Cutting 1/4 plate

im having a hard time with setting for 1/4 plate. what everyone using, i got a 30 amp plasma ?

max it out, 30-50 IPM? what are you trying?

0.25” mild steel cut with my Hypertherm Powermax 45. This is fresh off the table practically no dross on the backside as well.

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What was your 9pm setting on that? Just got my 45xp and starting some test cuts.

ive been cutting 1/8 at 50ipm and 30 amp. im trying around 25 and getting lots of dross and then not fuly cut at other places

Make yourself a line test and assign each cut path a different IPM setting to determine where you need to be in the ballpark. I started doing this for my different materials and my gosh did it take a lot of the headache away.

I just draw a simple 5x5 square, though you could do 10x10 if you so wish. Within the square you would draw 10 lines spaced out appropriately and setup the cut paths in F360 CAM with different IPM settings. For example, you could start at 60 IPM, 50 IPM, 40 IPM and so on. I have a line test file setup for my aluminum that I could share. You would need to change the CAM profiles to meet you needs. PM me and I’ll gladly send it.


I agree with thatguytom, Line tests are the way to go, I posted up a sample file here How do I set up a line test?. Every machine can be different so it comes down to trial and error but if somebody is getting a clean cut and can share the info, then I do a line test around that number in increments of 5 ipm to dial it in.

Also when people give feed rates, you really need to also say what machine it is, not just 30 or 45. I had a Razorweld 45 and now have the Hypertherm 45xp and feed rates are totally different. For example with the RW45, 10ga I was at 40-45 ipm for a decent cut where with the Hypertherm 45xp I am now at 130 ipt for an extremely nice cut with little dross. So far the Hypertherm cut chart in the manual has been spot on.


Exactly! We’ve done this for years in the laser world. I have a cut & engrave design I use on every new material on my lasers. It let’s me get the settings dialed in right away. It also let’s me see if the laser is starting to age over time and lose power.

The same technique can be used for cuts. The line test file doesn’t need to be big but I like the 5x5 reccommendation - gives enough time to accelerate the head to speed.

Also you might want to add a couple of cut outs - a couple of circles & squares. One each for inside & outside cuts so you can see what a couple of standard lead-in/out distance/angle/radius will look like.

The circle & square cutouts will let you measure your kerf and the lead-in/out variations will give you a handle on what works so you can adjust those for other designs.


I would like this file if you could share it please. I have a harbor freight cutter so I am sure it will be different but should be the same principal. I grabbed the one Rusty posted too.
Thanks, Rob

I have this file that I run after I get the speed dialed in with the line test. Need to work on the inside squares in Sheetcam as they are getting rounded out on the thinner stuff. I come from about 18 years of having a CNC router so a lot of the speed/feed and test cuts are normal for me.


beautifully done good sir!

I use the CNCcookbook feed & speeds calculator for the Shopbot but there really isn’t anything similar I’ve found for plasma CNCs.

so finally got to try a line test today i did everything from 5ipm up to 35 ipm and it went from massive amount of dross to not cutting at all.

im running a miller spectrum 375 x at full amps, 30. also using the 1/16 shim for torch height ?

what am i doing wrong

also forgot to mention that ive been cutting lots of 1/8 and it comes out nearly perfect with very little dross at 30 amp and 50 ipm with the 1/16 shim. so i know the plasma consumables are good

Hypertherm 30 xp I cut the following with fine tip (I just tried regular tips again and quality just wasn’t nearly as good, so dunno what the issue is)

18g 100 imp pierce at .2 or less
1/8 aka 11g I cut 56 imp pierce at .5
3/16th I cut at 26-30imp pierce at .7 or .8
1/4 is 17-20 ipm pierce delay 1

all of which is the thicker torch height shim

I highly regret not getting the XP 45 right now, but I plan to eventually get another whole setup for thick stuff and just keep this table and plasma for the thinner stuff. I normally cut at 12x24" pieces and on 3/16 with all my “chains” aka pierces, my average cut time is about 17-20 min I have upwards of 100 pierces in my files tho. Which sucks bc I have to watch for tips almost the alot of the time.

soo, i think i finnaly got it, did some more playing today
using the miller spectrum 375x at full 30 amp, .5 pierce delay, 1/16 shim and cutting at 15 ipm. its not perfect but pretty close, still think my plasma is too small for the 1/4, hopefully get a hypertherm 45xp in the near future :slight_smile:

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try a 1 second pierce since its only 30 amp. I use .5 on 1/8

While that works you should not that having too long of a torch firing without cutting will wear down on consumables. However cutting a part vs not makes a big difference too :stuck_out_tongue:

the pierce delay of .5 is good with my set up, its always fully pierced thru, just getting alot of dross on the back side of my cuts

I use .7 on 3/16 and .8 on 1/4 with my hp xp30 I get dross on the back but its easy to scrape off. I have been noticing some dross coming up on the pierced hole, perhaps it too much delay or not enough? I dunno I’m on auto pilot with my machine as I been so busy. I have not time to experiment and or even think to expand my table or anything of the sort. if anyone can weigh in on the dross on top from the pierce I would appreciate it.

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