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  1. #1
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    May 2015
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    684

    Rod's Aussie Plasma Build

    Well, I really have no idea what I'm doing but after playing with an Arduino to make a rotary table controller, I got interested in steppers and seeing I had a basic plasma cutter here, I figured I'd have a go at building a CNC plasma cutter. I've decided to start with the electronics which I'm going to squeeze into a 40 amp plasma cutter case seeing I ended up with one that was beyond repair.

    So after accumulating some stuff which includes a mini ITX pc and an 8 gb industrial SSD unit, and a 12 volt Xenarc 7"touch screen, this is the mess I have (ignore the Arduino)


    Then I spent a fair bit of time designing some shelves for the enclosure to hold all the stuff



    So from the top down. Existing breaker switch and terminal, 12v/5v power supply,
    shelf for 48 v power supply
    4 x DM348A stepper drivers, 2 x relays, 24 volt power supply

    and room on the bottom for a breakout board behind the THC main board.

    And this afternoon, it started to come to life



    The THC controller interface box has a RS232 display on it and works in conjunction with the black knob to set voltages etc. there are heaps of connectors so I can't pass the wires through a grommet so have fed them out from under the panel. The THC is longer than the original slanted panel so I've extended the panel I made and folded it back to meet the case (you can see this detail on the rendered image). I did think about trying to mount it flush but in the end, I decided it was nice and easy to service this way even if the wires are a bit untidy.

    The Black knob is part of the THC. Selecting a THC took me quite a while as with the way the AUD is these days, it was not viable to import stuff from the US. In the end, I purchased a stand alone Torch Height Controller from Robot 3T in Vietnam THC3T-03: Stand Alone Plasma Torch Height Controller .

    You can find them on eBay but I bought direct and have been very pleased with the support received to date and the completeness of the kit which includes all the wiring, a voltage divider board and a proximity sensor for the surface sensing on the Z axis. Cost me USD $250 delivered. Not having a voltage divider or Arc OK signal in my Plasma was the deciding factor in selecting this unit over others, Plus Mesa were out of stock of their THC card. They emailed me the instruction book which is very complete and surprisingly well written.

    For software, I am going to start with LinuxCNC and may end up with a Mesa board down the track but my PC has a Parallel port on the motherboard so I will give an ordinary breakout board a try first as I have one here. I am absolutely blown away by the quality of the LinuxCNC documentation and the installation was a breeze even though I don't know much about Linux. If I run into problems getting the THC going, I might try Mach3 as Mach3 config instructions were included. From what I read, I will get better performance from LinuxCNC.

    Hopefully, tomorrow, I will be able to get the hardware off the design bench and folded up and the hardware installed in the case. I've got a small 24" pan brake here and have found it is pretty easy to print out a plan at 1:1 scale, glue it down with repositionable spray on glue and then it is simply a matter of cutting, drilling and folding along the dotted lines and peeling off the template later. In this case, I have had to join 2 A3 pages together. I had to bell out the shelves so they are wider at the bottom. I just hope those folds work out OK.

    I am certain I will have heaps of questions along the way. I'm lucky enough to have a mate who lives in the same street who is well versed with CNC builds and he's been helping me out a bit but any advice from the forum will be much appreciated.
    Rod Webster
    www.vehiclemods.net.au

  2. #2
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    Sep 2005
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    1195

    Re: Rod's Aussie Plasma Build

    What is your plasma cutter? Is that CUT40 Chinese Plasma Cutter?

  3. #3
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    Re: Rod's Aussie Plasma Build

    Quote Originally Posted by asuratman View Post
    What is your plasma cutter? Is that CUT40 Chinese Plasma Cutter?
    I bought my Plasma from BOC here in Australia. A well respeted brand here. Probably Chinese made but running a Thermodynamics torch.
    BOC Smoothcut 40 Plasma Cutter | BOC Australia

    Yes, I know its only a baby (quite adequate for home use) but the electronics should handle pretty much anything so an upgrade to a better plasma cutter won't be a drama.



    The case I'm using for the electronics came from a Boss 40 amp plasma cutter. (An Australian brand and I have their 202 Amp MIG welder)

    Anyway, quite amazed that my chassis folded up perfectly. Even bolt holes to hold the pieces together lined up!

    Here's where I got to today






    I have to mount up the last layer for the electronics (layer 4) whihc comprises the BOB and THC control board pictured. I decided the Parallel port will poke out the bottom front panel and if it does not work out, It will be easy to make a new panel and add an Ethernet port for Mesa Card or Smooth Stepper. All of the wiring to limit switches and steppers will exit from the rear panel and I have not tackled that yet.



    Peeping into the middle of the machine where the stepper controllers and relays for the THC are mounted. I think the controllers are good for 4.2 amps and rated for 50 volts so I'm running at 48 volts. Once the fan is back in, there should not be any dramas with cooling!



    This shows the 12v/5v power supply (top) and the 48 V one below. Also the terminal block that was in the old plasma. I put the 12v/5v power supply at the top because it does not have a cooling fan and the 48 V one does. I mounted the 48v power supply further forward so the fan was not obscured by the smaller power supply.



    And what it looks like when closed up (minus a bolt or 2 to hold the cover on.)

    I'm hoping that this box can become a portable CNC controller that can be plugged into different machines but if that does not work out, It won't be too much of a drama. ONce I get to the wiring, I'm sure I'll have questions.

    I still have to find a source for good quality shielded wires to use so if any Aussies have ideas, please let me know.
    Rod Webster
    www.vehiclemods.net.au

  4. #4
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    Sep 2005
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    1195

    Re: Rod's Aussie Plasma Build

    Have you got any experience before with THC product you will use?

  5. #5
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    Oct 2006
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    17

    Re: Rod's Aussie Plasma Build

    I am going to be very interested in this build as I am currently building a Mechmate Here is a link to cable that I used PPCY4C1.00 - PRO POWER - CABLE, CY, 4 CORE, 1MM, PER M | element14 Australia
    Cheers Mal

  6. #6
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    Quote Originally Posted by asuratman View Post
    Have you got any experience before with THC product you will use?
    None at all ☺
    Rod Webster
    www.vehiclemods.net.au

  7. #7
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    Quote Originally Posted by slipery View Post
    I am going to be very interested in this build as I am currently building a Mechmate Here is a link to cable that I used PPCY4C1.00 - PRO POWER - CABLE, CY, 4 CORE, 1MM, PER M | element14 Australia
    Cheers Mal
    Mal, thanks it looks like they only have 2.0m left in the UK so I might give them a call. Is 1.0mm a good wire size to use? I might have to keep looking...
    Rod Webster
    www.vehiclemods.net.au

  8. #8
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    Oct 2006
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    17

    Re: Rod's Aussie Plasma Build

    For control circuitry you could go smaller .5mm would be fine. For the stepper motors I would not go smaller and in fact I used 1.5mm but then I am using 800 oz in 2A steppers. If they have it in stock in UK not a problem just takes a few days longer (about a week) in my experience.
    With the THC3T series of devices are they giving you hand with configuring as their web site doesn't give much away. For example it is not clear between the THC3T-01 and 03 or how you connect the arc_div connections to the plasma. Do they give you any sort of manual at all.

    Cheers Mal

  9. #9
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    Quote Originally Posted by slipery View Post
    For control circuitry you could go smaller .5mm would be fine. For the stepper motors I would not go smaller and in fact I used 1.5mm but then I am using 800 oz in 2A steppers. If they have it in stock in UK not a problem just takes a few days longer (about a week) in my experience.
    With the THC3T series of devices are they giving you hand with configuring as their web site doesn't give much away. For example it is not clear between the THC3T-01 and 03 or how you connect the arc_div connections to the plasma. Do they give you any sort of manual at all.

    Cheers Mal
    Mal, thanks, I don't mind waiting for stuff frkm the UK but they were only showing 2.0 metres in stock with a 6 week lead time.

    On their ebay listing or their website somewhere, there was a link (not clickable) to a wiring diagram but when I emailed them, they sent me a much more detailed manual including Mach3 screen dumps and listings of required Mach3 macros and lots of screen dumps of the menus in the display. Kit came with divider board, display, controller box, wires for the voltage signal to use inside the cabinet and a proximity sensor to use to sense the material surface to incorporate into the Z axis. Runs off 24 volts and has 5v on board for BOB. It needs 2 x 24V relays for torch on and to output ArcOK signal to the BOB.
    Rod Webster
    www.vehiclemods.net.au

  10. #10
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    Jul 2005
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    2415

    Re: Rod's Aussie Plasma Build

    You cannot use any of the MACH3 instructions for LinuxCNC other than you need some inputs and an output.. See, it' s a bit puzzling why you need MACH3 macros (which are not usable in LinuxCNC) at all for a stand alone THC (?) You have to tell the control software to "hold" motion until the torch fires and you get ARC OK.maybe the macros control that part(?) You have to fire the torch from G-Code. If it is a true stand-alone it should have all of the settings internally for the: Preset volts, THC delay, touch off cycle, stop on fault and torch lift between cuts. How you set all those parameters and change the cutting parameters should be clear. Don't mount the THC control head on the gantry or you will find yourself running back and forth to change settings doing a test cut. If they cannot give you specific help (i.e. HAL driver and macros for LCNC) then you are in for a long journey for a non-linux guy. You may need to consider using Windows and MACH 3 or rethink your choice of THC's.

  11. #11
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    May 2015
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    Re: Rod's Aussie Plasma Build

    Torchhead, thanks. Either way this will be a long journey given what little I know. I posted the stuff about Mach3 for others interested in this THC. The Mach3 macros are for M3 and M5 which control torch on and off. M3 is just a loop that waits for an ArcOK signal before proceeding.

    I know enough about Linux not to be frightened. I've got a Raspberry Pi in my garage receiving data via bluetooth from my solar inverter and also receiving power consumption data from a wireless power monitor via a USB TV dongle and posting it up to pvoutput.org every 5 minutes and a lot of the code I wrote. Its worked flawlessly for 12 months. I figure getting to know a few LCNC text files won't be too hard.

    LCNC is my first choice because it seems to have a more viable future outlook than Mach3. From what I've read, non THC plasma is supported out of the box. My fall back position will be to use Mach3. All of the features you list are supported in this THC. Point taken about location of the controller for the THC, my thoughts exactly.

    This contoller synthesises ArcOK which my machine does not have. I did consider adding my own ArcOk sensor or buying yours and did make up a Hall effect current sensor which I played with for this purpose but decided to go this way.

    I decided to get the electronics sorted first before physically building the table so I identified any limitations in my hardware up front.

    Its taken me 6 months to get this far so don't expect to see a working machjne in a hurry.
    Rod Webster
    www.vehiclemods.net.au

  12. #12
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    Re: Rod's Aussie Plasma Build

    You cannot edit the Mcodes in LCNC like you can in MACH3. It simply turns on the spindle with no parameters . There are other G-Codes and M codes that will take parameters but no added code. It's better in some ways and more confusing in others if you are used to MACh3. You can write custom Macros using BASH or Python,. but that means calling them in the G-Code in place of the canned ones. There is some good documentation on the G and M codes used in LCNC.on the LCNC website

    Here is a little interesting reading for you about an upcoming release for the DTHCIV http://www.candcnc.net/images/downloads/CommandCNC.pdf

  13. #13
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    Re: Rod's Aussie Plasma Build

    Torchhead, thanks for ongoing info. I am an absolute noob with any CNC stuff so have nothing to unlearn about Mach3, just heaps to learn.

    So decided to look where the divider card might fit.



    Hmm, not a lot of room but there is a bit of space to the left of the large aluminium heat sink if I fold up a bracket

    Getting some wiring to the outside world seems to be easy enough. So much so, I drilled a 16mm hole in the front panel while I was at it. Absolutely amazed the instrument panel was fairly thick aluminium. I had assumed it was plastic like the rest of the case...



    So now to make sure I have shielded cables on the low voltage side of the divider card, I believe I need solder the earth shield to 1 pin on any connector. This is not the final connector I'll use but is what was handy to check for fit. I was planning on using a 3 pin version of this connector for the shield and low voltage wire back to the controller. Does that sound right?

    Off to design up a folded bracket to hold the voltage divider card......
    Rod Webster
    www.vehiclemods.net.au

  14. #14
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    Re: Rod's Aussie Plasma Build

    This should do the trick to squeeze the divider card in



    Should mount using the 5mm screw that holds on the handle like bracket up the top front of the machine. Card will be upside down to give access to the connectors
    Rod Webster
    www.vehiclemods.net.au

  15. #15
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    Oct 2006
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    17

    Re: Rod's Aussie Plasma Build

    Rod,

    Just thought I should mention when you buy that 3 pin connector I would recommend a female so that pins are not exposed with live voltage3 on them.
    Cheers Mal

  16. #16
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    Re: Rod's Aussie Plasma Build

    Quote Originally Posted by slipery View Post
    Rod,

    Just thought I should mention when you buy that 3 pin connector I would recommend a female so that pins are not exposed with live voltage3 on them.
    Cheers Mal
    Mal, Thanks. Got me thinking. This type of connector does not give you a choice for panel mount so If it looks to be a problem I'll turn up a cap to protect the pins when being used as a manual machine. I've ordered some 3 pin connectors off eBay as Jaycar did not have any.

    IT looks like I have just enough room for the divider card.



    This pic is upside down on the opposite side of the machine but it shows how little room there is for this.


    I need to find some nylon nuts and bolts to secure the card to the bracket.. Jaycar have a listing for them so I'll grab some by the weekend.
    Rod Webster
    www.vehiclemods.net.au

  17. #17
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    Feb 2007
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    60

    Re: Rod's Aussie Plasma Build

    Hey Rod I actually use RS Components for most of the stuff I buy, found them to be cheaper and free deliver if I order before 5pm I have it the following morning.
    Jaycar just never seems to have what I need.

    Really interested to see how the smoothcut works out for you as I will be looking for a backup for the Hypertherm 45.

  18. #18
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    Re: Rod's Aussie Plasma Build

    Quote Originally Posted by WillyInAus View Post
    Hey Rod I actually use RS Components for most of the stuff I buy, found them to be cheaper and free deliver if I order before 5pm I have it the following morning.
    Jaycar just never seems to have what I need.

    Really interested to see how the smoothcut works out for you as I will be looking for a backup for the Hypertherm 45.
    Willy, thanks happy to exchange plasmas at any time so you can run your own experiments

    I got the smoothcut and a matching BOC TIG welder on special at BOC a while ago. I think the plasma cost me $600 and now they want $988 for it.

    I have used RS Components a few times as they have an office 10 minutes from home but have found Element14 generally better priced. A mate has offered me some shielded stepper cable so I might borrow some to sort out my cabinet wiring. Element14 have some shielded 3M ribbon cable sold by the metre so I thought I'd get some of that as well as it will save a lot of soldering. I might get a bit more done over the weekend.
    Rod Webster
    www.vehiclemods.net.au

  19. #19
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    Re: Rod's Aussie Plasma Build

    Today was a bit mixed up and I did not get the few bits of hardware I wanted until about 4:00pm so nothing much got done. I had a :idea: brain f@rt :idea: last night and realised that I should be able to use the torch from my scrapped plasma that is providing the case as a machine torch. My BOC Smoothcut plasma came with a Thermodynamics PCH/35 torch that can't be straightened and the scrapped plasma came with a Trafimet CB50 torch. I opened it up this morning and sure enough, it had a copper tube that could be straightened and turned into a machine torch so that's what I did.



    The pic shows the guts of the red CB50 torch after I (roughly) straightened it so it can go into a body I'll machine on my lathe.
    The black torch is what came with my BOC machine. Don't ask me how hard the copper shield was to source. BOC never listed the part but the thermodynamics documentation said it should be used.....
    I've got a 25mm dia piece of Acetal rod here that might have done for the torch body but of course I need 30mm

    No matter, I've got to buy some HDPE plastic rod for another product during the week so I'll get a metre of the right diameter so I can turn up a machine torch handle.

    So now the question I have is:
    To upgrade to a pilot arc torch, do all I have to do is connect the red pilot wire (shown in the pic) to the ground electrode at the plasma end? I found some stuff on Google that indicated that is all that's required. If so, all I have to do is to fit the pilot arc terminal from the scrapped plasma to my BOC machine and wire it in and I have a very handy upgrade....
    Rod Webster
    www.vehiclemods.net.au

  20. #20
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    684

    Re: Rod's Aussie Plasma Build

    Hit a bit of a snag today. The 5v/12v Meanwell Power Supply I bought proved to be DOA. Very annoying.

    THe plasma is wired up and waiting for a plug to arrive for the voltage divider.
    Rod Webster
    www.vehiclemods.net.au

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