Ben's 2.x Laser Build

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Re: Ben's 2.x Laser Build

Postby sliptonic » Sat Dec 03, 2011 12:47 am

Ben,
Just finished reading through your log. Great stuff.

I'm in the process of converting an old ULS-25A and I'm using Bart's interface/pololu driver controlled by EMC2. I'm not as far along as you but I'm really interested in what you've done with EMC2. Do you think I can get a copy of your configuration?

If you're willing to share it and have a git repo, put it there. Perhaps we can get a stock machine configuration included in EMC2.

I'm also interested in writing a custom post-processor for HeeksCNC but that'll have to wait until I'm actually cutting.
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Re: Ben's 2.x Laser Build

Postby BenJackson » Sat Dec 03, 2011 7:22 am

I will try to put something up soon. My wife has planned activities for me this weekend and I'm also quite distracted by aichallenge.org.
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Re: Ben's 2.x Laser Build

Postby sliptonic » Tue Dec 20, 2011 2:33 pm

Thanks. I'm still waiting on my power supply but hoping to have it over the Christmas break. I've been reading the forum messages about PPI and I'm curious how your pure EMC2 implementation compares.

And if it's easier to just zip up the emc2 config and email it, that's fine with me. Thanks again.
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Re: Ben's 2.x Laser Build

Postby sliptonic » Thu Dec 29, 2011 4:40 am

I finally got my power supply and hope to be burning in the next couple days. With all the chat about PPI, I'm anxious to try reproducing your success with EMC2. Any more details about your custom HAL component and your configuration are greatly appreciated.
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My EMC2 Configuration

Postby BenJackson » Thu Dec 29, 2011 7:25 am

I've pushed my git repo to github:

https://github.com/bjj/2x_laser

I just wrote a README (which github formats nicely) which tries to document what I've done. I'm sure it's incomplete, so please ask questions and I will improve it.

This includes all the rastering support if you insert a few lines of gcode for it, but not the other work I was doing to try to automate the creation of gcode with rastering from a print job.
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Re: Ben's 2.x Laser Build

Postby sliptonic » Fri Dec 30, 2011 6:59 am

Wonderful. Thanks Ben!
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A cascade of failures

Postby BenJackson » Sun Jan 01, 2012 6:24 am

While doing a test run in cardboard of my first full-area "production" build things suddenly went haywire. My cuts got wobbly, the steppers were making a bad noise, and eventually despite the laser firing no beam was hitting the workpiece. Luckily it was a test run so I was right there to hit E-stop.

The root cause appears to be one loose stepper wire on the X axis. That caused huge vibration (and unreliable movement) of the X axis which backed out the thread on the final lens assembly. I had thought that the air nozzle was trapping the threaded lens holder but apparently not!

The loose wire was comparatively easy to fix once I found it. Getting my lens back into shape was much more trouble. I never got around to cutting a retaining ring for it so my first reassembly had the lens off-center and I couldn't get the beam to pass the air assist. Once I got around that (used a bit of blue tape from the bottom to hold the lens in place while I threaded it together) I found that my air assist was actually wobbly. In my efforts to keep the brass fitting close to the nozzle I threaded it in so tightly that I deformed the aluminum. You can actually see the threads from the pipe fitting telegraphing through the aluminum at the mating surface! My first few attempts to ignore that and get the nozzle back on resulted in very oblong "spots" when the laser was test fired (despite nice clean results without the air nozzle). Finally I took the nozzle to the garage and ground off the offending bump so I could get it on straight.

So now my final lens has some teflon tape to keep it from backing out and I solemnly swear I will cut the adapter ring for next time.
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Re: Ben's 2.x Laser Build

Postby BenJackson » Sun Jan 01, 2012 11:56 pm

Aaand one final thing: I forgot to switch the laser back to computer power (rather than knob power for the test firings) so I ruined my first sheet and thought I had a whole other beam problem again...
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Re: My EMC2 Configuration

Postby sliptonic » Mon Jan 02, 2012 3:37 pm

BenJackson wrote:I've pushed my git repo to github
...
I'm sure it's incomplete, so please ask questions and I will improve it.
...


Well, I'm still fighting with my power supply issue and I haven't tried rastering yet but otherwise I've have great success with your config. I only had one small struggle: I'm generating my g-code from HeeksCNC with the emc2b simplified post-processor. When I'd run the g-code through your config, EMC2 would appear to lock up for a long time and then be incredibly sluggish when it came back. I finally realized that it's because your config has the manual tool change hal component disabled and Heeks was putting in an M6.

HeeksCNC uses the tool diameter to account for the kerf when calculating the tool path and the profile operations are configured to cut on one side of the line or the other (or on the line if you choose). Without tools, are you using EMC2 cutter compensation or accounting for the kerf in your design?

Very nice work, btw. Thanks again.
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Re: Ben's 2.x Laser Build

Postby BenJackson » Mon Jan 02, 2012 8:16 pm

I took out the manual toolchange module because it had a nag at startup and didn't seem very useful. It's likely that there are two HAL pins that need to be tied together to short-circuit :

Code: Select all
net tool-change-loop iocontrol.0.tool-change => iocontrol.0.tool-changed
net tool-prepare-loop iocontrol.0.tool-prepare => iocontrol.0.tool-prepared


I've used CamBam and while it also uses tools to do cutter compensation it doesn't use G41 cutter compensation, it just offsets the paths itself. So I still use "tools" in CamBam (well, one "Laser" tool and one "Laser Kerf" tool) but I modified the post-processor settings so that tool changes don't emit anything.

(note the edit, the "prepared" loopback is also required, I had a chance to test)
Last edited by BenJackson on Tue Jan 03, 2012 8:46 am, edited 1 time in total.
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