Starting a new build, lots of questions!

[Crawler374]

Hey guys, I have the urge to build me a plasma. I'm really new to the plasma scene, and i'm hoping for a little help as i go with the build.

So, for starters, i want to make a 4'x8' table. I plan on making some bumpers, axle truss's, skid plates, and gussets for my future rock buggy, and my daily driver. So i think that a 8ft table would be long enough. I don't have anything planned right now, because i need to know a lot of questions.


First question, is would i need a water table? Or would just a fall through table be good? If i need a water table, why?

I plan on getting a normal plasma cutter and mounting the torch to the Z axis. But, how would i trigger the torch? Would i use the Z axis to pull the torch from the material and go back down to arc, and keep the torch on all the time?

What kind of stock steel do you think i should use? I was thinking some 2x4" for the main truss, and some tube for the gussets?

any specific gauge steel for the cross member supports? Why are most of them curved?


Thanks guys, i hope to start the build soon

-Eric

[cnc for hobby]

Hi Eric the torch turns on and off for each cut. Ive ran large plasma tables with preset programs in it and now im using turbocad,sheetcam with mach 3 controller. Sheetcam is the way to go!!!!! Im about to start my table and have some of the same questions you have! I know the lighter the better.
Best of luck James

[millman52]

Hi Eric the torch turns on and off for each cut. Ive ran large plasma tables with preset programs in it and now im using turbocad,sheetcam with mach 3 controller. Sheetcam is the way to go!!!!! Im about to start my table and have some of the same questions you have! I know the lighter the better.
Best of luck James

The lighter the better may be ok for your gantry as long as it's heavy enough not to flex.

The remainder of your table however needs to be robust enough to load materials onto without flexing or moving underneath the load you are placing on it.

The best way to begin a build is plenty of research. Most of your questions are answered on this board somewhere. I suggest you read all the plasma build logs as well as Router builds. You should be able to find plenty of pictures along with text that will explain about everything you need to know for the mechanical build part

[cnc for hobby]

You are correct millman52!! Your gantry can be lighter and as far as flex in it, it will help if the gantry is drove from both sides!!! Ive seen alot of info about timingbelt and pulleys but they didnt say what the pitch dia. of their spur gear was

[Weldtutor]

First question, is would i need a water table? Or would just a fall through table be good? If i need a water table, why?

any specific gauge steel for the cross member supports?

Why are most of them curved?

You will "need" a water table when plasma cutting to help catch the great amount of plasma dust that is generated.
The water acts as a collector & this reduces the metallic dust debris in the shop by about 90%.
Less warpage of the work piece usually results from the chill effect of the water.

For work support slats, (cross members) 10 or 12 gauge to 1/4" thick steel 2" wide is common.
Spacing, thickness & overall design of the support system could be determined partly by the material commonly being plasma cut.

Curving the support slats tends to prevent them from rocking or moving during cutting.
Another theory is that a curve in the support is less likely to have a cut path lined up with the slat.

[Pandinus]

If you already have your plasma torch, and its a "less expensive" brand that requires you to touch the metal and pull away to start to start the ark, thin its not a CNC friendly unit.
I'm not saying it can't be done, but it will not be as easy as attaching a start relay.

If you don't have one yet, at least look at a Hypertherm. I have a Powermax45 and it is an awesome unit. I am in the process of making a THC circuit for it right now..... and it actually moves... but I have some Mach3 issues to look into at the moment.