TORCH NOT CUTTING STRAIGHT

[findau]

I have a Pcam DHC with a 900 Hypertherm using a RT60 torch and fine cut consumables. I have been cutting a lot of 3/16" hot roll for some gussets and they all seem to be cutting at an angle on one side. I have changed electrodes and nozzle and aligned the torch in the holder. What am I missing??

Chuck (az)

[Loyd]

Hey Chuck, Do a search in the box with the word "angle" in it. It comes up with some good guidlines. http://plasmaspider.com/viewtopic.php?f ... ngle#p7111 There is one that you can start with.
Good luck!
Loyd

[elkriverfab]

I have the same problem sometimes on heavy plate.
It seems to be a speed problem.

If you look at your arc very closely, you can see how the speed will cause your arc to move off center (bend) and give you an angle cut.

I also think it is because my cutter is under powered (small unit).

I have also found that heavy plate really shows you if your torch is at an angle rather than straight up and down in the holder.

I imagine Jim Colt has the answer you are looking for.

I too would like to hear the answer, I was cutting 1/4 inch plate all day yesterday and there is a slight angle on the corners mostly.
Luckily it is was not a huge problem because all my edges were welded after cutting.

[geo4932]

The cause is probably that the retaining cup is out of round. Most people never change the retaining cup and it is a consumable.
Also, the Plasmacam software has settings to automatically slow the speed down for holes and corners. It is "Corner Acceleration" and "Slower on Circles".
The smaller the number in Corner Acceleration, the more the machine slows down. The default is .1 The range is from 1.0 (no slow down) to .01 (probably too slow).
The Slower on Circles provides even more deceleration based on the diameter of the hole size you enter.

[findau]

Thanks to all for your replys. Some good suggestions. I was wondering if maybe a change from fine cuts to a 40A nozzle and electrode would help. I believe that I could be at the upper end of fine cut use.

Chuck (az)

[geo4932]

I looked it up and Hypertherm rates the FineCut up to 10ga. thickness.

[geo4932]

If your still seeing this with new consumables then I would check that your air pressure is set properly, set pressure while the plasma is flowing or purging air. If pressure is OK then your issue is likley speed related and/or cutting height (arc length) related.

The cause is probably that the retaining cup is out of round. Most people never change the retaining cup and it is a consumable.

Not sure how the retaining cup could become out of round or how it would be effecting your situation but I would like to learn.

The retaining cap is a consumable. It also has air holes that can clog and heat can deform them. I hear people say that they have changed the consumables when they have a problem but they only changed the electrode and nozzle. The retaining cap and swirl ring and shield are also consumables.

You are correct about the air pressure, speed and cutting height being factors. Also the right nozzle and amperage are important. It sounds like our friend is trying to cut thicker than the rating of the "FineCut" nozzle.

[Diver47]

I had this preoblem and found that the motor gears weren't riding on the track all the way, run it back and forth and watch the motor gears in relation to the track

[jimcolt]

Some rules of thumb about angularity with a Hypertherm Powermax type torch.....these do not always apply to all plasma torches!

1. If your angularity is uniform around the perimeter of the cut, as in all sides have angiualrity that is very close to each other.....then the likely cause is that the torch is too high off the plate , or that the cut speed is too fast. Open the Hypertherm manual and find the mechanized torch cut parameter chart (even if you are using a hand torch) and closely follow the recomended consumable part numbers (for mechanized cutting the shield is different than for hand cutting). Set the height exactly as the charts suggests for your material and thickness and power level. You will also notice a maximum speed column and an optimal speed column. Optimal is what you should be using for all mechanized cutting, and possibly even as much as 10 to 15% slower than optimal for the squarest edge.

2. If your angularity is relatively good on two opposite sides of a part, and bad on the other two opposite sides:
a. Check torch squareness to the plate, use a square (not a level) and check it on both x and y axis directions.
b. Assuming squareness is good, then you likely have a damaged nozzle or shield on the torch. Remove them and check using a jewelers 10x eye loupe. If there is any sign of out of round, or any nicks (even microscopic), then the shield or nozzle should be changed. Nozzle and shiled damage most often occur from piercing too close to the plate, too thick, or not having adequate pierce delay time for piercing. If replacing the nozzle or shield does not iprove the squareness....then try the retaining cap, then the swirl ring. These parts last a long time, but when they are used up they usually cause issues with angularity


The Fine Cut parts are rated for a maximum thickness of 1/8", however I have used them on 3/16" a few times. If you have a good torch height control with the ability to find the plate surface before each cut, then retracts to an accurate pierce height...then you can get good results from the FineCuts on 3/16". Use a .18" pierce height, about a .8 second pierce delay time, and a .08" cut height for best results. One pierce too close will damage the nozzle orifice, and all angularity bets are off!

Let me know if this helps at all!

Jim Colt

[wl5044]

Thats a big 10-4 on the retaining cup. Mine wouldnt fire so I would check all the switches in the torch and remove the "consumables" and reassemble and it would work for a while then just stop firing again. I finaly replaced the swirl ring and retaining cup both of them where original (6yrs old ). This thing cuts like a new one. Its a miller spectum 375 . Although I plan purchasing a hypertherm powermax 45 this next yr. Thanks to Jim my mind is made on this . I love Miller equip but I have never seen such customer service as he gives. Although I do wish my welding shop would sell hypertherm equip as they are wanting to (can you help me on this Jim?).

[jimcolt]

Actually your Miller Torch is made by Hypertherm but it is an earlier design. The newer retaining caps are of a more robust design......although I guess 6 years of life is proably not too bad! Hypertherm is , and always has been...selective in regards to the weld supply stores that can carry our products. We work hard to ensure that the sales and technical staff at the distributors are factory trained so they know our ordering systems and know the latest technology available from us. If you let me know who your local distributor is, I can forward the info to our District Sales Manager in that area....we have 4 sales manager that cover Texas! No guarantees, but I'll pass the info along.

Best regards, Jim Colt jim.colt@hypertherm.com

Thats a big 10-4 on the retaining cup. Mine wouldnt fire so I would check all the switches in the torch and remove the "consumables" and reassemble and it would work for a while then just stop firing again. I finaly replaced the swirl ring and retaining cup both of them where original (6yrs old ). This thing cuts like a new one. Its a miller spectum 375 . Although I plan purchasing a hypertherm powermax 45 this next yr. Thanks to Jim my mind is made on this . I love Miller equip but I have never seen such customer service as he gives. Although I do wish my welding shop would sell hypertherm equip as they are wanting to (can you help me on this Jim?).

[Streetwerkz]

I never have luck with fine cut consumables when used on steel thicker than 10 ga

[Wesley Nichols]

.....I have been having more trouble than almost possibly imaginable with my table this morning..... I am cutting out a bunch of bale hooks.... 14 of them out of 5/8" plate... I have a Hypertherm Powermax 1250 G3 series..... I am running an 80amp tip... I CANNOT get the thing to cut straighter than about a 30degree angle. Replaced all consumables, running 12ipm, cutting height .067 checked with calipers..... Got a guy showing up in an hour with a whole sheet of 3/4" he wants cut up in an hour..... Any suggestions........ right now i'd pay anyone about what they asked for this thing to work.

[jimcolt]

Wesley,

I don't know if I could make a 30 degree cut angle with the torch straight....maybe with a really messed up nozzle I could approach about 12 to 14 degrees....

You are not telling me much. What does the nozzle orifice look like after a few cuts where the angle was bad? Ii it cratered, is it notched? What does the shield look like?
What part number consumables are you using? What is your pierce height, pierce delay time? And, 12 IPM at 80 amps is way too slow.

Here are the specs I would use....You did not let me know what type and brand machine you are using, and what you have for a height control....so here is the best I can do:

shield...120930, Retaining cap...120928 (if ohmic contact IHS system such as a Hypertherm THC or a PlasmaCam DHC2 or Samson, 220061), Nozzle... 120927, Electrode...120926, Swirl Ring...120925

Set air pressure while it is flowing to 70 psi.

Set Amperage to 80

Set cut height to .060". If you have an arc voltage setting, adjust voltage up or down until the torch height is at .062" while cutting at the speed you plan to use. Any change in speed, then you will have to readjust the voltage so the height stays at .062".

Set pierce height to .18"

Set pierce delay to 1 second

Set cut speed to 26 inches per minute. You can go a bit slower (no less than about 20) for a squarer edge, or you can go faster (as fast as 40) for less dross

Make sure that your nozzle orifice is as round as a new one, same goes for the shield orifice. Make sure your air pressure (compressor) is keeping up (70 psi with air flowing out the torch) The pierce height and pierce time are critical. One incorrect pierce and you could ruin a nozzle or shield. If the bad angularity continues, but the nozzle and shield look good it is possible the retaining cap or the swirl ring are bad. Make sure there is no moisture in your air system. Make sure you have not mixed up part numbers of the consumables (a 40 amp, 60 amp, and 80 amp nozzle look very much alike) make sure the consumable parts are Hypertherm.....there are aftermarket parts that will provide stack up tolerance issues that affect cut quality.

It should be very easy...using the above specs to get a very nice cut on 5/8" steel. Call me if you think I can be of any help. 603 252 4603

Jim Colt

.....I have been having more trouble than almost possibly imaginable with my table this morning..... I am cutting out a bunch of bale hooks.... 14 of them out of 5/8" plate... I have a Hypertherm Powermax 1250 G3 series..... I am running an 80amp tip... I CANNOT get the thing to cut straighter than about a 30degree angle. Replaced all consumables, running 12ipm, cutting height .067 checked with calipers..... Got a guy showing up in an hour with a whole sheet of 3/4" he wants cut up in an hour..... Any suggestions........ right now i'd pay anyone about what they asked for this thing to work.

[geo4932]

I never have luck with fine cut consumables when used on steel thicker than 10 ga

Streetwekz,
10 ga is the max thickness that Hypertherm rates the FineCut.

george