Hi everyone, thank you guys again for all of your help with my sign project. A while back I posted, and you all helped me through my first project. In that thread I showed my final result had this issue where the arc seemed to not stop and like “trailed” along to the next cut path leaving a gouge (not through cut) between the “F” & “K” character paths. I ended up filling and painting that one, so no big deal. I thought maybe it was bad luck since it only happened once near the end of the job.
I haven’t really used the machine since then. Today I started cutting some test pieces on some 8ga. While I was testing my feeds/speeds (which are better than the picture at this point, but still need some tuning) I noticed the same issue. It’s like the torch doesn’t completely stop firing when travelling between cut paths. Does anyone know what I’m doing wrong here? Thank you in advance for all the help. It’s HUGELY appreciated.
I’m using a Cut 45 with THC and consumables from PlasmaDyn.
There are lots of Cut 45 models out there, but if yours has a 2T/4T switch on the top of the front panel then it’s probably in 4T mode. It must be in 2T mode for the torch to shutoff after each cut.
Thank you. I will take another crack at my fire pit project tomorrow. I’m hopeful that you might have found my mistake! I just went out and powered up to check… Thank you!
… Though I’m not sure how that would have toggled, especially mid cut on that last project.
Thanks for the help. Got through my project, but I had an issue with my THC. It definitely isn’t working right. At certain parts of the job it definitely got close if not hit the plate (which was very slightly warped). All of my wiring should be fine. I haven’t had an issue with it before. I went over all, disconnecting and reconnecting. Not that it’s changed but in case it got bumped like this 2T/4T switch must have.
If anyone has any advice that can help me get that sorted out I would really appreciate it. I’m really confused. Is it possible that the module failed? I’ve checked, re-checked and re-checked using the support page: LS-THC User Guide | Langmuir Systems
Have you verified what your system is actually setting your torch at when you designate the cut height of 0.06 inches? Many setups, once tested, sometimes reveal an amazing divergence from the actual setting you were expecting.
It will go thru the IHS (initial height sensing) and then go to the cut height of 0.060 inches and stop. Measure the distance from the torch nozzle and the plate of metal and see if you are at 0.060 inches.
The torch will never fire with this code as it never gets the command to fire.
Here is what the file is:
(v1.6-sc)
G90 G94
G17
G20 (Units: Inches)
H0
G92 Z0.
G38.2 Z-5.0 F100.0
G38.4 Z0.5 F20.0
G92 Z0.0
G0 Z0.02 (IHS Backlash)
G92 Z0.0
G0 Z0.15 (Pierce Height)
G4 P0.5
G1 Z0.06 F100.0 (Cut Height)
M5 M30
(PS100)
Notice it also includes the “springback/Backlash” of 0.02 inches. If you are doing this test on 10 gauge or thicker, you really don’t need any springback so adjust accordingly. You will also notice, this gcode file does not include the M3 (turn torch on) command.
Thanks for the reply. I just ran this program over .125" and it left a .054 gap. Is this enough discrepancy to throw off the THC to the point where the machine shield rubs against the workpiece at a point?
The THC takes a voltage reading at the start of each cut and uses that voltage to keep the torch at the same height during that cut loop. If the initial height was incorrect, the THC will keep it at that incorrect height, but it won’t drive it into the metal unless the voltage readings are way off.
If the voltage readings are correct during the cut, the torch should move up or down to maintain the same height above the metal.
You need to watch the voltage readings during a cut and see if the THC is commanding up or down movements to maintain the voltage. The readings are shown in Firecontrol and there are “up” and “down” lights to show if the THC is commanding movement of the Z axis.
Thanks. I wasn’t sure how big of a factor the cut height would be if the THC is keeping it a relative height, but yeah. I ran the test and those are my results. I think there’s something wrong with my THC, but I’m not sure how to test, fix or address it. I feel like the THC should be preventing this sort of thing, whatever my height is, right? I really suspect the flimsy plastic electronics box. It just looks, connects and feels so cheap that it has to be my problem?
The look and feel of the voltage input module should not affect its performance.
A better gauge for whether it’s working or not would be using some kind of electrical testing equipment to see what the voltage leading in and out of the unit is.
I’m just starting out, and found their prices reasonable and the guy was actually pretty helpful too. Are there better consumables that are also pretty affordable?
Not suggesting the outward appearance affects the performance, just that it doesn’t inspire confidence in the quality of the internal components. Thank you for the response. I will run this test and see where it takes me.
That box is a simple voltage reducer. If the voltage is being passed through to the THC chip on the main board, its probably working correctly.
The higher the torch gets from the metal, the higher the voltage goes. THC responds to changes in voltage during the cut, so if the voltage increases, it lowers the torch to try to decrease it to the target value.
Watch the voltage during a cut and see if it spikes above the target voltage that is displayed in Firecontrol.
That torch height test code, that was posted above, does nothing to test the THC. The THC isn’t active unless there is voltage from the torch firing. That test only tests the IHS system.
Thanks. I had a couple minutes, not many, to try the THC test, and it failed to light all three times. I remember doing the test when I set it all up, and it worked perfectly fine.
