Hood
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You should get very little dross if you get the feed right and even then it normally knocks off easily with a chisel/screwdriver.
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Brad93
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1500W, what’s that 10mm steel that will cut?
julianthegypsy
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The guys I use have a 3kw laser, which handles 15mm steel plate comfortably. It has two 1500 watt power supply units. One of them went down once and they could still cut 10mm plate, but at a slower speed than normal.
Munkul
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Have you found any cutters that can handle plasma cut holes?
I got a HMT impactamag reamer for final reaming of some laser cut holes, it seemed to hold up well but didn't have to work very hard - just tickling the bevel on around 50 holes so far. I'm not sure how it would have fared on plasma cut holes with more dross.
James1979
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I emailed HMT as I wanted to do that.
Got a strong email back saying that’s not what they’re designed for and I’ll bugger it!
Hood
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Plasma cuts shouldn't have much dross, look at the pics of the thick steel I posted above, very slight surface dross and usually none on the bottom but if there is it should knock off easily with a chisel or file end. Stainless used to be the worst for me, had a sugary dross on both sides and worse on bottom, with the water table there is hardly any.
I just use normal HSS drills on the Stainless and on the odd occasion I do steel it is the same.
henry Kadzielski
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Just a thought. I have a scriber on my machine that I use to mark 'stuff'. The critical holes I get the machine to mark and drill them, the not so critical I let the plasma cut those 
. At least they are exactly where they need to be, not ideal but it works. Unless you are using laser or min high definition plasma your holes won't be bolt perfect. I have slowdowns on my settings for holes and I can cut holes the thickness of the plate or just slightly smaller, there is taper however. In these situations I just put a drill to straighten the hole, using a Dormer drill and a good sharpener, not perfect but works
. At least they are exactly where they need to be, not ideal but it works. Unless you are using laser or min high definition plasma your holes won't be bolt perfect. I have slowdowns on my settings for holes and I can cut holes the thickness of the plate or just slightly smaller, there is taper however. In these situations I just put a drill to straighten the hole, using a Dormer drill and a good sharpener, not perfect but works
Hood
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I suppose it depends, if the clearance is to allow for alignment issue when fabricating then I would think if there is a bevel then that would reduce your overall size and could cause issues.
Personally I don't have too many issues with bevel unless the consumables are needing replaced.
As to @henry Kadzielski method of marking with the engraver, that would work but I have found it is just as easy, if not easier, to cut the hole undersize and then drill to size. Reason being that the top of the hole is round even if there is a taper and thus the drill gets centred automatically and has les material to take out and as such is quickly done.
Munkul
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If I did predominantly aluminium I'd be right with you - cutting undersize and opening up with a drill
Where I'm coming from, I'm wondering about using plasma cutting for making structural steelwork pads that need a quick clean up and straight on to welding.
So buying in steel plates at 8mm, 10mm and 12mm, rather than various sizes of flat bar, and skipping the cutting and drilling stages.
Yes i know you can do this with laser, but I'm looking towards having my own machine - a CNC laser is out of my reach, whereas a CNC plasma is maybe just about in reach in a year or so
Of course, if I could find some steady aluminium work, I'd be dancing.
Munkul
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En 1090-2 Table B-8 geometrical tolerances for holes - +/-1mm ovality (I can't find a tolerance for nominal hole diameter anywhere)
Surely a half decent setup plasma can achieve that... if not, I'm barking up the wrong tree.
Brad93
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Nope it’s nothing to do with 1090. @Welderpaul knows what the specs are from looking at the esprit tables.
Hood
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Just done a quick test, only bit of steel I could find was some 10mm. Never done that before with this plasma so just guessed at speeds, voltage and dwell.
Did it at 1000mm/min and his is how it came out.
Top
Underside.
12mm hole and slot programmed, holes measure 12.1mm above and 11mm approx underside. Slot is 12mm top and 11.8mm underside.
Could get thigs better by tweaking feed I would imagine.
Did it at 1000mm/min and his is how it came out.
Top
Underside.
12mm hole and slot programmed, holes measure 12.1mm above and 11mm approx underside. Slot is 12mm top and 11.8mm underside.
Could get thigs better by tweaking feed I would imagine.
julianthegypsy
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Not bad, especially considering that the steel is pretty rusty.
Munkul
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I wouldn't have thought NSSS spec makes you hold the tolerances any tighter, it's fabrication work, not aerospace
but I'll look shortly.Hood's cuts look fantastic, as good as any pad I've ever seen. If you picked nominal size carefully and paid attention to minimize the taper, it would pass most normal specs, I'd imagine.
Hood
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Pic of cut edge.
As said tweaking could get better as this is the first time I have cut 10mm with the Jasic so just guessed at speeds etc. Also it is an old nozzle so not even sure how worn it is but I have done a fair bit of Aluminium with that one since I last changed.
As said tweaking could get better as this is the first time I have cut 10mm with the Jasic so just guessed at speeds etc. Also it is an old nozzle so not even sure how worn it is but I have done a fair bit of Aluminium with that one since I last changed.
Munkul
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@Brad93 NSSS 7th Edition - identical tolerances to EN 1090-2 : 2018. Almost like they were written together...I wouldn't have thought NSSS spec makes you hold the tolerances any tighter, it's fabrication work, not aerospace
Hood's cuts look fantastic, as good as any pad I've ever seen. If you picked nominal size carefully and paid attention to minimize the taper, it would pass most normal specs, I'd imagine.
EDIT: I wasn't sure which followed which, but the NSSS 7th Edition states specifically it references from EN1090 and other harmonised standards.
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