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help with torch height
« on: June 08, 2016, 12:37:17 PM »
I am very new to CNC and trying to learn how to use mach software to run my plasma table. I have been able to cut parts after some trial and error, lots of reading and tutorials.
For some reason, my torch is moving off it's path and sparking about 2 inches off the table when it goes from cutting one part to the next. It cuts the first piece fine and then moves to it's next position in the cut sequence, then it raises about 2 inches and tries to spark. Sometimes it does not move to the next part in the cut sequence but goes way off course and tries to spark several inches off the table. I have all new tip, nozzle, cap etc. so that's not the problem.
I feel like it's something simple but I don't now what a lot of the controls in mach 3 actually do or mean. I have been reading and watching tutorials but just can't figure it out. I need to get it running. Any help would be greatly appreciated.
Thanks!

Offline Davek0974

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Re: help with torch height
« Reply #1 on: June 08, 2016, 02:49:27 PM »
Going to need more information  - do you have a torch height control? is it active? does it work without it?

what table, what plasma?
Re: help with torch height
« Reply #2 on: June 08, 2016, 03:01:13 PM »
As far I know the THC button is off(LED is off)
I have been able to run the table with it off.
It is a machitech 300 and Hypertherm Powermax 1650

I'm not really sure how to use the THC function. It seems like when I have it on, it doesn't work. torch drives right in to the plate if there are uneven surfaces. Ohmic sensing cap does not seem to be working. Please pardon my ignorance, this is all brand new to me.

Offline Davek0974

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Re: help with torch height
« Reply #3 on: June 08, 2016, 03:10:05 PM »
Start from the beginning, you should be able to turn theca off and make good cuts, maybe only short 100-150mm if the plate is at all warped or not flat.

do you have the torch doing initial height sensing (IHS) at the start of each cut - it should move down, ohmic should would touch the plate, torch should stop moving, it should then lift to pierce height (as per book for material/consumables/power) then it should pierce and start cutting.

if the ohmic is not working i would fix that first as you really do need good IHS and pierce height or you will not succeed much further.
Re: help with torch height
« Reply #4 on: June 08, 2016, 03:15:01 PM »
emily, can you upload your profile (the *.XML file to have a look at)   If you start Mach3, and look in the lower right hand corner of the screenset t should say somethng like profile: "plasma", you will need to rename it to something unique so it will upload like emily.xml


can you also post a section of your gcode to have a look at.... you can cut most of the first part and the second part out and just upload the bit where it changes from one part to the next.


I suspect that the THC may not be set up.... and the ohmic cap may not be assigned a pin.... but these are just guesses .... what torch height controller are you using?

I also suspect that your post processor is not generating the right motion...

i.e at the end of the cut (M05), it is going to the safe hight between moves (G00 Z-2 )
 then it is maybe not touching off on the metal (G31 Z-5 F30) or G28.1  [The "Z" and "F" numbers are just a guess of something that will work]

Wth G31 it will need to zero the Z axis (with G92 Z0 or Z-0.03 say at a guess)  [the number all depends on your switch offset, my ohmic probe has about 0.1mm clearance (Z-0.004)]
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: help with torch height
« Reply #5 on: June 08, 2016, 04:04:50 PM »
Thanks for the replies.
The torch seems to be doing initial ihs at the start of the first cut. When it moves to the second pierce it does not do ihs, it lifts from the table about 2 inches and tries to spark.
I do not now how to set up the THC, assign a pin to the ohmic cap and I'm not sure what thc I'm using.
Basically, I bought the unit from a shop where it was being used on a daily basis. I kept everything set up the way it was when I bought it. I was able to cut various pieces but something changed and I don't know how or why.
My profile is huge, won't let me upload to the forum. Is there a section that I should copy and paste?

GCode-

 M05 M15
G40
 G00 X0.875 Y1.
G41
 M03
 G04 p0.5
 G03 X0.0625 Y-0.0625 I0.0625 J-0. F30.
 G03 I-0. J0.125
 G03 X0.0625 Y0.0625 I-0. J0.0625
 M05 M15
G40
 G00 X0.875 Y-1.
G41
 M03
 G04 p0.5
 G03 X0.0625 Y-0.0625 I0.0625 J-0. F30.
 G03 I-0. J0.125
 G03 X0.0625 Y0.0625 I-0. J0.0625
 M05 M15
G40
 G00 X-1.125 Y-1.
Re: help with torch height
« Reply #6 on: June 08, 2016, 04:06:54 PM »
emily, you only need to upload the "XML" file which is located in the Mach3 root folder (C:\Mach3\******************.xml)
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: help with torch height
« Reply #7 on: June 08, 2016, 04:15:01 PM »
Can you open the "M15" code file and upload its contents.

go into C:\Mach3\macros\..... choose the folder that matches our profile name.... then open the M15.m1s file

you can open it with notepad and post its contents.

At the moment you are using G40 & G41 for cutter compensation, I have not used this for plasma as my software that generates the gcode allows for the plasma kerf (sheetcam) ..... what software are you using.

Can you also post the M3 file contents too.... as the M15 is probably just moving the torch to the safe height.... and the M3 once the torch moves to the next X and Y location is carrying out the touch off sequence.

A photo of you torch height controller may help.
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: help with torch height
« Reply #8 on: June 08, 2016, 04:17:29 PM »
.... hmmmm G41 should be followed by a D number  .... without a D********* number its doing nothing....
  and can be ignored

like I said I've never used G41/G42 of G40 before.
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: help with torch height
« Reply #9 on: June 08, 2016, 04:27:01 PM »
 here is an M3 to give you an idea of what it should sort of look like (many ways to skin a cat!)

Code: [Select]
Option Explicit
'Screenset variables
Dim PierceHEIGHT
Dim FeedHEIGHT
Dim PierceDELAY
Dim FeedR

PierceHEIGHT = 1.5
FeedHEIGHT = 3.5
PierceDELAY = 0.3
FeedR = 3000 / 60

If (Not IsLoading) Then

Code "G31 Z-100"
While IsMoving()
Wend

Code "G92 Z-1"

Code "G0 Z"&PierceHEIGHT
While IsMoving()
Wend

DoSpinCW()

Code "G4 P" & PierceDELAY
While IsMoving()
Wend

Code "G0 Z"&FeedHEIGHT

SetFeedRate FeedR

End If     


Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”