I need help thc robot3t up-down

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I need help thc robot3t up-down

Postby Optocoplado » Mon Jan 21, 2019 5:20 pm

good afternoon, first of all I apologize for my bad English. I recently finished my cnc for plasma and I bought a thc robot3t with outputs up and down. I'm not familiar with thc and I do not know how it works. In theory it must work by measuring the tension of the arc and correcting based on the setpoint that it places. The problem is that I am not very clear about the function of the thc parameters. Would someone be so kind to help me adjust the thc? I have all the wiring placed, the correct configuration in mach3 but the thc does not regulate the height of the torch as it should. Thank you
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Re: I need help thc robot3t up-down

Postby beefy » Mon Jan 21, 2019 9:05 pm

I had a look at a manual I found after Googling. No wonder you cannot figure out what everything means.

I'd contact the manufacturer and ask them a bunch of questions. It's clear their English capabilities are lacking so you may need to ask the same question several different ways so they understand exactly what it is you want to know.

The first thing I do before I buy any product like this is check the user manual. If it does not provide well written, comprehensive, easy to understand instructions for the product, I often don't buy it.

Have a look at some other THC user manuals which may give you a better understanding of the different settings.

Most THCs measure arc voltage, and if it's not at the correct set point, they move the torch up or down.

You have something called a "dead band" (may have other names) which is a form of hysteresis, where the THC is happy with the voltage value and does not go up or down. Example if your set volts is 140 and you have a dead band of 1 volt, then the THC will not make any adjustments if the voltage is higher than 139.5 or lower than 140.5 This helps prevent oscillating.

Another possible adjustment is for when the torch passes over a void (like crossing over an existing cut, or going off the edge). The voltage will suddenly increase when this happens and you can set the value at which the torch gets "locked" so that it doesn't dive down to try and correct the voltage. This is often called anti-dive but there are actually two types of anti-dive.

The other anti-dive is NOT in the THC but is in the cnc software. It freezes the THC control when the cut speed drops below a certain percentage. Example if your XY feedrate was set at 1000 mm/min and your anti-dive was at 80%, if the feedrate fell below 800 mm/min the cnc software would ignore THC UP/DOWN signals. This often happens at tight corners where acceleration and deceleration drop the feedrate momentarily. Why freeze the torch ?? When the feedrate slows down the torch burns more metal away and the voltage increases. Therefore the THC wants to move the torch down to correct the voltage, and it could drive the torch down into the metal.

There are more settings but I have to go out now. Look also at the UCCNC user manual to see what THC settings it has and the explanations of their purpose. Search for "THC" on the different forums too - Cnczone, Mach3, here, and read through the various posts.
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Re: I need help thc robot3t up-down

Postby Greolt » Tue Jan 22, 2019 12:26 am

I use one of these THCs

Agree the supplied info is not very comprehensive.

However I have found Toai's english is good and help is available.
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Re: I need help thc robot3t up-down

Postby Optocoplado » Tue Jan 22, 2019 12:30 am

Could you tell me what steps to follow to adjust it and be able to work with it? Toai does not answer my messages
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Re: I need help thc robot3t up-down

Postby laki » Tue Jan 22, 2019 1:34 am

I found this manual for THC Robot 3t on this link http://www.variometrum.com/PDF/USER_MAN ... P_DOWN.pdf
If I understand this manual correctly,
Parameter 1 (Set-height), from the image you supplied, is for setting the working voltage (torch height).

Parameter 2 (Area for control) is settings for ARC OK signal. For example: If parameter 1 is set to 125 and parameter 2 to 30, this means that the ARC OK signal will only be active if the voltages range from 95V to 155V.

Parameter 3 (Sensitive) is something called "dead band" as Beefy wrote in the previous post. This parameter determines the sensitivity (response of the Z axis) to changes in plasma arc voltages.

Parameter 4 (Arc-voltage), as indicated in the manual, shows the plasma arc voltage.

Also in Mach3 go to config / ports and pins / mill options and turn on Allow THC UP / DOWN Control option even if not in THC Mode.
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Re: I need help thc robot3t up-down

Postby laki » Tue Jan 22, 2019 2:45 am

If you've connected everything properly, try to do the following
Make trial cuts with THC off in Mach3 (Program Run tab). Also in Mach3 go to config / ports and pins / mill options and turn off the Allow THC UP / DOWN Control option even if not in THC Mode.
This will allow you to see the voltage of the arc on the THC (parameter 4) during the plasma cutting and the plasma torch will not move up and down. If the cutting parameters are well set (the torch height, the feed rate) and the cut is good, you should set the value of the arc voltage you see on the THC (Parameter 4 average value) as parameter 1 (Set-height).
Parameter 2. Set the value to 50V for the beginning
Parameter 3. Set to a lower value for start so that no oscillation occurs

Now in Mach3 turn on the Allow THC UP/DOWN Control option even if not in THC Mode and set THC Speed to 15 (on the Program run tab) and try to make a cut.
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Re: I need help thc robot3t up-down

Postby Optocoplado » Thu Jan 24, 2019 6:39 am

good morning again, friend laki, you have hit the solution to my problem, that was actually the solution, on the other hand the thc has two parameters that do not come in the manual and I had to find out by trial and error. thank you very much for your help.
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Re: I need help thc robot3t up-down

Postby laki » Thu Jan 24, 2019 6:54 pm

You're welcome. I'm glad I could help
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