I just purchased a thc unit from http://campbelldesigns.com . I haven't received it yet but it should be here tomorrow. Has anyone used their thc? Any dos...donts...anyones experiance with it would be great!!
I just got mine running 2 weeks ago, and will be completed very soon.
I had problems with the torch diving into the metal and then moving through the part pattern without the OK signal from the signal board. Turns out I had the current correction too large at -1 and +1.
Don't expect any one of the three breakout board power supplies to power any fans or encoders. The board needs all that juice.
The arc ok signal light on the front panel of THC 300 must come on when you test fire the torch. My plasma machine is a Miller Cutmate 375, a fairly small sized cutter, so after wiring the current transformer (clear instruction are given for this)and threading it with a hot lead wire inside the plasma unit, I had nothing. After an e-mail to Bob, who has been very patient with me and my questions, he had me wrap the same lead wire through the transformer multiple times. He said some have to swap the resister depending on performance. i had to wrap the wire through 4 times for it to register the arc ok light.
Not THC related, but I thought it was for a few weeks! I got worried when the pierce height in Sheetcam was ignored when starting the plasma cut in Mach 3. That was a problem with some Sheetcam versions ignoring that number ( .5" in my case ). After I downloaded the newest version two weeks ago, it worked like a charm. It seems the bugs in the software are fixed very quickly.
Overall, this system of Sheetcam, Mach 3 and the Campbell THC is fantastic!!!! The test cuts I've done have exceeded my expectations. If you want to really appreciate the THC 300, watch a machine with a dragging height correction tool operate; smile, and enjoy the beauty of auto current correction.
how exactly does the unit work from start to finish?
does the torch touch the plate then raise to the pierce height?
does it have switches ,rods, etc. to 'feel' for the plate?
i am looking at this unit for my machine. http://www.dynatorch.com/avhtctrl.htm
i use flashcutcnc with my machine and i am totally please with it's
operation . i also use torchmate cam to generate my toolpaths.
it is a very good program and also has built-in nesting which is very
handy.
thanks in advance.
The basic operation of a Torch Height Control is that it reads the volatge of the cutting arc and then that voltage is divided down to a useable level.
So what happens then is that, same with welding. If for example the plasma torch or even mig/stick welder is say 5mm away from the steel you will get a voltage reading of say 100. Then if you move away say to 10mm, the voltage reading will be say 150.
So having said that you now know that at 100volts you will be 5mm away, and at 150 volts you will be at 10mm away.
Thus you set yout THC settings to say 143v and depending on the thickness of the steel, that voltage will keep the torch 1.5mm above the steel.
Then when the steel has a warp in it and the gap is bigger the voltage goes up to say 150, it will automatically correct it back down to 143v, thus maintaining a cutting distance of the required 1.5mm.
You might want to have a "floating head" or an "ohmic touch off head". This is for the Inital Height Sensing or IHS.
There is no way that you plasma table top is going to be dead flat all the way across and along. These IHS, will rapid to the start position/pierce position. Then slowly move down untill it hits the plate, re-set the counter/dro to 0.00mm, then move up the the pierce height, then pierce then down to the cut height and away you go.
just a quick not on that particular THC you are looking at. It states that it can only go down to 100V, To use Fine Cut consumables in Hyperhterm machines, they have to go down to 80v or so. Just check this first with them.
what is the speed of your THC mine seems to react alot floating up and down. I was wondering if the speed is to fast or how I slow the reaction time. any suggestions?
Andrew: I answered the question over on the CandCNCSupport list. The bouncing is caused by a input debounce (applies to all inputs including the THC inputs). solution is to reduce the debounce setting to 200 or less (which may cause noise to false trigger input swtiches) OR upgrade to the latest MACH3 development version which has the problem fixed and will allow you to continue to use large Input Debounce but it no longer effects the THC inputs.
THe THC Rate should not have a lot of effect on the oscillation problem. Debounce does.
MAS. The ATCH from Torchmate is a stand alone unit meaning it is totally independant from the toolpath control. Only the THC300 or it's big brother, the MP1000-THC integrated with MACH3 as the controller offers true interactive THC control. Whatever you buy make sure it supports a motion hold for Arc Good (aka Arc Xfer). It needs a programmed pierce cycle that is not just a set delay and offers programmable pierce height and initial cut heights as parameters.
Running the integrated THC under MACH3 affords you toolpath "intelligence" like Anti-Dive (on tight corvers) and pierce reaction delay to prevent head bounce on a pierce. Throw in SheetCAM (159.00) for your palsma CAM functions and you get advanced tool settings and auto lead-ins/outs along with the popular "touch-n-go" auto surface referencing based on distance moved.
In order to use the units we are talking about here with MACH you need to have a fully functional Z axis under control from the software. If you don't have that then you need to factor that cost into the mix. Even with that, your total cost to do a THC with the cost of MACH3 included should still be less than 1500.00 (considerably less if you have any of the components already)
The MP1000 has a series of adapter cards to allow direct plug-in interface to several other controllers and the Torchmate Boxes that use the parallel port as input is one.
THC300 and MP1000 are supported by the designers at CandCNCSUpport Yahoo Groups.
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THC 300 works great! 
parallel port break-out board 
