Its a combined value that is referred to as IHS springback( the amount the material springs back after the torch presses down on it) and the Backlash( the amount of backlash in the lead screw/nut and the IHS switch) There are not separate fields for each.
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I have yet to have someone actually post where they have found this part of the instructions from Langmuir…
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It’s my sister in-laws birthday today. My wife is treating her to dinner for her birthday. I think all the local siblings are meeting up.
That’s allot of birthdays on top of each other! Happy Birthday!
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See post #8 above.
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I posted the screenshot from the instructions back in post #7…or maybe it was #8.
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Ah, I misread. Well happy birthday to your sister in law, and have a good night with the kids!
It is a lot of birthdays, but we kind of enjoy it. 
Thanks, Erik!
Forgive me for being so green here, but you’re giving me some really good information. So if I set a 0.060” cut height, and ZERO out the IHS spring back value, then I’m theoretically cutting at 0.060”. BUT, how do I verify? Do I pause the program in the middle of a cut, after the pierce, and after that smart voltage kicks in, and try to measure with a feeler gauge? Wouldn’t kerf and dross make it really hard to get an accurate number if I stop it in the middle of a cut?
I really want to get this figured out.
Thanks you for everything!
i have a program that will cycle the torch head and end at the cut height if you want it.
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I’d love it, but I have questions…
sure i will post it in a few .
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ignore the name you may want to rename it… makes sure you have a couple inches of travel x and y it will throw a code about the thc just ignore it… it will set it up like you will any ohter program it will move a couple inches then touch off go to pierce height then cut height and stop so you can measure. also make sure your material doesnt have a lot of spring to it.
test line.tap (245 Bytes)
it is set at .060
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This file will run the IHS cycle and lower to a cut height of .063". It has an IHS springback value of .040" in the program, so factor that into your measurement. Jog the torch to a clean spot and zero the machine. Then run the program and measure the actual torch height with a feeler gauge. If it is around .100", then you know that setting the IHS springback to zero should get you to .063". If it is higher than that, you will have to also reduce your programmed cut height to get to the proper height.
IHS Cycle.nc (188 Bytes)
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I just ran this program a few days ago and did not take into account the .040 springback.
I will have to take a look at this again.
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The program I sent you had .020. No need to account for spring back where the torch is is where it will cut. The purpose of the spring back is to take the slack out of the lead screw since it isn’t a anti backlash
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Maybe I could have explained that better. The program has a .040" springback/backlash in it. What that means is, after the IHS sets the zero, it adds.040" and makes that the new zero. Then it goes to.063" higher than that zero for cut height.
If that results in the torch being at .063", then everything is working correctly and you can set the springback at .040" and whatever cut height you set will be correct.
If it turns out that your Torch is actually at .080", then you can reduce the springback to .020" and your cut height should be correct.
If your torch ends up at .100", then you should set the springback to zero.
If your Torch height is above .100" , then you need to set the springback at zero and also reduce your cut height setting.
In Sheetcam, there is no springback setting, so the post processor automatically adds .020".
The only way to fix the torch being too high is to reduce the cut height setting or edit the code.
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I have not run either program yet.
Question:
Am I supposed to lower my torch to the work and zero my Z axis coordinates as a part of setting up my work coordinates, or is that all supposed to be figured out by the IHS system? Now that I have my machine torch mounted correctly in the machine torch holder, and the holder is pushed all the way up as far as it will go in the Z axis clamp, I only have about 1-1/2” of total Z-axis range (maybe there’s 2” there, I’m in the house now, but it’s way less range than there used to be).
I did find out that Fire Control will let you crash the Z into the top of the motor bracket if you’re not careful. 
Both programs are pretty much the same thing. With the same purpose. Set up and start the programs as you would any other. Mine make sure you have 4 inches in the x and 2 in the y to move. They will cycle your z for you. And the plasma doesn’t have to be on not going to fire. Mine will give a no THC error at the start don’t worry it works fine. Be sure to zero x and y tho.
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You just have to make sure the Z axis is above the material when you hit “zero all axis”. You don’t need to set the Z in any particular location.
The Langmuir machine torch mount isn’t ideal. There is no way to mount the Torch properly and still have Z axis travel. I suggest putting the mount where the carriage still has the full travel available. Then run the Z down until the carriage is about 3/4" from the bottom. Install the Torch with the tip touching the plate and tighten the clamps. Don’t over tighten the lower clamp. Jog the Torch up to a safe height and then hit “zero all axis”. That should give you plenty of travel and make sure the IHS system can work as designed.
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That’s exactly how I had it until George and NicaDd told me that this was wrong. The bummer about mounting the torch “correctly”, besides losing most of your Z axis travel, is that the entire weight of the torch and holder then has a leverage effect on the little metal strap that holds it to the Z-axis; the mounting loses what little rigidity it had…
It should be fine, as long as you don’t over tighten the lower mount.
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