I need to build a rather large cnc plasma table....in the 12x20+' range. Bigger the better right. I haven't found anything like what we need yet. We have a hypertherm plasma that will cut 4" and want a machine that will cut anything we throw at it. . I have the resources to build the table and I would rather just buy the bridge/gantry (I guess thats what its called) and all the drive motors and controls. Basically al we want to do is build the table and mount the rest and go. A couple of years ago I saw a company that sold just the bridge and you built your own table as well as customer supplied plasma and PC. Does anyone know of a company that sells the component like this?

Not for a 12' to 14' bridge. That takes it pretty much outside the realm of the Homeshop/SmallShop world. Even using conventional electronics and controls will be a challenge with a plasma unit that cuts 4" steel. Just the noise impulse from the HF start at 300A is enough to stop pacemakers and kill small animals! You will have to make sure your electronics are noise "hardened". It's not easy to build a system with controls in a factory with the ability to test and find RFI and EMI problems. It's even harder to build one from generic controls in the field and without access to engineers and expensive test equipment.

We supply electronics packages for plazma and router tables and the size of the table is not so much the issue, but I have enough experience with trying to make PC based electronics work with big nasty, noise generating industrial plasmas to understand why the commercial tables charge 10X over the light industrial and home shop units. It can take hundreds of man hours finding and fixing EMI and RFI based noise problems. Often it takes innovative cabinetry (metal equipment enclosures) and other tricks to just keep the pierce cycle from killing the PC and low level control electronics!

I would not advise an amateur built table for this application. It would be like building a B52 bomber from lawnmower parts.


tomCAUDLE
www.CandCNC.com
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I see your point. Is it possible to be able to use say....5x12 table and cut a 5x20' peice.....meaning to stop the cut and move the material and the machine takes off where it stopped? I read the plasma cam has this feature...I'm sure others have it as well. We can use a 10' wide as long as we can move the material and take off where the cut stopped. The plasma cam was the first one I came across and seems to have the features I want but its not near "industrial" enough.

Once again. The length of a table is of less concern than finding control electronics that will survive in the harsh environment with the HF plasma unit you use. A piece can be indexed to cut but it's more about the CAM software than the table. If you do an online cut (no offset) you can stop it and then join up a second continuing cut. It would need to be laid out that way in the cut program.

You are looking at $10,000 machines and trying to make them equal to machines that cost well into six figures by just stretching them a little. If you were cutting thin material (1/4" or less) with a smaller contact start plasma (like the Hyperthem 1000 - 1650 or TD81 - TD 151) then it just boils down to the physics of moving the added mass of a wider gantry. Like a bridge, the farther the span, the more rigid and the more mass you need to prevent bowing. The table length can be 50' if you want it. It's about the noise and HF start of that huge plasma and your desire to be able to cut anything you throw at it.

You need to talk with a few users of PlasmaCAM that actually do the indexing and see how painless it really is.

It also requires accurate table stops and guides and a lot of operator patience.

If you read their marketing material PlasmaCam has everything you will ever need/want.(wedge) Just be aware that that is a completely closed system and all support and repair parts will have to come from them.

Tom Caudle
www.CandCNC.com

I totaly agree with you about closed systems. I do not want proprietory parts. After reading this forum and researching the different companys I have decided its more cost effective to buy one already built...either completly assembled or in kit form. Its not that we "Have to have" a larger table but there have been times when we have cut 20'+ sheets of plate. Very seldom do we cut a 4" peice but it would be nice to be able to do it on a cnc plasma. And its not a full sheet of 4" plate its smaller peices like 2'x2' or so. I think I can get by with a 10x table as long as the software allows the plate to be moved and start where it left off.

Now the software on the other hand "Has to be" as easy to use as possible. IMO Plasmacams marketing for their machines make it look "easy" but I dont know if thats the case for open system software.

I was wrong about our plasma machine being a hypertherm. Its a Thermal Dynamics PAK 44G, 400 amp. Since we have owned the machine its only been used a couple of times and I'm not even sure if I want to use it for this application so buying a newer plasma machine better suited for this is an option. And more than likely will buy one due to parts availabilty on that machine. (so I have been told)

I am looking at Torchmate, ez-router and one more.(can't think of the name right off hand) Anyone with more info or recommendations PLEASE feel free to share it.

multicam will make plasmas up to 20' X 100'

We run a 4'x8' torchmate. Torchhead is right, indexing can be done if you have a good set of stops, and a very patient operator. We can hold our parts to +/- .06 when we index.