Hack.RVA's 2.x laser build

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Hack.RVA's 2.x laser build

Postby alan025 » Sun Sep 15, 2013 1:41 pm

We finally got underway with our 2.x laser build (summer vacations tended to interfere with our progress). The frame went up pretty quickly. I would note, however, that on some of the drawings the machine screws are mislabeled. The part numbers for the screws used to build the frame call out 10mm screws, but the descriptions call out 12mm screws. It appears that the 12mm screws are a bit too long when securing the cast brackets to the misumi extrusions (the screws bottom out before tightening fully). So, as Bart has mentioned in other threads, when in doubt the BOM is always (at least so far) the gold standard.

Ran into one other issue last night - the Z lead screw bearing brackets included in one of Bart's parts kits from last April (May?) doesn't seem to match the B17005-001 Rev 1 drawing. There is a little 2.25 mm hole that should be located next to the bearing that seems to be missing. However, the bearing included with the part (thanks Bart!) also has a flange on it that we weren't expecting. I suspect there may have been a design improvement that hasn't yet made it to the B17005-001 or C30033 drawings.

Now, on with the build!
Attachments
photo.JPG
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Re: Hack.RVA's 2.x laser build

Postby bdring » Sun Sep 15, 2013 10:33 pm

The bearing brackets were an improvement and the bearings were provided for free. They are much easier for me to make that way.
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Re: Hack.RVA's 2.x laser build

Postby alan025 » Mon Sep 16, 2013 4:25 pm

I suspected it was an upgraded design. Is there a particular orientation suggested for the new design (flange-side of the bearing on top or bottom)? It doesn't look like the upper bearing bracket takes much radial load so it shouldn't matter there. The lower bearing bracket appears to be captured by the hex nut and the pulley, so I don't see the bearing orientation being significant. Am I missing something?
Also, for long term maintenance/replacement, do you have a VBX part number for the new bearing?

Thanks,
Alan
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3 axis laser interface pcb has arrived

Postby alan025 » Sun Oct 13, 2013 4:59 pm

We've successfully had OSH Park make a few of Bart's "3 axis laser interface" boards. Bart's gerber files weren't fully compatible with OSH Park's requirements, but the good folks there massaged the files a little and everything seemed to come out ok. They generated an outline file from one of the other files. They also said the drills file "needed a little work", but I suspect that it was just that the drills file assumed some defaults that needed to be fully specified for OSH Park's process. Anyway, we have 3 purple boards in hand! The goal is to use one of these boards in the laser cutter with a DB-25 interface on the electronics module rear plate. In the short term we will drive it with linuxcnc. With a little more work we hope to drive it with a modified version of Lasaurgrbl running on an Arduino UNO.
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DSC_0052 2.JPG
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Re: Hack.RVA's 2.x laser build

Postby TLHarrell » Fri Oct 18, 2013 5:04 pm

Nice boards. Should see if we can get the files posted here as an option for others to source their own.
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Re: Hack.RVA's 2.x laser build

Postby alan025 » Mon Oct 21, 2013 4:06 pm

TLHarrell wrote:Nice boards. Should see if we can get the files posted here as an option for others to source their own.


Here's a zip file of the gerber files used to produce the boards. The files are identical to Bart's except for the holes file and outline file. The files have been renamed to meet OSH Park's naming requirements.



I've done a little continuity testing of the board and everything looks good so far. The proof test will occur once the board is populated and we fire up the motors and laser.
Attachments
laser_interface.zip
gerber files used by OSH Park to make Bart's 3 axis laser interface pcb
(34.83 KiB) Downloaded 1878 times
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Re: Hack.RVA's 2.x laser build

Postby leros » Mon Jan 06, 2014 3:13 am

Did the board work out? I'm considering placing any order from OSH Park using your files.
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Bench testing the 3-axis laser control board

Postby alan025 » Sun Feb 09, 2014 9:44 pm

I've finally found time to complete the bench testing of the laser control board with an Arduino Uno. The Uno was loaded with the LasaurApp firmware (a variation of Grbl). I used the LasaurApp web interface running on a Mac to exercise the motors, relays, etc. Here's a photo of my bench-test rig with one motor hooked up:

bench_testing.JPG


I used DB9, DB25, and RJ45 breadboard adapters to make it easy to jumper the various signals. My adapters came from Winford Engineering (http://www.winfordeng.com) and they worked like a charm. I had to put the motor enable/disable jumper to "disable" so that the steppers to disabled whenever the Arduino Uno was powered down.

Running everything from the Arduino required a few changes to the LasaurApp firmware. First, the steps/mm had to be changed to match the Inventables stepper motors and the belts/pulleys in the buildlog.net 2.x design. Next the logic used for limit switch sensing (and sensing the status of the chiller) had to be inverted. Finally, the INVERT_AXIS defines had to be tweaked so that the motors turned the correct direction when responding to manual commands.

I've still got one more tweak to make to the firmware - homing the laser from the web interface results in driving the laser head away from the X end stop rather than toward it. More difficult (at least for me) will be adding Z controls to the web interface. None exist at the moment because (I think) the Lasersaur has no motor-drive on the Z axis.

And one other thing for anyone using Pololu stepper drivers, Inventable stepper motors, and the 3-axis laser control board. I got the wiring to work by using the wires in a Blue, Red, Green, Black sequence from left to right (when looking at the card edge with the TB1, TB2, and TB3 connectors.
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