurgeon
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Joined: Mon Jun 08, 2015 9:18 am

Re: Shapeoko3 - Laser etching mod documented and posted

Post by apspurgeon » Tue Oct 06, 2015 5:29 pm

If you have inkscape, try the extensions in the documentation I created. I modified the phython scrip for the SO3, and it works well
You can draw or import something into inkscape and export, very easy

An important point! The SO3 uses M03 S10000 (yes 10000) to turn the laser on 100% PWM. Most software will output S255 as 100%.

Hope that helps

cvoinescu
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Location: Camberley, UK
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Re: Shapeoko3 - Laser etching mod documented and posted

Post by cvoinescu » Tue Oct 06, 2015 5:53 pm

apspurgeon wrote:An important point! The SO3 uses M03 S10000 (yes 10000) to turn the laser on 100% PWM. Most software will output S255 as 100%.
Good point, but it's very easy to change the spindle max rpm to 255 and recompile.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

FargoPhil
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Joined: Wed May 20, 2015 2:40 pm

Re: Shapeoko3 - Laser etching mod documented and posted

Post by FargoPhil » Tue Oct 06, 2015 6:48 pm

I am using s10000 as the max. If anything it's too high for the results I'm getting since the head is moving so slowly. I'll take a look at the inkscape plugin again and see how that does. Will be interesting to compare the gcode at least.

Thanks
Phil

apspurgeon
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Re: Shapeoko3 - Laser etching mod documented and posted

Post by apspurgeon » Wed Oct 07, 2015 8:30 am

If it's moving slowing that will be the feed rate, e.g a G1 x100 Y100 F1000.

FargoPhil
Posts: 62
Joined: Wed May 20, 2015 2:40 pm

Re: Shapeoko3 - Laser etching mod documented and posted

Post by FargoPhil » Wed Oct 07, 2015 3:37 pm

The issue I'm having seems to have more to do with acceleration. See topic http://www.shapeoko.com/forum/viewtopic.php?f=3&t=6970

I've got some ideas on things to try.
-Increase pixel size
-Increase acceleration

apspurgeon
Posts: 122
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Re: Shapeoko3 - Laser etching mod documented and posted

Post by apspurgeon » Wed Oct 07, 2015 9:03 pm

I can email you some GCode that works for me, I used GRBL sender that than Carbide motion as their is a delay in movement in Carbide that causes overburn but doesn't sound like that's the issue. Did you create using the inkscape plugin I provided?

FargoPhil
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Joined: Wed May 20, 2015 2:40 pm

Re: Shapeoko3 - Laser etching mod documented and posted

Post by FargoPhil » Thu Oct 08, 2015 2:13 pm

Yeah, I've been doing some experiments with different software to try and get a feel for what my setup is capable of. I don't see any issues with strict two-tone burning. The trouble is when I'm trying to do grayscale. Part of the trouble may be the cheap plywood I'm trying to burn. I haven't yet tried any decent wood like maple.

As far as senders, I've been using Universal Gcode Sender, which I've done a bit of tuning to. There is a pull request pending which substantially speeds up preprocessing for large gcode files. I've also been using a command line option to deal with the pauses due to garbage collection. I never attempted carbide motion for this since UGS works so much better for me. Chilipepr doesn't handle large gcode files well either due to being a browser based application. I think I tried Gcode Sender once and it crashed. picsender didn't do any better than UGS, so I've just stuck with that.

I did some test burns with two parallel lines to determine what resolution I should be shooting for, and with a .2mm spacing, there are clearly two lines. So .1mm is not an unreasonable goal based on that. So the challenge for me is to get the machine to run smoothly and do meaningful grayscale at .1mm resolution. It sounds like there are some fundamental issues with how grbl works. The queue is only 17 commands deep, so the planner can't run smoothly without a high acceleration. Of course the acceleration can't be too high because then the machine is going to have fits when cornering. It sounds like the current grbl implementation also doesn't accelerate through spindle speed changes. So even with a larger command queue the grayscale is going to be slow.

All that said, if you've got grayscale burns working and could post machine settings and gcode, I'd love to give it a try.

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