Arc failure

[TLJC]

I am new to this forum and would like to say high to everyone!!!
I bought a used FastCut G5 table using a Hypertherm 1650, and have only had it a couple of weeks, so I am very green to say the least. I have had it cutting and understand the basics. To me the table and cnc program looks very simular to a dynatorch. I am now encountering a problem with starting my cuts. The torch will come down touch of on the plate and raise to the proper height for piercing, pierce and then it shuts down saying that it lost its arc. (Basically its not sensing the arc). I have tested the leads and everything seems to work. Does anybody have any suggestions? This happened once before and I switched the stepper motor from the x axis to the z axis and that fixed the problem. But now its back.
Any thoughts or help would be apreciated.
Trevor

[admin]

Check this thread and it may help http://plasmaspider.com/viewtopic.php?f ... t=lost+arc

I just typed in "lost arc" in the search box in the top right side of the screen and came up with that thread.

[FiveORacing]

Are you grounding the actual piece or is the ground indirectly attached (ie: via a slat)? Seems to make a difference on my table. I rarely get a misfire when the piece is directly grounded.
I have also used the method I learned on here of refreshing the electrode with a fine file to eliminate the arc groove and getting a few more cuts out of it.

[TLJC]

Thank you for the quick responses. I tested the air pressure and that is not the issue. I have tried the ground clamp and that did not solve it. There is just no voltage reading coming back to the computer. I am wondering if this is a hardware or software problem.

[SignTorch Vector Art]

I'm no guru, but the stepper motor shouldn't affect the torch except as in maintaining correct motion and position.

If it goes out immediately before it even starts moving your pierce height and or delay might be too much so that it loses the arc while sitting over the hole it just made such that the torch needs to be closer or start moving sooner to maintain an arc. I suppose any Z axis motor problems could be causing that sort of problem if it's not positioning exactly where it's supposed to be.

[WSS]

If it is in fact like a DT, you can de-check the "stop on lost arc" box and try that. It is next to or around the volts set point button.

Give that a try first. If it works, then you are getting some noise trouble through the the master motor harness connector.

WSS

[jimcolt]

Trevor,

What power level are you set up at (Amperage) and what thickness material are you trying to cut?

Jim

[Bigrhamr]

I've got the same table and the reason it looks like Dynatorch is because the electronics and software are Dynatorch.
I think this is related to what WSS said but on mine particularly on thin gauge if you have the pierce delay set too long it will loose the arc before motion starts.

Other than that I have no other suggestions that haven't been mentioned but DT will give give you tech support just as if you bought one of their complete tables from DT. I don't think Fastcut uses the DT electronics anymore and they were not a wealth of information when I contacted them about mine.

I also got mine used and one of the best things I did was to get the latest software from DT, if you have an older version there have been tons of upgrades.

I'll be interested to see how you get along with the table, hope you keep us posted.

[TLJC]

I am using 60 amp consumables with a 1/8" pierce height on 3/8" plate. I have tried different plate thicknesses and different consumables (all new). I can manually start the torch and cut without issue. It just us when I run a program that this issue arises. I am going to check the wiring harnesses and try and see if these are the issues. I talked to the boys at FastCut (which are great) and they recommended not upgrading the software. They would remotely look at our machine but they lost internet access today. I am really getting anxious to troubleshoot and repair this machine as the work is starting to pile up.
Thanks again for all the responses.
Trevor

[TLJC]

Bigrhamr,
You have a G5 table as well? How do you like it? Have you had any issues with it? What size is it? What do you have for a power source? I am very new to the plasma world and also new to the cnc world. What nesting program do you use? You said you got updates for the software? What were they and would you recommend them?

[WSS]

If it is a harness /servo motor problem, you might not see it or feel it. I tried wiggling things around and no luck. The problem was like yours, intermittent. It would come and go. It would show up after lunch and hang around for a while and then go on to someone else's shop (probably yours) after he got tired of harassing me. Plain ol Bill named him murphy.

Seriously, what i did was add a capacitor inside the master motor connection housing. The tech from DT (Leon) gave me all the specs and I got em from radio shack.com. I think they were in the one dollar range. Fixed it.

bigrhamr, Amazing that DT would support a G5. They have always been johnny on the spot for me. Good to hear.

WSS

[Bigrhamr]

TLJC,
Mine is a 5'x10' with water table. I have a Powermax 45 on it now which I can't say enough good things about. I also have a 1650 that is ready to go if/when I ever need it for heavier stuff.
The software up grades are through Dynatorch. The current version is 3.6.0.something. If you get on their website and look under "what's new" and go back in time to the version you have then read all the updates since then it will fill you in on that and probably point out a lot of things you didn't know about the capabilities. I have the Wecim/Cutting shop for nesting and drawing. If you don't want to shell out the money for Wecim there's nothing wrong with SheetCam. Mine came with a very old version of One CNC which I worked with for a few days before deciding it wasn't worth messing with.
Problems: Check, Locktite when appropriate and tighten anything that isn't supposed to move but can. Start with the couplers between the motors and gearboxes, then every setscrew on the pulleys and the bearing flange bolts. On mine the Z axis developed a lot of backlash a few times, I don't remember the details but it's pretty simple to take the bottom half apart and remove the slack. Also check the V rollers on the Z, one side has a cam in it to remove play.When I got mine the tuning numbers were way out of whack and it was cutting terrible parts and throwing lot's of errors. The book settings were actually worse. With some help from Leon and a lot of experimentation I got that straightened out.
The heavy construction is great, hit it with a forklift or drop a heavy piece of plate on it and it won't hurt anything.
Driving the gantry off one end for loading and having no rails or parts above the table is a plus, as is having all the
motion parts for X contained inside the frame. I can run it fast, 230 IPM for 16 gauge with good results. The only nagging problem now is a very small amount of backlash on X which seems to be from the belts and I'm working on that.

Now a couple of qualifiers on what I have written. I am asuming you have the same setup since it is the same model of table. And secondly on the support from Dynatorch they support their electronics no matter who's table they are on but not the mechanical parts if they didn't build it.

[TLJC]

I found the problem. After virtually checking everything with the help from the guys at Dynatorch, we finally found the problem. Two of the pins in the connector going into the back of the plasma were not making a good connection. As frustrating an experience as this was, it sure forced us to learn a lot about our plasma. We are up and running again. Thanks for all the advice and suggestions from everyone. The guys at DT were absolutely awesome. A wealth of knowledge and a pleasure to work with.

Bigrhamr,
Thanks for the advice. I will go over the table tomorrow and tighten all the bolts up. I took apart the z axis to clean up the lead screw and bronze nut. What torque setting do you run your z axis at? I've had to up it to 100-110 in order for the torch to touch off on the plate. Have you cut much 1/4" - 5/8" plate? How about holes in this plate?

[Bigrhamr]

Bigrhamr,
Thanks for the advice. I will go over the table tomorrow and tighten all the bolts up. I took apart the z axis to clean up the lead screw and bronze nut. What torque setting do you run your z axis at? I've had to up it to 100-110 in order for the torch to touch off on the plate. Have you cut much 1/4" - 5/8" plate? How about holes in this plate?

I've been able to drop mine down to 45 now and have reliable touch offs. Also the number of missed pulses setting right below it is important to get as low as possible for light touch offs and accurate pierce heights. I think I have mine at about 80 or 90 now. Those numbers had to be much higher before I went through the Z to clean and adjust everything.

DT does have Ohmic sensing available now and I plan to make that upgrade soon.

I mostly cut 10-16 gauge, have done a little up to 3/8" with good results.