Newbie looking to buy plasma table...Which one

[3DSteve]

Hi all,
I am completely new to CNC and Plasma Tables and I have been assigned the task of choosing a plasma table for our prototype department. The boss said he would like to spend between 15,000 and 20,000 USD on a 4 x 8 system (possibly a plasma/router combo) He had done a little research and found a couple systems that he thinks would fit our needs. We will be cutting mainly mild steel up to 1” thick. An Oxy Fuel attachment would enable us to cut thicker if necessary. The machines that he had found are from DynaCNC, Dynatorch, Torchmate, Practicalcnc, Plasmacam and Samson.

I guess what I am asking of the group is to please give me your comments on any or all of the aforementioned brands, and some things to look for and to lookout for when purchasing a system.

Some other questions are?

1: We do our design in Solidworks and export to dxf’s for our vendors.
What is the software that we will want for nesting and tool path creation or other? (Remember Newbie)
2: Servo or Stepper motors?
3: Ball screw or rack and pinion, single or dual?
4: Torch Height Control?
5: Are there any “must have” items I should know about.

That’s it for now, I’m sure I will have a million questions to come.

Thanks
Steve

[millman52]

Dynatorch & Torchmate both have nesting software as well as CAD/CAM in some of their offerings. I can't speak good or ill of any you have listed above as I have no experience with them. Pros & cons for stepper vs. servo just have to read about both & decide for yourself there. Rack & pinion most definitely . I think a THC will be a must with plasma.

[3DSteve]

What is your experience with? I dont have to chose from the machines listed by any means.

[Eric B.]

Unless you have a year (or more )of time to kill, trying to get the new machine running, DON'T, repeat, DON'T buy a Practical CNC!! If you go to their website, you'll see lot's of "hype", but don't believe it. PlasmaCam is another "iffy" proposition. Surf around on this and other plasma cutting sites, you'll get a lot of great info from different people about the systems they own and make their money with!

[Torchhead]

1. Solidworks for shape cutting is way too much tool for a simple job
2. Steppers work fine for plasma and oxy and have fewer moving parts. Servos are faster with more torque but make sure they have differential drives for noise reduction on the encoders. Work with a vendoe that will give you a choice of either and tell you the pro's and con's of each.
3. Avoid ballscrew in plasma. Way too dirty an environment and lead whip on 8 ft ballscrews will limit rapids to well below the 300 IPM target speeds.
4. THC is essential for production cutting. You are skimming above the surface at 100+ IPM with a gap of .060 or less. Metal warps up and down while being cut. Let the tip touch the metal and your consummable life drops drastically. Consummables account for a major part of the cutting cost.
5. Try to pick a system that lets you pick and choose the three basic parts of CNC: CAD, CAM, Control. If you get boxed into a solution that makes you use their entire system (aka PlasmaCAM) or uses special hardware you cannot source or replace yourself then your flexibility and options are limited.

Look past next week and into the future and determine if your needs change you won't get stuck with a machine you can't upgrade or get parts for.

One thing that gets glossed over is the control electronics and the quality of the power controller, interfaces and wiring. One vendor (already mentioned by Eric B) builds a controller that resembles an IED. Case is cut on plasma, bent up and wires are all wrapped and soldered in a giant tangled bundle. What you can't see CAN hurt you!

Nesting is over hyped. Most programs nest the drawing (DXF) and make the CAM process more involved. Some do a fair job but unless this is something you do on a daily basis the increased cost and manual cleanup aren't worth it. Most of the programs get you close but you still have to check them and make edits. Really good prograrms are really expensive.

Check SheetCAM for plasma and shape cutting. www.sheetcam.com. It does not have auto nesting but does support part duplications, Arrays, and on-screen placement.

tomCAUDLE
www.CandCNC.com
BOB's
Digital THC
Complete Electronic Packages
Stepper & Servo Systems
Hand Controllers

[Scratch]

I have a Practical table, and although I have had no problems with mine yet, and was cutting the same day I got it home... I would still probably buy a DynaCNC table if lightning struck and I had to buy another one. I played with a friends and I like the way it operates a little better than mine. It's not a huge deal for me, but it does have some nicer touches than the Practical. It is also more expensive so I guess you get what you pay for.

[Graybeard]

I agree with Eric. Neve, ever, consider getting a PracticalCNC machine. The machine sucks, support sucks and the warranty is worthless. I know from my very bad experience with Practical. Nothing worked right until I finally got another company to help me; I got good help from CandCNC (Torchhead). Tom knows what he is doing.

[DISCONNECTED]

3dsteve,
Also check out TRACKERCNC.I never once heard anything bad about a tracker.If you can see someones machine before you buy it ,do it.I own a DYNACNC 4x8 plasma table for 5 months now,no major complaints.The only thing that I question is the 80/20 construction over time.Any comments on 80/20?anyone....

[Torchhead]

I have an 8020 machine I built myself over 5 years ago and it has been used for production cutting. It has lots of scrapes and scratches but it is solid. I built my newer 3 X 3 router from 8020 and it's as solid as a rock. Of you don't think aluminum is strong enough to handle the stress better not plan on flying commercial airliners!

[Scott V]

Originally Posted by Graybeard I agree with Eric. Neve, ever, consider getting a PracticalCNC machine. The machine sucks, support sucks and the warranty is worthless. I know from my very bad experience with Practical. Nothing worked right until I finally got another company to help me; I got good help from CandCNC (Torchhead). Tom knows what he is doing.

I could not of said it better myself!!! The Practical table will work just fine if you add all of Tom's stuff to it. (plasma only with my style of rails/racks)

My advice is to go look at a few tables running before plunking down the money. You will get a good feel of the quality of the table and the software. See if somebody is close by with a table you might be interested in. Buy a plane ticket if necessary.

Scott