Am I expecting too much?

[GPM870]

I just got a job cutting some small parts out of 3/8" aluminum. This is the first time I cut aluminum but I know from this site that it doesn't cut nearly as nice as the same thicknes piece of steel. And it didn't! Am I expecting too much or is this as good as it gets cutting aluminum? I am cutting with a powermax 85, machine torch using a 65 amp nozzle at 50 ipm (also tried 45ipm no change). I tried cutting some with the water table empty and some with the water slightly below the plate. The parts with the water looked slightly better, not usable, but better. Any thoughts would be greatly appreciated.
GPM

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[muzza]

When i first saw your pic's I straight away thought cutting too slow or too high but I run a 45 not an 85 so I went to the Hypertherm website and downloaded the manual to check settings and your 85 should be well within the limits for cutting 3/8" ali. Looking at the 65 amp cut chart 50 ipm is the ideal at 135 volts.
Are all your other settings as per the Hypertherm cut chart? especially height
As Jim says all the time these settings are proven to work. The heaviest Aluminium I have cut is 1/4" on my 45 and although not as clean as mild steel was much better than your pics but in saying that my cuts were nowhere near as small as yours.
I'm sure Jim will jump in when he visits, he's far more knowledgeable than me.
Sorry can't help more.
Murray

[jimcolt]

GPM870,

I have done a fair amount of aluminum at 65 amps with my Powermax85.....my parts certainly have looked better than the ones you posted! Aluminum does not cut as well as steel, however your pictures indicate to me that the nozzle was dmaged or that height was way off in your specs. You do not mention your pierce height, pierce delay or cut height settings....and I am assuming you are using the 65 amp shielded consumables. What make and model machine an height control are you using? Can you take a picture of the nozzle and shield that was used in the torch for cutting these parts?


Jim Colt Hypertherm

[GPM870]

Good evening Guys,
I was using new 65 amp shielded consumables. The closest I could get to the .150" pierce height was about 3/16" and a one second pierce delay. The controller goes in 1/2 second increments. I have no idea on cut height, I set the pierce height by trial and error with the plasma source off and torch height on using "the Knob" to get an idea how far the torch is off the plate using a piece of keystock as a gauge. Once I turn the plasma source back on and re-run the program it will fire the torch which will raise up and sometimes go back down. There isn't any good way to monitor the cut height other than watch the arc. Yes, I am wearing glasses! I can turn the cut height "Knob" while cutting but still don't know how high the torch is off the plate. Usually it don't change the torch height anyway.
I will have to get a picture of the consumables tomorrow evening when I get home from work. I will also get the cut inches from sheet cam on how many inches were cut.
I am running a 4x4 burntables with their own torch height control.
I believe I have answered most of my questions on why the cuts aren't very nice but still don't have a solution yet.
I would be open to any thoughts anyone might have for me to get better cuts.
Thanks to Murray and Jim for the replys
If I forgot any needed information let me know,
Gerry

[muzza]

G'day Gerry,
I work in metric so I had to have a look at the relevant imperial specs. Looking at the 65amp on aluminium the manual lists 0.15" pierce and 0.06" cut height. As you can see the cut height is below half that of the pierce height so if you don't have your torch travelling down immediately on the pierce you are always going to have an ordinary cut.

I'm not familiar with Burntables and how their height control works but I'd suggest you really need to sort out your height control before you can really expect an improvement in cut quality. It'll be worth the effort.
Murray

[GPM870]

Good evening,
I did a report from sheetcam and took some pictures of the consumables. New 65 amp consumables when i started but a like new nozzle shield. Sheetcam calculated a total of 176 inches and 10 pierces. As you can see by the earlier pics none of the parts look good even from the beginning.
I think I will hold off trying to cut the rest of the aluminum parts untill the weekend, hopefully I can figure out somthing by then.
Murray, you are correct about the torch height. I have contacted burntables about it no less than a couple dozen times but no results yet. I'm still fighting with it.
Thanks again for any information that might help me.
Gerry

[muzza]

Jim would be the best one to respond here but the hole in your nozzle looks very out of round in that pic, that will affect your cut quality. Why it's like that again Jim would be the best to answer but I'd guess it's probably height related.
Murray

[trucutcnc]

Fresh consumable might help, but the reason your parts look sort of melted, is because that's what's happening. The letters are very narrow and aluminum conducts heat much better than steel. As the part heats up, the cut degrades. That's why adding water and keeping the part cooler helped a little. I think you're pushing the limits with a part that small and narrow. If you cut something larger, like a 2 or 3 inch circle at the same speed, it will probably look great with very little dross.

[Largemouthlou]

I got lucky on these, but did have to cut them twice to get this good.. Mind you there is some clean up on them already done.
This is also .25 so a little thinner.. 1250 HT machine torch and 40 amp nozzel

[GPM870]

Wow! I wish i could get cuts half that good. The nozzle got that bad of shape some time in as few as 10 pierces and 170 inches. No not knock off consumables, genuine Hypertherm nozzle. How long should the nozzle last? Ya, I know you can't put a hard number on it but a good estimate... 100 inches, 500 inches, or 1000 inches. One thing I didn't do is give you guys dimensions for the parts I was cutting. The "U" shaped piece is 1 1/2" long and cross section of 3/16". The circular part has a 1" hole and 3/16" cross section.
Here is my theory and someone can tell me if I am wrong... Just the opposite of Trucut said (no disrespect intended) I would think it takes a lot more power to cut aluminum because of the heat dissipating so fast. I remember a long time ago a classmate of mine was trying to tig an aluminum plate together and couldn't get enough heat to get a puddle. I tried it and sure enough at 300 amps I couldn't get a puddle to form. I looked at his set up and determined he had the half inch aluminum plate clamped solidly to a one inch aluminum plate to keep it flat. That much mass sucked the heat right out of the upper plate.
My rambling point is the remaining plate mass and the water splashing on the entire bottom of the plate should keep it from melting.
Thanks everyone for helping me out.
Gerry

[trucutcnc]

My rambling point is the remaining plate mass and the water splashing on the entire bottom of the plate should keep it from melting.

As you cut, the part you're cutting becomes disconnected from the rest of the plate and thus you don't have the mass of the entire plate to conduct the heat away from part.

The concept is different than TIG welding. TIG welding requires heat to flow the weld. Plasma does not rely on heat to cut. It uses electric current. Heat is a byproduct and the hotter it gets the worse it is. The parts above look like steel. I see what looks like mill scale. Steel doesn't conduct like aluminum so results will be better. Because aluminum conducts heat so well, it heats up much faster than steel. Water should help, but it won't be enough on something this small.

We cut a fair bit of aluminum. Mostly .080 and 1/4". I use the same current settings I use for steel and get good results.

[Largemouthlou]

All the pictures in this tread look like aluminum to me, mine were cut using the HT 1250 book specs for the 1/4" aluminum 40 amp shielded, there was some clean up needed on the parts but that is to be expected due to their size..

[jimcolt]

If you are following the cut specs in the Hypertherm manual (Pierce height, pierce delay, cut height, cut speed, amperage, correct shielded consumables) then you should achieve 300 to 600 starts on a nozzle and electrode when cutting aluminum. The nozzle shown in the picture is notched on the exit orifice...this indicates at least one pierce that was too close to the plate. Once the nozzle gets notched like this the cut quality will vary wildly around the perimeter of the part.

Aluminum is tough to cut with an air plasma...and it is not just the plasma that needs to be working correctly...the torch pierce height and cut height are absolutely critical. Aluminum does transfer the heat away from the cut edge....water makes the dross worse. As I have mentions dozens of times in many online forums...the best cut quality always is in a dry cutting situation (ok, with a few minor exceptions with stainless).

Regardless....if you want to see some cuts on the same thickness of aluminum cut on a dry table with my Powermax85...let me know the thickness and I'll cut a part and post pictures.

Jim Colt Hypertherm

Wow! I wish i could get cuts half that good. The nozzle got that bad of shape some time in as few as 10 pierces and 170 inches. No not knock off consumables, genuine Hypertherm nozzle. How long should the nozzle last? Ya, I know you can't put a hard number on it but a good estimate... 100 inches, 500 inches, or 1000 inches. One thing I didn't do is give you guys dimensions for the parts I was cutting. The "U" shaped piece is 1 1/2" long and cross section of 3/16". The circular part has a 1" hole and 3/16" cross section.
Here is my theory and someone can tell me if I am wrong... Just the opposite of Trucut said (no disrespect intended) I would think it takes a lot more power to cut aluminum because of the heat dissipating so fast. I remember a long time ago a classmate of mine was trying to tig an aluminum plate together and couldn't get enough heat to get a puddle. I tried it and sure enough at 300 amps I couldn't get a puddle to form. I looked at his set up and determined he had the half inch aluminum plate clamped solidly to a one inch aluminum plate to keep it flat. That much mass sucked the heat right out of the upper plate.
My rambling point is the remaining plate mass and the water splashing on the entire bottom of the plate should keep it from melting.
Thanks everyone for helping me out.
Gerry

[GPM870]

Thanks everyone for your input. I really appreciate it and learned a lot. I'm still under the newbie status.
Here is what I learned...
Aluminum doesn't cut as well as steel. (I knew that but didn't think it would be this bad)
Pierce height and cut height are a lot more critical than I thought.
Burntables torch height is a piece of S... ! (almost for got this is a family site) There isn't a way to control it with
any accuracy let alone to the accuracy of book specs.
Cutting on water will make the dross worse.
One bad pierce can ruin a perfectly good nozzle. (or tip for Jim! )

If I forgot to mention something important let me know.

Now going toward the future... Where can i get a torch height contol that will work for my table? Getting a torch height control to work with my table might just make the table somewhat usable with out the "What bad things are going to happen when I push the start button" thought everytime I try to cut a part. Imagine the start button giving you a shock when you push it. That's how leery I am to push it to start cutting.

Thanks again for everyones help. I just hope I can get good enough to help someone else out in the future.
Gerry

[muzza]

Now going toward the future... Where can i get a torch height contol that will work for my table? Getting a torch height control to work with my table might just make the table somewhat usable with out the "What bad things are going to happen when I push the start button" thought everytime I try to cut a part. Imagine the start button giving you a shock when you push it. That's how leery I am to push it to start cutting.
Gerry

Two options come to mind.
CandCNC have a very tried and proven THC system which should be compatible with what you have and in my opinion very reasonably priced and shouldn't require any major learning curve or alteration to how you do things now.

The other one I'd look into is Trucut's TruTrac Pro http://www.plasmaspider.com/viewtopic.php?f=76&t=9747 That's if its available as a stand alone to add to your existing setup, I'm sure Cindy or Ross will let us know. Looking at what I've seen about it via the internet, I'm interested in it myself for my next table and Ross has incorporated it their own tables to run with Mach3 so again I assume fairly adaptable. Mind you I haven't seen or used it first hand yet where as I have with Toms.
Murray

[trucutcnc]

Now going toward the future... Where can i get a torch height contol that will work for my table? Getting a torch height control to work with my table might just make the table somewhat usable with out the "What bad things are going to happen when I push the start button" thought everytime I try to cut a part. Imagine the start button giving you a shock when you push it. That's how leery I am to push it to start cutting.
Gerry

Two options come to mind.
CandCNC have a very tried and proven THC system which should be compatible with what you have and in my opinion very reasonably priced and shouldn't require any major learning curve or alteration to how you do things now.

The other one I'd look into is Trucut's TruTrac Pro http://www.plasmaspider.com/viewtopic.php?f=76&t=9747 That's if its available as a stand alone to add to your existing setup, I'm sure Cindy or Ross will let us know. Looking at what I've seen about it via the internet, I'm interested in it myself for my next table and Ross has incorporated it their own tables to run with Mach3 so again I assume fairly adaptable. Mind you I haven't seen or used it first hand yet where as I have with Toms.
Murray

Our TruTrac will be available as a stand alone by mid summer. Like our integrated version, it will run independent of Mach3. It will work with any system that has IO. It requires one input and two outputs. One output tells the THC to initiate the start/cut sequence and the other tells it to stop and retract. The input is the OK to move from the THC to controller.

If you're building your own controller with Mach3, you could integrate what we have now with out too much trouble. We also sell controller kits which include the controller, integrated THC and custom screenset with shape library and tracer.

[GPM870]

Thanks Trucut. I will look into this further. I keep e-mailing burntables about the torch height and all I get is "your too worried about the numbers, just eyeball it". When I can find time to get back into the shop I will try to get some more information for you to see what we can do.
Gerry

[bobrl]

Your Burntable THC sounds like mine!!! It is a Start,by Shaphon SH-HC30. What a work of art!!lol I feel just like you do about ,every time you go to push the start button!!!Am I going to get "Burned again!!!"The manufacture says,no difference between pierce height and cut height!!! It is a different problem every cut!!!!!But I have no help from any direction,Table manufacture, THC manufacture, or plasma machine manufacture!!! I guess I messed up big time!!!!
Bob

[bobrl]

Cindy,sounds like he has tried to get help from Burn tables,no luck!! Like me, from my manufacture,no help!!! So what can you offer??
Bob

[GPM870]

Cindy,
I have contacted them many many times, most questions go unanswered. Burntables are located in Hutto TX. I am in Wisconsin. I was planning on going to their shop to check it out but a long drive for a couple of hours of training.
Gerry

[vmax549]

GPM could you post the DXF files for a couple of your parts I would like to give them a try here. We work with air plasma alum cutting almost everyday from 16ga to 3/8. We use a very uniquie combination of consumables to get a very clean precise cut(for alum). We do a lot of artsy stuff for custom gates and ornimental alum work

I would like to try a couple of your parts here before I say what the combination is. It might just be the way I stand and watch with one leg up and waving my left arm. (;-)

(;-)TP

[Largemouthlou]

I would like to try a couple of your parts here before I say what the combination is. It might just be the way I stand and watch with one leg up and waving my left arm. (;-)
(;-)TP

Now that is a combo I haven't tried yet and I thought I tried them all, including closing my eyes and praying combo!!

[GPM870]

Usually I load the code in Mach, locate my start point on the material, cross my fingers,toes, and legs for luck, say a short prayer to the plasma gods, then push start!

I will post the DXF tomorrow, it is on the shop computer.
Thank you,
Gerry

[slimshady20043]

Usually I load the code in Mach, locate my start point on the material, cross my fingers,toes, and legs for luck, say a short prayer to the plasma gods, then push start!

I will post the DXF tomorrow, it is on the shop computer.
Thank you,
Gerry

LMAO. I do the exact same thing !!!!!! It's like did I make all the right changes, are all my settings right, damn I don't wanna hit start. Awww piss on it. Here goes nothing !

[GPM870]

Vmax,
Attached is the DXF of the part I am trying to cut.
I've actually built up enough courage (or stupidity) to try the part again today. It is a flashlight holder for my firemans helmet. Not shown on the print are the four screws that hold it together, attach it to the helmet, and hold the flashlight in place. I hope to post some pictures of the "attempt" later today or tomorrow.
Gerry