High power laser control, basic questions

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10 Jan 2020 20:40 #154575 by rdrr
This is my first fact-finding round for a project.
Basically, I have a high power laser to get running reliably (~kilowatt fibre). It certainly works and we've blasted through and welded a few materials in testing. However, the (Windows 7..) control software leaves much to be desired and is buggy and unreliable. Rather than spend thousands on new (proprietary..) software, i'm curious about using LinuxCNC. I've set up a simple hobby mill using it once before, so setting up the motion control stuff is 'relatively' straightforward; although I don't know very much about control hardware outside of the computer. The part I don't know about is the laser itself.

What I know from minimal poking around:
Control seems to be by some kind of D-sub connector as well as by an Ethernet cable.
It is able to control 4 axes (X,Y,Z, and a rotary head); these have stepper motor drivers.
Laser power output can be controlled fairly finely from 0-100%, although I can't tell if that can be done on the fly in G-code (or interpreted by the control software)

So I guess what I'm asking is:
1. Is controlling such a laser advisable in the first place, using LinuxCNC (outside of time and effort to figure out how to get it to work with this system)?
2. Is LinuxCNC capable of controlling/tuning a laser system of this sort? particularly, changing power levels and adjusting other features this laser system/ typical lasers might have [i'll need to look into that in a little more detail]. There are a few things such as shielding gas control that seems to be using the coolant G-code so I don't expect trouble there.
3. Maybe, any other advice on such a project?

Thank you very much!

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10 Jan 2020 21:12 #154583 by andypugh

1. Is controlling such a laser advisable in the first place, using LinuxCNC (outside of time and effort to figure out how to get it to work with this system)?

It should be as good as any other control system, but the same precautions as any other control system would have to be in place.

2. Is LinuxCNC capable of controlling/tuning a laser system of this sort? particularly, changing power levels and adjusting other features this laser system/ typical lasers might have [i'll need to look into that in a little more detail].


It's been done several times before, admittedly generally at much lower powers.
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24 Jan 2020 23:41 #155702 by rdrr
Now i've installed linuxcnc to the control computer, a small lesson in frustration as I had to backtrack to get the RT-PREEMPT version since the control is via the Ethernet port to a break-out-board (and an RS-232 9 pin D connector for the laser). But fortunately the packaged download from linuxcnc installed and seems to work.

So the big question is now: How the heck to configure for Ethernet output to that BoB? I can't find any options for doing so, and haven't found instructions about how to do so on the forum or otherwise, so any pointers or links are appreciated.

Also the BoB has a "Huazhong University of Science and Technology" stamp on it, I'm trying not to hold any hope that it follows some kind of protocol similar to Mesa or what not.. (trying hard not to fry anything that isn't under the laser..)

Thanks again.

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25 Jan 2020 00:23 #155704 by tommylight
Lots of pictures would help, especially the electronics and how they are wired together.
Most China fibre laser machines use Yaskawa or panasonic drives and motors, so should be fairly easy to control with linuxcnc, that leaves only the laser source and me hoping and praying they do not use RS232 to control them.
Laser sources are mainly fro RayCus/china and IPG/USA and almost all use the RayTools/Swiss focusing head.
No idea what the latter use for control, so any info would make it easier to decide what route to take.
Another thing i heard/read from users of such machines is that the software is very buggy.
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25 Jan 2020 00:39 #155705 by rdrr
1. I can confirm the software is very buggy. Hence this project!
2. Laser is a Raycus.
3. Control is indeed RS232, but there is a squid of a connector with many cables in there, I could follow to find out what types of stuff the other end plugs into.
4. The manual prefaces that the guy writing it didn't have much time. So it's very basic... We've asked the (Chinese) company for details about some additional things we see on it, and mostly they answer "we don't use that function." So for instance, i have no idea if the focus can be changed on the fly.

Will see if i can get some photos inside the panels. i'm new to industrial CNC stuff, so has taken me a while to not be fully confused.
I'm having trouble finding out what's sort of the 'official' way to do things with linuxcnc. Right now I'd just like to figure out the 4 axis motion, and that definitely comes out the Ethernet hole. I found a few people talking about Mesa 7i96 in some other forums, looks like a python setup tool here:
forum.linuxcnc.org/27-driver-boards/3276...ard?start=180#131322
In a config file in that link, i see the HOSTMOT2 declaration below. Is the idea that the Ethernet output is controlled as if it is a SSERIAL_PORT? Or better, where do I go for info on configuring Ethernet outputs?

[HOSTMOT2]
DRIVER = hm2_eth
IPADDRESS = "192.168.1.121"
BOARD = 7i96
STEPGENS = 4
ENCODERS = 0
SSERIAL_PORT = 1
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25 Jan 2020 19:20 #155747 by tommylight
Some 3 days ago a client asked me to check something similar he is interested in importing here, after about an hour of looking at those things i started thinking about how hard would it be to retrofit it as i am sure the motion will be easy, but the laser control was less than informative.
Thank you for confirming the buggy part.
The ethernet part for the Mesa boards is in regards to how it is connected and communicating with the PC, there are no ethernet outputs. Do not worry about configuring them, they are very easy to configure and use after you get over the initial "to complicated" moment and there are plenty here that will gladly help with that, just a bit of caution during wiring and checking and rechecking all the wiring.
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26 Jan 2020 01:35 #155771 by thefabricator03
rdrr,

I would appreciate if you could take pictures of the laser head mounted on the machine and the laser power unit if you would not mind. In the future I would like to build a fiber laser CNC machine and any pictures would be very handy.
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29 Jan 2020 00:59 #156058 by rdrr
Just posting the break out board for motion control, and laser head.
Laser is fiber, camera on top of the head for positioning when using CNC.

Something I've found, is I have no idea how to stop melting the laser protection glass, under the blue cover towards the bottom of the laser head photo. It keeps the laser from blasting itself with back-radiation. We managed to get more than halfway through the first one before realizing that we were pointing directly into a corner, which is not good.

A couple fun notes on how the software is finicky:
- 2013 Windows 7 with SP1 (we keep it offline)
- pushing the 'Origin' button either:
1. moves the laser head to 0 0 0
-or-
2. Sets the current position as 0 0 0
- Getting it able to fire is a finicky series of steps that is not well laid-out in the manual. But we're getting better at it.
- but once we have run it once it will keep working; ran a safety test of how to ensure the laser could not emit. Went through step by step pushing the off buttons, and with the 'laser' button on the table off and e-stop pushed in on the laser itself, it still was able to emit.. Only sure way is the complete system E-stop.

Anyway, the BoB communicates to the computer using Ethernet. I still don't quite understand how to get linuxcnc to talk to it (or a Mesa board) over Ethernet, I think the "DRIVER = hm2_eth" line in the config file is part of it, but there are a lot of technical parameters and I don't want to damage stuff.

Also, how-ever-to output to RS-232 is still a mystery! Doesn't seem like there's any support for that in linuxcnc. I followed the other input 'tentacles' out and they seem to just go to the laser head - so probably some sensors in there in addition to the trigger button.

Thanks
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29 Jan 2020 01:11 - 29 Jan 2020 01:12 #156060 by thefabricator03


Also, how-ever-to output to RS-232 is still a mystery! Doesn't seem like there's any support for that in linuxcnc.


Thanks for the pictures, If you would take one showing the whole gantry arm that would be very helpful.

You machine sure does look nice and expensive compared to my filthy plasma machine.

I am still testing out Phill's modifications to PlasmaC that allows communication with my plasma unit via RS485. Maybe ask Phill about it with some specific details you want to know and he might be able to help you out. I know RS232 is not RS485 but they way it works should be similar.

Also you might get more help if you post in the Driver Boards section of the forum the specific details about getting the ethernet communication working with LinuxCNC.
Last edit: 29 Jan 2020 01:12 by thefabricator03.

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24 Aug 2020 22:16 #179281 by Clive S
I wonder how this has got on.

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