Our 1390LC Laser Cutter


  • Design Lab

    @pierre can you paste the laser manufacturers guidance you’ve paraphrased into this thread verbetim for reference, please?

    we need to leave a good trail of pertinent info on this thread - for example the specs and manufacturer of this purchase, costs, etc.

    thanks man



  • @Vaughn I’ll do that, I need to go back through many emails to get all of the information together in one place, so I’ll probably post it some time after getting the chiller, and maybe the rotary tool set up.

    On that front, @Grant-Fraser came up with a much smarter way to lay out my resistor matrix for reducing current through the motors. The problem with the approach I was using is that the motor drivers are a chopper arrangement, so I should be bleeding the excess current, not trying to limit current drawn. The driver goes “Only 100mA? I’m supposed to provide 2A. I’ll increase the voltage!” So to get 100mA through the coil, I need to drop 1.9A through a bleeder in parallel with the coil. Putting a choke resistor in series with the coil just sees higher voltages at the same current through the coil.



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  • Noting this here, mostly so I have the info saved somewhere… You can tell things about your power stability by what the aiming beam (before the lenses focus it down to a tiny dot… ) looks like.

    https://en.wikipedia.org/wiki/Transverse_mode

    We’re getting a TEM02 beam, and as far as I can tell should be getting a TEM00 beam if we have clean power. I’m going to at some point try swapping the power supply out for the spare 100W supply that we have. It is supposed to be a better made unit, but needs a wiring harness made up to be compatible with our machine. Doing that will also mean that we have a drop-in spare supply.



  • Tonight I have good news and bad news. I’ve got the leak plugged finally… It was still leaking today when I filled the cooler, so I gobbed more silicone onto every damn place and then checked back in about 6 hours. Leak seems to have finally stopped. So, put everything together, bodging as I went to try to get it up and running.

    While I was aiming the mirrors, I’d noted that the pump had an intermittent problem where it would stop moving water every once in a while. Opening it up, there was a lot of rust build-up on the rotor (which is, after all, a diametral permanent magnet) and @Grant-Fraser and I theorized that cleaning the damn thing would probably fix it. Seemed to work for a while, but now when I tried to fire up a test burn tonight, I had the pump cut out again. Fuck it, says I, tomorrow I’ll install one of the heavier units that @MIPS supplied. I just need to get a fitting to take 1/2" NPT and let me jam a latex tube on the end.

    Hope to get it up and running reliably tomorrow. At least with water in the chiller. Once we have everything finalized we’ll dump the water, and put in the glycol to prevent rust next time.

    We now know positively that the flow interlock works properly. First clue that the pump had stopped pumping was that the pulse on the laser did not flash or draw any current.



  • Also… there is still a mis-wiring in the chiller control panel, some but not all of the buttons work. Enough to make it cool the water to 25 degrees Celsius, but not enough to adjust that temperature.

    I started the process of tracing the circuit to figure out which pins I need to swap to set the temperature. Looks like they’re using polarity and diodes on the buttons and LEDs to get 32 IO signals to travel on 13 wires. There are 3 unused wires on the 5-pin connector that are intended for the IR controller that is not included in this model.

    0_1505112028739_controlboard.png



  • Picked up a half inch threaded to pex barb reducer this morning. That should let us use @MIPS ’ pump



  • Please verify the seals on those pumps are intact. While they are grounded devices I’m sure moisture in the motor housing will not be nice. I noticed during the first chiller test at least one had mineral oil escaping from it. The seals are easy to access. There are four screws holding the bottom of the pump housing on.
    Specs for the pump can be found here: http://littlegiant.com/products/industrial/small-submersible-pumps/3e-34n-series/#Features


  • Design Lab

    A straight up shout to @pierre and @Grant-Fraser for their work on the laser - thanks, you guys. It was super to see Corey Doyle making his deadline for the Warmachine World Championships and, more locally, Susan Knox from the arts council children’s festival this weekend making hers.
    What a machine - thanks to all who have made that capability happen for the Space.


  • 3D

    It sounds like the laser cutter is up and running. Are there any changes to the operations that we should know before we set to cutting?



  • Yes, the water chiller pump isn’t automatic.
    1 plug in the water pump. Cord is beside AC
    2 power up AC. Control box is hanging from the shelf. Don’t put your fingers on the back of it.
    3 power up laser
    4 power up exhaust fan. If you’re cutting plastic please leave the van running for 10 or 15 minutes after you’re done cutting to get more smells out of the room. Leave it running between cuts.


  • 3D

    @Grant-Fraser Thank you! A new protractor for a new school year is on its way :)



  • The new tube appears to be more efficient than the old one. They tell me it’ll get much longer life if we keep it below 16mA. Cory’s been cutting 4.5mm acrylic at that power without difficulty. If you’re finding it hard to cut at that power level, please let me know so I can check mirrors and alignment.

    I’m going to try to order the needed sensor to measure power at each mirror and keep records.



  • This changes everything. I needed to cut a rectangular recess to adjust the latch on the wood shop door. Making it fit tight for winter. I’d been putzing around with a chisel and a forstener bit when I realised that we have a damn laser cutter.

    I don’t need more than a quarter inch or so recess in a three quarter inch spacer… So I can laser it and pop out the piece with a chisel. I focused about 3mm into the 19mm birch ply scrap I dug out of the bin, set up my cut at 3mm/s 45% power. It ran at about 16mA as expected… And I’ll be damned if it did not laser all the way to where the last ply was barely holding it together… A quick tap with my pocket knife and the rectangle dropped neatly out of the part. We can cut three quarter inch ply in a single (slow) pass.

    0_1507423177750_IMG_20171007_172619.jpg


  • Design Lab

    @pierre, OMG really? We need to get onto controlling the Z axis dynamically


  • Design Lab

    @pierre, or even statically with some test cuts. We should grab a depth gauge and see how far we actually cut at a pass of say 25 mm/s at “full” power (i.e. 16 mA or w/e).

    If we did a few quicker passes and adjusted the laser focus in between, we may be able to get a cleaner cut without adding on much time, and help punch out the back. 3/4" is much wider than the plane of focus of the laser, so what we are losing in cutting efficiency, we are making up for in brute force by slowing the laser down, so it may not even necessarily take longer in the long run. Without automation for this in the software, we would have to make some adjusted focusing jigs based on the depth actually cut with a standard speed and power pass (would need different jigs for different materials).

    It would be cool to play around if you have something that could measure the depth of cut accurately.



  • @kile right after three rotary cutter, my next upgrade is a more versatile controller… Call it “advanced mode” if you will… I’d like to have a tested plug-in replacement for the current controller that runs on standard g-code running by mid winter. From there I can make the z-axis move dynamically, mostly so I can vary the kerf of my cut on the fly by changing both z-height and either speed or power at the same time. I want to do some vector calligraphy… I see no way to make the controller on there do that, and a working spare as an upgrade seems like the way to go.



  • @kile said:

    It would be cool to play around if you have something that could measure the depth of cut accurately.

    I will bring in my Mitutoyo depth micrometer, it’ll measure to 1/1000" easily. I need to use it to make a new power/speed/depth board anyway.


  • Design Lab

    @pierre this will allow acrylic ‘oragami’ as well??? cooool



  • @Vaughn Yes, I’m not sure how it would know how long it needs to laser to get the desired bend though? The g-code could certainly tell it to drop the Z by a certain amount (the wider kerf would define your bend radius?), set the power and cutting speed to specific values and make a certain number of passes, but I think you’d need to trial and error how many passes to make?

    I’d be tempted to design a laser-cut fixture that the part folds around to make critical bends. Super interesting stuff.


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