Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: bdrotaru on December 12, 2011, 12:12:38 PM

Title: Mach3 and THC Problem
Post by: bdrotaru on December 12, 2011, 12:12:38 PM
I have Capacitive THC installed on my table. I'm very satisfied on the performance (at least at cold run) :D
When I run a cutting program it moves Z axis  in position and then XY motors stops. The only thing makes them run is to minimise or maximise distance between plate and sensor ring and then motors start to run until arive in position to cut and stops again.
THC inputs are:

Torch Up
Torch Down
In position
Probe (or Touch Plate)

Can anybody help me with some info?
Title: Re: Mach3 and THC Problem
Post by: bdrotaru on December 14, 2011, 01:28:48 AM
So. I watched at Diagnose page on inputs. Looks like Arc OK input is making XY motors to stop. Or maybe something elese. But when Torch is in position an ARC OK led is on the motors stops.
Any ideea???
Title: Re: Mach3 and THC Problem
Post by: BR549 on December 14, 2011, 10:37:14 AM
THe best approach would be to get with the MANF of the Capacitance height controller. They are the only ones for sure that will KNOW how it is suppose to work.

Just a thought, (;-) TP
Title: Re: Mach3 and THC Problem
Post by: bdrotaru on December 16, 2011, 12:21:14 AM
Ok. I understand.
As long the device send right signals to mach i'm thinking maybe is my fault because i don't know how to configure mach, or mach software has issues that cannot handle inputs from THC.
The THC is sending right signals to mach and mach recognize'it. The only problem is that X and Y axis is not responding after cut begins
Title: Re: Mach3 and THC Problem
Post by: stirling on December 16, 2011, 05:12:01 AM
Not sure I can help but from your previous post and this one I wonder if you're getting mixed up with your inputs. In your first post you said the inputs were:

Torch UP
Torch Down
Torch ON (given by a capacitive sensor which considers optimal cutting distance)
Probe (Touching the board)

In this post you say they are:

Torch Up
Torch Down
In position
Probe (or Touch Plate)

You should have:

Torch Up
Torch Down
Probe (or Touch Plate)

These should ALL be TTL (digital i.e. approx 0..5V) signals so I'm not sure what you're meaning in your first post when you say:

Now ... Depending on the condition that the z axis is found to give an appropriate signal pin MACH3 attributed to the state and activity is 15VDC and inactive is approximately 3.2 VDC at about 100mA

TorchUP/Down are self explanatory. Your probe input is (I'd imagine) for TOM/IHS/touch off. The one that seems to causing the confusion is ArcOK. This is a signal from your plasma cutter when a good arc is established. Without this Mach's THC function will not work (properly anyway).

Typically (and briefly) a Mach THC cut will work like this:

Mach moves to the cut start position in X,Y
Mach tells the Z to move down until "something" tells Mach the tip has touched/sensed the surface of the metal. The mechanics can be some sort of mechanical probing mechanism, ohmic sensing, capacitive sensing or perhaps "other".
Mach then moves back up to "pierce height" and fires the torch.
Mach then waits until it gets an ArcOK signal from the plasma supply (usually via the THC electronics).
Mach then pauses for pierce and then drops Z to "cut height" and only THEN Mach moves in X,Y.

Just one more thing to note: Mach's THC functionality is (or at least used to be) disabled in demo mode.

Hope this helps in some way.

Title: Re: Mach3 and THC Problem
Post by: tripleblack on December 16, 2011, 12:36:08 PM
from your discription, it seems to me that you are not getting arc ok signal. if your thc or plasma does not output a 5v ttl signal, then to work around that is connect a relay that closes when arc is started. attach the relay to an input  pin  and ground on the breakout board.
Title: Re: Mach3 and THC Problem
Post by: bdrotaru on December 17, 2011, 02:26:51 AM
Sorry but i'm new to CNC.
I'm confusing ARCOK with THC ON (or not. I'm not even sure right now)
My THC send Up/Down/Probe signals to MACH wich i understand what they are doing and configure'it properly.
In addition it send the fourth signal wich tells MACH that torch is in right position and it's ok to fire the torch and start the cut and wich i configured in my system as THC ON
So in my inputs panel things look like this:

As i understood from previous posts ARCOK and THC ON are two different things and MACH will move my torch in position to start the cut, will fire my torch, but if there is no signal comming from plasma or relay that's telling mach the Torch on (ARC OK) then the XY motors will not move to run the program.
If so then how i configure ARC OK

The macro was provided for cutting is this:

Option Explicit
Dim PierceHeight, PierceTime, PierceTime2,THC_ON, THC_LED, OK, Z_Min_Height, Z_Pos
THC_ON = 123 'torch on screen switch
THC_LED = 24 'torch on screen led
OK = False
PierceHeight = 0
Z_Pos = 0
PierceTime = 0
PierceTime2 = 0
PierceHeight = GetUserDRO(1000)
PierceTime = GetUserDRO(1001)
Call DoOEMButton (THC_ON)
OK= True
End If
Z_Min_Height= GetUserDRO(1003)
code "G31Z"&(Z_Min_Height)
While IsMoving()
Z_Pos = GetDro(2)
Call SetDro(2,Z_Pos)
code "G4P1"
code "G1Z"&(Z_pos+PierceHeight)
While IsMoving()
code "G4P"&(PierceTime)
PierceTime2 = PierceHeight * 200

Title: Re: Mach3 and THC Problem
Post by: stirling on December 17, 2011, 07:27:14 AM
The THC On pin in ports and pins is poorly named IMHO. It actually IS Arc OK so you appear to have things wired correctly.

Looking at your macro I'm thinking that's probably where your problems lie. I'm guessing it's meant to be the code for M3 but whatever it's complete cr*p. I'd throw it in the bin and replace it with the standard Mach M3.m1s. It's attempting (badly) to do the TOM or IHS function but you don't need a macro to do this anyway and "most" people do this in gcode. I'm also guessing you have a custom screenset because of the reference to user DROs 1000 etc. You may need to use the standard plasma screen. Here's a piece of code I just knocked out of Sheetcam - check it out and give it a try if you're happy with it. I've highlighted the bits that do what your macro was trying to do. This code is from the Mach3 Flame with THC - G31 post processor.

N0000 (Filename: rectangle with hole.tap)
N0010 (Post processor: Mach3 flame with THC - G31.scpost)
N0020 (Date: 17/12/2011)
N0030 G21 (Units: Metric)
N0040 G53 G90 G40
N0050 F1
N0060 S500
N0070 (Part: rectangle with hole)
N0080 (Process: Outside Offset, 0, T1: Plasma, 1.5 mm kerf)
N0090 M06 T1  (Plasma, 1.5 mm kerf)
N0100 G00 X61.7500 Y25.0000 Z4.0000
N0110 G31 Z -100 F500.0                          (find metal)
N0120 G92 Z-0.0800                                     (offset for switch travel)
N0140 Z3.0000                                             (move to pierce height)
N0150 M03                                                   (light the fire)
N0160 G04 P0.5                                            (wait for pierce)
N0170 G01 Z1.5000 F100                               (move to cut height)

N0180 G02 X61.7500 Y25.0000 I-11.7500 J0.0000 F2000.0
N0190 M05
N0200 G00 Z4.0000
N0210 X-0.7500 Y0.0000
N0220 G31 Z -100 F500.0
N0230 G92 Z-0.0800
N0250 Z3.0000
N0260 M03
N0270 G04 P0.5
N0280 G01 Z1.5000 F100
N0290 G03 X0.0000 Y-0.7500 I0.7500 J0.0000 F2000.0
N0300 G01 X100.0000 F2000
N0310 G03 X100.7500 Y0.0000 I0.0000 J0.7500 F2000.0
N0320 G01 Y50.0000 F2000
N0330 G03 X100.0000 Y50.7500 I-0.7500 J0.0000 F2000.0
N0340 G01 X0.0000 F2000
N0350 G03 X-0.7500 Y50.0000 I0.0000 J-0.7500 F2000.0
N0360 G01 Y0.0000 F2000
N0370 M05
N0380 G00 Z4.0000
N0390 M30
N0400 %

Title: Re: Mach3 and THC Problem
Post by: bdrotaru on December 17, 2011, 03:10:05 PM
Thank you very very very much.
It looks like my problem was solved thanks to you.
I replaced ArcOK from THC with ArcOK from cnc interface i have at my plasma like it should be.
Then i used gcode provided by you with original M3 code and everything works perfect.
I purchased sheetcam a while ago but i didn't knew what postprocesor to use.
Thank you very much.
Title: Re: Mach3 and THC Problem
Post by: stirling on December 18, 2011, 05:26:17 AM
Pleased it's all ok now and thanks for reporting back.

As you have sheetcam, I should say I editied the post a little for the puposes of my example code. You may want to look in function OnInit and change these vars to suit your system.

refdistance = 500 * scale
switchoffset = -0.08


Title: Re: Mach3 and THC Problem
Post by: carlos cortes on November 08, 2013, 08:17:28 PM
Hey guys

I got the same problem but, I have actually seen the ARC OK - TORCH ON signal on mach3. It appears when the sensor ring tourch the plate ("touch" on thc leds). I should appear when is in probe ("in position" on thc leds).

I read that you solved the problem with a relay, well, it can work to me too, bur i think is more cheaper an proper to put that signal on the right position, any suggestions??  Have you heard somebody that can solve this without the relay?

Thanks a lot.