Plasma Table Build - Plasma Bot 4.0

[acourtjester]

Sean
Be sure we laugh with you as we all have made mistakes too. Posting these things other can see that problems happen and with a little help they can fix them too.
Be careful if you have Pneumonia as I have heard once you get it is very easy to get it again. Some time its better to take an extra day of rest to be sure you are ok. Sparks will fly maybe a day latter.
Best to you
Tom

[SeanMurphy265]

The good thing about my THC is that can work with any plasma cutter and it's designed to read full arc voltage. I have it wired to pins 5 and 7 on the pp60c cnc port plug. If that will not work I can change those wires to the ground clamp and the +on the torch plug. The guy at Eagle Plasma told me to check the voltage with the plasma cutter running. The good thing about my THC is that you can find youtube video's with import plasma cutters running THC.

I am not using the Arc OK or OK to move pins 9 & 10 on the plasma cutter. From what I have read the OK to move has been an area of trouble for people who are using import cutters or any other non thermal arc or hypertherm plasma cutter. I'm using pins 1 & 2 for on/off and pins 5 & 7 that should read full voltage. I really hope it works well because it's a simple THC. I also like that I can change the torch height while cutting. It will require some note taking to learn the correct cut height and voltage settings.

Here is the youtube link for Proma Elektronica It's really a novel idea to build something that will work with any brand plasma cutter!

[sportbike]

. I also like that I can change the torch height while cutting. It will require some note taking to learn the correct cut height and voltage settings.

The THC from canccnc has control built into a MACH3 screen that can dynamically tweak the settings.

It is a bit pricey at $575, but might be worth it in better cut quality, pre-stored settings, etc.

The one you bought has been around for awhile I think. I looked into building a plasma table quite a few years ago and I believe that one was around, perhaps in a different version, back then.

Hopefully you get everything working.

[Rambozo]

It does look like a nice unit. The one thing I noticed is that you will have to set it for the delay for piercing as well as your gcode since there doesn't seem to be any way for your computer to talk to the THC directly. Not a big deal, but something to remember. I'm anxious to see what EmptyNester comes up with for an Arduino based solution. Having all the parameters stored in the gcode would be nice. One less thing for me to forget to program when I change materials. I'm looking forward to seeing you make some sparks real soon. Just be sure to take care of yourself, too. Being sick is no fun at all, so don't do anything to prolong that.

[acourtjester]

HI Sean
What size tip are you using the kurf width look big I think the smallest tip for that torch is a 1.0 for 60 amps.
Here is a cut I made with pierces for drilling holes latter and then cutting the part out the kurf looks smaller then yours.

[SeanMurphy265]

HI Sean
What size tip are you using the kurf width look big I think the smallest tip for that torch is a 1.0 for 60 amps.
Here is a cut I made with pierces for drilling holes latter and then cutting the part out the kurf looks smaller then yours.

I honestly do not know! I'm using the consumables that came in the pp60c box!

[SeanMurphy265]

Well I finally had a day to work on my plasma cutter! I have some video I will post later. I spent a little time working on my THC. I know it works, because I found the test mode! Some how either I have a loose wire or my THC is not reading the voltage. When the torch fires the voltage appears and then goes away. I'm not sure if I have a loose wire, or if the THC is not getting a good arc voltage reading. Still have lots of learning, but I'm close.

[SeanMurphy265]

Here are some pics of some hinges I tried cutting yesterday. I'm not sure what happened if the plate moved, but the holes were suppose to be on the hinges. I'll work out that problem later! I hope to get some time tomorrow and see whats going on with the THC not reading the arc voltage.

[SeanMurphy265]

[EmptyNester]

I am not using the Arc OK or OK to move pins 9 & 10 on the plasma cutter. From what I have read the OK to move has been an area of trouble for people who are using import cutters or any other non thermal arc or hypertherm plasma cutter.

Sean,

Any idea what the problem with the Arc OK is? I haven't played around with that yet because I haven't wanted to start cutting and measuring voltages and signals until I had more solid hardware and a software framework in place. (I do know that it doesn't trip with the pilot arc. You have to get a cutting arc.)

[SeanMurphy265]

Sean,

Any idea what the problem with the Arc OK is? I haven't played around with that yet because I haven't wanted to start cutting and measuring voltages and signals until I had more solid hardware and a software framework in place. (I do know that it doesn't trip with the pilot arc. You have to get a cutting arc.)

My setup does not have the arc ok option, but there were some threads on cnczone (johndjmix build thread) with people having some problems with it. The easy fix was to jump the two wires together. From what it has something to do with how a specific brand of THC (geared towards hypertherm and thermal arc) reads divided voltage. This could be fixed by purchasing a product from the same company, and then the divided voltage could be read correctly. The end results that I have read usually ends up with a person forking out $2,000.00 for a hypertherm. You have to give hypertherm props they only make plasma cutters and they make them well. Hypertherm was also smart enough to get in the CNC market and made a niche market for themselves. If you think about it Miller does not have a plasma cutter with a cnc port (you can purchase a machine torch for the spectrum 875). Lincoln has only one plasma cutter with a cnc port. I'm at the point now where outside of spending money on paint, primer, and metal slats I'm done spending money on my cnc! If it can make money I may invest in a better THC, but for right now it will have to do. I will say that after running some g code last week I think you can get a good cut without THC. It may take a little time learning your pierce and cut heights, but it can be done and its all over youtube. There are several youtube videos with Everlast and other import cutters cutting just fine. For some reason there seems to be a problem with import cutters and a certain brand of THC.

I think if you can get your audrino working then you probably make a little money.

[Rambozo]

If the arc ok signal is working correctly, can anyone tell me if it goes high when the cutting arc starts, or after the pierce is complete?

[SeanMurphy265]

If the arc ok signal is working correctly, can anyone tell me if it goes high when the cutting arc starts, or after the pierce is complete?

You set that up in sheet cam. You have a pierce height and cut height.

[Rambozo]

You set that up in sheet cam. You have a pierce height and cut height.

I know the heights are setup in the gcode. What I meant by the signal going high is that it goes to a logic level of 1, which in this case is +5v. I just don't know when this actually happens. If it happens after the pierce is complete you can use it to instruct the CNC to start the next motion command. That would be really nice as it would account for any difference in material and how long it takes to pierce. However, if it is triggered by just the start of the cutting arc, it is of much less use, as you will still have to program in the pierce delay in the gcode, and it will always be the same. (with your THC you will also have to match that delay in the THC settings) It can't compensate automatically for colder or hotter material, or anything else that effects pierce time. In CNC it's what's know as an open loop. You pre-program what it should be, but there is no way to be sure it has properly happened. Closed loop gets a signal back that says something happened, now proceed.

I also don't know if the signal happens differently from the ok to move pins on the plasma cutter, or the arc ok pin on the THC. From the graph in the Eagle manual, it appears they just trigger the arc signal after the delay time. But from the voltage graph it looks like it might be possible to measure just when the pierce takes place. I can see how having a more precise pierce dwell would give you a much cleaner start. This would help for places where you have to have a short lead-in or no lead-in. It also means you would not have to pad your dwell time to account for inconsistencies.

Maybe this is another feature EmptyNester can incorporate into his THC. I bet if you take a few traces of the voltage during a CNC cut, there might be something you can trigger off of. Just a thought.

[sportbike]

Perhaps it woudl be beneficial for those that have plasma tables if we started a sticky with settings used for different materials, consumables, etc. Might help in the future for build start-ups as well as help those that already have tables when they come across a different material, etc.

[EmptyNester]

Perhaps it woudl be beneficial for those that have plasma tables if we started a sticky with settings used for different materials, consumables, etc. Might help in the future for build start-ups as well as help those that already have tables when they come across a different material, etc.

I'll second that!