Setting up a plasma cutter and looking for some help.

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23 Mar 2020 16:39 #161233 by tommylight
forum.linuxcnc.org/9-installing-linuxcnc...cnc?start=140#159518
Get the first one from there, the RT_PREEMPT one, it is Mint with XFCE so it is lighter and up to date.

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23 Mar 2020 19:26 #161256 by rodw
It will be interesting to see if the newer builds of PREEMPT_RT will be suitable for your older hardware. I had to buy a new PC.

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23 Mar 2020 20:10 #161265 by tommylight
Runs fine on a Dell Optiplex 780 with Core2duo at 3.2GHz, but it will jump to slightly over 100000 on latency under heavy load. Usually it stays vel under 50000, had not time to see why it does jump.

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23 Mar 2020 21:34 #161283 by Birdman3131
It works. Ended up with the stretch iso already installed before I saw to go with mint. Hopefully everything works well.

Gonna be a few days on the Z axis as the coworker I was told to ask for help has actual production work going. (Assuming my state does not shut down although as we make parts for the bottling industry to stay running we might be considered important.) Dunno. That's somebody else's issue.

1drv.ms/u/s!Anw0aD8CF6Z_huI7kfTt7fa1F0Wplg?e=686fgf is my stats although this was only running about 30 seconds.

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23 Mar 2020 22:23 #161288 by tommylight
That looks good, if it stays that way, but since you are using Mesa even if it goes quite high it will still work.

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31 Mar 2020 19:00 #162284 by Birdman3131
Back again. Think I have a handle on things but want to say what I am doing to double check.

Ohmic sensing.
I don't seem to have any opto relays that can use DC on the contact side. I do have a few That work with AC only and thus was going to have the mesa turn that on or off and have it control some standard coil based relays. This should still provide the protection needed for the board if I understand the purpose of the optically isolated relays on the diagram from the plasma primer. If i really need all the relays to be optically isolated I can look harder or order some but this seemed viable.


Cnc connections:

I can set ok to move to either be a relay contact (Default) or a DC voltage. Is there a reason to choose either? Thinking a voltage output seems better but I don't really know

The connections I should have are:
Mesa Outputs:
Start/stop
Ohmic sense enable (To the opto relay from above)

Mesa Inputs:
Thcad-10 as encoder input. (30:1 divider on a 180V plasma should be a 0-6v signal.)
Ok to move (I believe this is the same as arc ok)
Ohmic sense input.

Para port. (Tried hooking this the the mesa board but was not able to get it to work so its hooked to the pc directly)
All home switches. Was not sure I had enough room on the mesa board. This also gives me room for some physical control switches if need be.


onedrive.live.com/?authkey=%21ALTdAndnUh...5&parId=root&o=OneUp The description of the cnc connections.

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31 Mar 2020 22:41 #162310 by phillc54

Ohmic sensing.
I don't seem to have any opto relays that can use DC on the contact side. I do have a few That work with AC only and thus was going to have the mesa turn that on or off and have it control some standard coil based relays. This should still provide the protection needed for the board if I understand the purpose of the optically isolated relays on the diagram from the plasma primer. If i really need all the relays to be optically isolated I can look harder or order some but this seemed viable.

They should be isolated for safety.

I can set ok to move to either be a relay contact (Default) or a DC voltage. Is there a reason to choose either? Thinking a voltage output seems better but I don't really know

Don't let Rod hear you say that :)
If your machine has the output, use that.

The connections I should have are:
Mesa Outputs:
Start/stop
Ohmic sense enable (To the opto relay from above)

Mesa Inputs:
Thcad-10 as encoder input. (30:1 divider on a 180V plasma should be a 0-6v signal.)
Ok to move (I believe this is the same as arc ok)
Ohmic sense input.

Yep


Para port. (Tried hooking this the the mesa board but was not able to get it to work so its hooked to the pc directly)

I'm not sure what you mean here


All home switches. Was not sure I had enough room on the mesa board. This also gives me room for some physical control switches if need be.

Use them if you think it make life easier/better

I would consider having a float switch as a backup for the ohmic and also a breakaway switch. They can be the one switch.

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01 Apr 2020 04:39 #162329 by Birdman3131
The instructions for the 7i96 say you can hook a parallel port breakout card to the expansion port. But they don't clarify much more than that and googling did not find much info. But the connector is the same as the one of these connectors that you use if you have a motherboard with parallel port support but not the actual port. And there are 17 i/o pins listed on the page for that connector during setup which is the same as what a parallel port has.

I did not spend long on trying it and just hooked it to the pc instead. I might email mesa if I get bored but I doubt it matters.

I do plan on a breakaway switch but a floating switch won't work with the holder we made. Not sure how viable it would be but there is a magnetic encoder on the linear stage I am using for the Z and depending on how plasmac/LCNC works it might be possible to watch the position of that and infer when the torch hit the table but unless ohmic probing fails a lot it sounds like a lot of work to set up. For now I am not wiring up the encoder.

Really hoping to see sparks tomorrow. (The good kind. Not the short circuited the 480v kind.)

Oh by the way I did find a bug in the PNCconf wizard. If you tell it you have a para port and then on the page for that para port tell it that it is set for input it ignores it when you actually write the files. It sets the pins correctly but at the beginning of the hal file I have to change it from "out" to "in". And of course because the wizard overwrites any changes I have to do it every time I rerun it. And I ran it a lot setting up homing and limits.

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01 Apr 2020 05:05 #162330 by phillc54

Oh by the way I did find a bug in the PNCconf wizard. If you tell it you have a para port and then on the page for that para port tell it that it is set for input it ignores it when you actually write the files. It sets the pins correctly but at the beginning of the hal file I have to change it from "out" to "in". And of course because the wizard overwrites any changes I have to do it every time I rerun it. And I ran it a lot setting up homing and limits.

You should report this on the pncconf section of the forum.

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01 Apr 2020 05:17 #162332 by Birdman3131
The following user(s) said Thank You: phillc54

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