Poor cut quality

[little blue choo]

Tonight I was cutting a bunch of split monogram letters with the last name in the split when my machine started acting up. I would hear the plasma start to get load, the flame would get really bright and the torch would raise up way to high to cut and I noticed my torch volts would go up from 75 volts to 150 or more. Air pressure good, air clean, replaced consumables, nothing works. I will get about 3/4 of the way through the cut and then it happens. Do you think this is a problem with the torch height control. I will have to call ARCLIGHT in the morning. Thanks in advance for any help.

Rick

[mechanicalmongoose20]

Check ground.

[little blue choo]

Grounded to the work piece and it looked OK. checked the clamp to be sure it wasn't corroded everything looked good.

Rick

[beefy]

I would not think the ground would be a problem because if you had a bad connection that would cause a voltage drop across that point which ADDS to the total voltage drop (i.e. torch PLUS ground clamp). To keep the overall set voltage correct the torch would be commanded to go DOWN thereby reducing the TOTAL measured volts to get it back to where it's supposed to be.

So something off the top of my head is to check the volts feedback and see if its' correct. Bad connections here would mean the voltage feedback is too low and so the torch would be commanded to go UP in order to increase the volts.

Example if your system had a 50:1 voltage divider and your torch volts were say 150v then you'd expect to measure 3 volts from the voltage divider card.

Maybe do a run with THC off and the amps / feedrate / cut height at book specs and see if your voltage divider output represents something close to what the THC volts SHOULD be. Your steel of course will want to be flat and parallel to the XY rails for the cut gap to stay consistent.

This next suggestion you do at your own risk but you could also use a multimeter to measure the torch volts and at the same time have a 2nd multimeter hooked up the voltage divider output. Monitor the 2 voltages when everything is good and when the torch rises if the voltage from the volts divider card stays the same then either the THC is going loopy and doing the wrong thing, OR the THC is commanding an up move to keep the feedback voltage correct when there's a bad connection in the feedback circuit.

Keith.

[sphurley]

RIck, if your DRO readout shows the voltage is raising then the voltage divider is fine. If the torch is raising then the voltage would also raise in order to maintain the AMPs you had set. Plasma is a constant current power supply. You set the current and the torch control will raise or lower to maintain it. The question is why is it raising. As stated above loose connections (increase resistance) can cause it. Try cutting some lines with and without DTHC on and watch the volts. That should narrow down if its a DTCH issue or not. Does the screen show the UP light on the DTHC lighting up?

[Brand X]

Check your THC settings. What THC are you using? Ethernet? I had mine change for some unknown reason, but It was doing exactly like yours was doing..It happened right after I changed out my Cutmaster 52(A-40 specs) to my other Plasma cutter. Powermax 65.. Both use the same connection setup, and 50-1 voltage..

[beefy]

Plasma is a constant current power supply.
You set the current and the torch control will raise or lower to maintain it.

The first sentence is true.
The 2nd sentence is not.

The torch control DOES NOT raise or lower the torch to maintain current. The Hypertherm unit itself maintains the constant current (or attempts to do so within the limits of its voltage output capabilities).

The torch control is monitoring one thing VOLTAGE and it has no idea what the current is. If voltage is low it commands the torch to move up. If voltage is high it commands the torch to move down. That's it. As far as the THC is concerned, current does not enter the equation.

Keith.

[little blue choo]

OK according to the guys at Arclight my problem has turned into a cutter problem not a table problem. Will call Hypertherm on Monday. Man I really need to cut this weekend. Now every time I start a cut the torch will fire and start to cut but will go out with in 1 inch. They think it's a solenoid in the cutter.

Rick

[littlefatbuddy]

Rick, I responded to your other post also. It is weird that I have had this exact same problem also. I sent my cutter back to Hypertherm and they found absolutely nothing wrong with it. Sent my control box back to Burntables, nothing wrong. Then sent my cutter to Brian, of Hypertherm, in Dallas and he drove to Hutto and had burntables hook up the cutter and again everything worked perfectly. Hypertherm had my cutter for almost two months, Bt had it for another two months. I still could not make the THC work at my shop. I just gave up and have been cutting without the THC for almost two years now. I was so aggravated and frustrated I just wanted to cut something. Sorry it isn't really a helpful post and I never found a solution but at least you know it isn't only at your place.

[little blue choo]

littlefatbuddy, I appreciate your response. I have been cutting with this equipment for 15 months with no problems. I really don't understand why this problem can't be solved. I will check into the air solenoid theory on Monday. I'll let you know if I find anything.

Rick

[blackandtan]

I had something similar to this happen last week but when I turned off the tip saver it would not happen.

[motoguy]

I have had mine rise to height during a cut as well. Seems like it will follow a warp "uphill" sometimes, but won't follow it "downhill" when the cut reverses. Ends up at .25” or cut height.

I wonder if this is related to the tip saver function. It seemed to get better when I changed tip saver from 3% to 5%, but that may just be me. Perhaps I will disable tip saver altogether. It's my understanding it shouldn't be necessary with DTHCIV, anyway.

[tcaudle]

Typically you don't need Tip Saver on the DTHCIV because its many times faster than the DTHCII and will move the torch quicker than the tip saver can react. It all depends on the tuning you have . The Tip saver can "lock " if the DTHC IV DOWN velocity is set low AND you have Tip saver on AND the material drops away rapidly.

If you don't have good workcalmp connection the plasma unit raises VOLTAGE to try and force the current UP. If the DTHC is on (blue LED is on) then it should go DOWN to react. There are some min and max voltage values taht can cause the DTHC to simply quit moving but those settings shoul dbe outside the range of normal open circuit voltages (50 to 200)

The Screen has the UP and DOWN indicators and show which direction the Z SHOULD be moving.

If the voltage goes up then the DTHC has stopped adjusting. The UP led should NOT be on (the down should be but its obvious that its not if its going up)

If you have problems with corner diving or end of cut you can lower the down velocity in the DTHC motor tuning and turn on the Tip saver but it can also result in "head lock" if the warp is aggressive.

5% is over 5 volts of tolerance at mid range (125volts)

[motoguy]

Tom,

I was cutting 14ga HR at book specs (220 ipm, IIRC). The issue was at the edge of the sheet. The edge bowed up maybe 1/2", and settled down say 10" or so in. Cutting out to the (raised) edge of the sheet, the torch raised just fine. Coming back in from the edge, it seemed to "lock" too high (around .23", IIRC). So, it ramped "uphill" with the warp fine, but locked on the way "downhill".

I just went into my Hub admin to check on the Tip Saver settings. The box was NOT checked in the Hub Admin, which means tip saver was NOT turned on. The setting had been changed to 5%, though (I believe it shipped at 3%). Volt tracking tolerance is 0.5

My Z up is 110ipm, Z down is 30ipm. Accel is 30 i/s^2. This is current design Bulltear machine. I did notice that my lower volt fault limit was set at 20. Perhaps that is a part of the problem? Upper fault limit is set at 250. DTHC sensitivity 16, DTHC tracking 4.

Since getting my DTHC delays and "length before DTHC" settings (relatively) dialed in, I've not had problems with the torch diving on corners. Combined with Sheetcam rules, of course. Maybe increase the velocity on the Z down, and see if it tracks better, without bouncing?

[tcaudle]

It should be able to handle a 1/2" fall in 10" set at 30IPM . Next time watch the UP-DONE indicators and the voltage. If is locked from TIp sver or a voltage fault the DTHC stops sending UP & Down. If the DOWN LED is on and the Z quits moving it indicates MACH has decided not to move the Z. There are limits in the distance it will let it move in Up or down direction. THC Corrections set the upper (Max) and lower MIN points. MIn needs to be negative (below zero) Defaults are +1 max, and - 1 min if running in inches. Its in "units" so if you are running in mm it has to be +25 and -25 . I have seen where both are set positive so it will ratchet up but refuse to come down.

You can raise the Down velocity and see if it helps but I suspect something else is at work here .

[motoguy]

I've had an issue in the last few days, with the machine not cutting all the way through the material in random areas / lengths. It appears to be THC related, as it'll cut just fine if I put it in manual mode. These have been with Finecut at factory specs (+~5v per Jim Colt Finecut recommendations, and to compensate for worn electrode) on 14ga, water table (water about 1/4" below bottom of metal), HR steel sheet.

It's odd...it'll just randomly "gouge" instead of making a clean cut, then it'll make a corner or curve, and cut fine again. I run back to the M05 prior to the "bad" cut, run it with DTHC turned off, and it'll re-cut the area just fine. When it catches back up to fresh steel, I'll turn the DTHC back on, and it'll cut fine again. It seems like it was just on the past couple sheets of 14ga. I cut some 11ga today (same nozzle, electrode, etc) and it cut beautifully.

I'll do some more testing when possible. Right now, I'm busy enough that I'm just dealing with it, re-cutting the problem areas, and moving on. I may have to touch up a bad edge with a flap wheel/dremel/file when done, but 90% of the cut is fine.

[tcaudle]

Is it possible its over a slat when it gouges? I cut 14ga with a 45A set of regular consumables . It seems to be a lot more forgiving of metal thickness , density variations and a slat being under a cut. Its THC because the feedback voltage is dropping and causing the torch to raise up to try and hit your Preset value.

[flathummer]

Grounded to the work piece and it looked OK. checked the clamp to be sure it wasn't corroded everything looked good.

Rick

I had a problem same as you and was told it was hypers issue-turned out the mach 3 box had a board go out-(hyper guy was not happy with time spent on my issue) changed board and still working- been a while but really do not cut a lot
chris

[tm america]

Sounds like you either have moisture of oil in your air.. What are you running for air filter-air dryer system and do you have an oil separator in the system to.. IN general you should run a Oil separator,then a filter then thru your air dryer then to the cutter.. i have found refrigerant air dryers to not be as reliable as a system such as the Htp max dry air system that is a 5 stage with desecant ....Could also be faulty consumables or an issue with your cutter i have seen several hypertherm cutters have issues with the control board and do that