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CNC Plasma Table Which Controller where to start.
« on: September 26, 2019, 06:20:42 PM »
Hello everyone I am new here. A friend of mine just purchased a 4x8 plasma table without controls. The table brand is a burntable but the previous owner wanted to keep his controls. Since I have messed with CNC in the past along with 3d printers and other similar things I have been charged with building the controllers etc. My fee is use of the table on occasion.  ;D

SO where am I right now, I have a table, gantry, with steppers for x,y,z, no stepper drivers, no controller, no software and apparently no limit switches. We do have hypertherm 65 & 85 plasma machines but will have to purchase a torch for the table. And I have enough extra computers around that I could run Either windows, linux or both. The steppers I have are basically these here. https://www.probotix.com/CNC-CONTROL-SYSTEMS/CNC-CONTROLLER/3-Axis-Monster-Hybrid-Stepper-Motor-Driver-Kit

I am pretty sure that I am going to get Mach 4 and want to make sure I am looking at the proper controllers. I have been looking at the PoKeys57CNC for my controller but have read a few things that I am not so sure about the support and reliability on. Anyone have any input on the pokeys system or alternatives. If I get the Pokeys my major question is where do I hook up the torch set up. The motors, stepper drivers and all that is pretty self explanatory but the torch I am kind of lost on. In 3d printing it would be considered an extruder kind of.  Then I was looking at the plasmasense thc from prolabs but have also read about issues and that there are better ones.

Any thoughts and guidance is appreciated. This is only day 2 of my research so anything helps.

 
Re: CNC Plasma Table Which Controller where to start.
« Reply #1 on: September 26, 2019, 07:36:51 PM »
Hi,

Quote
I am pretty sure that I am going to get Mach 4 and want to make sure I am looking at the proper controllers. I have been looking at the PoKeys57CNC for my controller but have read a few things that I am not so sure about the support and reliability on

Mach4 is highly appropriate for what amounts to a new build.

At this time there are only two Mach4 ready motion controllers that support realtime THC, the Hicon (Vital Systems at approx $1000 with required activations) and the
Ethernet SmoothStepper (Warp9 at approx $180 PLUS the T3CM controller which I understand is several hundred USD).

Mach4 also has a script based THC facility, new several months ago. That means that any controller can do THC but the response is a order of magnitude (or more) slower
than the realtime controllers. NFS are clearly of the opinion that the script solution is sufficiently responsive for most users, if however your demands for THC response
are high (thin gauge metals which distort/warp rapidly for instance) then realtime THC is a must.

I would commend you look at the Ethernet SmoothStepper closely as it has the most comprehensive range of realtime supports.....backlash comp, lathe threading, encoder/index
spindle PID, laser vectoring/rastering, realtime THC, plus all the usual home/limits/probing/squaring supports that you would expect of any controller.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC Plasma Table Which Controller where to start.
« Reply #2 on: September 27, 2019, 06:49:36 AM »
The vital systems  is out of my price range for the controller. I am looking into the ESS thanks for that. I like their documentation much better than the Prokeys. The T3CM is more expensive than I thought it would be but still should be able to keep it in budget with it, which is about $1500 for software and all. Still reading up but from what I gather the t3CM is where you hook your torch up to then into the ESS and that controls it all right, height and burn?

Next is stepper drivers, reading up on those this weekend on better brands etc. Like I said I already decided on Mach 4 need to decide on which sheet cam type software I am going to go with. I need something that is pretty user friendly, me and my buddy are pretty good with computer use but another guy that's going to use it will need point and click.

I think the most difficult part for me is going to be figuring the gear ratios and steps per mm of the existing setup. Will be fun.
Re: CNC Plasma Table Which Controller where to start.
« Reply #3 on: September 27, 2019, 02:40:59 PM »
Hi.

Quote
Still reading up but from what I gather the t3CM is where you hook your torch up to then into the ESS and that controls it all right, height and burn?

That is essentially correct. There is a voltage divider (50:1) in the Hypertherm plasma. Thus the torch voltage, which is lets say
150V when cutting is presented to the TCM3 as a 3V signal. If the target voltage is 120V the TCM3 will issue a THC_DOWN
signal to the ESS and the ESS will lower the torch a step or two. Note that Mach4 is not involved, the communication delays
and the buffered control loop would mean many milliseconds of delay if Mach4 were consulted.

As the TMC3 talks directly to the ESS and the ESS has direct control over the Z axis pulses the delay is reduced to microseconds.

The closed loop bandwidth, a measure of speed of response, with the TMC3 and ESS is around 100Hz whereas if you use
Mach4s script solution, with all those pesky delays, the bandwidth is down to a few Hz. As you can see the realtime
hardware solution (TMC3/ESS) is somewhere between 10 and 50 times more responsive.

Unfortunately that speed of response, while highly desirable, is not cheap. Firstly only two controllers (Hicon and ESS)
support realtime THC and in the case of the ESS has been written and optimized with a particular THC controller (TCM3)
in mind. You want good....you can have it....pay up and no whining!!

As far as stepper drivers go you want the highest voltage ones available, at the current time 80V is the practical max available
commercially. All steppers lose 'grunt' the faster they go and a high voltage driver counteracts that, and you'll want your
steppers to go as fast as they can if you are going to cut thin metals.

Gecko is the stand out brand for quality and reliability but their  80V capable models are up to $150 each.
Leadshine AM882's can be had for around $70 from Ebay and they are 80V and up to 8.2A capable.

I would recommend a toroidal transformer/rectifier/capacitor power supply......they are much more forgiving than
the cheaper switchmode power supplies commonly used. This is an example:

http://www.antekinc.com/ps-15n80-1500w-80v-power-supply/

It has two 80V 9A outputs and will keep on going when all your switching power supplies have let out a puff of smoke
and are no more than a grease stain on the floor!!!

Craig
« Last Edit: September 27, 2019, 02:53:38 PM by joeaverage »
My wife left with my best friend...
     and I miss him!
Re: CNC Plasma Table Which Controller where to start.
« Reply #4 on: October 07, 2019, 06:33:46 PM »
So I have been digging and I have a list of major components that I need to buy. This does not include things like the limit switch or E-stop relays but please take a look and let me know what you think. Am I missing hardware? Am I missing any plugins that need to be paid for? Its attached in an excel document.

Re: CNC Plasma Table Which Controller where to start.
« Reply #5 on: October 08, 2019, 01:26:13 AM »
Hi,
I see you have not allowed for a breakout board/boards. While all the smart motion control stuff happens in the ESS
a breakout board allows you to match the ESS inputs and outputs to real world components.

A common example would be  a 24V relay to turn on a blower. 24VDC is very VERY widely used in industrial practice
and as a consequence the range of 24V parts, like relays, lights etc is very extensive. On the other hand 5V relays with
sensitive coils that could be operated by the low currents available direct from an ESS are available but rare.

Simple C10s ($23 each) are birectional so can be adapted to any one port (of three) of an ESS. Note that they are still
only 5V boards, they have a TTL buffer good to about 20mA only. Note also that they do not have any relays or a PWM
to analogue circuit nor do they have any opto-isolated inputs. If you need these features you need to add the extra
few electronic components to effect them.  They are cheap and flexible if you are  prepared to add the extra bits.

If you are not inclined to add extra circuitry you might look at an MB03 from CNCRoom ($180). All three ESS ports are
developed/exploited with a range of inputs and outputs and a variety of signaling arrangements (single ended, differential,
opto-isolated etc). Naturally you will have to conform to the choices the manufacturer made but all in all its a well thought
out and executed breakout board.

You should allow for a bottle or two of whiskey to calm the nerves when wiring it all up!

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC Plasma Table Which Controller where to start.
« Reply #6 on: October 08, 2019, 06:48:05 AM »
Joe, pardon my ignorance but do I really need a bob and why? If I have ribbon cable cant I just go from the ESS/thc to the stepper drivers?

The c10s is cheap but I think I like the MB3 more.
The MB3 appears to use the headers that the THC will need, how would I use both together? I like the look and format of the mb3 better just not sure it will work with the THC.

I am very familiar with relays and micro controllers 5v relays are pretty easy to get now with the pi being around. I actually have several realy boards with 8 to 16 relays on them that are 5v signal controlled.
Re: CNC Plasma Table Which Controller where to start.
« Reply #7 on: October 08, 2019, 10:38:48 AM »
Hi,

Quote
Joe, pardon my ignorance but do I really need a bob and why? If I have ribbon cable cant I just go from the ESS/thc to the stepper drivers?

Yes, you can go direct from the ESS to the stepper drivers if you wish.....but the slightest hiccup in your wiring and you blow the ESS.
A BoB provides an easier and more secure means of attaching wires to drivers, switches etc and buffering that will go some way to
protecting the ESS.

Quote
I am very familiar with relays and micro controllers 5v relays are pretty easy to get now with the pi being around. I actually have several realy boards with 8 to 16 relays on them that are 5v signal controlled.

As I said, 5V relays are available, less readily than 24V relays however. Also if you are restricted to the output current of the ESS,
supposedly 20mA, but you would be advised to stress the ESS less by demanding 5mA or less, then the relays are small
and therefore unlikely to be able to handle significant current.

By all means use the ESS without a BoB but when you blow it up.....no whining or moaning....you were warned.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC Plasma Table Which Controller where to start.
« Reply #8 on: October 08, 2019, 01:10:50 PM »
Joe I hope I didn't strike a nerve, just trying to understand why I would need the BOB. Your first reply seemed to be just for hooking up other items. That why I did not see why I need a BOB. Not saying I wont use one just trying to understand why I need one. Also the stepper drivers I will be using have i/o protection so that should help.

Also am I correct in assuming the mb3 that you mentioned wont work with the THC without a bunch of extra wiring?
Re: CNC Plasma Table Which Controller where to start.
« Reply #9 on: October 08, 2019, 02:37:28 PM »
Hi,

Quote
Also am I correct in assuming the mb3 that you mentioned wont work with the THC without a bunch of extra wiring?

No, the THC will work, better in fact, with the presence of a breakout board.

Craig
My wife left with my best friend...
     and I miss him!