Finecut and Stainless

[rwskinner]

I've been using finecuts for several years and love them, however, I always seems to have issues on thicker materials that the book specs say I can cut, but sometimes they don't cut all the way thru.

This week, I'm cutting lots of 12 ga 304L, using the finecuts and book specs, I have serious edge bevel and some of my cuts are not cutting all the way thru. I'd like to get this figured out. I have checked my DTHC and then made sure my cut height was correct, but I have the same issue.

I can switch over to regular 45 amp nozzles and everything is fine, but I loose some of the finer details I need for these parts.

Any recommendations?

[SeanP]

I use finecuts a lot for anything under 3mm as well, get great cuts on mild steel and thinner stainless, I tend to slow down a little to book specs though, 3mm stainless I would be at 2400 (book 2550) 3mm stainless is ok, but not as good as the thinner stainless.

One other thing, I hate that ohmic shield 220948, it clogs easily and to my mind have more problems with not cutting through in places.

I made up a 2 legged shield from a old 220817, been using it for the last six months every day and to my mind it's way better, better cuts and lot less trouble with spatter.

Nozzles need to be clean and in good condition to get good cuts, 6mm is the thickest I have cut if you wanting good detail.

2mm & 1.5mm 304

6mm mild steel

[jimcolt]

Finecut consumables, especially with a new electrode occasionally need you to cut at a higher voltage and cut height than the book spec....if they are not fully penetrating the material. Set your cut height at .080", and increase the arc voltage (maybe 5 to 7 volts) to maintain the .080", and you will then solve the issue. Usually the issue is with the material, especially on 14, 12 and 10 gauge steel when the silicon, carbon or manganese levels are higher than normal. Jim Colt

[rwskinner]

Jim, for 12 ga SS my book says 0.020" for cut height, so when you say raise it to 0.080," was that for steel or the stainless?

Finecut consumables, especially with a new electrode occasionally need you to cut at a higher voltage and cut height than the book spec....if they are not fully penetrating the material. Set your cut height at .080", and increase the arc voltage (maybe 5 to 7 volts) to maintain the .080", and you will then solve the issue. Usually the issue is with the material, especially on 14, 12 and 10 gauge steel when the silicon, carbon or manganese levels are higher than normal. Jim Colt

[rwskinner]

I cut 14 ga 316 SS perfectly fine, no issues. This 12ga 304L sucks. I quit using the fine cuts on the 12 ga as I'm wasting WAY to much material.

Right now, I'm cutting a bunch of 1/4" 304L and I'm using the 65 amp settings because I can't chance the 45 amp messing up stuff.
The cut is nice, and almost dross free, but no matter how much over cut I do, it leaves about an 1/8" of tab at the intersection of where the original lead in started. I'm up to .375" over cut and I tried also a lead out. Funny thing is, the lead out is cut fine, but there is still a tab where the paths cross. I didn't have any of these problems when I cut the same stuff in 316 ss.

[SeanP]

Yes that happens to me on thicker stainless, mild steel as well, if you create a rule to slow down 75% 4mm from the end (not including leadout) that should sort it.

[motoguy]

I cut 14 ga 316 SS perfectly fine, no issues. This 12ga 304L sucks. I quit using the fine cuts on the 12 ga as I'm wasting WAY to much material.

Right now, I'm cutting a bunch of 1/4" 304L and I'm using the 65 amp settings because I can't chance the 45 amp messing up stuff.
The cut is nice, and almost dross free, but no matter how much over cut I do, it leaves about an 1/8" of tab at the intersection of where the original lead in started. I'm up to .375" over cut and I tried also a lead out. Funny thing is, the lead out is cut fine, but there is still a tab where the paths cross. I didn't have any of these problems when I cut the same stuff in 316 ss.

This is due to the arc lag (angle the arc is trailing in the metal). The overcut won't matter. As you're finding out, with the arc lag, the torch loses the arc to the metal (at the top of the metal) before the trailing edge of the arc (at the bottom of the metal) has cut through. So you end up with this tab (that is likely cut at an angle as well). I ran into this as well.

Slow down your cut at the end, and that should make the arc more vertical, and let the arc at the top of the metal and the arc at the bottom of the metal, exit the metal in similar places.