Help! Torch not raising for second cut...

kb8wmc
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10 Feb 2018 01:42 #105678 by kb8wmc

Help! Torch not raising for second cut... was created by kb8wmc

On my brother's plasma table after completing the first cut, the torch does not raise high enough to do touch off for the second cut and I get an error that the Z axis would exceed negative limits on attempt to touch off for next cut...

We are using JT's touch off subroutine, the only change being the distance for the touch off (1.25")...Also using JT's post-processor in sheet cam...

The one thing to note is that when making the gcode in sheet cam and when then viewed in linuxcnc, there are two different elevations the objects to be cut are placed on...I have posted questions in the sheet cam forum related to this but as yet no responses...

Any suggestions will be appreciated...

Thanks in advance

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BigJohnT
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11 Feb 2018 23:06 #105773 by BigJohnT

Replied by BigJohnT on topic Help! Torch not raising for second cut...

What is your max Z limit? Sheetcam likes to have a positive Z clearance so when I home Z I make it Z0.250 so a Z clearance of Z0.125 in Sheetcam does not throw an error. Another crazy error by a programmer trying to force you to do something lol.

JT

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Grotius
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11 Feb 2018 23:19 - 11 Feb 2018 23:24 #105774 by Grotius

Replied by Grotius on topic Help! Torch not raising for second cut...

@kb8wmc,

You can change your name in the section : My profile.
Please do this.

Hmmm, quick solve, is increase soft limits in your ini file.

also quick solve is but not permanent is to change sheetcam postprocessor in section " pen down "

orginal code linuxcnc plasma processor :

function OnPenDown()
   if (preheat > 0.001) then
      post.ModalText (" G00")
      post.ModalNumber (" Z", cutHeight * scale, "0.0000")
      post.Text ("\n G04 P")
      post.Number (preheat,"0.###")
      post.Eol()
   end
   post.ModalText (" G00")
   post.ModalNumber (" Z", pierceHeight * scale, "0.0000")
   post.Text ("\n M03\n")
   if (pierceDelay > 0.001) then
      post.Text (" G04 P")
      post.Number (pierceDelay,"0.###")
      post.Eol()
   end
end

changed code example :

function OnPenDown()
   if (preheat > 0.001) then
      post.ModalText (" G00")
      post.ModalNumber (" Z", cutHeight * scale, "0.0000")
      post.Text ("\n G04 P")
      post.Number (preheat,"0.###")
      post.Eol()
   end
   post.ModalText (" G00")
   post.ModalNumber (" Z", pierceHeight * scale, "0.0000")
   post.Text ("\n G01 Z10\n")
   post.Text ("\n M300\n")
   post.Text ("\n M03\n")
   if (pierceDelay > 0.001) then
      post.Text (" G04 P")
      post.Number (pierceDelay,"0.###")
      post.Eol()
   end
end

So you can add some g-code or macro code if you want to lift the torch extra up.

Just a question. When i tested the THCUD or THCAD component's the z-axis value dro is not real time changing.
I only see the z axis offsets in the halmeter changing.
I dis done by purpose?

Last edit: 11 Feb 2018 23:24 by Grotius.

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kb8wmc
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12 Feb 2018 14:16 #105792 by kb8wmc

Replied by kb8wmc on topic Help! Torch not raising for second cut...

JT, Originally my Z limits were set to -3.5min and 0.00 max...After reading you post I took a hard look at your .ini settings for your plasma table (where you use +-4)...I changed the .ini to the same min and max as you are using, although I don't have that much total movement...I viewed your video on your plasma machine and I am guessing you don't have that much total movement either...I have tried to picture this in my mind as to the effect and am not sure I understand what it will be but I will give it a test...I have always used the physical limits on router tables and other cnc machines so I understand the effects there...I use a limit/home switch at the top of the Z axis and that becomes my 0.0 maximum...On my brother's plasma, I located the Z limit/home at the top as I have done in the past...I changed the Axis simulator to the 4.0 min/max to see what homing would look like...

"Sheetcam likes to have a positive Z clearance so when I home Z I make it Z0.250 so a Z clearance of Z0.125 in Sheetcam does not throw an error."

I am not exactly following what you mean by the above...

Thanks for your input JT

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Grotius
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13 Feb 2018 00:15 #105804 by Grotius

Replied by Grotius on topic Help! Torch not raising for second cut...

Hi kb8,

Where is JT?

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kb8wmc
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13 Feb 2018 02:40 #105808 by kb8wmc

Replied by kb8wmc on topic Help! Torch not raising for second cut...

This is a screen shot of what I get with Sheet CAM...

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Grotius
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13 Feb 2018 22:05 #105840 by Grotius

Replied by Grotius on topic Help! Torch not raising for second cut...

Is your plasma machine working at the moment?

If you still have problem's you can ask. My previous post has a example how to change the standard sheetcam postprocessor.
This can sometimes solves issue's like height problems. But you can also do other things with this.

I always use the z zero value at programmed cut height. That is about 3-4mm of the plate surface. For sheetcam you can
use rapid height 10mm. Pierceheight 2-7mm depending on material thickness.

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kb8wmc
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14 Feb 2018 01:41 #105850 by kb8wmc

Replied by kb8wmc on topic Help! Torch not raising for second cut...

The plasma is and has been working as far as cutting...BUT, only makes one cut at a time...As the screen shot shows above, with 4 holes and one profile to cut, we have to make 5 separate gcodes and run them one after the other to make the cuts...

I am tearing my hair out...

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rodw
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14 Feb 2018 10:50 #105911 by rodw

Replied by rodw on topic Help! Torch not raising for second cut...

G code does what you tell it to do so my guess is that you are not telling it to do the right thing. Examine your gcode, work out whats going wrong and then open your sheetcam post processor to find what is generating the erroneous gcode and fix it!

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Grotius
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14 Feb 2018 18:19 #105939 by Grotius

Replied by Grotius on topic Help! Torch not raising for second cut...

@kb8wmc,

How is your machine setup, is it with a standard break out board?
Or do you have a mesa?

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