CNC Plasma Table

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nick7251
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CNC Plasma Table

Post by nick7251 »

"Isn't Plasma cutting awesome?" I thought to myself. "wouldn't CNC plasma cutting be even better?" So I did the logical thing and went and bought a CNC table. It has been fun and frustrating at the same time to try to get it up and running. Lately I've been trying to figure out the correct voltage setting on the Proma THC. My plasma cutter is likely a source of some of the frustration. It is a Longevity Weldall 200pi with an S45 torch. I hope to upgrade to a Hypertherm once the table proves itself a good buy for me. I hope to by making some off road parts, and some signs for people here an there, but mostly I wanted the table for various hobby projects of mine.

If you are reading and have any info on the CNC port pinout of the longevity weldall 200pi I would love to know. I've searched all over the web. All I know for sure is pin 1 and 2 fires to torch. What I would like to know is if there is a 1/50 voltage divider in there too?

Looking forward to being a part of the community.
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acourtjester
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Re: CNC Plasma Table

Post by acourtjester »

Welcome aboard to the site here is a video I created to how to find the arc voltage for different metal thicknesses. It show a Price THC but the process is the same for most THC units. As to the pin outs for the CNC ports It may be the same a many CNC ports on other units. You can check the output of the voltage divider with a meter on pin 5(-) and pin 6 (+) when cutting if it is a 50:1 output the voltage should be about 2 volts for 100 volts arc voltage.
https://youtu.be/EyZJVMtzKzY
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nick7251
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Re: CNC Plasma Table

Post by nick7251 »

Awesome, Thank you very much for the reply. Nice video. I have been trying to use the Proma THC voltage readout to see where things are at, but I didn't consider turning off the ability to move the torch based off that voltage in Mach to see what nominal was. So as you can imagine the voltage was jumping around very quickly and I would just choose a number I saw. Your way in the video is much better. Thanks again. I will also see if my Pins 5 and 6 are the voltage divider pins.
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Re: CNC Plasma Table

Post by SegoMan DeSigns »

You have to rethink how things are built now that you have a machine that is only limited by your imagination. I started ff with a 2x2 Torchmate that I am using to make the parts on my 6x12 build.
nick7251
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Re: CNC Plasma Table

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acourtjester wrote: Tue Dec 17, 2019 10:22 pm Welcome aboard to the site here is a video I created to how to find the arc voltage for different metal thicknesses. It show a Price THC but the process is the same for most THC units. As to the pin outs for the CNC ports It may be the same a many CNC ports on other units. You can check the output of the voltage divider with a meter on pin 5(-) and pin 6 (+) when cutting if it is a 50:1 output the voltage should be about 2 volts for 100 volts arc voltage.
https://youtu.be/EyZJVMtzKzY
Just wanted to thank you again. I turned off the ability to move the torch up and down on the THC and was able to get a much more accurate voltage for the THC. Made all the difference. Also figured out how to change the post processor in Sheetcam to do touch off on the floating head which made a big difference. This is getting really fun.
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Re: CNC Plasma Table

Post by Scratch »

Welcome to the site. These big expensive tools are a lot of fun, but can be frustrating also. Once you get past the learning curve though... they're awesome!
I think I'm the oldest 10 year old boy on the forum...
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Re: CNC Plasma Table

Post by acourtjester »

Happy to help after you have things working as you like them, you may want to look into a Ohmic sensor for metal surface detection and keep the floating head switch as a safety. the Ohmic sensor is much more sensitive and works better with thinner metals. This is wired to the Probe input and leaves the floating head switch as a limit. There is a simple change in the post processor to use the G31 command in place of the G28 for floating head.
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nick7251
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Re: CNC Plasma Table

Post by nick7251 »

I will have to look into that in more detail. I've already had issues with the limit switch method pushing too far on thin material before it actuates the switch. Annoying issue. I was thinking last night that I wish there was some sort of way to measure the resistance of the metal at the probe to get initial cut height. haha. Seems like a good way to go. Am I to understand that I would still use my Proma THC during the cut? I figure you just use Ohmic for initial material sensing?
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Re: CNC Plasma Table

Post by acourtjester »

Ok many new to the game have a operational flow problem as to how thing interconnect. At the start of the cut operation you move to the start location, next you locate the metal surface and then the pierce height. The torch fires and then drops to the cut height and then starts moving to finish the cutting operation. This is the flow of the G-code, There is no connection between the pierce operation and the THC operation other then as part of the flow. the THC only comes into play after the torch has started moving after the pierce and drop to cut height in about .5 seconds.
Here is the module I and many use for a Ohmic sensor and it works great very easy to hook up.
https://www.amazon.com/Waterswitch-9-12 ... B00U0R2272
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nick7251
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Re: CNC Plasma Table

Post by nick7251 »

I purchased the water switch you recommended. Thanks. Now I have to figure out how to incorporate it. I probably will make sure the table is running perfectly first before I introduce another variable, and as you noticed based on my questions, I am novice. I am gaining confidence and understanding daily though. I do try to get answers online before I ask, but I haven't been able to find this answer specifically:
Question 1: If I change the G28 code to G31 in the post processor, how does it then use the floating head as a backup limit switch?
Question 2: What is the input name to assign the pin for IHS in Mach 3?

Thanks again,
Nick
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Re: CNC Plasma Table

Post by acourtjester »

The way I have mine hooked up is all Home/Limit switches are in series, this includes the floating head switch, and they are in the NC positions.
The probe input pin is shown in Mach 3 Ports and Pins Input signalist lower on the page near the THC pin inputs
I have attached 2 zip files for 2 different post processors both using the probe routine these should help if not just ask
BOB signal inputs, Ohmic, and THC.jpg
ohmic sensor water switch.jpg
probe2.JPG
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nick7251
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Re: CNC Plasma Table

Post by nick7251 »

This is fantastic. You have been great. Truly the heart of a teacher. Thank you. Also I see you live in Pensacola Florida. My parent used to live there before I was born. I know that means nothing to you, but I thought it to be a point of interest.
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Re: CNC Plasma Table

Post by acourtjester »

Happy to help they would not recognize it today, we have been here for 40 years big changes :HaHa
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Re: CNC Plasma Table

Post by nikolakuzzz »

Guys, I want to ask if it is possible to use https://www.sick.com/be/en/fiber-optic- ... /p/p238165 as a source for my pierce height adjustment? I am wasting electrodes and nozzles way too fast because of tilted metal that touches my nozzle during piercing.
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Re: CNC Plasma Table

Post by acourtjester »

I watched the video on the web page and I'm not sure it would work for pierce height sensing. The method used by the sensor you are looking at is more of a breaking a beam type, not a distance type. It is more of a interrupting between a transmitter and receiver thing. There have be people using proximity sensor for height sensing but that is a different method. The simplest is a floating head switch, where the torch is allowed to move up and down to trip a switch. A homing command is given in the G-code and the torch drives down until it hits the metal surface and it trips the switch. Then retracts closing the switch and the g-code sets the surface as 0.0 and then backs up to the pierce height. And fires the torch. Here is a video of that action, it is not perfect as the torch is retracting to high at first, but you can see the motion after that before the torch fires.
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Re: CNC Plasma Table

Post by nikolakuzzz »

Since I already had a floating head, I just bought a microswitch today. Can you point me to how do I proceed next after i wire it to my BoB? Especially the part about making the G code in SheetCam do the metal surface touch.
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Re: CNC Plasma Table

Post by acourtjester »

Ok you will need to use a Post Processor that is setup to use a floating head switch (G28 Z). this tells the software to home the Z and look at the pin input from the switch. I wire mine along with the other home switches in series. I tried to attach a Post processor here but they will not allow that file type.
Here is a video on how to setup the switch offset in Mach 3
switches.JPG
A code.JPG
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Re: CNC Plasma Table

Post by djreiswig »

Acourtjester, if you add .txt to the filename you will be able to attach it. Then the op can simply remove the extension to be able to use the file.
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Re: CNC Plasma Table

Post by acourtjester »

here is the file. tried 2 different methods
no go :Sad :Sad
no go file.JPG
no go 2.JPG
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Re: CNC Plasma Table

Post by djreiswig »

Huh. The second one should have worked. Maybe try dxf. I thought text files were okay on the forum. I don't think it matters as long as the op changes it back.
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Re: CNC Plasma Table

Post by nikolakuzzz »

I might need some help guys. Can i connect the Proma 150 Ground and a switch ground on the same pin on the BoB?
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Re: CNC Plasma Table

Post by acourtjester »

On the Proma there are 2 connections that some call ground, the DC power input is the negative connection to the power supply. The other is a signal connection which you will need to connect to the BOB, in what many call ground but is really signal return (common). They should not be connected together and this is in the Proma manual
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