Bevel issue made me punch my kids in the face!

[motoguy]

Ok, not really...but it IS frustrating.

I continue to fight a bevel issue with my table/cutter. It's not a big problem on artsy stuff or 3/16" fire pits. It starts to be an issue around 1/4", and it's a big thorn in my side on 1/2". Here's what's going on today, that's pissing me off...

I'm cutting some 1/2" thick wheel centers for a guy building a monster truck/mud truck/whatever. 1/2" material, 24" diameter, 10 lugs .745" studs. My test pattern from 14ga fits like a dream:

Here is the test pattern I cut from 1/2". I'm using a customer supplied plate of 1/2", and wanted to make damn sure I had it right before I started cutting up his plate. So, I cut this from one of my drops. Drop is roughly 24"x24". X+ axis is to the right in this photo, Y+ axis to the top. 3 test cuts (lug hole in 1" square) are visible in the lower right:

Here I am using my Starrett machinist square to ensure the torch is perpendicular to the material.

X+ side of torch:

X- side of torch. The camera seems to magnify that thread of light somehow, but the torch is indeed perpendicular:

Y- side of torch:

Y+ side of torch:

Torch is nice and square to material.

I also used all new consumables. Never been installed before, never cut an inch, never pierced a hole. New:

1) Swirl ring
2) Electrode
3) Nozzle
4) Retaining cap
5) Shield

The new nozzle after cutting the wheel ring (visible in photos above). The ring/holes and practice cuts (lower right on plate) are all this nozzle has ever cut. I babysit the whole cut (practice as well), to make sure the we did not have any issues of the torch contacting the plate. There is a bit of discoloration in that one area, but no blowout/ovaling/cratering. Nozzle looks good.

Inside of nozzle:

More after the jump...I'm out of attachments...

[motoguy]

Electrode:

Cut part again. I used a perpendicular lead in of .5", with an arc lead out of .5" on the lug holes. I had been using arc lead in and lead out, but I was having issues with the torch running into the slag pile created from the pierce.

And the issue:

X+ side of perimeter/outer cut:

According to my digital protractor, that's an 8.6 degree bevel. Almost 9 degrees. VERY noticeable.

X- side of perimeter/outer cut. Slight undercut.

Y- side of perimeter/outer cut. Looks great.

Y+ side of perimeter/outer cut. Also looks great. I took the photo at the lead-in/lead-out point, so there's a bit of irregularity.

X- side of bore/inside cut. Significant bevel.

This is where the battery on my phone died, so it's charging before I can get more photos.

The issue is, this bevel situation is keeping the 1/2" ring from fitting on the lugs. The lugs are digging into the sides, due to the "slant" in the holes. I'd be ok with it if the bevel was consistent around the whole perimeter, but it's not. It's consistently "slanting" to the X+ direction.

I've checked torch perpendicularity. I've replaced all torch electrode components (I was obviously having this same issue with the "used" components too). I made sure cuts were on correct side interior/exterior (finished edge on right of plasma arc). I've removed/checked/inspected/reinstalled the consumables many times. I know the electrode/nozzle are not going back in the exact same relative location. The retaining cap likely is, as it bottoms out at the same spot (stop spinning) every time. As such, the shield is likely in the same relative location. I need to manually rotate the swirl ring, and see if that causes a change in the bevel.

However...I was having this same issue with a completely different set of consumables. Swirl ring, electrode, retaining cap, nozzle, shield...all changed, same issue.

I'm kind of at my wits end with fighting this. This wheel hub job has been on the back burner for a while, but I need to get it cut for the guy. I feel I've got the geometry of the hub correct (stud placement, stud circle centerline, etc), I just need some damn straight cuts in the 1/2", so it'll slide over the studs!

FWIW, I use a magnetic clamp for the work lead. It's this 300A Magswitch model:

https://smile.amazon.com/Magswitch-8100 ... =magswitch



The magnetic clamp IS always on the X+ side of the work...surely this thing couldn't be "pulling" the arc...right? That's where I'm currently at...wondering if my damn magnetic clamp is causing the bevel!

Anyone have any ideas on this? I've already punched my kid in the face...I'd hate it if I drove my wife into the arms of an Elvis impersonator as well!

[Brand X]

65 amp nozzles for .500?

[motoguy]

65 amp nozzles for .500?

The cut chart for my PM85 goes up to 1/4" for 45A shielded in mild steel. No settings for thicker material. 65A shielded is the lowest amperage I find in the cut chart, which lists 1/2".

I know others have cut 1/2" with 45A, and when I find the settings, I'd like to do so. I was hoping to get this cut today, however, and just used the book cut specs for it.

[beefy]

I really feel for you with this problem. I've had it plenty, and like yourself everything seems to be in place, perpendicular torch, ALL new consumables, etc. In my case the lean was often always in one direction, i.e. as though the torch actually was leaning relative to the table.

Just for the heck of it I'd try slowing you feedrate down by quite a bit. Do a small test piece so you don't need your THC enabled. Just get your starting height correct and note the voltage at that feedrate. If the cut is better you can use that feedrate and those volts for the THC. If I remember correctly I think this helped on a cut I did some time ago. I've heard someone else report improvements in bevel when he slowed down.

Good luck,

Keith.

[Brand X]

Use the Powermax 45 cut chart,and now there should be some for the 45 XP available.. I seen some great results with the 65 amp nozzles on .500 (factory 30 ipm) Could just be the steel itself or something is up with your THC..

I generally just use my Victor at 50/55-60-70 amp nozzles for .500 :)Nice to have two different machines to try when issues like this show up.. Then I really can narrow it down farther. Have to admit I would still have my Esab 1600 if it was a bit more reliable unit..Last one was, but I could not take a chance on keeping it when out of warranty.. Cut 1/2-5/8 super nice with 70 amp nozzles.. I am not brand loyal,and would use any machine that does the best job. That's why I have two machine torches on my table.. I can always get something to work,no matter the color. If I had some .500 laying around I would show you what I can do with 45 amp factory and 45 amp Thermacut stuff. I will work out of the box to get what want..That's how I solve my problems..

Bevel drives me nuts, along with cut face smoothness...Most of the rest of the things don't bother me at all..

[motoguy]

I really feel for you with this problem. I've had it plenty, and like yourself everything seems to be in place, perpendicular torch, ALL new consumables, etc. In my case the lean was often always in one direction, i.e. as though the torch actually was leaning relative to the table.

Just for the heck of it I'd try slowing you feedrate down by quite a bit. Do a small test piece so you don't need your THC enabled. Just get your starting height correct and note the voltage at that feedrate. If the cut is better you can use that feedrate and those volts for the THC. If I remember correctly I think this helped on a cut I did some time ago. I've heard someone else report improvements in bevel when he slowed down.

Good luck,

Keith.

That's the confounding part...the lean is usually the same direction for me, as well. Like you said, it's as if the torch is out of square, but it isn't. I've considered manually shimming the torch 4 degrees in the X- direction, to see if that will negate the issue.

The lug holes were cut at 60% feed rate (18 ipm, I believe). The inner and outer edges were cut at book rate, 30ipm. Bevel is still an issue in the lug holes. Which is why the plate won't slide over the lugs.

[motoguy]

Use the Powermax 45 cut chart,and now there should be some for the 45 XP available.. I seen some great results with the 65 amp nozzles on .500 (factory 30 ipm) Could just be the steel itself or something is up with your THC.

I downloaded The 45XP cut charts last night, after reading your response. I'll try the 45A settings.

THC was disabled on the lug holes. In the "inches before DTHC" field in Sheetcam, I put 10. The holes are around .825, so circumference is still under 3 inches. THC never activated.

THC did activate on inner and outer perimeters, but the result was the same.

[acourtjester]

duplicate post

[acourtjester]

Ok with this though.

The magnetic clamp IS always on the X+ side of the work...surely this thing couldn't be "pulling" the arc...right? That's where I'm currently at...wondering if my damn magnetic clamp is causing the bevel!

As a test have you moved the magswitch to other locations on the plate, I have read tig welding can be effected by magnetic influences.
Another thing is try a standard clamp for the work lead to metal, it would be easy to remove the magswitch and clamp the cable connector to the metal alone.

[jimcolt]

Great pictures. The electrode pit is way off center....indicating that there is something amiss with air flow in the torch. Be sure you are using genuine consumables (all of them). Make sure that they all match the part numbers listed in the mechanized cut charts in the manual.

- The retaining cap controls the mix between shield and cut flow.....which can cause this type of issue.
- The swirl ring controls gas swirl.....which also can affect angle deviation (varying angularity).
- Be sure the oring on the torch that seals the retaining cap is in good shape...this can cause flow irregularities.
- Be sure your height control keeps the torch at .060" through the whole cut....higher height increases angularity.
- Be sure the cut air flow is in Auto mode.
-Be sure inlet pressure remains stable between 90 and 135 psi...measure with a gauge right at the inlet, hard plumbed.
- Occurs rarely, but could be a torch with some sort of internal leak, a pinch or a cut in the torch lead.


Jim Colt Hypertherm

[motoguy]

Ok with this though.

The magnetic clamp IS always on the X+ side of the work...surely this thing couldn't be "pulling" the arc...right? That's where I'm currently at...wondering if my damn magnetic clamp is causing the bevel!

As a test have you moved the magswitch to other locations on the plate, I have read tig welding can be effected by magnetic influences.
Another thing is try a standard clamp for the work lead to metal, it would be easy to remove the magswitch and clamp the cable connector to the metal alone.

Not yet. I will try that this afternoon. Next step after that, would be connecting a standard work clamp.

[motoguy]

Great pictures. The electrode pit is way off center....indicating that there is something amiss with air flow in the torch. Be sure you are using genuine consumables (all of them). Make sure that they all match the part numbers listed in the mechanized cut charts in the manual.

All are genuine consumables, from Baker's. Part numbers match for Ohmic mechanized cutting. I see what you mean about the pit being off center. I'll look at some of my old consumables, and see if they look similar. Now that I think about it, I seem to remember noticing an off-center pit in another electrode, a while back. I think I noticed it while I was dealing with this thread:

http://www.plasmaspider.com/viewtopic.p ... 87#p130087

- The retaining cap controls the mix between shield and cut flow.....which can cause this type of issue.

This is why I installed the new cap. I've checked my "used" cap, and all the holes appeared to be clear, free from debris, etc. Generally good condition (original retaining cap, approx a year old). Still, I thought "perhaps there is some airflow issue that I can't see". Hence the new cap. Which didn't change anything.

- The swirl ring controls gas swirl.....which also can affect angle deviation (varying angularity).

Replaced as well, for this reason. I occasionally get a "stuck consumable" error (on the same swirl ring I've been using since table was new, approx a year), so I was wondering if the swirl ring was becoming abraded/worn, and affecting the bevel. It does not appear the new swirl ring helped.

- Be sure the oring on the torch that seals the retaining cap is in good shape...this can cause flow irregularities.

I did NOT replace the O-ring. I always keep it lubed and checked for damage, but I did not think to replace it. It's the original O ring, in use for the last year or so. I'll replace that ring today, as I have several spares.

- Be sure your height control keeps the torch at .060" through the whole cut....higher height increases angularity.
- Be sure the cut air flow is in Auto mode.
-Be sure inlet pressure remains stable between 90 and 135 psi...measure with a gauge right at the inlet, hard plumbed.

Check, check, and check.

- Occurs rarely, but could be a torch with some sort of internal leak, a pinch or a cut in the torch lead.

I'll rule out the magnet/clamp and the O-ring as variables. Assuming no change at that point, are there any field tests that can be performed on the torch lead? Or does the torch need to be sent to HT to be checked? This is something I'd like to have corrected, whatever the cause.

[jimcolt]

Tech service at Hypertherm may have some tests for the torch or lead...I'm not sure. Magnetic fields can pull a plasma arc causing severe beveling. It could explain the off center electrode wear as well. Jim Colt

technical.service@hypertherm.com 1 800 643 9878

[motoguy]

Picked up a standard work lead clamp, replaced the magnetic one. I'll see if that makes any difference. I also replaced the O-ring that seals the retaining cap. The old ring appeared ok, supple, smooth, no nicks/cuts/abrasions, but who knows. I sent an e-mail to HT technical services, inquiring about field tests or inspections I can perform. Thanks.

[cutterguy]

motoguy, Let us know how you do with this issue. I've been having trouble with my HT85 and machine torch as well. The problem is a little different but it could be related. Mine has intermittent severe cut angle also but it changes from deflecting to one side or the other.

[motoguy]

- Be sure the oring on the torch that seals the retaining cap is in good shape...this can cause flow irregularities.

Ever want to just kick yourself in the nuts? Repeatedly?

I purchased a regular (non-magnetic) work lead clamp, and installed it last night. Also replaced the O-ring (which still appeared to be in great condition). Cut some 2" squares today to check...and it was BEAUTIFUL. Put the magnetic clamp on the part, then clamped my lead to the magnetic clamp (to simulate the magnetic interference), and cut another 2" square. STILL BEAUTIFUL. My digital protractor was measuring just ~2 degrees of taper (keep in mind, it was ~9 degrees before).

Cut a test template of the part, angularity was great. Still some bevel, but it was regular bevel, equal all the way around the lug holes.

In all...it looks like this ONE part I forgot about, the $.02 O-ring, has been responsible for this issue.

I then changed settings, and cut at 45A from the XP cut chart (45A, 141v, .15 pierce, .6 cut, 18ipm). 18ipm is slooow, compared to 30! And cutting those holes at 10ipm (just less than 60%) is even slower! Taper is great, though. Cut edge looks fantastic.

Honestly, it's kind of like having a new cutter! I'm not sure exactly how long I've been having this issue, but it's been several months. I'd just been cutting thin enough (1/4" or less) non-dimensional parts, that it wasn't really a problem.

I'm super excited now! Bring on the thick stuff!

Yet again, thanks to Jim and the technical guys at HT for helping me out. I'll put this o-ring on the "replace couple of months, whether you think you need it or not" list.

[beefy]

- Be sure the oring on the torch that seals the retaining cap is in good shape...this can cause flow irregularities.

Ever want to just kick yourself in the nuts? Repeatedly?

In all...it looks like this ONE part I forgot about, the $.02 O-ring, has been responsible for this issue.

Well, that's an eye opener, thanks for keeping us updated.

Got to say that's the one part I haven't considered on mine, I just didn't connect a rubber O-ring with positioning accuracy of the consumables. Many have pulled their hair out with this bevel problem and now I'm wondering if this has been the cause

What's especially interesting is that you say the O-ring looked OK. I'm in the same boat and have checked my O-ring on various occasions and it looks fine. I'll get a case load of them now.

[motoguy]

What's especially interesting is that you say the O-ring looked OK. I'm in the same boat and have checked my O-ring on various occasions and it looks fine. I'll get a case load of them now.

The one I pulled out looked great. Still supple (I wipe it down with lube about every 2nd time the cap comes off the torch), round, smooth, no visible nicks, cuts or scrapes, etc. Never would have guess there's an issue with it. However, it and the mag clamp are the only things that changed since my last cut. Putting the mag-clamp back on the plate had no effect (I even noticed I had another magnet lying up there as well, which I used to pick the part up). It looks like that O-ring is the only variable that changed...

[beefy]

If I was in your shoes I'd be doing "repeatability" tests to confirm this, i.e. stick the old O-ring back in and do a test cut, then put the new O-ring in again and test again (repeat several times).

That should be a rock solid indicator that indeed the original O-ring was the culprit. If that's the case we can only assume the original O-ring had some sort of dimensional or softness irregularity.

Jim,
if you're reading this, would it not be a good suggestion to the design team to review the torch consumable area design so that a less than perfect O-ring won't knock the cap out of alignment. Seems a poor design when precise alignment depends on a flexible rubber part having perfect consistency in softness and dimensions. Hydraulic rams often have hard fibre rings next to the sealing O-rings, and these fibre rings take the side loads, etc and keep the metal parts accurately located. Don't know if something like that could be added into the design of the torches.

[acourtjester]

Great news this is something all of us will file away (hopefully remember) if we start seeing a wobble bevel cutting pattern. I bought a few spare "O" ring (058519) at the beginning and have not used it yet, small tube of lube (027055) also.

[motoguy]

If I was in your shoes I'd be doing "repeatability" tests to confirm this, i.e. stick the old O-ring back in and do a test cut, then put the new O-ring in again and test again (repeat several times).

That should be a rock solid indicator that indeed the original O-ring was the culprit. If that's the case we can only assume the original O-ring had some sort of dimensional or softness irregularity.

That would have been the correct methodology. . I was simply thrilled the bevel was gone, and went ahead and cut the parts (which turned out great). "The proof is in the pudding", so to speak.

Keep in mind, I'd been having this issue for several months. I wasn't often cutting thick material, and on thinner stuff, it wasn't an issue. During those several months, I'd checked torch mount for squareness, changed consumables many times (fine cut, 45a), etc. I'd been hunting (on the surface) for the problem, but it wasn't causing enough grief to dig into it. Until this 1/2" plate, with dimensional requirements.

Jim,
if you're reading this, would it not be a good suggestion to the design team to review the torch consumable area design so that a less than perfect O-ring won't knock the cap out of alignment. Seems a poor design when precise alignment depends on a flexible rubber part having perfect consistency in softness and dimensions. Hydraulic rams often have hard fibre rings next to the sealing O-rings, and these fibre rings take the side loads, etc and keep the metal parts accurately located. Don't know if something like that could be added into the design of the torches.

I don't think it's an alignment issue with the seal/cap. Rather, I think it's a gas swirl issue. I think the cap was perfectly straight, but there may have been some "blow by" through/past/around the o-ring, which was disrupting the engineered swirl pattern. Perhaps the oring was in good mechanical conditions but had shrank/contracted, thus looking good, but not sealing?

Also, keep in mind this o-ring is over a year old. I purchased my table in August (and purchased PM85, had it shipped to Bulltear), took delivery sometime in October, and didn't start cutting until January.

You know how those first several months are, and the learning curve that follows. Diving into plate, blowing out consumables, knocking the torch off the mount, etc. More damage than cutting! More abuse than it sees now, for sure. I don't think I started lubing that o-ring until the summer, when cutting was getting "good enough" to start focusing on little issues. It's ENTIRELY possible I did something to damage that o-ring early in it's life, and just started to notice the symptoms. Or, hell, perhaps using the same o-ring for a year is a bad idea all itself.

[tnbndr]

So did the pit on the electrode move back to center after the O-ring change?

[motoguy]

So did the pit on the electrode move back to center after the O-ring change?

Yes. I meant to mention that. I checked that exact thing last night. Same electrode, pit is now centered in the hafnium.

[steel 35]

Ever want to just kick yourself in the nuts? Repeatedly?

I'll put this o-ring on the "replace couple of months, whether you think you need it or not" list.

I have nerves from my back that do the very same kicking thing for me so that's taken care of.

As for the Oring going on two years same one no spares yet. I read silicon long ago, don't use spray on thats another story!
Now from here I have the part numbers for both, Thanks for the trouble shooting; And the #s Tom