Plasma!

[bradblazer]

At Welding Web there are a couple of importers, Everlast and Longevity, that regularly post specials. I am leaning pretty hard towards ordering the Longevity February special - 60 amp dual voltage plasma with consumable kit for $400 shipped.
weldingweb.com/showthread.php?t=49835

[Rich Waugh]

Brad,

I've had a Longevity TIG welder for about 3 years now and like it just fine. The first one I got was DOA but they replaced it without argument. It seems like a well-built unit though I did have to tighten up connections before I used it due to stuff getting rattled around in shipping so many times. No surprise there. I wish I'd waited a few months longer before I got mine, since they added the plasma feature to their TIG welder just after I got mine. I still don't have a plasma cutter, dammit. Someday.

I think you'll find that cutter to be a pretty good unit. Hard to beat it for that price. Get plenty of consumables when you buy the cutter because you'll screw up a few learning to use it properly I would guess. Never hurts to have them anyway, right?

Rich

[bradblazer]

Hey Rich,
Thanks for the Longevity review. Is your welder an AC model that will do aluminum? I seem to remember you posting about it but I can't find it.

The plasma cutter deal includes a 30 piece consumable kit. 13 each tips and electrodes plus 4 cups in addition to the few that are normally included. I'm hoping that will last a while because it's normally $170.

[Rich Waugh]

Brad,

Yeah, my TIG welder is an AC/DC unit and I do use it for welding aluminum, though I'm far better at welding steel, stainless, bronze and copper than I am at welding aluminum. The problem is definitely with me, not the welder.

That price combined with the free shipping (as far as Florida) and the consumables was just too good for me to pass up. I certainly think it should be possible to find an alternate source for the consumables, though. Once I get the machine in the shop I'll do some searching around on the 'net for a better deal on them - in the meantime I'll go through what they provide. My guess is that they make the bulk of their profit by selling the consumables rather than the machines. There just can't be much of a profit margin left when you sell them for $400.

Rich

[GuglioLS]

Nice find Brad.

My experience with plasma cutter consumables is the drier the compressed air the longer they last. So much so it might be worth the expense of a refrigerated air dryer. The long term cost of replacing nozzles alone will pay for the dryer, especially if using the cutter for many and long cuts. (hint - industrial use). The next consumable killer for nozzles and electrodes is touching the work piece during a cut or stray slag getting into the nozzle shorting out the nozzle. Once the nozzle is shorted by slag or touching the work piece the nozzle is trashed instantly. Looking at the pictures of the consumables it's a little hard to tell if the cups are the "contact" type meaning you can "drag" or allow the cup to touch the work while making a cut, although you don't have to (touch the work piece). Usually about 1/4" or so above the work is ideal and minimizes the possibility of slag shorting things out. The worst part of plasma cutting is the start of the cut as slag blows right back at the nozzle, kind of like blowing into a straw immersed into a narrow glass of chocolate milk. To minimize blow back start the plasma then plunge into the material.

On average you will go through many more nozzles than electrodes about 4 to 1 and cups are the least replaced consumable as they usually last a very long time.

Not so sure about a 60 amp cutter being "rated" for a 1" thick cut unless they are some new technology above the 60 amp Hypertherm I've been using, it barely cuts through 3/4" and you must travel very slow to do so.

I wonder if the 80 amp machine for 600 includes the free shipping?

Larry

[nuno]

Hey,

i have bought one last year on ebay, it is only an 40 Amp Cutter but it is good enough for 12mm, i try also to cut 15mm Steel but this needs a lot of time and i have to cut very slowly so i think it worths to have a few Amps of reserve for thicker Steel.

with my plasma cutter i have to touch the Workpiece to start the cutting arc and sometimes i wish i have one that doesn't need to touch the workpiece for contact but ok,
for the low price i have pay for the cutter i must make some compromises.

for consumables i have found on ebay a few seller that offer large sets of consumables with free shipping worldwide for only a few Bucks (as example,170 pieces for 44 USD for the 40 and 50 Amps Cutter)


Nuno

[Rich Waugh]

Larry,

The Longevity plasma cutter we're talking about (LP-60D) is not equipped with drag cups. They recommend 1/8" to 1/4" height above cut for the tip and it is a lift-arc type of start. Touch it to the work and the arc starts when you break contact. They also sell a "pilot arc" model for a couple hundred bucks more.

They don't rate the 60-amp cutter for more than 3/4" actual cutting - the 1" rating is for "severance" only. And that might be stretching it a bit, I'd guess. No amount of new technology is going to make a 60 amp machine cut thicker stuff, I don't think. Since my uses for it will primarily be much lighter gauge material in the .040" to 1/2" range, it should do fine for me. When I need to cut heavy plate (up to 4" thick), I use the oxy/propane or oxy/acetylene rig.

I'm getting the plasma cutter primarily for for some projects I have in mind for using salvaged compressed gas cylinders and scrap sheet or plate, stuff that is too big to fit through the band saw. I prefer the band saw when it will do the job, as the cut is very clean and I can maintain high accuracy with it, but my vertical saw is only a 14" and the horizontal is a 5x6 so I need a freehand rig for breaking stuff down. The plasma should be dandy for that.

I'd like to have a 100-amp Hyertherm with a machine torch driven by a plotter table, but it just ain't in the cards for this poor boy.

I sure do like the small size and light weight of the new inverter machines and being able to run it on 110 volts in a pinch is a plus, too.

The cutter comes with a little air regulator/filter nit but I'll be adding a good Parker or Norgren coalescing filter immediately, and possibly a drier someday. I'd like to have a drier for my spray painting and my big air hammer anyway, but so far I've been too cheap to drop four or five hundred bucks for one. One of these days though I'll have to do it - just too humid here a lot of the time, and as you note that raises hell with the consumables on the torch and tears up the air cylinder and valves on my power hammer. I just wish we didn't have to pay $0.75/kWh for electricity here - running a refrigerated drier could get spendy pretty damn quick.

Rich

[GuglioLS]

Rich,

$ 0.75 / KWH - OMG!! that's insane. At that rate you could afford to build your own personal nuclear power plant. At the least I would think Solar panels and an inverter would pay for itself in no time. Or pay some unemployed islanders to crank a generator. Even a gas powered generator has got to be cheaper than that criminal rate.

IMHO - If this cutter has no pilot arc or cannot cut expanded metal I would look for a cutter that does. Just my spoiled rotten privileged Hypertherm CNC plasma cam table operating opinion.

Keep in mind I have never hand held or hand cut a single piece of metal with a plasma cutter. All my "experience" is with pushing buttons on a robot then looking in amazement at the results. ;D


Larry

[Rich Waugh]

The local hospital has two big diesel power plants that they use for most of their power since it is cheaper to do that than to buy form the public utility. There's something wrong with that picture, I think. There are plans afoot to try to link us up with Puerto Rico for a small power grid, which might help marginally. Unfortunately, the government has, over the years, passed up several great chances to have alternative power sources. Stupid.

Just last year our senators in their wisdom, voted down a proposal to contract with a company that would supply power from burning trash and pet coke. They were okay with burning garbage but not with the pet coke. Again, really stupid. They could have gotten the pet coke almost for nothing - we have the largest refinery in the western hemisphere right here on the island and they have mountains of the stuff to get rid of. But narrow minds and suckers gullible enough to believe deliberate misinformation killed the pet coke deal. They seem to be determined to remain a third-world state.

When I build the new house it will be as much off-grid as I can afford to make it.

[bradblazer]

Well, I listened to Larry and ordered a 50 amp cutter with pilot arc instead. Not as good of a bargain as the 60D but I think I'll be happy with it. Maybe someday I'll get around to putting my scrap linear rails, ballscrews and Bosch tubing together into a cnc table.

Wow Rich, you do pay a lot for power! Way past break even for solar, etc. Our power is cheap enough that resistance heating is cheaper than the current propane prices. (I don't use propane but a friend at work mentioned it.)

[Rich Waugh]

Yep, they zing us pretty smartly for electricity down here - and it isn't all that dependable, either. My new house will be as off-grid as I can make it. Fortunately, we don't need heat for anything except hot water and cooking, and propane is fine for that. I don't feel much need for air conditioning, though Sally likes it in the bedroom during the hot months. Hard to avoid electricity for AC, unfortunately. Maybe I could put in a subterranean bedroom just for her...nah, probably not.

That 50 amp pilot arc cutter should do just fine for you. I'm cheap so the lift-arc will have to do me. I doubt I'll use it all that much, anyway. But better to have it and not need it than to need it and not have it, right? ;D

[Rich Waugh]

Well, today I finally hooked up the new 60-amp plasma cutter I ordered form Longevity. I wasn't expecting much, since it only cost $400 and even came with free shipping and a hefty batch of extra consumables. The thing really surprised me - it works just great and I think I'll get a fair bit of use out of it.

I looked it over petty thoroughly, both inside and out, and this is a well-made unit. Nothing sloppy or half-baked about it at all. A very solid unit that will operate on both 110v and 220v with, of course, reduced power when running on 110 volts. Still, it has a solid output and performs a bit above its stated ratings.

Now I just need to get busy o some of the projects I've been putting off because I didn't have a plasma cutter to do them. That excuse just won't fly now. (grin)

[GuglioLS]

Congratulation on the new plasma cutters there Brad and Rich.

Now that we've got a review on Rich's, I'd like to know a little more about Brads.
Have you tried it out yet? How's the pilot arc work for you? With a pilot arc you can zip right through expanded metal without skipping a beat, or if you pull the torch too far back during a cut you don't loose the plasma right away. Did you spring the extra $$$ for consumables kit? I think that model did not come with the bonus parts but did it come with free shipping?

Brad if you can make a CNC table with the parts you have that would be totally awesome. I suppose the biggest challenge in making one would be the software that runs it. I think it would need an interface that can read DXF files then convert that into X-Y cut paths and Z axis height control. If I ever build my dream shop / barn (it's getting closer to reality) I might just spring for a 4' X 8" Plasma Cam table to have as a hobby / small business when I retire. The Plasma Cam table that I used for all the grapple jaws and the likes is a 4' X 4', it does allot but so often customers want cuts that are longer than 4'. Once we had a order for an 8' x 3' ellipse, doable but time consuming moving the work then aligning perfectly to start the next series of cuts. Steel is heavy! 4X8 1/4" plate is nothing to sneeze at. One guy came in and ordered a 4X8X 1/2" thick sheet of armor plating (1 grand just for the steel plate). We cut it up into various little squares and rectangles for his gun club target practice, talk about heavy! Good thing they have a fork lift.

Anyway I'd like to know if you like the cutter.

Larry

[bradblazer]

Hi Larry! You know me - I need prompting sometimes. I hadn't even taken any pictures so I went out and took some tonight.
The cutter is good!
I got the ForceCut 50D HF Pilot Arc cutter with a 30 kit of consumables for $575.

It sounds like Rich got the better bargain.

At first I wasn't that impressed with the pilot arc - it would work to start the burn but go out when I crossed a gap. Yesterday I disconnected everything to re-do the plug and when I put it back together I noticed the pilot arc wire connector on the machine got hard to turn before the nut was tight. I got it all tightened up and the pilot arc now stays lit consistently.
Overall the quality of the machine seems quite good. The only thing I am a little concerned about is the stock power cord. It's only 14 gauge and this thing is rated to pull up to 31 amps. I was going to swap it out for a dryer cord but the job isn't quite trivial and the internal wiring past the switch doesn't look any heavier. My 80 amp inverter from Harbor Freight came with a 12gauge cord by comparison.

Here are a couple of test cut pics. One piece is from the end of an old bush hog blade about 7/16 thick. The other is a little piece of 3/4".The roughness of the cuts is mostly due to my lack of hand control. I used a guide on the 7/16 piece and cut the 3/4 piece freehand.



I have used it on a couple of mini projects - I cut some leaf springs up to make a blade for a manual sod cutter, even cutting the majority of the cutting edge bevel with the plasma. It didn't seem to affect the temper and it saved me a lot of grinding.


The other mini-project: I bought a weight distributing hitch at a great price www.pplmotorhomes.com/parts/rv-hitches/weight-distributing-hitches.htm but the trailer brackets were made to clamp on 3" trailer rails. My trailer is made with 5" channel so I had to scab in an extra 2". I cut the brackets and insert pieces with the plasma.

[bradblazer]

Here is some of the junk I have that might be useful in building a CNC plasma.

The pair of steppers with holding brakes came with a set of 8' Thompson rails and ballscrews. Are holding brakes useful for this? They prevent motion unless the motor is energized. I am thinking it would be best to drive both of the x-axis rails.

Here are some short, heavy THK style stages, some Thompson bearings, and a longer THK rail (about 6'). I don't know if I have a longer ballscrew for the y-axis. If not I could put together a linear timing belt drive. Those stages are attached to nominal 2x8x6' extrusions that might be ideal for a y-axis bridge.


Stash of Bosch extruded tubing.


That's most of the best stuff except for a couple of long THK rails I have buried in a corner..