Plasma THC

[coherent]

Well I've decided to dive into the plasma side of things and mount a plasma setup to my existing gantry style CNC router that uses Mach 2. I have ordered a Hypertherm cutter, Bob Campbell's torch height controller and a second parallel port. Also coming is a dryer, extra cartridges and extra consumables. Now that I'm broke, I'm trying to get a jump on setup issues. Will I need anything else switch, relay or cable wise? I know this is a fairly new THC setup, but has anyone already purchased his THC set up and running?... Any comments, problems, issues or future help (I already know I'll have questions!) would be greately appreciated. Thanks a bunch!
-marc

[coherent]

hmmm... no one? Well guess I'll be the first to try it out. Anyone able to help with a manual torch mount design and info on mounting the torch to a spring loaded setup with a micro switch to detect the metal height?
thanks!
-marc

[ger21]

Marc, you might want to check the Mach2 Yahoo groups for more info. There are a few plasma users there that could answer any questions you might have.

[jeffery71]

I've been using it for a few months now and am happy with it. Before I just had a "drag head" design. The THC sure is nice.
You will need a relay for your plasma torch to turn it on and off. I'm guessing you already have 2 parallel cables. You'll want to mount your torch on a "floating" head and will need a switch on the floating head. Some type of box to mount the control panel to the THC. Depending on what type of stuff you are going to be cutting you may want to check out Hypertherms "finecut" consumables. they are good for 10 gauge and thinner stock.
The THC kit is very complete and has pretty much every thing you will need in it.

Jeff T.

[coherent]

Thanks Gerry & Jeff. If anyone comes across plans or photos of a floating head design, please let me know. I have a plan in mind, but it would be nice to see others. Jeff, when I placed the order Bob Campbell told me they are now providing the THC300 in a case with new pannel for $25 more. I don't think he'd mind me posting a picture here...
-marc

[jeffery71]

If you look under the old Master5 Yahoo group, in the "Photo" section You will find a folder titled "THC Project" there are some pictures of a floating head that Tom C. uses. He is the one who originally started the Mach1 THC project. Basically it is just a linear slide mounted onto your z axis. Your torch will be attached to this slide... When the z axis goes down the torch will touch the table and will trigger a switch taht is also mounted on the Linear slide.. This will allow your machine to find the top (home) of the material no matter how warped it is.... If you use the M3 macro that Bob Campbell provides then at the start of each cut your z axis will "home". If you decide to go with a Cam package like SheetCam then you can specify how often you want the Z axis to "home".

One note Campbell uses the "digitize" input in Mach2 where Sheetcam uses the "home" input. same switch just differnt use in the mach2 software

Jeff T.

[coherent]

Jeff... so the digitize input is simply the THC300 script probe feature for a floating head? I guess this was used in the xml script instead of a home (I think it's pin 13 on port 1), so you could still use a Z "home" code for homing? I'm just finalizing my testing and connections and starting construction of my torch mount now. Thanks for the info on the photos from the old master5 site... I'm just trying to figure out the best torch mount to afford simple mount/removal of a hand torch. I did note a few others on some machines or kits offered at various web sites and every one is different.

One question for other plasma cnc'rs.. is it just a matter of trial and error finding the best voltage and cutting speed to minimize slag with a particular model/make cutter, or are there some general rules of thumb that help?
-marc

[jeffery71]

Yes the digitize input is for the floating head it uses a custom M3 Macro. You should still beable to use your switch as a home. You couldnt' use it as a limit ofcourse. I would recomend that you first use the THC just as it is.. Get use to it so you understand it. Then decide if you want to keep using it that way or if you feel there is a better way you could do it. I started using the THC just as it is then later I cutomized my Mach2 screen to my liking. I then decide to use Sheetcams post wich is specifically for THC.

Speed of cut is pretty much trial and error.. I know hypetherm has some charts that give the height of torch and cut speed. But they are just a ball park figure. Using a hypetherm 1000 torch with there "finecut" tips I cut 14 gauge around 60 ipm and about .1 height. I have cut it as fast as 80ipm but the cuts did not seam quite as good. On straight sections you should have little to no slag but on corners you will have slag. I've found what works best to remove it is a twist knot wire wheel in an angle grinder.


Jeff T.

[Txfatboy]

Marc I am also researching the idea of using the campbell THC
What driver are you using?
It seem to be the best for the money. I would like to see picttures of your table if available. thanks

[coherent]

Drop me an email and I'd be more than happy to answer any questions or send you some photo's. I'm using Mach 2 which is a necessity to drive the Campbell THC. I'm cutting metal, but still working out a few THC issue bugs as time permits.
-marc

[Txfatboy]

Marc. Sent you an email but havn't heard from you wondering if you got it thanks.