Getting nasty tapers on my cuts

[gamble]

Did some 3/16" steel and some .100 aluminum and I keep getting a lot of taper. Never really had this issue before. The holes on the 3/16" steel are very tapered. With the aluminum it seems that two sides are pretty good but the other two sides have a lot of taper.
So I've tried new electrode, new nozzle and new shielding cup. On the aluminum I've tried from 25amps to 45amps. Taper remains the same. Speed as low as 90 as high as 150 (my usual settings) same issue. I have a level on the side of torch holder and made it centered.
Don't have a way to center the torch in the other axis but it's never been an issue in the past.

Torch height varies with no height control, but I try to run them about .080-.100 off the work piece.

About to pull my hair out trying to figure this out for the better part of the day. Any thoughts?

The ONLY thing I can think of that changed was the addition of a motorguard m60 in line with the hypertherm air filter kit, but I can't imagine that making things worse.

[sphurley]

Not that sure on the PM45, but I do run 3/16 and you seem high on your cut height. I'm at .060 and pierce is .12-.15. Right out of the book for my PM65. Do you have a floating head?

[gamble]

Not that sure on the PM45, but I do run 3/16 and you seem high on your cut height. I'm at .060 and pierce is .12-.15. Right out of the book for my PM65. Do you have a floating head?

No height control, no floating head. The height control is $2800

[sphurley]

I just looked at a PM45 manual and yes you should be at .06cut. You are double that so you should get a wide kerf at the top and a narrow on at the bottom and be eating consumables.
Jim Colt will likely chime in here and set us both straight.

Steve

[jimcolt]

If you are concerned with taper......then you need height control. The Powermax45 when used with the machine torch shield needs to run at .060" off the material. Run .010" higher than that and the taper gets pretty bad. There is no metal plate or sheet on the planet that will set flat enough to maintain accurate height......so without height control you will get excess and varying edge angularity.

Height control needs to achieve the following:

- find the surface of the plate accurately before each cut cycle (on materials thinner than 1/4" the use of ohmic contact is the most accurate method as it does not deflect the material causing incorrect pierce height)
-Retract to the suggested pierce height
-Pierce and maintain x, y and z position until the recommended pierce delay times out. (this allows for the arc to fully penetrate material and for the torch air pressure to stabilize before any movement occurs)
- index rapidly down to the physical recommended cut height.
- Once x,y motion achieves speeds above 80% of the recommended (part program speed) activate the arc voltage feedback circuitry. (on many height controls this is an operator voltage setting....higher voltage = higher height, the voltage must be adjusted until the physical height (recommended cut height) maintains accurately throughout the cut)
- Better height controls interface intimately with the cnc and deactivate (freeze height) whenever the machine decelerates for holes, corners, fine features and kerf crossing.....if it does not, expect the torch to dive closer to the material...or even drag on the plate.

Of course to do all of the above requires some well thought out electronics and an active interface between the plasma and the cnc control......and also requires a motorized z axis (lifter) to hold the torch. This is why height controls are considered "expensive, in fact Hypertherm has an industrial height control system that can cost over $15k (fully optioned of course!). There are a few companies advertising plasma height controls in the $300-$400 range, these do not have a lifter and generally have no means of interfacing with the cnc for height freeze when necessary.

Jim Colt Hypertherm

[gamble]

Thanks Jim. I'll let you know how things cut today, but it was never this bad before. So not sure what changed.

Height control will be in my future, just not sure how soon probably going to be another year or two. So I'm doing the best I can with what I have.

[Brand X]

Gamble,
a quality THC is mandatory. Does not matter what brand cutter you are using either. All are much improved with it.. On thin metal without a ohmic sensor, you can push the plate with a stick to hold the deflection to a min. when using the other style torch height setup.. The THC will take over, and cut at the correct height, and also pierce at the right height too.. I always check to deflection before I pierce anything.. Just to make sure the plate does not move.. Always one more way to skin a cat..

[gamble]

Well after killing a full sheet of aluminum yesterday and a half sheet of 3/16" steel trying everything I could think of. Air hoses, regulators, filters, torch height, distance to work piece, speed, amperage, cleaning the slats, leveling the slates. After all that the solution was simple. New electrode and nozzle. Which makes no sense since I just put new ones in right before this problem happened. Maybe I got a bad set? Maybe the nozzle shit the bed after the torch rubbed on the metal a few times? I have no idea. But the taper on the 3/16" is very very minimal. I'll get some pics in a bit.
Wow I feel stupid today.
I swear sometimes this thing will make consumables last 2 weeks and other times it will chew them in a few hours.

[acourtjester]

AS they say "sometimes you eat Bear and sometimes the Bear eats you" I think we all have been through a problem like that and we drop kick our butts all over the place. So my friend you are in good company. I was cutting some thin metal and the torch pushed it down and it flexed back up just under the torch, poof went the shield and tip but I did not think it did that much damage. And after some ugly plasma flames and bad cuts I looked at it and it was time to change them.