THC config that works.

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18 Aug 2017 11:07 #97695 by jeroenl
jeroenl replied the topic: THC config that works.
Hi Tommy, my CNC - Plasma is really starting to work :) Thank you for all your work and help in this topic.

My plasma is a cheap one, and it needs to touch the material to ignite. Is there a option to automatically raise the torch after ignition? Or should the THC take care of this?
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23 Aug 2017 13:55 #97931 by morocco119
morocco119 replied the topic: THC config that works.
Hello, I have been trying to get this configuration up and running for the past few weeks, finally got my machine and THC to respond correctly.

However using inkscape as a Gcode generator has proven to be an issue, when I load up a file the entry point for the Pierce is not on (0,0) and when it jogs to the Pierce it wants to cut, ruining the part and cutting it in half.

Is there a way I can modify or delete some files so I can use fusion 360 as a post processor? If not can someone show me how to fix the earlier issue with inkscape?
Thank you.
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30 Aug 2017 12:39 #98200 by andypugh
andypugh replied the topic: THC config that works.
Have a look at SheetCAM. It isn't free, but it is designed for Plasma and runs natively on Linux:
www.sheetcam.com/downloads
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13 Oct 2017 18:47 #100331 by kpj10
kpj10 replied the topic: THC config that works.
Hi Tom,

I have posted a question regarding remembering the last position and to continue from where it left, then. Now I'm ready with a plasma table and below I mention where I'm finding it difficult to manage:

1. The complete configuration works on inches scale, I have edited LINEAR_UNITS = inch in "ini" file is this sufficient or I need to edit something more. The settings are done accordingly in other velocity, acceleration, and other section.

2. This is how I understood how to get an arc:
a. Let the Z-axis go downward until it detects the metal, as soon as it detects metal the torch is turned on.
b. Then torch moves to a certain height (I'm assuming this is the gap value, that can be adjusted in right hand side of the panel) above the surface of metal to trigger arc-ok signal.
c. Then the cut continues and the process iterates according to the program.

In my observation when I press F9 if Arc-ok signal light is green it starts taking the torch upwards, instead moving downward for metal detect. It is obvious the THC will not assign true signal for Arc-Ok until it triggers the Arc, what could be possibly going wrong. What i feel is my settings, do point out where I'm wrong:

My Z-axis is only capable of moving 0.75 Inches of total travel, so in travel height I'm setting it to 0.6 Inches. Travel height is the height I'm assuming at which plasma torch travels. I'm not getting what does switch travel value signifies, and what should I set it to.

Next is the Delay value, also I don't know what it is for but only once I have seen it to be triggered but I didn't get it why.

The gap value which need to be set is in the gap section, as 0.250 inch is sufficient should i directly set it to that value? Or is there any different math.

Threshold settings also I didn't get it.

I'm using a locally available THC, which function almost same like the Proma THC.

Thank You,
Kunal.
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14 Oct 2017 18:35 #100352 by tommylight
tommylight replied the topic: THC config that works.
Sorry for the delay, been busy working with crypto currency mining equipment, way to much work.
Let me try to answer latest questions in one go:

There is no reliable way to fire a "scratch start" plasma controlled by cnc, the only way that might work is to make the torch touch the material, fire the torch and imediately start moving the torch sideways for a half a second and then move up and hope it started the arc. That can be done in gcode so do some testing and report back.

When using Inkscape, you have to go to toolsand choose Plasma, and then output to gcode. That will insert M3 and M5 for every cut.
IMPORTANT : after inkscape outputs the gcode, you have to edit that gcode and delete the first M3 at the very begining of the file, or it will fire the torch the moment you press run, and make a mess.
There are also explanations on how to make blank files for header and footer, so you dont have to edit that for every file. Also the gcodetools can be edited for almost any machine.

F9 or M3 precedure:
Move torch down till it triggers the switch
Move torch up for the sum of switch travel and pierce height ( 5mm is ok for most plasma, some will not transfer if above 3mm)
Fire the torch, wait for ArcOK
If there is no ArcOK, repeat for the amount of times set in the ini file
At ArcOK wait for the time period set in Delay, when 0 go down to cut height and start movement on XY axes.
Note: pierce height can be anything from 2mm to 6mm depending on the material thickness and the type of plasma cutter. Some can start an arc at 10mm but some will not even at 5mm. Do some testing to see at what distance can yours fire reliably and set that as pierce height.
Cut height should be 1.5 to 3mm or even 4mm in some cases, but not more, so 8.3mm is way to much.
Again sorry for the delay.
The following user(s) said Thank You: kpj10
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14 Oct 2017 19:12 #100357 by kpj10
kpj10 replied the topic: THC config that works.
Dear Tom,

First, you don't owe any apology, and as in this case I accept your apology as you did make one. Now, let's get to work as it's 1.00 am here in India, I can't report you results right away, but will tell you by tomorrow. I hope you will understand. I would like to tell you that in your response you didn't bring up the matter of: why is the torch moving upwards if there is no Arc-ok signal, while I'm testing it up with F9 procedure. As the THC will not give any Arc-ok signal when trying to start up.

Thanks,
Kunal.
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15 Oct 2017 15:36 #100394 by kpj10
kpj10 replied the topic: THC config that works.
As you suggested:
"F9 or M3 precedure:
Move torch down till it triggers the switch
Move torch up for the sum of switch travel and pierce height ( 5mm is ok for most plasma, some will not transfer if above 3mm)
Fire the torch, wait for ArcOK
If there is no ArcOK, repeat for the amount of times set in the ini file
At ArcOK wait for the time period set in Delay, when 0 go down to cut height and start movement on XY axes.
Note: pierce height can be anything from 2mm to 6mm depending on the material thickness and the type of plasma cutter. Some can start an arc at 10mm but some will not even at 5mm. Do some testing to see at what distance can yours fire reliably and set that as pierce height.
Cut height should be 1.5 to 3mm or even 4mm in some cases, but not more, so 8.3mm is way to much.
Again sorry for the delay."

This procedure didn't work because the plasma started moving up, instead of moving down when Arc-ok was no there.
Then we connected Arc-ok signal to the limit switch of float (as it was double pole), then plasma did move down but when it tries to get arc the float limit contact loses causing false arc-ok moving the plasma unexpectedly. This absence of Arc-ok causing upward movement is the problem I feel.

With G-code, this is how I did: I knew torch was 0.250 inch above the material, then using g-code moved plasma 0.25-inch downwards, using M03 fired plasma moved plasma upward to 0.105 inches height upwards, then had a 4 inches straight line cut, and then halted using M05.
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20 Oct 2017 09:14 #100579 by tommylight
tommylight replied the topic: THC config that works.
If the torch is moving up when you press F9, you have the direction set incorrectly, or wrong limit settings.
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21 Oct 2017 17:00 #100613 by Plasmaguy
Plasmaguy replied the topic: THC config that works.
Toma;

Will this configuration work with the MiniTHC also?

minithc manual

I have a Proma SD which I unwittingly bought for my plasma table only to find out later it's not a good product for achieving near the speeds my powermax45xp wants to run.
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21 Oct 2017 17:42 #100615 by kpj10
kpj10 replied the topic: THC config that works.
Thank You Tom,

Sorry that I'm reporting late. Yes, there was an issue with input pins and changed them accordingly. Still not able to get arc working out to sort that out, probably issue is with the THC. If I need help I will write you back here.

Regards,
Kunal.
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