THC settings in Sheetcam

Hi guys, I’v had two crossfires so far been on here a while. Patiently waiting for the Pro to show up. Been kinda dreading the learning curve and issues. I have enough issues between my machine now and hyp 65 on a daily cutting basis (story in of itself). My question is, what is an ideal plunge rate? All my programs have tons of pierces, I’m talking almost 100 in a 1x2ft piece of material. The hyp systems as great as they are, have issues with very fast back to back pierces, thus creating misfires. I’v talked to them multiple times about this and they are well aware. So my cut times are very critical since I basically cut production. I’m hoping the THC will help with cycle time for my plasma to catch up but I don’t want to add too much time in between cuts either.

1.So question again, what is a good plunge rate?
2. were do I program in sheetcam how far up the torch goes after a cut? or is that just a default height?
I would like the torch to only travel UP a small amount when Im doing back to back circles, no point in the machine running up 3" for something like that.
3. I’m assuming in sheetcam I can adjust the THC plunge rate just like I can the feed rate.

The Pro has both Initial Height Sense IHS and Torch Height Control THC. Both require a powered Z but both do different things. THC is used to vary the height while the torch is cutting based on voltage readings from the plasma cutter. IHS is used to set the pierce and initial cut height based on material height, a simple switch with floating head is used to implement the feature. I believe what you are referring to is IHS.

1 - plunge rate is only used for the distance between pierce to cut. Unless you set it really low, it will not have a dramatic effect on your overall cut times compared to the IHS routine as the distance moved is small. I’m using 50 IPM.
2 - Currently you don’t. It’s hard coded to 1" in the supplied post processor, look in the OnPenUp() routine. You can edit the post to change it, it’s trivial.
3 - Yes but see 1.

I think you might want to reset your expectations with respect to cut times. Go to youtube and search for videos on the Pro and you’ll see the IHS in action (the probe before each cut). Without knowing the specifics I would guess that overall your cut time will go up, more pierces equals more probing. You will probably have less misfires as there will be more time between cuts while the IHS routine is done. And, this is important: Hypertherm and Langmuir measure pierce time in different ways. Hypertherm starts the clock on the arc lighting while Langmuir starts the clock on giving the command. This may seem trivial but it is not, as the time to close the contacts and then initiate the arc on the plasma can add up to 0.5 seconds to the pierce delay. So if Hypertherm says it’s 0.5 secs, and you input that into Sheetcam, you will most likely get an arc fault from Firecontrol because the torch will move before it’s actually pierced. I think I’ve read that Langmuir is working on a solution but for now you’ll need to increase pierce delays from those given in the Hypertherm cut charts.


Thanks for the reply. Good point and thought on the pierce delay with the fire control! Again kinda just dreading this all a little bit. I know in the end it should make for better cutting. I cut over 10 different files to make my product, so its a ton of programming. Iv seen some videos and i have seen other machines working with z axis. I know it will slow down run times but I’m ok with that if i could have better results with misfires.

Another point on Z control is that you should have longer life on your consumables (and consequently better cuts when the tips don’t wear as quickly). The reason for this is that you will have better heights on pierce and then ‘plunge’ to cut height once the torch is firing and the top surface has been blasted out of the way.

I hadn’t considered this aspect when I added Z axis to my CF 2x2, but realized it after the fact. Nice bonus.


Yeah that is def another reason why I decided I need THC. Wanted to see how much more I can get outta my consumables. I haven’t followed too too much with the pro and kinda glad I did wait bc I figured there would be some bugs to work out. I just simply have zero time for hickups. I’v been pretty blessed with my crossfire thus far. Def some quirks like lead screws coming loose, debris coming up onto rails, bearing going to crap and slop here and there, but for the price and abuse I put it through, can’t complain. That is why I decided to go with the pro. I have two xfires now. Was going to try another company but didn’t want to wait. I thought I like this forum and the customer service seemed to be decent. So I’ll give the pro a try and if it doesn’t work out for me I can always go with another brand.