Prime cause of a flame-out???

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davek0974
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Prime cause of a flame-out???

Post by davek0974 »

I did the first full sheet on my new table today, tightly nested and all arty-farty stuff, loads of pierces etc.

I had four flame-outs which, luckily i recovered from by re-running the code segment and manually firing the torch when needed.

All the same - cut starts perfectly, then midway the flame just extinguishes and the torch carries on a way then re-fires or if i set Mach to stop on arc loss, it will just stop as expected.

The air is dry, refrigerated dryer fitted, i purged the line for a good minute or so before cutting and saw no moisture ejected.

This was cutting 3mm cold-reduced at 4100mm/min, 45A, 1.5mm height, 107v, work lead was direct to sheet.

This has happened before but prior to this job I have only really cut single items at each run as my stuff is usually small so the odd flame-out here or there is not noticed as much.

Consumables still appear very good.
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Re: Prime cause of a flame-out???

Post by SeanP »

Never had a single loss of arc part way through a cut, had a few when piercing, usually put that down to bad consumables nowadays although I had happening a lot more often with the previous pc.
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Re: Prime cause of a flame-out???

Post by davek0974 »

It definitely starts cutting ok, can be anywhere mid-cut when it does it.

I have not thought of looking at Mach screen when it does it yet to see if the torch led is on or off, usually just panic and get it going again ;)
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Re: Prime cause of a flame-out???

Post by tnbndr »

Start narrowing down the cause by changing one thing at a time.
Watch the physical movement of the Z axis, is it searching for height? When flamed out check the voltage on Mach screen, mine usually is spiked at like 205 or something.
I just went through similar issue.

http://www.plasmaspider.com/viewtopic.php?f=3&t=17595
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Re: Prime cause of a flame-out???

Post by davek0974 »

Thanks, I do think it may be THC related as I'm not happy with that yet, not sure what THC Rate should be set at yet, plus my voltages are always 8-10v lower than book specs.

I might try turning it off on the next big job, see if that makes a difference.

Will also look at swirl ring but its all pretty new so would be very surprised if its that, it looks doubtful any way as my flame-outs are always mid-cut not at or near a pierce.


Dave
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Re: Prime cause of a flame-out???

Post by vmax549 »

HI Dave. If you are using a CanaCNC system there may be a problem with the torch control output. It is not really a CandCNC problem but stems from a trashy signal that the PC is sending out across the port. When it gets trashy then CanCNC using multiplexing of the signals cannot see it and it shuts OFF the torch. There was a work around where the Torch signal was rerouted to a signal that was NOT multiplexed and that solved that problem.

Some PCs have the problem and Some don't.

That is one of the reasons I do NOT like systems that multiplex their signals just to gain a few more pins. THAT is what the 2 second lpt port is for (;-) more I/O without multiplexing.

(;-) TP
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Re: Prime cause of a flame-out???

Post by vmax549 »

To test for it you hook a Light bulb up across teh torch relay. IF when the problem the light goes OFF then you have that problem IF the light stays on it it is a torch side problem. Your system May have an led at the TORCH sensor that you can look at to see IF the Relay is still active.

(;-) TP
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Re: Prime cause of a flame-out???

Post by davek0974 »

That sounds most plausible, I recall reading that many months ago.

I think my relay has an LED next to it so i will check that first after setting the system to stop on all faults etc.

Thanks
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Re: Prime cause of a flame-out???

Post by suttoncnc »

HI Dave. If you are using a CanaCNC system there may be a problem with the torch control output. It is not really a CandCNC problem but stems from a trashy signal that the PC is sending out across the port. When it gets trashy then CanCNC using multiplexing of the signals cannot see it and it shuts OFF the torch. There was a work around where the Torch signal was rerouted to a signal that was NOT multiplexed and that solved that problem.

Some PCs have the problem and Some don't.
This is exactly what my machine was experiencing. I solved it completely by doing this:
http://www.plasmaspider.com/viewtopic.p ... tor#p73290
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Re: Prime cause of a flame-out???

Post by davek0974 »

Thanks, that capacitor seems to be a fix for the same issue caused by some pc's and the port saver feature on the CandCNC boards, I have ordered up some caps but will try and find the method of controlling the torch directly and not from a 'saved' pin.


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Re: Prime cause of a flame-out???

Post by davek0974 »

Managed to find a few more posts here and there with the same issue, seems some PC's can't handle the port multiplexing that CandCNC use.

I'm going to go through the PC optimising schedule again just to make sure there isn't something running in Windoze that upsets the signals, then turn my Kernel speed down in Mach, its on 45k and was set that way when i upgraded the screens for their Mp3000 system. I will try the 37k option(i think) before going to 25k as i'm not sure i can my pulse rates at 25k, maybe wrong though.

If all that proves fruitless i will throw the capacitor in to the mix and try that, it seems to be just working as a pulse delay, holding the torch on when the signal blips off and on again, what i do not want to do is lengthen the torch-off stage which is very possible when doing this.
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Re: Prime cause of a flame-out???

Post by tcaudle »

Find the referene to the "Lamp Test" on the support forum With that you can narrow down one the three causes for that in the older systems:
1. PC background processes running that cause MACH to hickup and that flases the ouputs
2. PC speed not high enough to handle both the motion AND added processes fromthe plugins
3. Noiss. Noise fromt he plasma gettinginto into the data stream (parallel port pins) and disrupting the signal

The Lamp test involves pluggin a table lamp to one of the aux relays (so you can see a slight flicker) and activating the output
Allit takes is a fraction of a second dropout to cause the torch to shut off.
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Re: Prime cause of a flame-out???

Post by suttoncnc »

I completely agree with Tom's assessment of the causes. I do not think that the CANDCNC controller is the issue at all. My CAND system is bullet proof and I highly recommend it to everybody. However, the capacitor fix that I installed over a year ago totally solved the problem and took about 1 minute to install. The "Off" delay is about 20 milliseconds, completely a non-issue with torch off. The loss of signal was only 15 milliseconds at the high end, so the cap bridges the signal and buffers it with 5 milliseconds overage. So, you could go through a lengthy cause and effect trail of diagnostics.....or put in a cap and forget it. In my mind, the cap has me covered with a number of possible scenarios that could flame out the torch. I have had absolutely ZERO flame outs since installing the cap. Hope you get up and running soon.

Scott
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Re: Prime cause of a flame-out???

Post by davek0974 »

I'm definitely not blaming the CandCNC stuff here, damn good kit. ;)

99% certain this is a PC issue now, I turned the torch (plasma system power was off) and both aux relays on and at the same time fired up XP's Task Manager, one relay turned off straight away, when I moved the TaskManager window around on the screen - giving the system something to think about, the other relay and the torch relay both merrily turned on and off.

My diagnosis - marginal PC system.

So, I went through and killed loads of unwanted services, file indexing was already off, wallpaper was already off, did a reboot and then reduced the Mach Kernel speed to 35K from 45K, repeated my video-drag test and this time things held up 100%. I could try going to 25K but not sure if i can get my pulse rate at that setting.

The PC is above most of the specs but does have onboard video, it's all i have at present.

I will be cutting again soon to test it but at least this is a promising change.

The caps arrived today as well so i have that to fall back on.
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Re: Prime cause of a flame-out???

Post by jimcolt »

Plug your PC into a standard office type UPS with surge protected outlets. Often the low voltage logic in a computer gets shaken up from the inrush current and the electrical noise that can get into your AC power lines (from the plasma and the drives)....enough to lose communication with the electronics. I a majority of the cases where I hear of issues such as this...the UPS solves the issue, often only cost about $50 (US). I need it on my Plasmacam table.....solves a lot of weird popups that show up on the screen!

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Re: Prime cause of a flame-out???

Post by davek0974 »

Thanks Jim, another useful idea.
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Re: Prime cause of a flame-out???

Post by davek0974 »

OK, getting a little vexed now, tonight had a nice job - big sheet, 150 pierces, lots of parts and fiddly cuts.

6 flame-outs, managed to rescue 3 parts but rest were lost.

I fitted the capacitor after the first one but it made no difference at all.

Also had the flame out but with no post-flow from the torch, I'm guessing the only way that happens is to lose the signal then immediately reinstate it but then lose it again - this would kill the post-flow.

I really don't think UPS will cure this, it has never lost a step or frozen, or shown any other signs of instability, just this damn flame-out issue. I need to decide where to attack this now as its wasting a lot of time and material now.

Do i source another PC?

I have tried to find out how to de-multiplex the torch signal but help on that point seems very hard to get, I have read it can be done but nobody will tell me how - this would at least show me if it is really just the multiplex port signals getting messed up or something more sinister before i start throwing cash that i don't have at the issue.

Does anyone here know how to de-multiplex the torch signal???
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Re: Prime cause of a flame-out???

Post by suttoncnc »

Dave,
Sorry for your ongoing trouble. If you know of someone who has an oscilloscope have them probe the torch fire signal from the controller while you are running. It may have nothing to do with your torch signal at all but maybe an underlying plasma cutter issue. At this point, you really need diagnostic data to determine root cause.

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Re: Prime cause of a flame-out???

Post by davek0974 »

Hi

I have a digital 'scope myself, will connect it up tonight and make some cuts, its supposed to be a simple switch closure with about 15vdc on it is it not?

I have two more pc's on the way, both higher spec than my one, but will still try the test

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Re: Prime cause of a flame-out???

Post by beefy »

Dave,

a very simple "test" would be to put a manual switch in parallel with the TORCH ON relay contacts. For each cut, just after the computer has fired the torch, put the manual switch to ON. Doesn't matter what the computer does now, the manual switch is giving the TORCH ON signal. Just before the end of the cut, flick the switch to OFF.

You could put that switch on a long lead so you can be watching the cuts. If you never get a flame out after lots of cuts, for the duration the switch is on, then that is pointing to the TORCH ON signal being lost somewhere.

If you get a flame out while the switch is on, then it's on the plasma cutter side.

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Re: Prime cause of a flame-out???

Post by tcaudle »

I know you enjoy the drama but the Lamp test, if done per the document, WILL tell you where the issue is. TORCH FIRE is NOT a voltage signal, its switch contacts. Hard to see something on a scope that is first OPEN then CLOSED. There might be a pullup on the opto circuit on the plasam if you monitor that side. You can take th etime to do the switch trick , but you already know its because the output is flickering.
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Re: Prime cause of a flame-out???

Post by davek0974 »

Turns out i only had one part to cut tonight and it worked ok so no room for tests.

Yes, as Tom says, the output is flaky from this PC, I ma hoping one of the newer pc's i have coming will sort it out.



Did the MP3000-DTHC2 need a certain version of Mach3 or not, can't remember.
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Re: Prime cause of a flame-out???

Post by tcaudle »

MACH3 version 3.043.022 or higher. Lqatest version 066/067 works best even on older systems
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Re: Prime cause of a flame-out???

Post by vmax549 »

Tom was the one that explained the bypass trick to me. It has worked flawlessly since I did it. It involved putting a shorting pin on a set of pins inside of the DTHC case.

(;-) TP
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Re: Prime cause of a flame-out???

Post by davek0974 »

vmax549 wrote:Tom was the one that explained the bypass trick to me. It has worked flawlessly since I did it. It involved putting a shorting pin on a set of pins inside of the DTHC case.

(;-) TP

This might be useful if the PC change does not work out, any idea of the full details??
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