Comments on: Sliptonic has a (frickin) laser!

By: Ben

Ben — Sun, 16 Dec 2012 21:26:16 +0000

Hey man,

So I’ve been playing with my stepper settings, motor currents and belt tensions, and I haven’t been able to correct the missed steps. I’m wondering now if maybe the 19v laptop power supply I’m using just isn’t up to the job. Would you be able to let me know how many volts you’re running your motors on, and what kind of power supply you’re using?

Cheers

Ben

By: Sliptonic

Sliptonic — Mon, 03 Dec 2012 21:29:40 +0000

I’m running 1/16th. BTW, I keep my configs on github (I only had to screw up a config once to learn) here https://github.com/sliptonic/2x_laser

By: Ben

Ben — Mon, 03 Dec 2012 21:16:37 +0000

Cool, thanks. I’m hoping its not a driver failure as it has been this way from the start. I did notice that Linux cnc actually has published recommended settings for pololu drivers here, so I will try these next as I think my system is still on the defaults. Also I am using 1/16th micro stepping right now so maybe I should try switching it up to 1/8th. What do you end up going for in terms of micro stepping?

Cheers

Ben

By: Sliptonic

Sliptonic — Sun, 02 Dec 2012 15:29:59 +0000

Hi Ben, I’m glad to hear it’s going well. I’ve checked in on your blog from time to time and it looks great.

You’re right that mine uses Pololu’s. I’m using the the board from Buildlog.net. My experience with 3D printers is that there’s a lot of variability with Pololu stepper drivers. I’ve had some go bad but the failure mode didn’t look like what you’re describing.

I was using Mercury motors on a 3D printer and they DID fail exactly this way — All three of them one at a time. Still, if you’re loosing steps in both directions, I’d look elsewhere.

LinuxCNC tuning shouldn’t be any more complicated than 1) Making sure the PC has appropriately low latency 2) tuning the axes with stepconf.

Just a note for future readers: As happy as I’ve been with the Buildlog board (very) I’d do it differently if I was doing it today. I did a milling machine conversion and used Mesa’s products. They were a bit more expensive and a bit more complicated to set up but wow. Very powerful, very flexible, tons of extra pins, and great support.

By: Ben

Ben — Sun, 02 Dec 2012 13:41:20 +0000

Hey man!

So we’ve made some excellent progress on our U25A conversion! We even managed to sell the old defunct laser tube to photovac laser for $375 (you should look into this if yours is still lying around). The only problem we are having now is that the motors seem to be skipping steps on small detailed items… Am I right in thinking your system also uses pololu stepper drivers? I dont seem to be able to stop it from loosing steps by upping the motor current, so I’m thinking maybe I need to go deeper into the stepper driver timing settings in Linux CNC. Did you have to mess with these at all to get yours cutting accurately? If so, are there any pointers you could give me?

Thanks!

Ben

By: Ben

Ben — Sun, 09 Sep 2012 20:10:08 +0000

Oh ok, I am calling the left-right axis the X axis. I think the whole idler pulley assembly for the front-back axis can be moved backwards and forwards inside the rail, then secured in place by 2 screws in slotted holes. You can see these 2 screws half way undone on either side of the rail in this picture: http://beentheunseen.files.wordpress.com/2012/09/2012-08-26-11-42-15.jpg

By: Sliptonic

Sliptonic — Sat, 08 Sep 2012 16:38:26 +0000

Nice blog!
When you had the XY gantry disassembled, did you see how to tighten the the belt that moves the last optical element? For me, that’s the X axis and runs from the front to the back of the machine.

It’s clear to me how to tension the other belt with screws on the right end but I’ve never figured out how to tension this one.

By: Ben

Ben — Sat, 08 Sep 2012 13:36:27 +0000

Hey, just to let you know, I’ve started a blog and put a few picures up here: http://beentheunseen.wordpress.com/

By: Ben Minton

Ben Minton — Thu, 30 Aug 2012 19:43:43 +0000

Oooh, that makes much more sense. Thanks!

By: Sliptonic

Sliptonic — Tue, 28 Aug 2012 13:41:01 +0000

Sounds like things are going great. Did you figure out how to tension the belt running on the gantry? I figured out how to tension the fixed axis (my Y-axis) but never figured out how the other one tensions.

As for the beam size, I think someone dropped a decimal point. The tubes I’m seeing on ebay, which is where I got mine quote the beam diameter at about 1.95mm and that seems about right.
See this one for reference: http://www.ebay.com/itm/HighQuality-40W-CO2-Sealed-Laser-Engraver-Tube-Water-Cool-70cm-Engraving-Machine-/230805293427?pt=LH_DefaultDomain_0&hash=item35bd114973#ht_2197wt_1398