help troubles with thc up down

[wilkies]

hi need help i have a home made plasma table with a proma thc when cutting with the proma on it goes up fine but doesn`t seem to go down,it works fine in test mode. thanks dave

[jawslandshark]

I assume you are using Mach3? Where are your THC settings and how are you at zero?

[wilkies]

yes mach 3 and has floating head,thc settings were set in mach 3,same as most set up the proma. plasma screen thc settings arethc is on, speed 20% up,max -5.000 min is -3.000.these two dont change. dave

[acourtjester]

On the Proma working in test mode do you mean you see the LEDs indicating movement or do you actually is the Z move up and down?
If you check on the diagnostic page you should see the LEDs light up there too for torch on, torch up , and torch down (lable is up the page).
To see the movement I think you need to enter a larger voltage (The hysteresis voltage) for it to have time to move.
I had problems with the output relays going bad and not actually triggering Mach.

[wilkies]

yes the z moves up and down in test mode,also on the diagnostic page the lights work as they should,only when trying to cut out a part is when it raises to high and loose arc. dave

[wilkies]

ok on the plasma screen just below torch on/off is thc max 5.000 and thc min -3.000 ive read where the min-3.000 needs to be 0.000 in order for the torch to go down and work right,i cant seem to change the -3.000 to 0.000 any one know how to

[acourtjester]

Did you buy the license for Mach 3?
it will not let you use the THC among other things with out a license.

[wilkies]

yes licensed

[acourtjester]

If you click on the number and type a replacement seems to work here

[wilkies]

i tried that it works until u click save or click anywhere and it goes right back the way it was. dave

[acourtjester]

Here are 3 changes I made and it saved them I exit Mach and come back in and it is there as I left it. I know you cannot enter a minus number.

THC 1.jpg (27.31 KiB) Viewed 2973 times

THC 2.jpg (23.92 KiB) Viewed 2973 times

THC 3.jpg (22.99 KiB) Viewed 2973 times

[wilkies]

i will change the numbers and exit mach3 plasma tomorrow hope it works.thanks dave .
nope just tried that came back on -3.000

[East German]

Hallo,

Here is a Mach3 Set File.
I changed the DRO with MachScreen!
Minus input is possible!

Regards Peter

[acourtjester]

To load Peter's screen set download his .zip file and then move the file "PlasmaTHCMin.set" to the Mach3 folder on you hard drive. Then run Mach and go to the View menu drop down and click on "load screens" this will bring up the folder that has a few screens listed they have the extension of (.set). Click on the set shown above the screen blanks and loads his screen set so you can make the changes to the THC numbers. I use this same method to change from the DTHC screen to the normal Plasma set to run Axis Calibration for the stepper motor calibrations.

[tcaudle]

MIn and Max (MACH calls them THC Corrections) are the excursion limits (like soft limits) for Z you allow when the THC is in control of Z. If you get a DOWN LED from the THC and it refuses to move Z down , its MACH that is refusing. Most likely the setting above. You have to have a way to do touch offs or the Z does not know where 0 really is (top of the material) . So setting it to just 0 assumes materiel is perfectly flat and never warps . The type of numerical input in a DRO box is set in the screen file . As explained you have to tell it that the box will take a negative number and also how many decimal places it will display.

[wilkies]

To load Peter's screen set download his .zip file and then move the file "PlasmaTHCMin.set" to the Mach3 folder on you hard drive. Then run Mach and go to the View menu drop down and click on "load screens" this will bring up the folder that has a few screens listed they have the extension of (.set). Click on the set shown above the screen blanks and loads his screen set so you can make the changes to the THC numbers. I use this same method to change from the DTHC screen to the normal Plasma set to run Axis Calibration for the stepper motor calibrations.

ok down loaded copied to mach folder opened mach opened the new folder ,changed the new numbers and pow just like before just returnes to all 00000 Os

[wilkies]

ok heres what i found out ,the thc is working up and down its just moving too slow,and just like the numbers i cant shange i cant change the speed????. any one have a sure fix????

[acourtjester]

Have you calibrated the axis speeds (acceleration and velocity), when you use the page up and page down keys on the keyboard does the Z move faster then when the THC moves it? The speed when using the keys is controlled by the jog speed, if you hit the TAB key and the jog pendent shows there is a speed value with a % next to it. I don't think that would effect the THC Z speed but it does effect the jog speed.

[wilkies]

i can speed the z way up and that helps some,but the z going down cant catch up ,thc speed is set at 20 and will not change.

[acourtjester]

I have change the speed on my THC by just clicking on it and typing a new value in to in.
If you go up to help and click to get the drop down menu then click on about and see what version you are using mine is 067.

[wilkies]

seems every things works but this mach3 i paid for!!! r3.043.066 is the version # mach3 #2 on the start page?

[wilkies]

does anyone know if i just need to change these numbers,in the machine folder with an editer sounds a lot easier then what ive neen getting?????

[sphurley]

http://candcnc.com/images/Mach3Version3.043.067.zip

[tcaudle]

does anyone know if i just need to change these numbers,in the machine folder with an editer sounds a lot easier then what ive neen getting?????

There is no such thing as "THC Speed" in MACH using the internal THC logic (like your Promo uses) Its actually called THC Rate and its a percentage of the Z max velocity and ONLY used when the Z is moving from the THC UP and DOWN inputs. So for a given Z velocity you can only move the THC moves at the THC Rate. Get it too high and it hops down the cut like a monkey on a pogo stick. The Promo is not exactly a high speed THC. Any MACH internal based THC can only do around 30 to 40 IPM true speed on Z but there are also delays based on the Promo's use of mechanical relays to isolate the UP and DOWN signals so it lags quite a bit.

The other day I watched a video titled "cutting corrugated with plasma ". There was a closeup of the screen (MACH) and the feedrate was around 600 mm/min (about 20 IPM horizontal speed) it was a pretty long and boring video creeping along.