THC on off not working..

[davek0974]

The THC on and off button on my new build plasma table does not work.

I fitted a proma THC yesterday and have the arc-ok, up and down signals showing up nicely in mach diagnostic screen but the THC on/off toggle does nothing?

The only way I can get z action is to tick the "allow THC even when not in THC mode" box under config. With this ticked it all works but I can't stop it now if I want to cut small holes etc, I have to manually disconnect the THC!!

The software is licensed but how do you get this button to work?

Similar Threads:

• What is the difference between wood working and metal working routers?
• Newbie- Something I am working on
• Got it all working
• Need Help!- M8 Not working?
• thc working or not?

[davek0974]

It turns out that the THC on/off button only works when code is running AND there is an arc-good signal.

[planescott]

how is it supposed to start and stop the torch , do you have the torch trigger hooked up to a relay? I am looking into using one of these I read the manual and didn't understand how it would fire the torch without a relay hooked up. sounds like you got it going now I could use some good info if you don't mind.

[davek0974]

Hi

it's simple.

The torch trigger is connected to a small relay, this relay is controlled by the "motor" relay on the break-out board, that relay is controlled by Mach3 using the spindle on/off commands. There are other commands, but this is the easiest straight-out-of-the-box method and works well.

Make sure you have the spindle commands in Mach setup set for instant stop/start and not ramped up/down.

The torch can be controlled directly from the "motor" relay on the BOB, I am just using another one for a bit of added isolation.

Dave

[planescott]

ok thks Dave that sounds like what I was thinking. is your proma thc working with good results? one other thing do you have the anti-dive button on your mach3 screen. I have the basic mach3 plasma screen and its not on there. I seen a guy on youtube with it and he sets it to 25% to help cutting across lines an not diving into the piece.

scott

[Torchhead]

The anti dive button / setting in MACH is based on the Feedrate (actual versus the commanded) s o it only works if the toolpath is such that it causes a slowdown. it won't help crossing over a cut line or hitting a void. It also dose not stop the dive at the end of the cut

[davek0974]

The antidive setting is called "THC Rate" in Mach, I have mine set to 95% - if the speed drops below 95% of my coded feed rate then antidive is switched on.

No, it does not stop it diving due to a gap in the cut, you need a standalone THC for that.

The Proma unit is ok at cut rates below about 3300mm/min, above that i have no idea but its a pretty slow unit. My table can only cope with about 8mm of warp in the sheet, so no cutting corrugated sheet with this unit !

[Torchhead]

The antidive setting is called "THC Rate" in Mach, I have mine set to 95% - if the speed drops below 95% of my coded feed rate then antidive is switched on.

No, it does not stop it diving due to a gap in the cut, you need a standalone THC for that.

The Proma unit is ok at cut rates below about 3300mm/min, above that i have no idea but its a pretty slow unit. My table can only cope with about 8mm of warp in the sheet, so no cutting corrugated sheet with this unit !

THC Rate is NOT anti dive. It is how fast (the rate) your Z moves during a cut with THC on. Trust me on this. I worked with Art in 2000 to put THC logic into MACH3 and he came up with the THC Rate setting because the Z may do a lot of Up and down short moves and there is no time to apply the acceleration number for Z. Setting THC RATE too high will stall the Z (lose steps) The anti-dive DRO is a totally different setting and as I stated, based on the actual feedrate.

You do not need a "stand alone" THC to get true anti-dive based on a voltage spike from crossing a void.....all of our THCs for the past 8 years have had "Tip Saver" (anti dive) set as a % of the Torch Volts. Even the hoby grade LCTHC has it and So do several other brands of MACH based THC. The horizontal speed for THC is dependent on the vertical warp of the material which is dependent to a large extent on the material thickness and type

[davek0974]

Yes, my mistake, apologies.

The box is called AntiDive% NOT THC Rate.


While you are there, I have sent several emails requesting information on the LCTHC unit to see if it will work with my setup, but not had any reply, I guessed you were away??

Will it work on a system without a built-in cnc socket on the plasma??

Many thanks

[planescott]

ok thc rate mine is at 60%, to fast and stalls the motor but what about to slow?

I cant get my proma to work right I have it hooked up to 50:1 should I hook it inside to raw arc and see if that helps (hyp45pm) when I start to cut(14ga mild steel at 30amps) goes about an inch at 110ipm it goes up until torch goes out.

any ideas I know a better thc would help but just cant do it at the moment.

[davek0974]

I'm having issues too with my Proma but thats a different story.

How did you arrive at your cut voltage?

I do a straight cut with THC off, about 150-200mm long at my chosen cut height and speed, while its cutting I monitor the display on the Proma and note the most steady voltage shown, this seems to work ok.

[planescott]

I put new tip and electrode in cut 1 piece with proma disconnected got very good cut then turned on proma and just guessed at a voltage , I will have to try watching the voltage like you said.

[davek0974]

Its really the only way to find the correct setting, I found some very odd behaviour was being caused by having the volts set too far out of correct.

[planescott]

Sounds logical, you would think they would put stuff like that in their directions lol. What about the voltage tolerance + or - 1v to much or need to be higher I think default 8

[davek0974]

Yes, way too tight, I went through this only last week.

The best setting seems to 4 which is +/-2v, it seems it can handle that ok.

The most warp i can handle is 8mm across a 625mm sheet, any more warp and my system craps out and the torch hits the sheet, that is running at 3300mm/min though, a slower cut would give it more time to react, much faster and forget about it

[Torchhead]

Yes, my mistake, apologies.

The box is called AntiDive% NOT THC Rate.


While you are there, I have sent several emails requesting information on the LCTHC unit to see if it will work with my setup, but not had any reply, I guessed you were away??

Will it work on a system without a built-in cnc socket on the plasma??

Many thanks

Emails to me or the IM in this list? i don't use the list here for messages. We only sell the LCTHC to US and Canadian customers. We support the LCTHC at the same intensity as the our other products and cannot do that on a low margin item across more than a couple of timezones. Since it is an add-on THC there are some BoB's it will work with and others it will not (like the THA6560 units) Instead of just selling you a cheap product and let you get support off the forums we write extensive manuals and answer phone calls and use our Support Forum.

The LCTHC does not work with the 50:1 divider because it is not designed to mount at the plasma cutter and trying to get the 50:1 to work more than a few inches from the plasma is futile unless you use the analog to digital conversion method like we do on our MP3000 series.

The LCTHC comes with a remote pickup voltage divider /filter and torch relay card (THC SENSOR Card) It is designed to work with any plasma and has inputs for a low cost current transformer (optional) to measure the AC side

We have a direct connect to the Hypertherm 45 (single cable.to the rear CPC) but once again ti takes the MP3000 technology to use the internal 50:1 divider. Go back and review the earlier post on why the 50:1 is harder to use. It is not just simply mounting it closer but also the design of the THC input. We have Universal connection kits for virtually all plasmas for the MP3000 but we worked with Hypertherm to support their advanced options (like the RS485 remote control available as an option on the Powermax 65 - 125 line) )

[davek0974]

Emails to me or the IM in this list? i don't use the list here for messages. We only sell the LCTHC to US and Canadian customers. We support the LCTHC at the same intensity as the our other products and cannot do that on a low margin item across more than a couple of timezones. Since it is an add-on THC there are some BoB's it will work with and others it will not (like the THA6560 units) Instead of just selling you a cheap product and let you get support off the forums we write extensive manuals and answer phone calls and use our Support Forum.

The LCTHC does not work with the 50:1 divider because it is not designed to mount at the plasma cutter and trying to get the 50:1 to work more than a few inches from the plasma is futile unless you use the analog to digital conversion method like we do on our MP3000 series.

The LCTHC comes with a remote pickup voltage divider /filter and torch relay card (THC SENSOR Card) It is designed to work with any plasma and has inputs for a low cost current transformer (optional) to measure the AC side

We have a direct connect to the Hypertherm 45 (single cable.to the rear CPC) but once again ti takes the MP3000 technology to use the internal 50:1 divider. Go back and review the earlier post on why the 50:1 is harder to use. It is not just simply mounting it closer but also the design of the THC input. We have Universal connection kits for virtually all plasmas for the MP3000 but we worked with Hypertherm to support their advanced options (like the RS485 remote control available as an option on the Powermax 65 - 125 line) )

Thanks for the reply, I was emailing tom@candcnc????

Anyway, the manual for the LCTHC shows an interface card that connects to the torch terminals and uses a current transformer and needs three inputs on the BOB???

Is that not the way it still works?

That sounds exactly like what i need, I do not want a divider as my little machine has no divider output.

I'm just desperate for a THC that is better than the Proma POS I have currently

any help appreciated

Dave

[Torchhead]

I put new tip and electrode in cut 1 piece with proma disconnected got very good cut then turned on proma and just guessed at a voltage , I will have to try watching the voltage like you said.

All THC is about very precise voltage feedback and control. Every volt out of range for the arc gap you need (.060 for Hypertherm torches) products about .010 to .015 inhes of variance....what that means is to get acceptable tracking you have to keep the voltage variance with in 2 volts and most THC's will work around 1 volt. Resolution (smallest voltage the unit can read ) is typically 1/4 volt. The resolution on our new DTHC IV is .06 volt and with PID feedback outside MACH3 it can actually tack and high speeds well within 1/2V.

So...you first have to determine the voltage you are getting back during a manual cut and use that as the baseline Preset Volts. It should be close to the voltage you see in the cut chart (if your plasma has one)
As I stated a few volts off is a LOT in the plasma cutting world.

I understand the desire to have a cheap THC but nothing is a good deal if you can't make it work and hold a height that gives you a good cut.

You might get the manual for the LCTHC off my website (manuals page) it covers a lot of plasma theory and setup procedures that could help fill in the blanks you have now.

[Torchhead]

Thanks for the reply, I was emailing tom@candcnc????

Anyway, the manual for the LCTHC shows an interface card that connects to the torch terminals and uses a current transformer and needs three inputs on the BOB???

Is that not the way it still works?

That sounds exactly like what i need, I do not want a divider as my little machine has no divider output.

I'm just desperate for a THC that is better than the Proma POS I have currently

any help appreciated

Dave

and I did reply with it mixed into your email to me . Check your inbox.
The LCTHC still has the THC sensor card and still has the voltage divider , torch relay and the Current transformer input