plasma cutters

[Renze]

I am looking to buy a plasma cutter and a MIG.

I put a bid on a Miller 280 (i know Miller is -THE- brand in the USA) a Tico (Dutch brand, good quality copper spools) and a Kemppi, all 3 are barely used, and regular machines so i am not afraid that i cant get parts for them, like with the first gas welding machine we bought.
They say 3 phase welds much nicer than single phase 230V or two phase 400V because the alternating current is transmformed into DC but there are dips between the waves of the current: With 3 phase these waves are allmost eliminated. Does anyone confirm that ?


40A plasma cutters have ratings from 10 to 12mm nominal cutting (3/8 to half inch)
I have a 7x12 band saw for anything thicker than that, so the 40A machine will do for my main purpose: However i also have another purpose: We have 3 pig barns which are to be tore down, and there is a LOT of scrap in there: cages, feeders, structural steel. (i will need a frontloader boom pole) Abrasive disks are too expensive to use for demolishing, and i simply refuse to use an angle grinder on a ladder !

So the other question is: If this 40 to 50 ampere plasma cuts CLEAN through 10 to 12 mm steel, what will be its maximum cut depth, if i simply want to tear things down and the smoothness of cut is totally unimportant ? (i'll clear cut the beams to length on the band saw, before i weld a new structure for a horse and machinery shed from the salvaged steel)

Clean cutting 10mm is more than enough for me, but i'd also like to be able to cut some scrap, regardless the smoothness of cut. What will a small plasma cut ?

 

[jenkinsph]

Three phase power converted to dc is very smooth and ripple free as you suggested.


Why not use a regular torch for the demo? Seems it would be easy to use for that purpose.

 

[dfkrug]

So the other question is: If this 40 to 50 ampere plasma cuts CLEAN through 10 to 12 mm steel, what will be its maximum cut depth, if i simply want to tear things down and the smoothness of cut is totally unimportant ? (i'll clear cut the beams to length on the band saw, before i weld a new structure for a horse and machinery shed from the salvaged steel)

Clean cutting 10mm is more than enough for me, but i'd also like to be able to cut some scrap, regardless the smoothness of cut. What will a small plasma cut ?

My 40A PC (Thermal Dynamics CutMaster 51) is rated for something like
5/8 cut and 7/8" sever. I do 1/2" all the time. A lot has to do with the
condition of your tip, however. They don't shoot too straight after a while.
I probably should change my tips more often, but I try to get as much use
from them as possible. So, with a new tip, I can do a very clean cut in
1/2" mild steel. It also makes a diff if you contact-cut or standoff-cut.

Anyway, isn't your basic electrical service 220V 50Hz? You do need a 50A
circuit.

 

[Renze]

DFkrug, our basic electricity net is 3 phase 400V but between a single phase and a null wire, you get 230V

In fact you could get 3 phase in every household because the phases are in every main cable, but you have to pay a lot for just having them fused in. Since we have a farm, we need that anyways.

So your machine is a 40 amp ? Or 50 ?

 

[J_J]

This is the plasma cutter that I have. #8 wire on 60 A breaker.


http://content.lincolnelectric.com/pdfs/products/literature/e1160.pdf

 

[Eagle Dude]

The quality of the rectifier and filters is what eliminates the ripple voltage. With a real good rectifier filter set-up you would not be able to tell the difference between half wave and 3 phase full wave rectified DC. Quality manufacturers provide quality rectifiers in their equipment.

 

[charlz]

Plasma cutters have short leads and you always need to have the unit grounded to whatever you are cutting. Personally I would go with O/A torch for cutting salvage... going to be way faster than always moving your ground, cleaning a spot for it etc. not too mention having to have a good air supply on site. Of course I already own a 100' set of O/A leads so that may influence my choice

 

[brandoro]

My brother has a small plasma cutter, can't tell you the specifics on that but, on occasion he removes old boilers from basements and for that he rents a larger machine that will cut faster. Because these boilers were generally put in place first and the building constructed around them the pieces need to be cut to a size that can be hand carried. Makes for a lot of cutting.
He has mentioned to me that the air supply needs to be dry. He also said he has heard of people using bottled oxygen as supply air. He hasn't tried that himself but it would be about as good an air supply as you could get.

 

[dfkrug]

So your machine is a 40 amp ? Or 50 ?

Mine is 40A (see above). That is plenty for my use. I pay very little for
"consumables"....way less than having to buy oxygen all the time for
my O/A torch. I recently bought a nice circle cutter guide that helps
a lot with all those pesky holes I need to cut in 1/2" plate. Certainly
not as clean as drilling, but if I cut them extra big and weld in bushings,
then I do no drilling or reaming at all. Sweet.

 

[J_J]

Plasma cutters have short leads and you always need to have the unit grounded to whatever you are cutting. Personally I would go with O/A torch for cutting salvage... going to be way faster than always moving your ground, cleaning a spot for it etc. not too mention having to have a good air supply on site. Of course I already own a 100' set of O/A leads so that may influence my choice

Lincoln ProCut-55 Plasma cutters can use a 50 ft hose with no problems. It was optional when I purchased mine. I also have the machine torch for use with a computerized cutting table. You can also use compressed air, nitrogen, hydrogen, helium and argon. It gets kind of expensive using anything other than compressed. air. The air must definitely be dry, or the plasma wave will spread out to much. Standard tip is .043, optional tip for gouging is .068
Air used is 6 cu ft per minute

Anybody know how many cu ft of air you can get from a divers tank. Some plasma cutters use 4 to 6 cu ft per minute.

I have a Lincoln ProCut-25 that I don't use much. PM me for negotiation.

 

[Renze]

Personally I would go with O/A torch for cutting salvage... going to be way faster than always moving your ground, cleaning a spot for it etc. not too mention having to have a good air supply on site. Of course I already own a 100' set of O/A leads so that may influence my choice

I am a hobbyist with a near professional workshop... i have to draw a line, i cant just keep on spending on tools. the barn demolition is mostly 42x3mm pig sty pipes, and a couple of structural beams. I doubt if you cut thin stuff faster with O/A because you need to heat before applying cutting oxygen, the plasma allmost cuts right away.
The barn demolition is something i wont do every day, but its a justification to buy another tool.

He has mentioned to me that the air supply needs to be dry. He also said he has heard of people using bottled oxygen as supply air. He hasn't tried that himself but it would be about as good an air supply as you could get.

I have a moisture absorber in my 3 cylinder workshop compressor, for spray painting. For just a month of barn demolition, i can unscrew it from the big compressor and put it to my brothers little one, to use with the plasma.



..so.. 40A plasma will cut 7/8 or 22mm ?? Thats bigger than any of the beams in our barns. I can get them for 350 to 600 euro, depending on brand. I do concider the brand of what i buy, because i want something which is known by repair shops and parts are available. Therefor, i dont want an older heavy duty industrial unit: We once bought a 450 amp mig welder which was a real beast: but we had to scrap it because our dealer couldnt get just a small part for it, required to fix it.

 

[J_J]

Renze,

This ain't no plasma cutter, but it will out-cut just about anything out there. Check it out and see for yourself.

Petrogen | Petrogen Oxy-Gasoline Cutting Systems Home Page

 

[Therios Pendragon]

Renze,

This ain't no plasma cutter, but it will out-cut just about anything out there. Check it out and see for yourself.

Petrogen | Petrogen Oxy-Gasoline Cutting Systems Home Page

So... does anyone actually have any experience with these? I am intrigued.

 

[Reg]

Round numbers, it is possible to "sever" about twice the "rated" capacity, but it will be slow.
I suspect that it would be less than half the speed, in inches or cm per minute, though I don't have the specs of my cutter here.

 

[JoeL4330]

I have a plasma cutter, which works fine, and O/A ...but also have two metal cutting circular saws, that would be my first choice for what I think you want to do ...you can google them, see what you think ...I have a 7"+ and a 9"+ and it's like a hot knife through butter.

 

[J_J]

So... does anyone actually have any experience with these? I am intrigued.

You would see more of these units except for the price. About $1300 for the portable unit. I have read quite a bit about and watched the videos, and I am very impressed with the cutting capacity. The concept is simple, and gas has the energy. A lot of the rescue people have these units. They even work underwater. The cost of consumables is much lower.

Just imagine one of these units on a computer cutting table.

Have you ever seen the jet rods cut up stuff? That is also impressive. You just strike the rod with oxygen flowing through, and cut anything, including cement. There is a chemical in the rod, that when combined with oxygen, it burns like a rocket. They use them to cut through safes.

They also call them exothermic or slice rods.

 

[jenkinsph]

The quality of the rectifier and filters is what eliminates the ripple voltage. With a real good rectifier filter set-up you would not be able to tell the difference between half wave and 3 phase full wave rectified DC. Quality manufacturers provide quality rectifiers in their equipment.

Quality manufacturers build 3 phase welders with quality rectifiers and filters.
It is much easier to filter 3 phase to a high degree because the ripples are smaller to start with.



Steve.

 

[SpringHollow]

He has mentioned to me that the air supply needs to be dry. He also said he has heard of people using bottled oxygen as supply air. He hasn't tried that himself but it would be about as good an air supply as you could get.

There is no way you want to be using bottled oxygen as your supply air. That is just asking for trouble. And i assume it is more expensive than straight bottled air.

Ken

 

[Scotty370]

".....Barn demolition is something I won't do everyday, but it's a justification to buy another tool." Ah... the real truth emerges......! I say O/A is the cheapest way to go aww , duh....... I mean buy the plasma cutter!

 

[J_J]

There is no way you want to be using bottled oxygen as your supply air. That is just asking for trouble. And i assume it is more expensive than straight bottled air.

Ken

They do use oxygen. Here is part of the article.

The HySpeed HT2000 200-amp oxygen plasma cutting system incorporates the company's patented coaxial-assist jet technology to boost cutting speeds on mild steel by as much as 50 percent over conventional designs. Designed to cut most metals from gauge to two inches thick, this system can benefit all mechanized cutting operations. Both the HySpeed HT2000 and HySpeed

http://www.used-robots.com/articles.php?tag=1658

http://www.thefabricator.com/PlasmaCutting/PlasmaCutting_Article.cfm?ID=2135