Plasma CNC for Sign Making

[Robin3295]

Hi,

I'm new to this site. I have searched for similar threads but have found none.

My question is this - I make signs the traditional way - vinyl cut, printing, etc. I am interested in using a plasma CNC machine to produce metal signage and as a spin off, other custom metal projects - whatever they want. I am an advanced CorelDraw/graphics software user. Has anyone done this and what machine would you consider? I like the idea of a machine (like the Torchmate) that can have multiple roles - plasma, wood/acrylic router, etc. The Tracker seems like a great machine as well but the company does not sell/support alternative attachments.

Any thoughts?

Thanks.

[Torchhead]

Go to www.FourhillsDesigns.com. (my commercial steel and glass site) All of that art, most of it decorative signage, starts out with CorelDraw CDR files, gets processed by our DXFTool and imported into SheetCAM. Same basic files can be used for plasma or router but the CAM process is different. Plasma is not as simple as just putting a shape file on the table and making a cut. There are a lot of variables in plasma you don't have in routing. Pierce height, pierce delay, cut height, lead-ins/outs, kerf offset, clean compressed air, correct tip, correct cut gap, etc. Unlike wood or plastic, Metal moves up and down (sometimes a LOT) as it's heated from the cutting process. From experience I can tell you that trying to do decorative cutting with a plasma that does not have Automatic Torch Height Control is a frustrating and expensive process. You will go through consummables like they are free (they aren't).

The Torchmate system uses proprietary hardware (Flashcut) which only works with their control software. You will need to buy their THC solution.

We also have the vinyl cutters, wood router and desktop engraver and there is a market for shops that can do all of the aspects of signs and decorative accessories.

Don't let someone sell you something that won't work with Corel (i.e BobCAD) or some nesting solution. You don't need either.

If your intent is to have mulituse table, you need to buy for both purposes. The table needs good speed and acceleration for plasma. Ususally plasma gantry's are lighter and not as rigid because it's non-contact cutting with no cutting forces. For routing of wood, plastics and light aluminum you need a bigger gantry to carry the added spindle weight and to handle the cutting forces involved. That means you would normally gear the table differently and trade high speed for more torque to move the heavier gantry.

Typical plasma cuts are done from 80 to 280 IPM. Wood and plastic is cut (with conventional routers) at 15 to 60 IPM. Signfoam is cut at higher rates but you need better accuracy.

With a combo table you need both speed with acceleration AND torque and precision with a heavy gantry. Also understand that plasma cutting is a VERY nasty, smokey and messy process and you need things like a water table and/or heavy downdraft dust extraction system, where as routers need more focused dust extraction close to the cutter. If you are in the same building as your business the plasma needs to have it's own sealed room.

I don't like any direct coupled rack and pinion drive system. Without some form of gear or belt reduction, you have speeds you can't use and a lack of torque you do need. Most rack & pinion has about a 3:1 speed increase with a corresponding torque decrease and the resoltuion (smallest incremental distance you can move the machine) is low. Since most steppers can spin 600 to 700 RPM when driven properly and 3:1 step up results in potential rapids of 2100 IPM...... way too fast for most machines. So all the speed you can't use (anything over about 400 to 500 IPM) is just wasted. Some just oversize the motors like crazy and call it good. Consider also your resolution is at something like .0152. Microstepping can help with resolution but cannot be counted on for accuracy (totally different thing than raw resolution). A 4:1 belt reduction can result in 4X the torque, 4X the resolution and 1/4 the speeds.

Do some research. You are welcome to join my CandCNCSupport Yahoo group and there are free decorative CDR's there in the files section. You can get a free 30day trial of our DXFTool for CorelDraw and a free demo of SheetCAM. Understand the technical aspects of plasma cutting BEFORE you write a check.

Tom Caudle
www.CandCNC.com

[Robin3295]

Hi Torchhead,

Excellent info in your post. Thank you!

My biggest concern is making sure that there is the business to justify the investment - a little market research will rectify that. Although the plasma cutter would be relatively dirty (compared to a vinyl cutter) I do like the fact that it will diversify our business.

The direct drive vs belt/gear reduction is an interesting point. It seems to me that no one cnc system offers the best of all aspects - always seems to be a trade-off of some sort.

I like the idea of some sort of machine to run a router - getting tired of custom cuts by hand. Will have to do some research on that as well.

I will join CandCNCSupport Yahoo group. Thanks.

Tim

[ewest]

Hey Tim,

I'll tell you from experience...
We bought a "Practical CNC" - 5 x 10 plasma / router. It looked like it would work great, but unfortunately, we were mistaken. I know it's not polite to bad-mouth Practical CNC, but we really wish we got a chance to take a good look at the machine and run one before we invested. There are a lot of corners cut that make their stuff completely unsuitable for any important work. The cabling is cheap, the servos badly tuned, the NON HELICAL rack and pinion gear train FILLS with dust, the limit switches look like the optical sensors they use in cheap computer mice, there IS no limit switch on the Z, and if an axis errors out, the other two keep going, further destroying your work piece. The encoders on the servos are cheap US digital units, and completely unprotected from dust and garbage, not to mention spec'd out with WAY too few counts-per-revolution. The router mounts also require machining to make them properly fit the specified porter cable router. As far as plasma goes, their control doesn't work with anything but the plasma cutter they spec (a hypertherm I think?) and even then, its poorly executed in hardware. Also, the software.... You have to edit the configuration text file in Notepad to change the pierce time (as in any time you cut a different thickness material)

Also, the change over time from plasma to router is about 2 hours, and then, since you've been dropping metal sheet on the table, it tends to go out of level, so you have to spend another hour squaring the machine back up before you can cut anything important.

It's also an incredible pain in the ass to clamp stuff to.

And now about plasma..
It's a horribly filthy process, producing a cloud of noxious orange smoke when it's really "in the zone" and cutting well in mild steel. The evil slag dust gets everywhere. This is DEFINITELY not a machine that can share a space with any thing else aside from maybe an angle grinder and a hammer. Plasma is filthy and evil, but it's a great thing to have in your metal fabrication shop.

My advice to you: Get a CNC router and forget the plasma end of it. There's gotta be a shop in your area that can do plasma cutting. As long as you can give them a DXF file, they shouldn't complain. And as a plus... if they screw up a $200 sheet of steel or aluminum, it's their problem, not yours... and the edge on a plasma cut sheet, especially when you get in to thicker materials, isn't quite as pretty as you'd expect, so it's going to require more finish work.

Just my $0.02

Andy B

[Scratch]

Yeah there's alot of dust, and some smoke... but I'm assuming you're prepared for that, or least expecting it. It does take some time to swap from Plasma cutting to routering, stuff like sweeping, and changing heads, but it's not that bad. And you're gonna have that problem no matter what table you get if you go with a dual purpose table, but I think the pros of having a dual purpose table outweigh the cons. They work great for making signs like this 30" wide sign:



By the way... I have a Practical table and haven't had any of those problems. I also use a Thermal Dynamics torch, even though they did reccomend a Hypertherm, (I'm guessing because they are a Hyperthrem dealer) I did have one change in the configuration when I first started which they told me I would need if using a TD. I've never gone back into the settings again.
I brought it home, squared it up, and never had a problem.

But like you said, no table is perfect. Make a list of what each company offers for specs and figure out which one will work best for you.

I'm glad I got into the CNC business, I make mostly steel signs and artwork.

[massajamesb]

The dust and smoke is a deal killer for some. The only way I have heard of reducing/removing smoke is either a water tray or a very large dust collection unit. I suppose if you had two cutting tables, one with metal suspended over/in a water table, and another table for wood only, then you could get by with a "dual purpose" machine. You would have to design the cutting rail system to be mobile, and move over each separate cutting bed.
Although that would entail you building most of the machine, and I don't know of any manufacturer that would sell something like that....
or you could try your hand at a very big and nice dust extraction unit. I would be concerned about how long any fans or vaccuum units would last, as the plasma dust is pretty abrasive. That is the situation you are in. The tool change over sucks at the very least, but it is not half the problem that the resulting mess is. Wood dust + plasma sparks = bad (where I come from).

I would say that there are a number of choices out there for a decent plasma table, including building your own, though this is not for everyone.
Torchmate, Trackercnc,Dynacnc,Dynatorch,EZrouter,Practical all make a machine, I would search the threads on this site for feedback, good and bad, about each. There are a number of other machines out there in the "small industrial" size, but don't crucify me for not thinking of them offhand

Now, as far as cut quality, most signs I have seen are no thicker than 11 ga, if that. I doubt that you will see any poor quality edges or cuts on metal that thickness or thinner. I have some 3/16 tabs I cut, right next to some 3/16 tabs cut with a laser. The cut quality is negligible.

[Robin3295]

Andy, thanks for the reply. I had to chuckle when reading your post - sorry. Sounds like everything that could go wrong did. Everyone will have a different opinion/experience. Your's seems to be on the far end of not so good. Good to hear all.

Scratch - that is one very cool sign. That is what I'm interested in. I am assuming it's metal. How did you mount the letters? Is it possible to control head speed - ie slower for wood? This seems to be an issue that I keep hearing.

massajamesb - good info, thanks. Good to know that the edges are relatively clean on lighter gauge - I was concerned about that. I am prepared to build the necessary environment for the cutter, especially an effective smoke extraction unit, etc. But I'm not reeeeealy prepared to build two tables - although in a perfect world that would be nice.

I am impressed with the Tracker system - and they good reviews for their support and they're not to far from me. Have a bunch of promo material from a number of manuf. arriving this week.

Appreciate everyone's input.

Tim

[Scratch]

Yes it's all mild steel. Each letter and the "swoosh" has one or more bolts welded to the back, then a couple of nuts screwed on for spacing it away from the back oval, and then holes were drilled through the back oval to get a nut on.
Speed on all 3 axis is controlable with whatever table you get.