I wrote the original setup guide for the THC300. I worked with Art to get the THC logic into the core of MACH. I did the same with Les at SheetCAM to add plasma features The THC300 uses a 2nd parallel port card. With a single parallel port you have a total of four open inputs (after the required e-stop). You need three for MACH THC. Leaves you with one input for everything else. You gotta have at least one input for the IHS (touch-off). You can run a table without Homes or other inputs but it sure limits the functionality.
The thread is about DIY THC. I think I am qualified to discuss that since it's my original design that is the subject of discussion. You are one of the very few that ever built one completely and made it work. I ran my original design for over a year doing commercial cutting with a ragged old Miller 500 HF start POS.
I learned that most builders would rather spend their learning curve solving problems with the motion components and software than stick build the electronics.
Thanks for the information guys!
Here`s the deal. 3 years ago I built a Solsylva cnc router, but after I was finished with that one I didn`t get the time to use it. I only hocked it up with my Laptop and run a couple of g-codes to test.
Today I want to use my Solsylva machine as a cnc plasma cutter. I have a Cut 40 plasma cutter in my shop. But after reading about this cutter on this forum, I understood that I have to buy a better cutter (Hypertherm or similar). But for this I also need a THC system. In the start I considered building one my self. But I realized that I don`t know enough about this subject, so I changed my mind pretty fast.
Later I will build a bigger cnc plasma cutter (minimum 5x10 feet), so I think the best thing for me is to buy a MP3000-DTHC system now. Then I can use it on my Solsylva until I have completed the build of the bigger cnc table. To control my Solsylva I now have a Xylotex kit with 269oz Stepper motors. Can I connect these motors directly to the MP3000-DTHC system? What do you guys think, should I do something else or...?
You can use the Xylotex but you need to be aware that you MAY face noise issues. The Xylotex inputs are not isolated from the Motor DC (power supply) and if it's grounded to the same ground as the table/plasma some of the nasty cutting noise can find is way back into the step & dir logic signals.
The MP3000-DTHC comes with an external card that has several forms of connections to motor drives. One of them is a 26 pin header, that coupled with a IDC to DB25 pin adapter cable (free if you ask for it), will allow you to directly connect to the DB25 input on the Xylotex 3525 card. It will also front end the Gecko 540 unit as well. It just passes through the step & dir signals on the right pins. All of the I/O goes through the UBOB directly, including the THC signals to MACH.
The MP3000-DTHC is not a motor driver and power supply. We do have a series of units that are a complete system including Gecko drives and power supply and hign torque (620 oz-in) steppers. It is basically an MP3000-DTHC + 4 axis of drivers + 4 motors + cables, connectors and support CD.
If your plasma cutter is either HF start (will start in the air) or internal blow-back contact start (like the Hypertherm or TD and newer ESAB units) then you can make it work with our electronics. If the unit has to be down against the metal to start an arc then you won't be able to use it for CNC cutting.
The IHS (touch-off) feature is very important to get the correct pierce height (usually about 2X the cut height). The easiest way is to have a "floating torch holder" that allows you to use software (automatic) to go down and "feel" for the top of the material before a pierce. Material being cut with plasma tends to warp from heat and stress relief so the surface changes. While the THC will track surface changes as it cuts it cannot predict where the surface is at the next pierce point. You have to re-establish Z zero. There are several sources for ready made Floating Torch Holders or you can make your own with a short slide and microswitch.
I do appreciate your contributions, both to this forum and the CNC community as a whole. I couldn't have built my THC without your old schematic. I've made many changes to your design, but it's still yours and I've given you credit every time I've made a post about it. You are more qualified than anyone to discuss this subject, but more often than not you are plugging your products rather than giving real tech advice. Go back and read your posts in this thread, the first two which I was commenting on yesterday are flat out advertisement for your products, with no technical advice for building a THC. Your only advice was basically don't do it, which in some cases is very good advice, but not fitting the topic of discussion. I understand you are in business to make money and not spend hours answering questions for free, but it often seems like your posts are nothing more than free advertising. Or maybe you are a $$$upporting Member of CNCzone, and I should stand down or be banned.
Not everyone builds their own stuff just to save money. I've completed many projects that took more time and money than what an off-the-shelf product would cost. Some guys still take pride in building things themselves and knowing they can fix it when it breaks. That said, I don't think I have more than $20-30 in my THC. It did take hours of learning and troubleshooting, and I'll be the first to admit it doesn't work as well as a superduper3000, but I wouldn't have it any other way. If I ever need another one I will strongly consider buying one, but I'm glad I built this one.
My machine is running a single parallel port and I don't think it's functionality is limited at all. It has homes and limits on all axis, Mach controlled THC with IHS. I used one input for homing on all axis, and the only limitation is that each axis must home and park one at a time. What am I missing? I'll have to dig out my notes to remember what I did.
I just want to add one more thing. The learning curve for building and operating one of these machines is huge, especially if you're like me and have never operated a CNC machine. It's so huge that adding a home-built THC is like a drop in the bucket. In fact, the best way to learn how to operate a machine is to know how it works in every detail. If you know exactly how and why everything works, it's that much easier to figure out why it's not doing what it's supposed to do. That's an advantage that you'll never get from a pre-packaged system.
Also, Tom, I hope if we ever meet we could shake hands and enjoy some cold ones!
Thanks allot for the contributions from both of you guys. Either I`m going to build one self or buy a ready system, I have allot of studying to do. I think I will buy I ready system, but I guess I would learned allot if I build a system of the schematics in the Mach manual (maybe I do both. Time will tell. When I look at candcnc.com I get a little bit confused, because of all the different cards and solutions. But I have downloaded the manuals, and they look very nice. So I just have to print them out, and do some serious reading
Can anyone email me these pages from Section 12.2 is called Torch Height Control Interface the manual seems to be gone>
Here's the direct link to the document from the Mach Support site:
Section 12.2 is called Torch Height Control Interface and contains schematics by Tom Caudle.
Nice new products, Tom. Looks like you're making it simpler and simpler.
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hi guys i was wondering if anyone could give me some ideas about the IHC ( initial hight controller) for a plasma cutter? was also wondering if i use a initial hight controller would i need a protection circuit for it in order to protect it from the high voltage once the arc goes on ?