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View Full Version : plasma cutters - what one?



snowman
05-21-2008, 03:34 PM
I'm in the market.

Here are my needs:

Max size for plasma cut, 1/4" steel (absolute maximum, very rare)

Average cut, 12 gauge mild steel

I want to be able to do it at a reasonable speed.

Who has the most affordable consumables in the name brand companies?

Any advice?

macona
05-21-2008, 03:47 PM
Hyperterm Powermax 30.

chipmaker4130
05-21-2008, 06:39 PM
Hi. I use a Hypertherm Powermax 600 and I think you would be very happy with it. It will cut 1/4" steel as fast as you'd want to go by hand, and the consumables last a whole lot longer than any of the other brands I have any experience with. It will make a nice cut in 1/2" steel at a slower speed, and you can use 'fine-cut' tips for beautiful work in thin sheet metals of all types.

Gordon

japcas
05-21-2008, 07:04 PM
Hey guys. I've never run a plasma cutter before but I have thought about adding one to compliment my welding machines. What kind of air source do they require? Any general info about them would be helpful.

oldtiffie
05-21-2008, 08:48 PM
Hey guys. I've never run a plasma cutter before but I have thought about adding one to compliment my welding machines. What kind of air source do they require? Any general info about them would be helpful.

And that japcas is the item in the equation that too many forget.

My plasma cutter specifies the litres per minute required at a specified pressure, so my compressor has to meet that critera - at the plasma cutter - so allow a margin for line loss in air pressure and delivery. Further, the air has to remain on after cutting for cooling of the cutter itself.The electricals and electronics are cooled by a fan. Thus air and power must remain "on" until cooling is complete.

That "free air delivery" is not always clearly marked on a compressor and is very much less than the "rated" air use. My compressor "free air delivery" capacity is just over the plasma cutter requirement. I made sure I had as big a pressure vessel/reservoir as I could reasonably use so as to have a good back-up if the cutter got ahead of the air supply.

The compressor may be a bit bigger and use a lot more electrical power than many anticipate.

The plasma cutter can be an electrical power hog as well - so check it out.

Power supplies will need to be pretty good to cope with the compressor and the plasma cutter running together.

Plasma cutters are rated at the thickness of steel plate that can be cut at 10" per minute.

Mine is 3/8" but will cut 1/2" at a slower rate.

Just as in electric welding, the earthing is very important so as to reduced resistance.

A plasma cutter will cut just about any metallic conductor - steel, copper alloy, stainless steel etc. They will cut through rust/corrosion/oxidation as well which is very handy.

They do have a large diameter cutting head and it can be hard to see the cut/kerf at times - so access is not as good as an oxy/acet cutting torch.

Keeping the correct distance of the cutting head from the work is essential both for quality and depth of cut as well as minimising use of fairly expensive consumables. It is much harder to control than oxy/acet and so most/many users will use guides for tip-to-job clearance as well as guides for keeping the cut on-line (straight edges and circle/arc guides - used as templates as with a wod-working router).

They are really great for sheet metal or thin plate work as the cut is excellent as very high speeds.

They do take some practice though.

I don't use mine too often but I sure am glad I've got it when I need it!!

chipmaker4130
05-21-2008, 08:56 PM
Japcas, I'd have to look in the documentation for specific cfm requirements, but a 5hp compressor will run standard tips all day on the Hypertherm 600. My compressor is a 7 1/2 hp and it doesn't cycle all that often even with steady cutting.

One thing to remember is that if you get a 40amp cutter, it will draw 40amps. No step-down transformer like with a welder. (The Hypertherm is an inverter unit).

I just read OldTiffie's post, and I should mention that I use un-shielded tips 99% of the time because they don't block the view as he mentioned. I only use the shielded 'drag' tips when I cut using a template. I don't know about OldTiffie's machine, but mine is very tolerant of tip to work distance and I find it equally easy to use as the OA torch. The neat thing is: NO preheat time! The Hypertherm arc starts instantly, cuts a narrower kerf and produces about half the slag of an OA cutting torch. Also, you don't have to change tips for great cuts on any thickness within the range of your machine. (The exception being if you need a really fine cut in very thin ornamental sheet).

oldtiffie
05-21-2008, 09:57 PM
I agree with chipmaker4130.

My set-up is in a domestic environment. I have a 240v 50Hz 2ph 60A/phase supply in my shop. The 2 phase is a hang-over from when I had (and still have and use) my 200A "choke-y" "stick" welder and a 2 phase supply for a then 2-element hot water service.

I suspect that chipmaker4130's supply is considerably bigger or better than that!!

So, I'd start at the plasma cutter specs, shop around for one that suits and again, check its requirements as regards electrical power and air supply. I'd add 20% to that air supply as the minimum spec for the compressor "free air delivery" (to allow for line losses - including the regulator) and then shop for the compressor and check its required electrical supply.

My guess is that if there is a limited electrical supply that it will govern just what capacity compressor and plasma cutter you can fit in.

As chipmaker4130 says, they are a great asset in the shop - but I sure wouldn't get rid of my oxy/acet set!!!

wierdscience
05-21-2008, 10:22 PM
Don't buy a Miller spectrum 375,expensive consumables and not capable of it's rating.

I like the Hypertherm units much better and I also liked a Thermal Dynamics unit I used on a lease.

Clean DRY air is a must also.

JRouche
05-21-2008, 10:59 PM
I have had a Thermal Dynamics Pak Master 50 for about twelve years now. Now problems at all. Consumables are plentiful and priced about the same as all the rest. It cuts 1/2" stainless with a thin 1/16" curf. Slices up 16ga cold rolled steel like butter, just about as fast as I can sweep through the cutting template. I use thin cardboard for my templates. If Im going fast enough and dont jump onto the cardboard I can reuse the templates, doesnt burn it. I dont take any extreme precautions for dry air. Just a small drier mounted on the inlet side, small cheap one. JR

Oh, I gotta add though. The newer homeshop type units from TD appear a lil "cheaply" made. Not that looks are anything but I wounder if they have outsourced the manufacturing for some of their boxes. And mine wasnt cheap, bout 2500 twelve years ago.

piniongear
05-21-2008, 11:51 PM
[quote=snowman]
Max size for plasma cut, 1/4" steel (absolute maximum, very rare)
Average cut, 12 gauge mild steel
Who has the most affordable consumables in the name brand companies?
/quote]

My plasma cutter is a HTP brand. The model I have is a 625. The air supply takes 70 psi at the machine.
The cutter is a 220V single phase machine with an output of 50 amps.
This machine is reasonably priced compared to a Miller. The customer service is excellent and parts are in stock. HTP is located in the Chicago area I believe.
The 625 will cut up to 5/8 inch thick cleanly, and sever cut 7/8 inch. On 1/8 inch steel plate it cuts like you would draw a pencil line, just as easy and just as quick. Check them out before you decide to buy some other brand. I have owned mine for 10 years now and never had a problem with it........pg
www.htpweld.com (http://www.htpweld.com)

torker
05-22-2008, 12:54 AM
I have a Lincoln Procut 25 that's been a very good machine. Cheap consumables.. a very nice sized torch.. all in all a good machine but it was pricey when I bought it(7 or 8 years ago??).
I then bought a Hypertherm 600.
Uses a lot more air than the Lincoln. I don't like the torch compared to the Lincoln.
However.. it's a lot more powerful machine and the price is lower than what I paid for the Lincoln.
The Hypertherm uses consumables a bit different than the Lincoln.
The Procut needed both parts replaced as they wore.
The Hypertherm uses the outer part the most. You get about 4 to 1 so it's fairly cheap to use.
Russ

Rookie machinist
05-22-2008, 01:23 AM
I have a thermal dynamics cutmaster 50 and it works great. I run it off a 60 gal. upright compressor and use a cheap air/water seperator. I don't think you can go wrong with thermal dynamics or hypertherm. Beware of the cheap cutters, my first plasma cost $1200 and was a total heap wish I could rember the brand.

RetiredFAE
05-22-2008, 01:36 AM
I have a Hyper Therm Max 42 I picked up for $300 4 years ago. It was a show room demo model, but looked like new. Came with 6 extra of each of the consumables, I still have 4 each of them left.
Has had lots of use since I acquired it, zero problems, and gets pretty long life out of its consumables. For a dryer it came with a filter/dryer that uses a roll of toilet paper for the element. Have heard that this is not the best (by far) for a filter, but 4 years of use and as
I said, zero problems. It might be because I live in the desert and our humidity never gets very high. It takes about 6 CFM at 70 PSI if I remember correctly, and will cut a bit over 1/2" if I go slow. Parts seem to be readily available, judging by what I have found on the web.

oldtiffie
05-22-2008, 04:06 AM
Perhaps this information might assist.

http://www.lincolnelectric.com/knowledge/articles/content/plasma.asp

http://www.millerwelds.com/education/articles/article97.html

http://www.millerwelds.com/education/articles/articles17.html

http://www.millerwelds.com/education/articles/articles55.html

motomoron
05-25-2008, 05:21 PM
I've picked up a like-new Thermal Dynamics Cutmaster 38 from the local Craigslist for about $800 with a pile of consumables and the matching cutting guide attachment kit.

After I sorted out that the torch was fitted with contact type tips, and that the clip-on metal guide that the previous owner had on the torch wasn't to be used, I've been quite impressed with the ease of operation.

It will run on 110 or 220V power, but works ~much~ better on 220. I have a 5hp-60 gallon quad cylinder Speedaire compressor and use a refrigerated air dryer, but it's not absolutely necessary; I happened across it and it followed me home. More for painting than cutting...

platypus2020
05-25-2008, 10:31 PM
Hyperterm Powermax 30.

I have had one for about a year and a half, great machine, cheap consumables, a nozzle and an electrode cost about $7 a set, and with clean dry air, they last a long time.

Jack

BobWarfield
05-26-2008, 02:38 AM
Hypertherm is the one I hear about all the time. Everyone seems to love 'em, especially the CNC plasma table crowd.

I've got a big ESAB that I got cheap. It was a sales demo unit, and they were selling them from the factory on eBay. Don't know if that still goes on.

It's a real nice unit, cuts well, and is easy as heck. Book says it'll cut over an inch thick. I've had no call to do that, but it cuts 1/2" like butter.

Cheers,

BW

macona
05-26-2008, 04:09 AM
Hypertherm makes the best plasma out there hands down. Thats what we sold the most of.

The Hypertherm 190C and Hypertherm 380 were both made by Miller. At the time Hypertherm had deemed not enough demand for them to design a small machine like those two so they had miller OEM them. Internally they are the same as the Miller 125 and 375. Just different tin. And the consumables are slightly different so they wont be interchangeable.

The newer Miller 380 Xtreme was built on the same tech as the Maxstat 150 welder. it was designed in response to the Powermax 30 coming out. Miller wanted to license the PMX30 from hypertherm but HT said no so they rushed to get the 380 out. There were quite a few failures on the 380 after it came out.

The Esab machines are a mixed bag. The smaller machines like the 125, 25, 550 are all made in Italy and are total crap. The mounts holding the main circuit board are very flimsy and easy to break. The self contained 125 is worthless.

The larger esabs with the molded round fiberglass cases are derivatives of the old ltec designs and they are pretty decent machines, although the torch sucks big time.

The thermal dynamics machines are so-so. I have had a LOT of bad boards out of the 38's. Never the same problem too. They replaced all these machines with newer ones with a blue bezel but I never got a chance to look at one before I got canned. The torches are pretty nice though, one problem I found was the joint between the torch head and cable can come undone and ruin the whole torch assy. It is designed for no-tools replacement but just comes undone too easy. As far as I know TD has always designed their own machine. I have one of the old Stak Paks here at home. Bad thing about TD is parts for older machines are unavailable or insanely priced.

The lincoln machines like the Procut 55 are typical lincoln shoddy design inside. Wrong materials and fittings used internally for the air line make leaks common. Odd torch design is overly complex.

Most newer plasmas are designed to be drag cut under 35 amps or so. Only when you get to higher currents do you have to worry about double arcing whch will toast your tip. Most machine want about 5 to 6 CFM at about 90 PSI to the machine. The machine have a regulator that is adjusted to a specific pressure for the process with the gas flowing. Air plasma machines will run on nitrogen with a better cut quality and better tip life. Do not use oxygen with a plasma cutter not designed for it. Bad things will happen.

You can cut non-conductive materials with a plasma cutter, Lay a thing piece of sheet metal over what you want to cut. The resultant plasma stream will cut through most materials.

If you are cutting aluminum buy a bigger machine than what you thing you need. Aluminum cuts differently for two reasons. First is the thermal conductivity. Heat leaves the cut very fast compared to steel and stainless.

Second is there is no chemical reaction that occurs like when you cut steel or stainless. When you cut steel or stainless the iron and other elements combine with the O2 and N2 in the plasma stream and burn like cutting with a OxyFuel torch. With aluminum the reaction is minimal and the plasma just melts the metal and blows it away. Copper is similar in this aspect.

Did I leave anything out?

oldtiffie
05-26-2008, 11:34 AM
You can cut non-conductive materials with a plasma cutter, Lay a thing piece of sheet metal over what you want to cut. The resultant plasma stream will cut through most materials.

Well I'll be damned!!

Thanks heaps macona - that opens up a whole new world!! I will try it out - eventually!

Just what sort of non-conductive materials does that cover - and what thicknesses?

I had thought about cutting multiple layers of similar conductive materials with my plasma cutter but didn't try it as I just presumed that I'd get the same or similar effect as cutting laminated/multi-layered steel with an oxy/acet torch - ie not very successful at all. This is the effect used in steel safes to prevent or minimise cutting without an oxygen lance as the heat dissipates at the layer junctions - ie as for a heat-sink.

kvom
05-26-2008, 02:58 PM
For the size material you're going to be cutting you might look at http://www.parkermetalworking.com/. If you call and say that you're a member of pirate4x4.com you'll get a discount.

I will be buying one of their machines once my shop build is finished.

macona
05-26-2008, 04:51 PM
I would really recommend agianst buying that machine from Parker. Its the same Chinese machine as sold in ebay. Torch is a copy of a 20 year old ltec design.

Really the hypertherm 30 is the best machine for what the OP wants. It will cut to half inch if you take your time. Also they figured out how to get rid if that annoying sticky tip action that previous drag plasmas had. also the machine will run off of 120 or 240 so power is not an issue.

platypus2020
05-26-2008, 07:51 PM
I would really recommend agianst buying that machine from Parker. Its the same Chinese machine as sold in ebay. Torch is a copy of a 20 year old ltec design.

I have some pictures, I was asked to check out a 3-in-1 tig/stick/plasma cutter, from China, for a welding supplier, I plugged it in and turned it on, within 20 minutes, it had burst into flames, had to use an extinguisher to put it out, call the wholesaler and asked what to do with it, they said after 2 weeks of dead silence, throw it away, it wasn't worth paying the return freight.

jack

kvom
05-27-2008, 12:18 PM
All I can tell you is that the users on pirate4x4.com who have reported on this unit do a lot heavier work the OP is planning, and have mainly had good experience. In addition the warranty work is carried out in the US.

I suggest looking at the thread on Pirate before discounting it completely.

If budget is not an object then certainly the Lincoln and Hypertherm units should be considered.