DIY Arduino THC - Video

[cwalker1960]

Hi EmptyNester,
If you still have any of the mega shield boards for sale , I'm interested.
I just found this thread yesterday and read it all the way through. Great work !! I have a different brand of plasma cutter but I'll try to work out the voltage divider. I've been searching for a while for an Arduino flavor THC and it sounds like you've nailed it down.

[EmptyNester]

While the software should be independent of the torch, the hardware is specific to the PP50 (which I highly recommend). Does your torch have a CNC interface?

[cwalker1960]

It doesn't have a cnc interface but it does have an arc good signal that is used to energize a trigger hold relay,, It's an esab powercut 1500. Am I wrong in thinking that if I can get the output voltage signal stable and within range everything else should work out okay?

While the software should be independent of the torch, the hardware is specific to the PP50 (which I highly recommend). Does your torch have a CNC interface?

[EmptyNester]

It doesn't have a cnc interface but it does have an arc good signal that is used to energize a trigger hold relay,, It's an esab powercut 1500. Am I wrong in thinking that if I can get the output voltage signal stable and within range everything else should work out okay?

When you are working with raw torch voltage you have a lot more issues with noise, isolation and negative (versus positive) voltage.

I've not played with raw voltage and I would think there's a good chance of frying the board immediately. If you want to experiment, I'd believe that you'd need start from the beginning with voltage dividers and looking at the quality of the signal you get. But, doing that can be very dangerous.

That's why I really endorse the PP50 for home CNC use.

[none]

Hi,

Im new to this forum and I just found this topic which I found it very interesting. I checked out your github and I noticed that you updated the kerf detection in your code 3 months ago but in your topic you didn't mention anything about the changes you made. Im also interested if you meet the problem when the tip accidentally hits the workpiece. What voltage did you measure or what your system does in order to stop the cutting process?
Very well done, I also really appreciate your hard work and effort you put into this even though it is just a hobby.

[EmptyNester]

Hi,

Im new to this forum and I just found this topic which I found it very interesting. I checked out your github and I noticed that you updated the kerf detection in your code 3 months ago but in your topic you didn't mention anything about the changes you made. Im also interested if you meet the problem when the tip accidentally hits the workpiece. What voltage did you measure or what your system does in order to stop the cutting process?
Very well done, I also really appreciate your hard work and effort you put into this even though it is just a hobby.

Thanks.

I had the kerf detection working great. I could cut a square with the 16 ga sheet at a 45 degree angle. In the process of refactoring (major changes to clean stuff up and integrate it with Mach 3) I broke the kerf detection. It still needs a little work but I haven't spent time on it in a while.

I'm not aware of any way you can tell if you've contacted the surface with the tip. The best thing to do for the tip hitting the surface is using the magnetic break-away mounts (I do not have one).

While I don't have the software proactively cut the torch off - it is possible. It just flips the relay to the torch to kill it and sends the PC the signal that there is no arc. Mach will stop movement if its in THC mode and the arc goes away.

I did do one dumb thing recently. I use SheetCam and I turned on the "leadout" feature for inner cuts. What happened is that it finished the cust and the piece started falling while the lead-out was being cut. It caused the torch to plunge. The easy fix is to no use lead outs on inside cuts.

[I build]

Hi EmptyNester

While searching for a low cost THC solution, I came across your videos you tube, which led me here. Having read through this thread, I really admire your dedication to design and build a working THC.

I'm very keen to build one of these as I have just finished my plasma table build. Do you still have any boards left? Preferably the micro board, as I have the arduino micro already. If not, I'm happy to get it made. When you discovered the micro board needed the solder bridges between tracks, did you alter the PCB layout? If not, would it take much work to do?

BTW, my plasma cutter is a powermax 45, which has the 50:1 divider, as well as the arc OK and torch on trigger, so it should play nicely.

[EmptyNester]

Hi EmptyNester
I'm very keen to build one of these as I have just finished my plasma table build. Do you still have any boards left? Preferably the micro board, as I have the arduino micro already. If not, I'm happy to get it made. When you discovered the micro board needed the solder bridges between tracks, did you alter the PCB layout? If not, would it take much work to do?

BTW, my plasma cutter is a powermax 45, which has the 50:1 divider, as well as the arc OK and torch on trigger, so it should play nicely.

Thanks,

I have not yet updated the schematic and board layouts. It was about $50 every time a did a new pass and I got to the point that it was "close enough" for me. The files are in Eagle CAD. I believe it became too large for the free version (it is size limited) and I have the lowest cost version (does slightly larger boards) and access to the professional version at work.

I've only built one of each from this last set of boards, but from that single sample of each, I've found that the shield version did not have as much noise as the micro version. I liked the smaller size of the micro, but the shield just performs better (that's what I use).

I've not used it with any other cutter, so you may have to play with the values of the voltage divider resistor. I do have some boards left, PM me with your email address.

[I build]

Hi EmptyNester

Took a while, but I sourced all the components and built a board. Then I installed the Arduino development environment and loaded your sketch file. Tried to compile the software and got the following error: Attachment 12044

I was hoping the code was finished & tested, ready to use. I'm not much of a programmer, so don't know what to do now. Any ideas?

I verified that the pro micro was installed OK, drivers were loaded and correct COM port chosen. I uploaded a sample sketch to it and it works as expected.

Do you know if anyone else has built one of these THC's and if they had any problems with the code?

[EmptyNester]

Hi EmptyNester

Took a while, but I sourced all the components and built a board. Then I installed the Arduino development environment and loaded your sketch file. Tried to compile the software and got the following error: Attachment 12044

I was hoping the code was finished & tested, ready to use. I'm not much of a programmer, so don't know what to do now. Any ideas?

I verified that the pro micro was installed OK, drivers were loaded and correct COM port chosen. I uploaded a sample sketch to it and it works as expected.

Do you know if anyone else has built one of these THC's and if they had any problems with the code?

Sorry, haven't been on the forum in a while.

Your attachment isn't valid. If you can load a sketch file and it runs, then you have the drivers loaded right.

You didn't say if you were using a Micro or shield system. Look at the file "Platform.h". If you are using a Micro, then make sure the following line is NOT commented out:

#define MICRO_THC

If you are using a Mega, then change the line to:

//#define MICRO_THC

That's my only guess without more details.

[I build]

Sorry, not sure what happened with that attachment. I think the forum has been having some issues, I couldn't log in for weeks.

I did build the micro version, and followed your instructions to the letter. The #define MICRO_THC line is exactly like that with no slashes in front of it.



I've attached a screen shot of the error. Let me know if there is anything else that can help

[EmptyNester]

You should take a look at the Arduino site. They have examples of including libraries in your programs. It looks like you don't have a library included. The other thing is that I'd recommend using version 1.0.5 of the Arduino environment. That's what I used to build it.

[I build]

I have done a lot of reading on the Arduino website over the last few weeks. To try to narrow down the error, I have d/l several simple sketches, u/l them to the micro and it works with them.

There are only 2 versions of the Arduino environment available on the Arduino website - Arduino 1.0.5 and Arduino 1.5.6-r2 BETA

I downloaded the 1.0.5 (which actually installs 1.0.5-r2. As far as I can tell, the r2 revision has been updated to add support for Windows 8.1) But I'm using Windows 7 so I think it makes no difference

It came with a lot of the Libraries already included as you can see below.



Am I missing anything that you might have on yours?

[EmptyNester]

I PM'ed some ideas to you.

On thinking about it, I recall running into a similar bug with the IDE (I am using 1.0.5 also). I think the project file got corrupted somehow. I had to create a new project and recreate the files.

[I build]

Its built, programmed and being tested. Don't think it's working just yet but hopefully it's just a setting or 2. I captured logs for 4 of the cuts, first 2 were cutting a flat piece, second 2 were cutting a piece that was raised slightly - can you please have a look and tell me what you think?

THC tests12.zipTHC tests34.zip

[EmptyNester]

Its built, programmed and being tested. Don't think it's working just yet but hopefully it's just a setting or 2. I captured logs for 4 of the cuts, first 2 were cutting a flat piece, second 2 were cutting a piece that was raised slightly - can you please have a look and tell me what you think?

THC tests12.zipTHC tests34.zip

Sorry for the delay, I was off on vacation.

I looked at both of the files. The best way is to import them into Excel.

You had it set on "volts" when you did the capture, so the column that says "current voltage" is in volts, while the column that says "set point" is in "counts". If you do a capture with "counts" it will help you determine how much noise you have.

In general, it looked good and was issuing "arc good" and "thc up" and "thc down" signals. So, it Mach wasn't servo'ing up and down - it's a Mach configuration issue.

The one thing that was a little bit of an issue is that your voltage when you're not cutting is 52 volts. It's normal to have some voltage their, but that's higher than it should be (I think I'm around 5 volts of noise when not cutting). The cutting voltages look about right though.

If you convert the cutting voltage to counts (it's around 97 or 98) it's between 679 and 686 (assuming you used the 7 counts per volt scaling). In the file, it shows your set point is 700 counts. So, it's issuing THC UP commands most of the time to raise the voltage.

If you're not seeing Mach actually move up and down, then look at you input configuration and your THC settings.

[furkanyilmaz]

Hi all,

I made some cnc plasma cutters before, I use some standalone voltage THC's, candcnc's thc and capacitive thcs.
I am using hypertherm plasma unit right now for test. Because I just found it from a friend for test the thc.


There are two options on hypertherm's connections;

1-Using the divided volts from a cnc interface connector.
2-Using the undivided arc voltage from the inside of the plasma.

I am using first option, there are 50:1 divided volts. I can reading this voltage well with voltmeter. And I am not using the voltage divider resistors.
I have arc ok output from plasma. And one dry contact torch fire input.



I have few questions;

1-In the revESchematic the C8 value is 10uF but in the manual thats 68uF, in the component list same(68uF).
Which one is right? My voltage isnt stabil enough and I am not sure why?

2-I am trying to use windows thc interface but I have some trouble about it. I cant changing the modes, set volts etc.
But I can see the leds and current volts working well with changes in arduinos Analog input. And I cant using the signal
test screen to. When I hit the buttons there are no changes at the arduino output. Whats wrong? I can write a program in C.
But I dont know so much things about object based programming languages like c++, csharp, java etc. So I cant commenting the
source codes of windows interface.

3-I couldnt install the mach3 files. I copy the dll files in to PlugIns folder and Mach3 folder but there are no wizards
or plugins to use? So is there an any info about how to use the mach's thc plugin?

4-In my country its hard to find resistors like 9.53k. So I am using trimpot as a resistor. And I need to redesign pcb
for my components. I am using proteus to design the pcbs.But to be sure I am drawing the pcb without any mistakes
I want to see pcb layout.But when I open the eagle layout there are some pins not connected
to anywhere. Is there an complete layout or what should I change to see the all connections or layers. I tried something
but didnt work. If there is a printed complete pcb for arduino mega it will be great, I can buy it.


So I know something about electronic but not so much. I need just filters, and another things from arc voltages to
Arduinos analog pin. After I make filters of project, other part is not hard to make i think. Could anyone help me
about this? I buy lt1632 op-amp from an other country because there are no lt1632 in my country. But currently my
filter is not working nicely. I need very stabilized arc voltages at my arduino's analog pin.

Very perfect work EmptyNester(regeg). I will share my updates and changes with you. And I hope you will like it...

I am so sorry about my bad english.
Thanks in advance, have a nice arcs :)

[EmptyNester]

Hi all,

I made some cnc plasma cutters before, I use some standalone voltage THC's, candcnc's thc and capacitive thcs.
I am using hypertherm plasma unit right now for test. Because I just found it from a friend for test the thc.


There are two options on hypertherm's connections;

1-Using the divided volts from a cnc interface connector.
2-Using the undivided arc voltage from the inside of the plasma.

I am using first option, there are 50:1 divided volts. I can reading this voltage well with voltmeter. And I am not using the voltage divider resistors.
I have arc ok output from plasma. And one dry contact torch fire input.



I have few questions;

1-In the revESchematic the C8 value is 10uF but in the manual thats 68uF, in the component list same(68uF).
Which one is right? My voltage isnt stabil enough and I am not sure why?

2-I am trying to use windows thc interface but I have some trouble about it. I cant changing the modes, set volts etc.
But I can see the leds and current volts working well with changes in arduinos Analog input. And I cant using the signal
test screen to. When I hit the buttons there are no changes at the arduino output. Whats wrong? I can write a program in C.
But I dont know so much things about object based programming languages like c++, csharp, java etc. So I cant commenting the
source codes of windows interface.

3-I couldnt install the mach3 files. I copy the dll files in to PlugIns folder and Mach3 folder but there are no wizards
or plugins to use? So is there an any info about how to use the mach's thc plugin?

4-In my country its hard to find resistors like 9.53k. So I am using trimpot as a resistor. And I need to redesign pcb
for my components. I am using proteus to design the pcbs.But to be sure I am drawing the pcb without any mistakes
I want to see pcb layout.But when I open the eagle layout there are some pins not connected
to anywhere. Is there an complete layout or what should I change to see the all connections or layers. I tried something
but didnt work. If there is a printed complete pcb for arduino mega it will be great, I can buy it.


So I know something about electronic but not so much. I need just filters, and another things from arc voltages to
Arduinos analog pin. After I make filters of project, other part is not hard to make i think. Could anyone help me
about this? I buy lt1632 op-amp from an other country because there are no lt1632 in my country. But currently my
filter is not working nicely. I need very stabilized arc voltages at my arduino's analog pin.

Very perfect work EmptyNester(regeg). I will share my updates and changes with you. And I hope you will like it...

I am so sorry about my bad english.
Thanks in advance, have a nice arcs

Furkanyilmaz,

I'll try to answer the best I can. I'm not at home, so I don't have everything in front of me. But I wanted to get you some answers right away.

On the torch voltage.....

Using a volt meter won't tell you how much noise you have on the signal. You really need to have an oscilloscope to get a good idea how clean the signal is. The other alternative is once you have the board working you can capture the input it's seeing using the PC app.

I found that the noise was to large compared to the signal if I used anything but full arc voltage. The PP50 is nice because it offers that voltage at the CNC port. You will need to change the voltage divider resistor values if you don't use full arc voltage.


1. I have to look at this at home. If C8 is the cap on the voltage divider, I believe it's 10 uF. (I'll have to check that when I'm at home.)

2. I had problems with communications. There were two main causes. Incorrect wiring and bad opto-isolators. The wiring is easier to check. I got my opto-isolators on ebay. They are higher speed, so a bunch on them were bad. I used an oscilloscope to see the wave form and determine they are bad.

3. You need the full licensed version of Mach for THC support. The Mach manual tells you how to install a plug-in.

4. The Eagle files on github are the files that I used to get the boards made. If there are missing connections, then they aren't needed. If you want the actual Arduino Mega files, they are open source and you should be able to find them somewhere on the web. But, the parts are high density and can't be hand soldered.

Rege

[furkanyilmaz]

Furkanyilmaz,

I'll try to answer the best I can. I'm not at home, so I don't have everything in front of me. But I wanted to get you some answers right away.

On the torch voltage.....

Using a volt meter won't tell you how much noise you have on the signal. You really need to have an oscilloscope to get a good idea how clean the signal is. The other alternative is once you have the board working you can capture the input it's seeing using the PC app.

I found that the noise was to large compared to the signal if I used anything but full arc voltage. The PP50 is nice because it offers that voltage at the CNC port. You will need to change the voltage divider resistor values if you don't use full arc voltage.


1. I have to look at this at home. If C8 is the cap on the voltage divider, I believe it's 10 uF. (I'll have to check that when I'm at home.)

2. I had problems with communications. There were two main causes. Incorrect wiring and bad opto-isolators. The wiring is easier to check. I got my opto-isolators on ebay. They are higher speed, so a bunch on them were bad. I used an oscilloscope to see the wave form and determine they are bad.

3. You need the full licensed version of Mach for THC support. The Mach manual tells you how to install a plug-in.

4. The Eagle files on github are the files that I used to get the boards made. If there are missing connections, then they aren't needed. If you want the actual Arduino Mega files, they are open source and you should be able to find them somewhere on the web. But, the parts are high density and can't be hand soldered.

Rege

Hi Rege,

Thank you so much because of your fast reply.

If you send me a pm about when you are gonna be available, I will be online in the same time.

So c8 isnt the cap at the voltage divider. Its right before Arduino's analog pin. I will wait to go your home about it.

In serial communucation I am using the arduino's usb port. I think I should tell I am not using the complete board. I install the filter circuit on a breadboard. And When I want to send a logic data to your design I am using jumpers on breadboard. So for example I am connecting the torch on pin to gnd after this I am connecting the arc ok input pin to gnd. After this arc ok and torch on leds turning on. And I am using leds on breadboard to see the output status of arduino...

I am going step by step because when I am designing a circuit, when I design everything and after build everything usually something going wrong. And in this method its hard to find whats wrong. So I am using one step, test, one step, test method.

And my friend have very nice soldering workstation, oscilloscope etc. When I am soldering a optocoupler, I am not burning out the ic. Usually I am using socket for ics like mcu, opto... But I couldnt use oscilloscope when I am making test cause my friend is out of the city right now. So dont worry about the component soldering. But I will take a look the system with an osciloscope soon.

My mach3 is licensed.

I tried to copy files like I did before. Ok I am gonna take a look to the mach3's manual.

But I am not sure about eagle files. Because some diodes and some capacitors one leg isnt connected to anywhere in eagle layout. I am skipping something about eagle or there is a different method about circuit designing, and I couldnt understand because of I am not a guru about electronics.

Rege Thank you very much again, thats really helpful documents. And thank you very much again for you are spending time for me...

Have a nice day

[I build]

Sorry for the delay, I was off on vacation.

I looked at both of the files. The best way is to import them into Excel.

You had it set on "volts" when you did the capture, so the column that says "current voltage" is in volts, while the column that says "set point" is in "counts". If you do a capture with "counts" it will help you determine how much noise you have.

In general, it looked good and was issuing "arc good" and "thc up" and "thc down" signals. So, it Mach wasn't servo'ing up and down - it's a Mach configuration issue.

The one thing that was a little bit of an issue is that your voltage when you're not cutting is 52 volts. It's normal to have some voltage their, but that's higher than it should be (I think I'm around 5 volts of noise when not cutting). The cutting voltages look about right though.

If you convert the cutting voltage to counts (it's around 97 or 98) it's between 679 and 686 (assuming you used the 7 counts per volt scaling). In the file, it shows your set point is 700 counts. So, it's issuing THC UP commands most of the time to raise the voltage.

If you're not seeing Mach actually move up and down, then look at you input configuration and your THC settings.

Hi EmptyNester

After a lot of time and trying many different things I finally got it working. There is a lot of rapid up/down movements, like it's sawing through the steel, but at least it does work. It looks like it overshoots and overcorrects constantly, similar to your vid on YouTube but more exaggerated, and I'm wondering if my Mach3 setting may have something to do with it? Do you think you may be able to check on some of them on your setup please? What should the THC speed be set at? And the THC Max & Min settings? And any other related settings that may be relevant.....

Also, I have a question re the Mach3 plugin. I have installed it but nothing looks different - what does it do?