Which THC works best with UCCNC

[nordwind]

Hi All!

I have a self built plasma table which runs now on Mach3 and has no THC at all.
However, Im planing to get rid of Mach3 and go all the way with UCCNC.
That means new Software, new controller board, breakout board and so on. On this occation I also want to include THC.

The problem I have now is, that im little overwhelmed by the huge amount of possibilities and boards and so on..
So I thought I ask you guys, if you can recommend which way I should proceed:

1. Which THC would you recommend best to work together with UCNC?
2. How serious is the whole Anti-Dive issue with THCs?
3. Has anyone experience with the Proma THC? Which version there is recommendable? Are there problems with diving torch?
4. What about the Neutron THCs? Are they worth the huge price?
5. Anything else THC vise to take a look at?

Im really looking into the most reliable way, which has the least amount of troubles and is well documented, as this is for a production machine. If there arise unforseen problems taking everything into a working state, that would mean alot of trouble for me.

Thanks for any advice!

Greetings from Switzerland

[Robertspark]

Works best is a difficult question.

In essence all thc that provide an UP, DN and ARCOK signal will work the same.

Uccnc gets the signal as responds accordingly.
________________________________________

You have to remember there are two bits of equipment at play here..... UC motion controller (they are all fast and work the same essentially ... Some have more pins and some have the option to run at a faster kernel speed)

The other bit is the THC.... They are all different... I am not a fan of either Proma, but you have other options (I will post a list later)

[nordwind]

Hi Rob

Thanks for your reply.

At the moment, Im planning in purchasing UCCNC + UC400ETH + HDBB2 Breakout Board.

I would really enjoy reading your list of THCs later! Can you give a hint on why youre not quite a fan of Proma THCs? For me, the product just seems to be a little bit "hobby" like. But other than that, I mean, when it does, what it promises, why not.. ?

To the Anti-Dive Function:
Am I correct, that this feature does not have to be supported by the THC controller itself?
I mean, the THC controller only gives signales to go up and down with the Z-Axis. It is in the responsability of the CNC Control Software to ignore these signals when slowing down the feedrate on corners and so on thus not allowing the Z-Axis to dive in this situations.
After the slowing down and speeding up again, the CNC control software will then again follow the instructions of the THC controller.

Is that correct?

[cncdrive]

Basicly any THC will work with the UCCNC. Even a simple window comparator circuit could work, because the UCCNC has functions implemented inside the software like the pierce delay which is an important thing and which the proma THC has, but even the UCCNC itself has that function.
The Neuron is probably the most advanced THC you can use and it has lots of nice features. If it worth the price for you only you can decide.

Here is a video of the UCCNC with NeuronTHC on a plasma machine:

[Robertspark]

Proma THC is available as the:
Proma Compact 150 THC
Proma THC SD

And I think there may be another compact solution.

I believe all the internals are roughly the same, although I've only ever owned and used the 150 so can only speak about that performance wise. (in short I was disappointed, but it depends on your expectation, as they have sold 1000's everywhere, and are used loads.... but I'm not sure if anyone will swear by them..... of just uses them as a fix to a solution..... the problem is settings and internal relays in my opinion with changing material thicknesses if you are like me and do any old thing with any old plate...... if all you do is the same old day in day out with one setting I'm sure they can be tuned great but I could not remember all the settings that I needed to change ever time I changed material.

The 150 basically takes the input voltage from the plasma cutter (either raw or 1:50 divided) and outputs 3 signals to the motion controller.
a) is the ARCOK signal.
b) THC UP
c) THC DOWN
The ARC OK is achieved when the voltage is below a single internal setpoint within the Proma, to be fair this setpoint is never really changed, and just indicates that the plasma cutter arc has changed from "transfer" (which is the plasma ignite) to the "cutting" arc phase.
The THC UP / DOWN are basically output when the sensed voltage is above / below the setpoint +/- the internal hysterysis setpoint which is a minimum setting of 1V (which is a lot in my opinion as its +1 and -1 to 2 volts around the setpoint of whatever you set depending upon what material and thickness you are cutting..... I cut 1mm, 1.5mm, 2mm, 2.5mm, 4mm and 6mm ....... all mild steel.... that for me is a PIA to remember the settings and remember to adjust them every time a throw a bit of plate on the table to be cut.

The Proma SD is different..... basically it interrupts your Z-axis and will step the axis up and down directly relative to the setpoint...... whist this sounds great as it misses out the requirement for a motion controller that is compatible with THC commands it also creates a few issues....... it has no acceleration parameter..... it will just shunt it up to the velocity you set for up and down motion.... the setpoint and hysterysis is just as large as the Proma 150, but their are a few more settings for the steeper motor such as steps and travel etc.

Another problem with the proma THC's is they appear to use relays for ARCOK, THCUP and THCDN...... relays are fine.... but they can be a bit slow when you are cutting thin plate fast .... when I want it to go up, I want it up now, not in 100mSec+ where at 300"/min (7.6m/min) it would have travelled 12mm to maybe 25mm before the torch begins to do anything...... and also by the time it stops (another 100mSec later) its probably missed the target and is now shooting in the other direction.... optoisolators would have been better (quicker).

Other options that I am aware of:
MiniTHC
Yes I have one of these and I've spoken to Denis many times and do recommend them.
Basically its like the Proma 150 in that it measures the voltage around a setpoint. the voltage and hysteresis can all be passed to the controller from the post processor as well as the ArcOK delay etc.... and it uses optoisolators..... it is not the best... but its quicker (20khz) I think is the voltage sense

Neuron Simplicity
Ok this is not cheap, it is a stand alone THC (truly stand alone) and will be very good. (I know Andrew and talk with him regularly, I am biased ..... I have a Neuron Lite THC {whole other league}, you will find him on various forums under the name "shad" including the UCCNC forum where is active
It is very different in that it will directly control your Z axis and basically all you tell it is when to start (a single digital output pin), when you want to inhibit THC (so that anti-dive and other THC motion lock base on voltage sensed functions work), and it provides a "motion" feedback signal which is the same as "ARCOK" and tells your X and Y axis that it can now move.
Problem in my opinion..... you need to set the voltage for everything you cut..... so again if you are like me and cut various thicknesses and not a lot of it it can be a PIA to reset and remember the settings (ok you could use a chart).


I will leave the discussion out of these as they are going to be out of your needs and price range I expect (but worth a flip through, it costs nothing to read but time):
Neuron Lite
There is a Neuron Pro, but you won't ever need that unless you do Oxy/Acetylene or Plasma + Oxy/Acetylene.
TMC3in1 only works with Smooth Stepper and therefore Mach3 (and if they ever get around to a driver for the TMC3in1 maybe mach4 one day.... it requires a special driver / plugin)
CandCNC in short is expensive and unless you're and american customer their customer service can be short and abrupt {there are a few posts on them from not happy customers on the net} , they are stand alone THC's and have a strong customer base with a lot of customers (they have been around a long time). I suspect that the abruptness comes from frustration with being asked the same questions over and over again over the years with users not able / willing to do a little research.

Now the other options which are promising (ie I don't have one, but would consider):
Razordance DTHC This one does have a plugin for UCCNC and the developer is Sterling who is well known on the Mach forum. And is now on the UCCNC forum. I would have bought one of these ages ago (before the proma), the website looked a bit old and I was not sure if it was supported, but I can assure you that it is supported and available (from last discussions I had) Terry / Vmax on here has done some work with one with a screenset etc.

Polabs they do two of them (only seen them recently) one is VERY similar to the Proma 150, the other will not be compatible with UCCNC and will require their own BoB with Mach3/Mach4. This does look interesting as this one uses optoisolators and is likely to be faster than the Proma 150, and its in a similar price bracket from Hungary.


Ones that I am aware of (but would not consider personally for various reasons, if you are interested in any I'll reply to them directly)
PriceCNC I know that Rtech use them with their plasma tables (appears arduino based), may be a bit slow in my opinion, and have not been around that long.
Agelkom THC (also known as CAP04 sometimes in searches)
Star Plasma / THC (got a few names this one, but all look the same)
Purelogic won't work with UCCNC, only Mach3 I believe and their own cnc software

And if you're really keen, time is cheap and you have loads of it you could build an Arduino based THC

There also a possibly simpler option..... to buy a MESA THCAD (they have two versions and 10V and 300V version, the 10V can be extended with additional resistors).
These are interesting and are used with LinuxCNC via an encoder input. Basically they are precision voltage to frequency converter boards and are isolated. So they offer the opportunity for you to use a PWM signal input via something like an Arduino board (or faster if you really require) to issue a THC UP/DN and ARCOK signal, you could also extend that to a full stand alone THC control should you have the wish.... Basically the THCAD resolves the most difficult part in my opinion, the isolated voltage divider. After that its mainly code and some simple IO hardware.

[cncdrive]

Proma THC is also available at us, we have them in stock: http://shop.cncdrive.com/index.php?sear ... hc&x=0&y=0

[Robertspark]

Stumbled across another one (can't vouch for it, don't know if it's fast / slow and how well it will track the voltage)

http://robot3t.com/en/san-pham/compact- ... wn-output/

[cncdrive]

Fast THC is not always good, if it is fast can be due to bad design.
I'm saying this, because the noise level (spikes) are usually high with plasmas and fast response means a low low pass filtering of the input signal and then it is likely to respond to spikes which is unwanted.
The best is to find a midway (not too slow and not too fast) in speed and noise rejection or even better if the input filter time constant is configurable.

[shad]

Rob, Thank you for short review about Simplicity.
I want to add that Neuron Simplicity controller has 30 cut settings profiles and Sample&Hold future.
Also UCCNC has a very nice function for plasma - it's automatically return on the Arc Lost position (XY plane) when "motion" feedback signal from cutter or controller is lost.

[beefy]

Fast THC is not always good, if it is fast can be due to bad design.
I'm saying this, because the noise level (spikes) are usually high with plasmas and fast response means a low low pass filtering of the input signal and then it is likely to respond to spikes which is unwanted.
The best is to find a midway (not too slow and not too fast) in speed and noise rejection or even better if the input filter time constant is configurable.

I would like to add to what Balazs said. I've seen a few sellers say you want the fastest possible THC reaction, even when cutting thick metal where the travel speed is very slow. I've found that is completely untrue and misleading, no doubt they say it to try and sell their systems. In any case, if a system controls a stepper motor (many do), how fast can the stepper motor react. Unlike servos which can react much faster due to a high current / torque boost, steppers are simply fixed current devices, and thus can only deal with a max accel/decel applied. The THC electronics may be able to output fast signals but can the mechanics follow ???????

For a certain cut, you only need enough reaction speed to deal with the conditions at hand. Why would you need a super fast reaction when a slow cut passes over a void/kerf. The torch would immediately dive down unless you have its super fast reaction dumbed down in the void anti-dive settings. But even then the problem would be the the rate of rise of voltage would never be acheived to operate the anti-dive, because the torch reaction would be so fast that it immediately starts moving down as the torch crosses the kerf, and thus a fast rate of change of voltage is never sensed. Result is the torch dives into the plate.

My advise is be very wary of sellers who tell you that a high speed THC is always necessary. To me it's a bit like saying you need a Ferrari to pop to the local shops in a slow speed zone. If you'll never need to do thin sheet, corrugated, etc, then as far as THC speed is concerned you'll probably get by fine with a basic system that outputs THC UP/DOWN signals to the cnc controller. Now there's more to plasma cutting than THC control so you really need to look at all features of a system and decide which ones you want.

Filtering of the plasma noise takes a finite amount of time, and as Balazs explained, the less time you have for filtering, the worse the filtering. I designed my own THC and for this reason I choose a longer filtering time, about 62 samples per second. My THC is only a stepper drive and I can't see any benefit in going higher than this sample rate for the cutting speeds I use. Is a mechanical stepper drive capable of changing direction 62 times in one second. Or think about it this way, at a fast cutting speed of 10,000 mm/min the torch would only travel 2.7mm for each 1/62 of a second. I never cut at this speed and so the relatively "slow" speed of my THC is more than enough.

Saying that I ended up using Andrew/Shads THC (Neuron), not because of its fast speed but because of the integrated features.