Just the facts...about plasma cutters

[drewworm]

Very clever. That last one must have taken some creative energy.

[jhndtwlr]

I was looking into buying a plasma for over a year. A few month back I borrowed a 27 amp 110 unit off a friend of mine, a Snap-on It was hard pressed to cut through 14 ga. steel. I had to make about 60' of cuts I wound up using O/A to do 90% of the job which sucked because of heat distortion. Anyway I just bought a Miller 625 Spectrum I just got done building a cart for it, the only thing I cut with it so far was a piece of 3/8 steel about 4" long just to make sure it worked. I made a track today for the standoff guide to cut long pieces. A friend of mine dropped off about a 1/4 ton of scrap steel and aluminum from about an 1/8" to an 1" thick.So tomorrow I'm going to see how well this unit cuts, if I can figure out how to post pictures I'll post. Whitey

[Tailshaft56]

I was about to order a Cutmaster 51 but wound up buying a used Esab PCM-875. I haven't cut thicker than 1/8 yet and it does leave a little dross on that. My LWS dealer said that pretty normal on anything thicker than guage such as metal siding. I still need the Motorgaurd filter and from previous posts may need a larger supply line. Hopefully I'll finish my wiring upgrade ( from #12 to #8) and get to try it on some thicker material.

[Rvannatta]

I've been using a Lincoln Procut 80 for heavy scrapping. It's rated at 80 amps output but has a setting at 85 amps. It is said to be able to cut to 1 1/4" and it the context of something at the 'outer limits' its true. I did make a cut with it on 1 1/4"---but is it practicial--did it look nice --no.

I"v done a lot of 7/8's with it and it will blow a hole in 7/8's with some struggle but it will do it and will cut 7/8's well with some practice.

1" is a hassle but doable.---ifyou have fresh tips, don't cross any weld beads and is well positioned.

somethings it is particularly bad at such as cutting off bolt heads.

1/2" and less you never even look for an edge to start if you are so inclined
it pierces immediately without blowing back which causes premature failure of the tips.

You will see noticable performance difference between a fresh set of consumables and ones that are close to being unusable.

[WolfMetalFab]

one plasma trick for cutting metal at max thickness and you need to do a middle start and have the room to you can tip/roll the torch in to the work, it will cause the plasma to gouge a starting slot on its way to finding the other side of the metal being cut

[drewworm]

Can't wait to hear how these machines work for you guys. If you can figure out how to post pics... please... give us some eye candy.

[Rvannatta]

plasma cut photos

Can't wait to hear how these machines work for you guys. If you can figure out how to post pics... please... give us some eye candy.

Presto and ther are photos...
click photo to expand

What you are looking at is the main frame of a 3 yard front end loader that turned into #1 scrap. I cut everything up to 1" with the Lincoln Plasma.

the two close ups are of a 1" cut and a 1/2" cut. the 1" cut was made on the piece in the far upper left hand corner of the photo. Dross tends to be prevelant on the heavier cuts but notice that the 1/2" is virtually clean.

the Inch cut was made onlly yesterday but notice how quickly it showed red. Someof that shows immediately.

[drewworm]

Funny, I noticed the rust appeared almost as I was cutting and wondered how it got there so fast.

[Rvannatta]

Funny, I noticed the rust appeared almost as I was cutting and wondered how it got there so fast.

I would assume it is oxidizing immediately while it is hot. heat usually makes chemical reactions happen quicker, but I can sometimes see a red stain on a cut within a minute or two......

though the photo here was taken a day later and as you can see has a little overnight snow on it as well.

[timw]

I have had my Miller Spectrum 625 for 2 years now and it does a great job. I cut a lot of 1/2" bolts (3/4" head) and I just wash the heads off just like using O/A only no pre heating. Another good feature is I use a wood 2 X 4 for a straight edge. It guides the torch and dosen't really burn because the cutting is so quick.
I have cut 3/4" plate but it wasn't pretty. I used the drag tip, it probably would have worked better with stand off tip.
I would have to say that getting a plasma cutter was one of the best decisions I have made. To refill my O/A is 2 hours round trip and the tanks never run out at the same time. Air is very cheap! I only use the O/A for heating now.
Water removal is very important because it hurts the quality of cut and ruins the tips. You should get the biggest unit you can afford because having reserve capacity will make it more efficent.

[Rvannatta]

I have cut 3/4" plate but it wasn't pretty. I used the drag tip, it probably would have worked better with stand off tip..

We use a drag tip all the time on the Lincoln--it works well and you can really drag it. keeps the spacing right.

I would have to say that getting a plasma cutter was one of the best decisions I have made. To refill my O/A is 2 hours round trip and the tanks never run out at the same time. Air is very cheap! I only use the O/A for heating now..

while we have used propane for years to keep the cost down, just the O2 can get spendy. I've looked real hard at the operating costs of the plasma
and relatively speaking they aren't bad. I use a set of consumableable every 4 or 5 clock hours scrapping plus I use the welder as a power supply so have to feed diesel to the Perkins in the range of a gallon an hour or so but I have convinced myself that it is cheaper than the gas fire in operation.

it's certainly in conveniece -- there is no down side to setting the torch down for a minute to knock things apart with a sledge hammer or toss thecut up piece out of the way etc.
.

Water removal is very important because it hurts the quality of cut and ruins the tips. You should get the biggest unit you can afford because having reserve capacity will make it more efficent.

unquestionably bigger is better. --- and I suggest the 50 foot umbellical.

[drewworm]

Like I said...I'd come back and restate my opinion of the Spectrum 2050. I used the machine lots this weekend to cut 6" .25 wall pipe and 1/2 plate. I took someones recommendation and swapped my 3/8 airline for a 1/2 line and applied some other advice as I set to cutting the 1/2 plate. First, I clamped a 2X4 for a straight edge. When I started my cut, I lifted the cord end of my torch higher so that the stream was angled about 10 deg. into the direction of the cut. Lo and behold, I got a really nice cut. Slag was still there but knocked off really easy leaving a respectable edge. I noticed in the past that the piece left behind when I cut a chunk off has an angled kerf. Coincidentally, I was wondering if this is because the ground clamp is on this piece. (Didn't think to experimenting with moving the ground.) To counter the kerf I angled the torch tip into the straight edge. That got rid of the bad kerf and still left a nice edge on the piece I cut off. Done with 1/2. Result: Fun and easy.
Pipe: Twenty foot length is 320#. Sorta tough to lift off the ground and slide a 2X4 under, but that's where I start. Then put Wizard wrap around the pipe and mark the line with soapstone. Remove wrap and get ready to cut. First, angle the torch about 45 deg. so sparks don't come back into your face. Almost immediately, rotate the torch perpendicular to the pipe to pierce. Easy. Follow the line - that was the hardest part. The torch however, cut right through. Anyone have suggestions on a type of edge that can be used as a guide around the pipe? My cuts were sorta "wiggly".
Result. One hour to cut 6 3ft lengths of pipe and 6 plates as bases. The time is invested in measuring and marking. The cuts went so fast I didn't get to enjoy it.
I like the machine better and think that just concentrating on technique helped. I have to admit, I think the airline swap helped a lot too even though I didn't initially think it would matter.
Sorry, I didn't have to cut anything thicker. I should have tried piercing some 1/2. It blew through the .25 so easy that I think 1/2 should be no prob.

[harcosparky]

I have to admit, I think the airline swap helped a lot too even though I didn't initially think it would matter.

Think of it this way, no matter how big the compressor, only so much air in a given time is gonna get through the hose to the plasma cutter. The is easily seen as a 'choke point'. By going from 3/8 to 1/2 you greatly increase flow rate through the hose. ( 33% ) I saw a difference and figure it was not me at this point, as my technique is developing, it had to be the air.

I am convinced now more than ever, feed em all the air you can, and then some more ... and DRY that air.

An added benefit by switching to 1/2 for us we reducing the number of sizing adapters inline. I have to believe that each one was doing more harm than good, so we now have !/2 out of the comp all the way to the cutter.

Next step, to shorten the line.

[drewworm]

The 3/8 line I swapped out was 25', the 1/2 I replaced it with is 100' (it was all I had). I did see an improvement. Don't know if a shorter line will make it even better. With my crappy Sears compressor, the 1/2 line acts as an extra reservoir.

[harcosparky]

The 3/8 line I swapped out was 25', the 1/2 I replaced it with is 100' (it was all I had). I did see an improvement. Don't know if a shorter line will make it even better. With my crappy Sears compressor, the 1/2 line acts as an extra reservoir.

WOW .. you went from 3/8"@25' to 1/2"@100' and saw an improvement.

That's good to know, I don't think my shortening the 1/2" hose from 25 to 10 would make a difference. I do know in my 3/8" install I had several downsizing adapters to go from compressor output to the 3/8" line, by going to 1/2" I got rid of all that crap.

As to fittings, I had a 1/2" Quick Disconnect ( silver colored ) fitting fail on me, the spring mechanism siezed up and I had to use Vice Grips to disconnect it. Cut it open and found corrosion internal to the disconnect but NOT inside the air path. I am guessing that at some time in its life one end of that hose had hit water outside and I was not aware. Switched all connector out and got BRASS ones instead. Will have to remind myself to check them from time to time. Hopefully switching out to brass will help out a bit.