Is my reasoning correct? Under Powered Cutter

CrossFire ®
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I purchased the CrossFire with the XL kit to specifically make one product, bat house brackets that use 12 GA (.120"), but I did (and am doing) a lot of artsy fartsy things with 16 GA (.062") steel as well.

First, a BIG thank you to this forum, I know I don’t post a lot and that is mostly because with bit of searching, I find what I need has already been posted. So, thank you to all the contributors, in my opinion it is this forum that makes CrossFire line so valuable.

For budget reasons, I chose to use a plasma cutter I already have, a Northern Tool 375i 40Amp cutter. I had no problems setting it up or triggering it etc… it works well and I was told 40Amps was plenty. However, I strongly suspect this cutter is under performing the more I cut with it.

My first hint is how fast it can cut with good result. The air pressure is set to 60 psi.

In 16GA (.062") I run at about 80 ipm on cut. I had expected that (based on reading) to be around 120 ipm (did I get that wrong?) But I used a coupon and was able to sneak up on 80 ipm, well here it is

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If I stray to far from those settings, I get bad results.

For the 12GA (.120") here are the settings, again with good results

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That 58 ipm has some wiggle room, but anything over 60 ipm and it starts failing to cut all the way through as it speeds up. By the time I reach 70 ipm, it no longer cuts through. Again, compared to the forum information, that seems slow.

If that is all I wanted to cut, I would probably say C’est la vie and move on. But, when I move to 3/16" metal (actual is .20") I have to cut so slow to get through it heats the torch head and burns up the consumables more rapidly. If I move faster, it fails to cut through in places and leaves terrible dross. If I slow down to 40ipm for good cuts, it is moving so slow for corners and small holes that the plastic on the torch started smoking.

I tried 1 piece of 1/4", that’s not happening.

I’m thinking that dial that says “40 amps” is lying and it is actually putting out maybe 30 or less in reality.

In short, do I keep messing with this trying to figure out if I’m doing something wrong? Or is this just an under powered cutter and thus I’m asking too much from it?

When it cuts, it cuts well (albeit slower than expected) I couldn’t tune it any better, my 12GA material comes off very clean, any dross easly chips off (no grinding required) size is accurate etc…

EDIT:
I have tried grounding the table, the metal itself and both with little change
I have tried air pressure from 40 to 80 psi, 60 psi has seemed to do the best (this is according to the guage on the cutter itself. I’m feeding it with dry air at 120psi with a screw compressor that easily keeps up)

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There is most definitely something wrong as it should cut 1/4" just fine. It won’t do large things as the duty cycle is to short. What consumables are you using?

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George, would a clamp on ammeter be able to tell if the current is forty amps? Clipped on the Work Lead should be easy to do… Can probably rent one from Home Depot or somewhere.

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Yes, but I don’t think that is his trouble.

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Thanks for the replies.

It has an S45 gun on it and the most recent consumables (used for the first time a few weeks ago) is “AWLOLWA” from Amazon. Before that it was branded Klutch and purchased from Northern Tool off the shelf. Not being able to find them at Northern Tool is what drove me to Amazon. I did not notice a difference when I switched to the newer stock. The tips all say they are 0.8mm / 0.031’’, I am not aware if different sizes are available.

This is the amazon link: https://www.amazon.com/gp/product/B089SPQ862/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I got this machine refrub’d from Northern Tool 8+ or so years ago. The original consumables are long gone. The newer cutters are branded “Klutch” but this one is marked as “Northern Tool”.

When I was originally cutting with it by hand I learned I will NEVER be steady enough to cut by hand and I basically went through a set of consumables every time I used it. I did an odd job with it here or there, but never anything productive. Everything looked like a beaver chewed through it. My Son was much better with it, but still, not good enough to make a product.

I can say, the cut quality is fine, just slow. I don’t understand why it is so slow nor why it seems to struggle with thicker material. My only conclusion is, it is under powered OR I’m missing something.

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First thing is buying these cheap consumables will never get you any were. 0.8mm tips are only rated at 30 amps. You need 0.9mm rated at 40 amps for 1/4" and 70 psi of flow air pressure. You have the original Trafimet S45 torch made in Italy on that plasma cutter. Those cheap consumables are not made to the same spec’s as the originals and don’t work very well on a CNC table. If you want good consumables contact me

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I am unaware of what constitutes “good” consumables and went with what was originally provided with the cutter as near as possible with what I could find. I did not know the .08 (which is what it comes with and mostly all I’ve found) were too small.

Of course, I would love to simply swap consumables and solve the issue. Are there suggested brands/sources to order from? I’ll order today.

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@harryball
George is our resident Plasma guy…he repairs plasmas and sells parts and consumables…

as for “good” consumables…get your stuff a reputable source as the knock offs sold on the large e-commerce sites are usually crap…

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@toolboy I’m figuring that out. Can’t even trust buying a broken hammer these days, you may get it and find it is not broken.

I PM’d mechanic416, I’m guess that is George. Hopeful at this point some good consumables will fix it.

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It will be one less thing to fix…

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I ordered a RazorWeld Cut 45 with the machine head moments ago. I watched several videos of it cutting 1/2" steel, I just want to cut up to 1/4". Looking forward to it arriving and being able to really cut something.

I’m done with this 375i plasma cutter. I did put new consumables on it, didn’t help, actually got worse. Never was able to get any help with how to test it or repair it etc… I just think it is cutting at 20amps or something lower even when set on max. It is just not cutting it (pun intended). It will slowly cut anything up to about 1/8" but after that, you’re going way too slow and get crap for quality while burning up the torch head. I figure I’ll retire it as a hand only cutter for making burn barrels.

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Did you have 70 PSI at the torch side of the plasma cutter? Not at the back where your hose comes in.

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Yes, I have 120psi shop air going in and the regulator is internal. I have varied it during testing as low as 40 and up to full pressure. When cutting 1/16" steel I run it at about 60 psi to get the best result. On 1/8 the machine is maxed out for cutting with any quality. Believe me, I’ve had this setup since mid 2021, I have spent hours and hours playing with the setup, watching videos, reading and trying settings from the forum, new consumables, it cuts the same it did on day one.

I’ve made do so far and can’t cut 3/16" or above worth a crap. I’m done with trying. I can get clean cuts in 1/8" when using the original “cheap” consumables running at full power and about 1/2 the speeds suggested on the forum. Making no other changes and installing the good consumables I got from a guy on the forum here, the quality goes to pot. If I speed up, it just fails to cut through leaving a mess.

I should know very quickly when I get the new one and compare. Looking forward to one that works well.

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I have a question…how big are the airlines and couplers feeding air to the plasma…there is a direct relation to air restriction and increase in pressure…meaning if you have air flow (volume) restrictions you will get false pressure readings…

so you may think you are getting good pressure but the flow is way lower than what you need…resulting in lower cut quality

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