Homebuilt plasma cutter?

How practical would it be to build a plasma cutter? I have a compressor, and 70 amp buzz box that I haven't used since I got my
mig. I am skilled in electronics, so building a rectifier / hf circuit won't be a problem.
Could I make electrodes for this? (I have limited machining capabilities) or should I buy electrodes for a brandname torch? Or even a complete torch assembly?
I probably won't be cutting anything over 1/4 inch.
Thanks in advance.
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On Sun, 10 Sep 2006 12:07:07 -0500, "Christopher"

oh oh........
Gunner, ducking for cover and doning his Nomex...
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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The answers are yes, no, definitely, and maybe.
I will be purchasing a PlasmaCam system within one year. A turnkey deal. It will be a daunting task to get it running and keep it running. But, it's like a car. It isn't worth anything if it doesn't run every time you want to start it up.
I belong to a Yahoo group on plasmacutting. In there, it has been stated that one can build a plasma cutting table with servos, etc, for about $3,000. Then you still have to buy the plasma cutter. Then the computer. And all the wires and connectors to make it all work.
If you have nothing but time and money, you can build one yourself. Question is, do you want to spend that much time doing all that, or do you want to just plug it in and start ringing the cash register? It is the same with welding machines. You get what you pay for, and if you want to go out and start making money tomorrow, you don't want something that you have to doink with every other hour. You get in more productive hours in a day.
Now, if this is just a hobby, and like model rockets or RC planes, you want to putter and build the stuff, go ahead. A setup will cost you in the range of $5k versus $15k for a turnkey plug and go version. Just know that you will have hundreds and hundreds of hours in labor, and if you multiply that by whatever you charge, that is what the system cost you regardless of the actual amount of cash you had to outlay. And, if you do your own, you have very little tech support, so have to troubleshoot everything yourself.
Depends on what you need as to what you do. Don't know about you, but I got lots of things to do, and don't particularly like having to stop and work on equipment.
HTH
Steve
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Steve B wrote:

You seem to be confusing a plasma cutter (manual) with a CNC plasma cutting table system, a completely different thing.
As for the OP's question about building your own plasma cutter, it's pretty impractical. Most of the "magic" is in the torch itself and you're unlikely to have the skill or facilities to build a torch yourself that will give any cut quality of consumable life. So you start with a commercial plasma cutter torch for $400 or so and try to focus on building the power supply.
The air solenoid valve timing, current control, etc. are all pretty picky so in trying to get those right you blow through a bunch of consumables and test scrap metal trying to get it right, if you are lucky enough to not damage the torch itself in the process.
The materials to build a 300VDC 5kW+ microprocessor controlled inverter power supply capable of running the torch properly are not going to be cheap even if you are good at scrounging. Air regulator, solenoid valve, pressure sensor, etc. cost $ as well. You'll note there is no HF here as most commercial units don't use HF starting anymore.
The time to build, test, troubleshoot, test some more, replace more damaged consumables, etc. until you get it working half as well as a complete commercial unit is going to equal the cost of just buying a commercial unit to begin with. You're better off just saving some money and buying a good commercial unit, which generally excludes the China import units.
Pete C.
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What he said. Which I thought was what I said, but apparently was mistaken.
Steve
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Steve B wrote:

The key difference between building a plasma cutter, and building a CNC table that can be fitted with a plasma cutter (or router, etc.) is in the availability of parts and modules and even kits to allow it to be largely an assembly project.
Outside of commercial replacement torches for commercial plasma cutters there are no parts, modules or kits available for construction of a plasma cutter.
For a CNC table there are numerous resources available which make construction of a CNC table a very practical option and one that can provide results / performance on par with any of the low-mid priced commercial units.
Items readily available include:
PC based CNC software (Mach3, EMC/EMC2, etc.) Stepper and servo drives (Gecko, Xylotex, HobbyCNC, etc.) Torch height controls (Campbell / Soundlogic and others) Stepper and servo motors and encoders (numerous sources) Linear rails, guide bearings, ACME screws, ball screws, timing belts, rack and pinion, etc. (numerous sources) Framing components such as Unistrut, Powerstrut, 80/20, etc.
There are also many plans and even some kits available.
With these resources, building a CNC table is a quite reasonable project for a month of weekends if you're handy and can save thousands of dollars compared to a "turnkey" commercial unit which you'd use with the exact same commercial plasma cutter.
Saving $5k-$10 in startup costs in exchange for a month of weekends is a very good option for people who already have a reasonably equipped shop to begin with. Those who don't may be better served with a commercial CNC table.
Even so you will find the need to eventually equip the rest of the shop to provide for the tasks related to CNC table offerings. You may start a business producing signs and lawn art with just a CNC plasma table, but in short order you will find the need for a welder, grinder, buffer, benders, ring rollers, shears, etc. to produce more finished pieces.
Pete C.
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plasma cutting requires voltages considerably higher than what a buzzbox can make. so you need a different transformer. There is a mailing list devoted to homemade plasmacutting.
http://groups.yahoo.com/group/ohpc /
i

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forgot to say. The materials required to build your own plasma cutter (if you include all terminals, connectors, doodads, switches, etc) is likely to cost as much as a decent used machine. Even if you are good at scrounging.
If you are smart enough to do it on your own, then you probably make decent money, and are a self starter, and thus taking time away from more profitable pursuits to make one, means that you forgo more profitable opportunities (in other words, your time is expensive).
So, a home made plasma cutter may be fun to build, but it would not be a bargain.
i
On Mon, 11 Sep 2006 01:08:40 GMT, Ignoramus27704

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iggy, you're a jewel. You nailed it.
Steve
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Steve, I feel that I do not deserve your compliment, but I am glad that we agree!
i
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That's great (the former part).

A good o/a set (well made professional set etc) you can scrounge for perhaps $50 or less.
i
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snip

A new set of Victor torches can be had for $150, used ones for well less. (My last set of Harris torches were free, the owner wanted to get the battered set off the premises so no one could use them)
But then you have to deal with getting a set of tanks that runs on the order of $300 or more (or try for some "owned" tanks and have to deal with a fairly large set of hassles. )
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I, for one am glad to see "a fairly large set of hassles" about "owned" tanks. Putting serial numbers on things, having to verify ownership, and being able to track goods through serial numbers has its advantages for "honest" men.
Steve
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