Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: scriptum on December 19, 2018, 06:49:18 AM
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Hi,
I have my DIY plasma with Mach3, Proma 150, floating head and Powermax45.
THC is connected to the raw voltage because I had problem when it was connected to divider (head is constantly go up and down).
Floating head, pierce high and cutting high works OK.
I have some problems.
1. After few seconds (not always) I get very short impulses from THC in down/up direction and then Z DRO change for example to +19mm but torch high is OK.
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I posted without finished ;D
2. When it finish cutting Z axis go to (for example) +9 mm and after that at home position it change to -40mm.
3. For what is this THC button?
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there is a Little bit of Information in the mach Manual.
maybe it help's.
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Thanks TPS. This is helpful. But most problem is first two problems.
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i do not have a Plasma with THC (maybe soon), so i am not realy able to help you.
maybe someone else can jump in.
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Today I found that THC send signal for UP or DOWN but Z axis doesn't move.
In test mode it is going up/down.
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is the THC ON Signal working?
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Yes, that is OK.
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Have you read and setup the proma thc 150 according to the primary manual
There are a couple of settings within the primary that inhibit motion until the arc voltage has stabilised and also another that activates a delay to allow the voltage to stabilise
http://proma-elektronika.com/index.php/en/products/thc-torch-height-control/compact-thc-150
The proma is a VERY basic thc it can also be a bit slow especially if you are cutting thin material fast
I did not get on well with the proma but what I did was the following to get it to work ok for me
YMMV
In the proma set the following up
HYS (hysteresis) set to +/- 1V (its as good as you can get and the error is 2v which is about 1.2mm (1/16") approximately!
d-t (delay time) set to ~ 2 seconds. What this does is when the proma detects the cutting arc voltage window (below H-U...see below) it waits the time delay before issuing an THCUP or THCDN signal.... It allows for an extra amount of stability once the voltage is detected.
H-U (high voltage) this is the transfer voltage detection limit (aka ARCOK signal).... What I did was set this to a lower voltage but slightly above the cutting voltage of my machine which was 160v.... This allowed for the the arc transfer to take place within the machine and for the voltage to stabilise. The knock on effect was that the pierce hole would be slightly larger because the machine will not begin motion until the arcok signal is received (providing you have ticked the box under config>>>ports and pins>>> spindle >>>thc )
As you have a powermax45 it gives you a arcok output indicating transfer has taken place so I would use that and ignore (not use) the arkok from the proma.
I would set the H-U on the primary to about 150v because this will act like a kerf detect THCDN inhibit. I would also consider playing around with d-t setting in the proma because if you do use the arcok from the hypertherm45 motion will begin when the hypertherm45 gives the arcok signal but the primary will not give the thcup/thcdn signals until both the detected voltage is below H-U AND d-t has elapsed. So if you are cutting some thin material at 400ipm in 2 sec it would have travelled 12" (ish {depends on your acceleration settings as motion will go from zero to your cutting voltage)
The proma IS a very low cost THC do not expect brilliant TH control. THC offered by some other manufacturers offer a lot of other options. Mach3 is now also very old plasma technology and many more plasma options are available so again don't expect brilliant finish... It's like cars... Newer models offer developments in performace, efficency, and automation that you won't get from an older model that's development has stagnated and has not been updated for many years)
Good luck
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Hi Rob,
thanks for your suggestions. In meantime I made it to work. Now I have only one problem.
Head going in pierce height, and after that into material and when THC start to give signal up/down, it going in correct height.
I am using MP1000-THC post processor. In SheetCam, cutting height is set to 1.5 mm.
What THC do you suggest?
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can you pls post your GCode ?
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Here is my GCode:
N0010 (Filename: Work1.tap)
N0020 (Post processor: MP1000-THC.scpost)
N0030 (Date: 01/01/2002)
N0040 G21 (Units: Metric)
N0050 G53 G90 G40
N0060 F1
N0070 (Part: Work1)
N0080 (Operation: Inside Offset, Layer 1, T3: Steel 3 mm)
N0090 M06 T3 F1500 (Steel 3 mm)
N0100 G00 Z10.0000
N0110 X22.6966 Y46.4400
N0120 Z3.0000
N0130 G28.1 Z3.00
N0140 G92 Z0.0
N0150 G00 Z0.0520
N0160 G92 Z0.0
N0170 G00 Z3.0000
N0180 M03
N0190 G04 P0.1
N0200 G01 Z1.5000 F100.0
N0210 G02 X25.2566 Y49.0000 I2.5600 J0.0000 F1500.0
N0220 G01 X49.0000
N0230 Y1.0000
N0240 X1.0000
N0250 Y49.0000
N0260 X25.2566
N0270 G02 X27.8166 Y46.4400 I0.0000 J-2.5600
N0280 M05
N0290 G00 Z10.0000
N0300 X0.0000 Y0.0000
N0310 M05 M30
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N0120 Z3.0000
N0130 G28.1 Z3.00
N0140 G92 Z0.0
N0150 G00 Z0.0520
N0160 G92 Z0.0
With the above code you are setting you Z axis home location as the top of the material.
You are setting via G92 as Z0.0 ..... you should allow for the switch offset
The torch then moves 3mm above the top of the material (but again.... you've not allowed for your switch offset).
N0180 M03
Fires the torch
N0190 G04 P0.1
Waits 100milliseconds
N0200 G01 Z1.5000 F100.0
And then drops from (3mm to 1.5mm..... but again.... you've not allowed for your switch offset....)
To set your switch offset, get something like thin paper and place it below the torch.
Perform the G28.1 which will home the axis, and probably set it to 0.0
then jog the axis upwards 1 step at a time until you can slide the paper out from under the torch..... this is your switch offset height
Add that switch offset to your G92 X____ withing the post processor (it will probably be called "switch offset") ....... note that it will be negative (because when you perform G28.1 the torch will be homed BELOW the switch offset height)
So when you retract for the pierce it will retact 3mm + the switch offset.
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Thanks robertspark, i was set switch offset in post processor but now i don't know if it is in negative. I will check and let you know.