Candcnc bladerunner problems

[peter_plasma]

Hello!

I have a 2013 CandCNC Bladerunner system with DTHC(DTHC II I think, not really sure), a windows XP computer with mach3 and a HT Powermax 45 plasma cutter. I have 2 problems:

- The arc shuts off for about a second sometimes. The motion continues as if nothing happened which leads to an interruption in the cut. It also stops the air to the torch. I thought it was bad air supply but the pressure are within recommendation. I have also tried increasing the pressure with the regulator on the powermax 45 but the problem persists.

- Sometimes after a cut is finished the z zero is reset at a position 7-9mm lower than the plate top. It seems to happen just at the end of the cut. This leads to the torch plunging in to the plate at the next cut and the magnetic torch holder breaking off.

Any ideas? Maybe both problems are caused by signal problems in the parallell port communication or some problem in the candcnc control box?

[WyoGreen]

Lets assume either the loss of the arc causes the air to shut off, or the loss of air causes the arc to shut off. Now the arc is controlled by the "arc ok" pair from the controller to the plasma cutter. The air is pretty much contained within the plasma cutter. Which leads to a couple of possibilities: The "arc ok" pair is defective in some way, maybe a loose wire or broken wire; or the solenoid on the air valve in the plasma cutter is having some kind of problem.
The simplest thing to check out first would be the "arc ok" pair. Just follow the pair from one end to the other, checking the connections to insure they are good. If that doesn't fix the problem, you could also check the continuity of each wire with a ohm meter, shaking the wire while watching the meter to see if there could be a problem in the wire.
The air shutting off is a bit bothersome. Normally the air stays on until the tip cools down or until the trigger is pulled again. Which I suppose leads us back to the 'arc ok' again, with the 'arc ok' dropping and then coming right back on again.
Well, that's my thoughts on the problem, good luck, Steve

[chattacuda]

Does the "torch on" icon on your screen go out when the torch stops firing during cuts? I think WyoGreen is on the right track. Electronics don't normally have intermittent problems; they either work or don't so focusing on the cables and connections are the right thing.

[peter_plasma]

The ”torch on” icon is not affected when the torch cuts off, the red light is there as if the torch would be on.

I will try to check the ”arc ok” cables and connections

[peter_plasma]

I have done some testing:

On the DTHC II module the ”torch on” red led is still on when the arc cuts off. The relay for the ”torch on” clicks when the arc cuts off which made me think it was a bad relay. I connected another relay instead but that relay also clicks(shuts off the arc for a second). I think it can be something wrong on the DTHC II module, circuit board or some component or soldering.

Since the red led for ”torch on” is always on when the arc cuts off and the ”torch on” button in mach3 is also on, I guess that the DTHC II module gets the correct signals from the main control box. Since the relay clicks when the arc cuts off it shouldn't be any problem with cable to the plasma cutter or the plasma cutter itself.

[Rodw]

There is little known possible gotcha that could possibly cause the behaviour you describe. The internal relay in the Hypertherms has a minimum current requirement of 100 mA up to a maximum of 10 amps.

If you are using electronic controllers, it is possible that the devise has a high impedance circuit. eg. My controller has something like 15 K Ohm resistance which means the current through the relay is < 100 mA. Over time, oxide builds up and the arc OK relay operation becomes intermittent.

The solution is to use a pull down resistor to increase the current flowing through the resistor. You need to know details of the controller before you can select the resistor. We aimed to get between 200-300 mA and the current handling capacity of the resistor became every important.

If you search this forum for my spaceship plasma build thread, there was a discussion about it and Tom Caudle added some good feedback. So, you'd like to think that CandCNC had accounted for this in their design.

[dodom]

A lot has changed in the Candcnc design in past 8 years Rod W. You would like to think you would be fully forthcoming in that fact.

[cutnweld]

Then offer help instead of turning on Rod. You like to talk of good support, give some instead of getting huffy when others know more than yourself

[dodom]

https://www.candcnc.net/supportforum/index.php 903-364-2740 Actual product help.

[tcaudle]

Since it seems that a technical explanation is needed here it is:
The Current DTHC has a low side power FET (several amps) driver at the DTHC module that turns on the relayy inside our PWMII moduel via the CAT cable . That relay is a small 1A 30ma coil 12V relay and that closes the START contacts on the plasma. Most torch-on circuits on virtuall all plasma just need a simple switch closure (aka relay contacts) No external voltage or current needed . We have not found a plasma yet (including some of the larger rigs and mixed gas ones that the simple relay won't fire.

The DTHCII used another method to fire the torch relay. The "driver (small FET- 200ma ) was on the UBOB card and just connected THROUGH the DTHCII module. The more likely problem is MACH and a condition it had with a parallel port system and our muxed Output circuit on older cads. Windows would "jitter" (glitch) when certain background processes were running and cause the pulse stream to hiccup . It was worse on some computers than others . A torch does not like a quick on-off/on sequence. The cure is software/settings and optimizing Windows , not hardware on a parallel port operation . We have a "Lamp Test" you can use to ferret out what is causing it. The torch fire noise spike was one source while background apps was another. It happens fast enough that you don't see the torch led flash unless you are starting at it . The MACH document on optimizing is a good source on this

I think I answered this person on our support forum where its aimed at fixing issues (especially on 7 year old equipment). We have been doing this for over 16 years and though Windows 95 to Windows 7 and MACH1 to MACH3

Not sure why Rod feels compelled to jump in on a question about a system he has absolutely no knowledge on but he is certainly welcome to do so if he does not mind my corrections .

I spend most of my time on our Support Forum and answering direct email on the older Windows based systems . I don't get on this list very often so its not the fastest or most accurate method of getting support on older systems.

[Rodw]

Not sure why Rod feels compelled to jump in on a question about a system he has absolutely no knowledge on but he is certainly welcome to do so if he does not mind my corrections .

Not at all. I often get things wrong about things I know something about as well! Getting corrected is how you learn.