[magma-joe]

tof1, How about posting a picture of your table?

[tof1]

It's amazing what a volt or two difference will make! Im starting to dial in the settings. It will be nice once I get a collection of them going in Mach and can just choose one for the material I'm cutting. I'm super busy trying to keep up with regular work while working on the plasma. I'll try get some pics up.

[jimcolt]

I have been working with cnc plasma systems for 30 + years.....and continuously educating users on the need for accurate torch height control- both real time height control during the cut, as well as having an accurate, repeatable pierce height. Torch to work distance is one of the three most imortant factors in achieving an accurate plasma cut part...at a reasonable cost per foot of cut.

The other two factors are accurate motion at the proper velocity.....and of course a good quality plasma system.

Glad to see you are making progress!

Jim Colt

[tof1]

Is it possible to cut 16ga steel with zero taper using fine cut consumables? I thought because it's so thin it would be? Or is it the opposite because it heats up so quickly?

[jimcolt]

No.....you cannot guarantee "zero" taper with any process (air plasma, high definition plasma, abrasive water jet, laser) on any material.

The Fine cut consumables will get you within level 2 of the iso9013 cut edge quality standards on 16 ga steel if you are maintaining the correct torch to work distance and cutspeed. I expect that the angularity would be relatively uniform and probably in the 5 to 7 degree (from 90 degree) range.

A High Definition plasma torch using oxygen as the plasma gas will do better, a laser will also do better. Some water jets (with the articulating head) will alos do better.

Jim colt

[tof1]

5 to 7 degrees is about what I'm getting so I guess it's as good as it can be. Should I expect more taper on thicker materials? Thanks for the help!

[Bigtoy302]

No.....you cannot guarantee "zero" taper with any process (air plasma, high definition plasma, abrasive water jet, laser) on any material.

The Fine cut consumables will get you within level 2 of the iso9013 cut edge quality standards on 16 ga steel if you are maintaining the correct torch to work distance and cutspeed. I expect that the angularity would be relatively uniform and probably in the 5 to 7 degree (from 90 degree) range.

A High Definition plasma torch using oxygen as the plasma gas will do better, a laser will also do better. Some water jets (with the articulating head) will alos do better.

Jim colt

5-7 degrees is a lot. My Powermax45 on 1/4" steel is giving me around 1-2 degree taper sometimes less, unless I do holes.(about .010 taper)

[Torchhead]

Finecut with lower currents and proper feedrates (and an accurate THC) will give you almost laser quality cuts of 16ga and thinner and leaves you with a small kerf and smaller heat effected zone. I have a customer cutting painted R-Panel (24 ga) with fine cut at 350 IPM and it barely scorches the paint on the edges of the cut!. 16Ga does tend to buckle easier than thicker stuff but it has to do with the stress relief of thinner material (cross sectional area). Finecut actually produces less heat than larger tips but doing lots of detailed cuts in a close area will let heat build up regardless of the nozzle size.

One of the most popular selling items we offer is a custom wallclock cut from 16 ga steel and finished with a copper plate and oxidizing patena. We have the main circular pattern in CorelDraw as a master and just drop in the circular text and the selected pattern in the center. See images.

TOM Caudle
www.CandCNC.com

[jimcolt]

Bigtoy,

I gues I wasn't real clear about angularity....the thicker you cut with plasma...the smaller the bevel angle will be. It is very common to cut 1/4" with plasma with a 1 or 2 degree bevel...which is hardly noticeable......and it is also common to be able to cut 3/4" or 1" with plasma with a .5 degree bevel.....or even 0. The difficulty is with thinner materials....the bevel number gets higher.....and it does with lasers and waterjets as well!

However....appearance wise....a 7 degree bevel on 16 gauge is hardly noticeable.....if you had a 7 degree bevel on 1/4".....or 1/2"...the part would likely be unacceptable!

Jim colt

[Bigtoy302]

Bigtoy,

I gues I wasn't real clear about angularity....the thicker you cut with plasma...the smaller the bevel angle will be. It is very common to cut 1/4" with plasma with a 1 or 2 degree bevel...which is hardly noticeable......and it is also common to be able to cut 3/4" or 1" with plasma with a .5 degree bevel.....or even 0. The difficulty is with thinner materials....the bevel number gets higher.....and it does with lasers and waterjets as well!

However....appearance wise....a 7 degree bevel on 16 gauge is hardly noticeable.....if you had a 7 degree bevel on 1/4".....or 1/2"...the part would likely be unacceptable!

Jim colt

I got it now. I guess I do get good angularity when I cut 16ga.

[slammedxonair]

And once you find the magic DFZ you can build a profile in the MP3000 Cut Profiles screen. The upper parameters are for information (Notes) about the feedrates and amp settings and selected nozzle and you can use them to remind you what settings to use for a particular type of material. The lower section is actual settings for the DTHC to use (Preset Volts, etc). Be prepared to do a LOT of entries and testing because even slight variations will bring back the dross. If you start cutting smaller features the feedrates change and guess what......the dross shows up on those cuts. After hundreds of hours of cutting for our decorative cutting business, I found out two things:

1. I could always get a dross free cut if I worked long and hard enough and made detailed notes and never cut anything but larger lines and arcs.

2. I don't have enough patience to do #1

I found that low speed dross is easier to remove with a simple tap with the angled edge of a cheap wood chisel. The time spent cleaning up cuts was less than trying to get perfect clean cuts. As you found, plasma cuts differently on different surface finishes, different thicknesses and different feedrates. Another dirty little secret was I found that having a tank of dilute HCL (Muratic Acid from the Home Center or pool supply) and hanging the cut pieces in the tank for a few hours did miracles and cut finish time by a lot. The acid etches off the rust, black mill scale and loosens the dross to a point a flat drop on concrete leaves you with just running a flap sander quickly over the cut edges before they go to paint or plating. WARNING the acid once it's diluted about 20 or 30 :1 from the muratic state is not too dangerous BUT it will oxidize (instant rust) anything metal in your shop that is exposed to the fumes. I keep my tank outside covered and a large box of Baking Soda handy. The pieces HAVE to be rinsed VERY well right after they come out of the tank and dried IMMEDIATELY.

Lots of other secrets too but Dinner is calling to me!

TOM Caudle
www.CandCNC.com

What do you need baking soda for? The only thing I dont like about using acid is that it leaves a green haze on parts it seems like. I have never really tryed using it for removing rust before. But do you really dilute it that much? Wouldn't it nutulize the acid? (havn't had a chemestry class in a long time lol) But I have found the best way to remove dross is with a knotted wire wheel cup on a electric grinder. It also leaves a nice finnish as well. But I am going to try building my tumber soon as well and experiment with different medias including the small metal slugs off the table. I also vote for more secrets!

[Torchhead]

What do you need baking soda for? The only thing I dont like about using acid is that it leaves a green haze on parts it seems like.

Baking soda neutralizes the acid if you spill any concentrate. It happens.

Green Haze? Not on steel. You can pull it out of the tank and all mill scale and rust will be gone. You rinse it very well with running water...then rinse it again! Towel Dry (towels don't last long so use old ones). A heated box in the Winter is a plus. One of the zirconium flap disks (4.5" disk) will clean up the edges and lasts a long time. If you want to plate, the metal has to be shiny clean so the flap sander can be used to take off the layer of grey oxide the acid leaves. For powder coating it just needs to be smooth. Biggest hassle is if you use rusted metal and the rust has pitted the surface, the acid will work in the pits and you have to really work with the flap sander. Textured powdercoat paints ( found a metallic bronze that went on thick and would hide a lot of surface flaws) works best. Glossy paint transmits ANY imperfection.

I have never really tried using it for removing rust before. But do you really dilute it that much?

Muratic in the gallon jugs is cheap but it's nasty stuff. The vapors should not be breathed and splash some on your skin and you will run looking for a water faucet (or the baking soda). Water can either be acid, alkiline or neutral. Adding HCL makes it acid and it stays that way. I have a 300 gallon polytank and I put in about 10 gallons to begin with and just add a gallon every few days. As the water evaporates the PH goes down (more acid). I add water to bring the level back up. I can get a 3 X 3 cutting in the tank and a 4 X 4 diagonally but the top sticks out. I have to turn it every hour.

The stronger the mix the quicker it works. I like it so it works overnight. It will etch the steel over time so leaving it too long will start to make the surface grainy

Wouldn't it nutulize the acid? (havn't had a chemestry class in a long time lol) But I have found the best way to remove dross is with a knotted wire wheel cup on a electric grinder. It also leaves a nice finnish as well. But I am going to try building my tumber soon as well and experiment with different medias including the small metal slugs off the table. I also vote for more secrets!

I tried needle scalers (really loud and slow) , wire brushes (really dangerous) and the hard grinding disks (gouged the metal). Best combo (fastest) was a set of cheap wood chisels and the flap sanders in two grits. I picked wire bristles out of my arms and once out of my head. The acid tank cut our manual cleanup of the pieces a lot. Letting it soak while you cut other jobs makes it a low cost process. I don't live in the city so it won't rust my neighbors car from the fumes!

Sandblasting, unless you are setup with a really big rig, is VERY slow but leaves a completely clean surface ready for paint.

You will find most people want a finished product even if it costs a lot more. I have pricing by the square foot and it varies if it's painted or plated and the thickness of the material. I can throw out a price just by knowing the size. I use the nearest 6 inch increment (UP). I always leave a "gripper" edge (about 1" border) and use the hand spring clamps to clamp the edges to the grid. Without them i have had thin material popup a couple of inches.

Okay here is a quick secret: When you take in a custom job present the customer with a drawing of EXACTLY what they are getting (use your drawing to print AND Cut from). Have them sign off on the "proof" or make any minor changes and check spelling. We used e-mail whenever possible so we had a record of the customer's OK. It saved my grits more than once and it helped me get business. I once did a very profitable job cutting out 24 " tall aluminum letters that ran all the way across the front of a stone faced building. I took digital photos of the building and superimposed the sign on the picture to scale. The owner changed their mind about placement and we had to change the letter size and layout slightly. A LOT easier to do it in the computer than when we got there to drill holes (in stone) and mount the letters. I even had a fullsized pattern printed out on paper and glued to masonite with the drill holes already marked to match the "studs" we had welded on each letter.

Later:

TOM Caudle
www.CandCNC.com

[WSS]

Finecut with lower currents and proper feedrates (and an accurate THC) will give you almost laser quality cuts of 16ga and thinner and leaves you with a small kerf and smaller heat effected zone. I have a customer cutting painted R-Panel (24 ga) with fine cut at 350 IPM and it barely scorches the paint on the edges of the cut!. 16Ga does tend to buckle easier than thicker stuff but it has to do with the stress relief of thinner material (cross sectional area). Finecut actually produces less heat than larger tips but doing lots of detailed cuts in a close area will let heat build up regardless of the nozzle size.

One of the most popular selling items we offer is a custom wallclock cut from 16 ga steel and finished with a copper plate and oxidizing patena. We have the main circular pattern in CorelDraw as a master and just drop in the circular text and the selected pattern in the center. See images.

TOM Caudle
www.CandCNC.com

Do you have to have a bare metal pierce point or can you blow through the paint?

Cheers!
WSS

[jimcolt]

A torch with a pilot arc will transfer through paint...as long as the plate is getting a good work clamp connection....

All Hypertherm plasma torches use pilot arc starting and have no issues with the arc starting on painted, rusty, or masked materials. Many import torches use scratch start...or a high frequency start that does has to be close to the plate to transfer the arc.....these systems do not work well with painted or rusty plate.

Jim colt

[slammedxonair]

"I have never really tryed using it for removing rust before." I ment so say dross I have only used it for removing rust in the past. But for the wire wheels I have never used the regular loose wire kind only the knotted ones and have never had an issue with the wires flying out like I have heard from so many people. They just kinda wear down real slow over time and leaves a nice clean finnish.

[slammedxonair]

I have more questions on the acid and wat to try this out more. I would I go about self P&Oing steel? soak it in some acid and water then take it out and dip it into baking soda water then dry it off and wipe some wd 40 onto it? alot of the parts I sell need a nice clean finnish and some are welded on by the customer such as tabs and brackets and things. Anybody have any input? Thanks.

[slammedxonair]

anybody on the acid question?

[towertek]

I was having wiring problems with a THC and it was affecting the ARC OK signal. It was turning the torch on and off very quickly which manifested itself like a herk jerky action and with bad looking cuts like this poster has.

I am assuming this poster is using Mach3 and can view what thepins on the parallel port is doing in real time.