Looking into Plasma or Laser cutter for sheet metal

[NeoMoses]

I'm looking into putting together a plasma cutter or a laser cutter for cutting sheet metal, mostly steel. I could use any recommendations. Basically, I'm thinking I may be cutting up to 1/4" steel with this. I'm looking for something with less than 1/4" effective tool diameter, and something that will leave a relatively smooth edge finish.

Am I thinking along the right lines? Will a CNC plasma cutter do what I'm thinkining, or am I way off?

[Klox]

Plasma cutting is a more cost effective than laser cutting. Did you investigate the pros and cons of waterjet cutting (components cut this way are very smooth on the edges) also?
Why not go overboard and get a wire edm! LOL! Sorry couldn't help to pull your leg....

Klox

[NeoMoses]

I've just recently started looking around, and I see that the main advantages of lasers over plasma cutters are:
- less kerf width
- less bevel
However, lasers appear to be much more expensive, and it looks like a plasma cutter will work for most of my general projects.

From what I've seen, it looks like I can expect a kerf width of about 0.070" with a plasma cutter. Does that sound correct?

What kinds of feedspeeds could I expect with a plasma cutter in 1/8" or 1/4" steel? Just a ballpark figure would work here.

How important is the Z-axis in plasma cutting? I've heard that thinner workpieces distort more than thicker ones (that's reasonable...). I just saw a device that adjusted the Z-axis height according to arc voltage to keep a constant distance between the tip and the workpiece. How necessary/useful is this?

I haven't really looked into waterjet cutting. Is it economically comparable on a small-scale?

[Klox]

NeoMoses, i don't know how favourable waterjet cutting compares to plasma cutting but plasma cutting is about 80% cheaper than lasercutting.

Klox

[balsaman]

I look after 3, 1500 watt steel cutting lasers at work. They cost $$$$$$$$$ to maintain.

What a great job tho... Very cool.

Eric

[dave@eew]

I have in house oxy fuel, plasma, hi-def plasma, laser, and waterjet.
All can give you various cut quality by what you are willing to pay. The laser and the waterjet are by far the best for smooth cut edges with no clean up.
Drop a line if you want to discuss.

[toolmkrman]

I am building a plasma table. I am going to use a hand held plasma and mount it to my x,y table. You don't have to make the machine big or out of thick mat. I am using angle iron for the frame . as to the edge of the part it will do better thin mat. thick mat. gives more kerf and slage . The speed is good with plasma. 1/4 and 1/8 should work good on the plasma table.

[Johnuk]

Originally Posted by dave@eew I have in house oxy fuel, plasma, hi-def plasma, laser, and waterjet. All can give you various cut quality by what you are willing to pay. The laser and the waterjet are by far the best for smooth cut edges with no clean up. Drop a line if you want to discuss.

How much maintainance does the water table require compared to the laser?

I've been reading about lasers since I was about ten and I know that a lot of the newer industrial lasers are either diode pumped crystal or sealed CO2 that are designed to cut down the amount of external handling equipment they need.

But water jets seem to be something that needs a lot of care and attention to run safely. I was reading things about how the intensifiers need continual care to keep their seals and such running okay. Are the nozzles economically acceptable - I mean, what kind of usage can you get from them in relation to their cost? Water jet must at least be close to the cost of a laser right?

[dave@eew]

We use a recycler on our table so we do not have the need to clean the media out of the table. Depends on how much thick material we are cutting is how often we need to change out the slats. On the laser table we change out the slats about 3 times a year.
As far as the maint on the intensifiers, the key is to keep clean filtered water going into them and the seals last a long time.
Cost compared to the laser is a tossup. Some jobs we choose to run on the waterjet over the laser but only because we have a 4 head machine. That is the only reason we can beat the cost.
As far as the inital outlay of cash the waterjet is the least expensive.

[Ries]

You do realize the kind of money you are talking about here?
Plasma is the cheapest- a hobby level plasma setup like the torchmate or similar, in a 4'x4' is gonna run you around 10 grand or so, with plasma cutter. This is ok for short runs, as long as your time isnt too valuable, as there is a fair amount of fussing with one of these.
A commercial plasma setup, that can run all day every day, and take full 4'x8' sheets, from somebody like Koike, or C&G, is gonna start around $25,000 to $50,000.
There are some small, tabletop waterjet machines, like the one they have been using on American Choppers on TV, that are in the $60,000 to $100,000 range, but most usuable commercial waterjet machines are more like $125,000 to $200,000.
Lasers are more- They can be way more, depending on the bells and whistles- 4 and 5 axis machines, with auto sheet loaders and unloaders, can easily run a half a million.
Add to all of these, except the cheapest plasma machines, the cost of software- which can get pretty pricey with some of them. Often you will need 2 or 3 layers of software- Autocad, which aint cheep, then digitising software, then the machine software.
Dont forget about the cost of running these bad boys- consumables add up quick. The smallest, cheapest plasma machines use shop air, from an air compressor- but it needs to be filtered well for water- I use a motor guard filter, and change the paper filter pretty often. Even a small, home type plasma machine eats lots and lots of $10 tips and electrodes- I buy em by the dozen.
But when you get bigger, the costs go way up- Bigger plasmas sometimes like inert gas, and their consumables of course cost more. Waterjet uses abrasives, and though they get recycled, they seldom get used more than once. Lasers need gases, and expensive optics- I havent had to pay for that stuff myself, but I know it aint cheap.

Realistically, with a machine costing over a hundred grand, you gotta be running it on profitable jobs, hopefully 2 shifts a day, or overhead is gonna snap your rear end off.
My local waterjet shop just sold one of their machines- business has slowed down for them lately, and that $5000/month payment, plus the salary of the operator and consumable expense was just too much. And that was a medium size machine- a laser would probably have cost them twice that.

So while the idea of a laser no doubt appeals to most of us, the cold hard reality is that unless you are grossing a couple of million a year, you probably cant afford it.

[NeoMoses]

Very well put, Ries. While investigating these, I realized I couldn't justify one just for hobby use, and don't really have the time/desire to make it a business. Once again, reality rears its ugly head and bites us right in the... wallet.

[accuratemike]

Don't give up !
http://www.cnczone.com/forums/showthread.php?t=6923
Mike