Dross removal. Best way?

[gamble]

I spent a few hours modifing this file to work for me, then 20minutes or so of cut time, then I burned up 4 flap wheels and about an hour of grinding.
I'm tired. lol
This is about 20"x20"
How can I speed up the clean up process?

Smaller parts I have in a small plastic bin of muriatic acid and water. Weather is getting colder and grinding in the garage with the door closed makes a lot of dust and debris I rather not breathe in. And rather not keep the acid in the garage. I hate how strong that stuff is. Would like something equally as strong just not harmful to the skin.


On a side note: I still have dross to remove when it sits in acid for awhile. That normal?

[wilber]

when was the last time you added acid to the mix?

After i let mine sit a while in acid sometime 2+ hours only because i am cutting other stuff. The dross should be coming off with just dropping it or a cold chisel should not have to sand most if it. I use 36 grit for quick clean, and when they are worn out the are great for cleaning up after the 120 grit.

what is the gauge of metal, cutting speed and cut height?

[jimcolt]

With my machine I use the Finecut consumables, cut at the book speed and height.....and what little dross I get knocks of in about 20 seconds with a scraper. Generally on parts like these there is no need to touch the part with a grinder. Use the smallest amperage nozzle at relatively low power, and experiment with speed....faster eliminates dross.

Some plasma systems only have one size nozzle for the entire amperage range.....this makes it difficult to dial the process in to eliminate dross.

Jim Colt

[jimcolt]

Best way to remove dross is to not make dross! See this post:

http://www.plasmaspider.com/viewtopic.php?f=4&t=14303

[gamble]

With my machine I use the Finecut consumables, cut at the book speed and height.....and what little dross I get knocks of in about 20 seconds with a scraper. Generally on parts like these there is no need to touch the part with a grinder. Use the smallest amperage nozzle at relatively low power, and experiment with speed....faster eliminates dross.

Some plasma systems only have one size nozzle for the entire amperage range.....this makes it difficult to dial the process in to eliminate dross.

Jim Colt

I wish hypertherm was in my budget for this one but it's not.
I set the machine to 150ipm 35 amps, I believe. Then when I started to cut I set it to 90ipm. It was cutting really fast so I don't know if it was at 150 or 90. The torchmate is buggy at times. Heigh is about .100 if I had to guess. I leave a little room for the plate to warp since I don't have height control and I try to keep putting water on the metal as it cuts to prevent it from warping. Metal is hot rolled 14 gauge.

So if i cut at 40amps at faster speed it's less dross than say 20amps at lower speeds?

I try to keep most parts at 35amps so I don't have to mess with it much. One less thing to play with
I'll do a line speed test later and post up some results.
what do you recommend for a good height for cutting? I can get a shim that size and use that as a guide.

[gamble]

Did a line speed test and found that 60IPM at 35 amps and used a shim of .100 for set height gave as close to no dross as possible. Really clean.
So I started cutting another one tonight and decided to not use any water on the part and just let it cut. Well silly me I forgot to turn on the compressor so some of it came out great, then on the feathers it started to get rough so I turned on the compressor. DOH!

And the plate warped sooooo bad. Torch dragged the metal around. LUCKILY for me i was able to line it back up and get it to finish cutting and looking like it never moved. I have never been able to do that before so glad I was able to on this large piece.

Tried to hit it with a hard plastic scraper I have and nothing happened. On the other side dross is pretty minimal but I'm thinking it still needs a grinder.

Wondering if there is a way I can get a stream of water to spray on the metal as it cuts to prevent warping.

[jimcolt]

Just turning the amperage down....but using a nozzle (tip) that is designed for full power...provides a low energy density arc with poor cut quality and high heat input (warpage). If your plasma torch manufacturer makes a 30 amp nozzle (tip), then you should use that at 30 amps....dial in the speed and height for minimal dross. Using a high amp tip at low amperage on thin material is an improvement, but using a low amp tip at low amps on thin material will be the solution. I get virtually no warpage on thin materials by using a Fine Cut nozzle at between 30 and 45 amps (depending on thickness, using specs from the Powermax85 cut charts), and this is on a downdraft table with no water splashing on the material (water is not the best solution for warpage as it also affects dross and edge roughness....and generally makes a mess)

The additional cost of purchasing a Hypertherm is made up pretty quick when you figure the cost of Flap Discs, your labor for secondary cleanup, and consumable life related cost savings. I have a customer that (monthly) sends me an order for about 1000 pcs of 18 gauge steel cutouts. Takes me less than 4 hours to do the whole job and pack it for shipping....not a piece is ever touched with a flap disc. After paying for the steel and the shop overhead I put over $2500 in my account from this job. There is a lot more than just a price difference between plasma cutters! Cut quality improvements can make you a lot more profitable.


Jim Colt

[Brand X]

Just to add a some kind balance..

On thin gauge metal you can fine tune a Thermal-dynamic or Esab Plasma cutter for very low dross also. They have a wide range of consumables in various amp sizes, and even go lower in output in some of the larger single phase machines. Plus with clean air, excellent consumable life.It's about knowing your system you have. All the good brand cutters have areas where they excel at.. Where I do agree is, ditch the water/fine tune your speed, and maximize your nozzle/amp setup.

Gamble,
you need to get a THC. It's causing you more problems then it's worth by not having one.

[gamble]

Jim
Money is really tight right now, can?t even justify getting a new welding hood.
Something like this blackhawks logo I had a few people request it, so I threw it up for $75 (into the material for $22 and $8 in flap discs) and people are complaining about the price. Or expecting it powder coated for the same price. Small pieces I start at $15 and people don?t even bite on that. It?s almost ridiculous how cheap people are up here.
I was using a 0.8tip and changed to a 0.9 tip. Any other tips to avoid warpage? That?s why I use 14g because it warps less than say 16 or 18g. I assume with all the detail on the one side of the piece that it?s going to warp a little regardless? Too bad I can?t put a hypertherm torch on plasma cutter

BrandX
I have a 2 stage filter setup at the moment and a water trap at the back of the plasma.
If the height controls wasn't over $3000 I would have one. It's hard to justify that option when it costs more than I have into the entire setup. lol

Maybe I'll try more amperage for a faster cut speed to reduce warpage?

[davek0974]

If time is not too critical, soak it for 24hrs in distilled vinegar, it removes the dross and the mill scale and leaves a lovely smooth surface.

I was amazed when I tried it.

Smell is not too bad and certainly safer than muriatic etc

[gamble]

I am going to try and find a tub this large to do that. A covered tube. How long can you use vinegar or acid before something else should be used?
I tried 100% white distilled vinegar before and it didn't do anything but I'll try again.

[davek0974]

No idea how long it lasts as I've only used it on small bits so far, probably not as long as acid, it's cheap though.

It does take a while and only works on steel not stainless etc.

[Brand X]

If the height controls wasn't over $3000 I would have one. It's hard to justify that option when it costs more than I have into the entire setup. lol

I would figure some way to get one. If you could get a Z motor lifter, and maybe figure out a way to change out your software to Mach-3/SheetCam, then maybe you could get a THC for much cheaper. At one time CandCNC made me a stand alone THC for my box. (12 years ago) Worked pretty well, and was not too much money.. You need to get onto a more open source software/hardware system, and stop getting bent over or held hostage. (IMO) You will be way better off long term, and short term too.

[jimcolt]

Gamble,

In the first post you said you used 3 flap discs (somewhere between $15 and $20) and an hour grinding.....and you could sell that part for $75 maybe? With the right plasma cutting process You could make 20 or more of those products in an hour, no flap discs. That's about $1500 worth of product to sell......pays for the height control and maybe a better plasma system real quickly.

When I bought my current cnc machine about 8 years ago (about $14k with plasma cutter)...I convinced my wife it would pay for itself in about 6 months. I'm 100% positive she did not believe me, but she still went along with the purchase likely to be able to prove a point. I decided to make it come true....and I worked hard on evenings and weekends selling, cutting and delivering plasma cut parts to every small shop within a 30 mile radius. I easily covered 100% of the machine cost in that time.....and now I consider the machine mine and it is used primarily for what I wanted it for.....my hobby cutting needs. I still occasionally take on small paying jobs, however I turn away more than I accept. The height control and the ability to fine tune the plasma allows me to easily profit (after cost of materials, consumables and shop overhead) well over $100 /hour when the machine is running. The more time you spend doing secondary operations (grinding, acid dip, etc) the less goes in your pocket.

I understand the budgetary requirements as I spent a lot of money in my younger days equipping my shop with imported and used equipment. Some worked out well, others were simply making me beat my head against a wall trying to use them. Just keep in mind that there are better ways to do many jobs.....usually it cost more for the equipment.....but the higher purchase price usually results in a better job in less time and lower operating costs.

I'm sure you will get yours dialed in.....we are here to help. Lower power, smaller orifice nozzles, tweak the speed and control cut height as accurately as possible....and you will see major improvements in dross and overall cut quality.

If you want....send me the .dxf file, I'll cut that part....with video running and we'll look at the time to cut and look at the top and bottom cut quality and warpage. You may be surprised at what height control and a good cutting process will do.

Jim Colt

[jimcolt]

14 gauge steel cut at correct height and speed with a Powermax plasma at 45 amps.

https://www.youtube.com/watch?v=0f9KBbnZfpE

[gamble]

Gamble,

In the first post you said you used 3 flap discs (somewhere between $15 and $20) and an hour grinding.....and you could sell that part for $75 maybe? With the right plasma cutting process You could make 20 or more of those products in an hour, no flap discs. That's about $1500 worth of product to sell......pays for the height control and maybe a better plasma system real quickly.

I had it for $75 sold 1 and everyone complained about price. Made some smaller ones. The other thing that hurts is my table is 2x2 so sheet of 14g hot rolled after shipping (when i buy 5 or more sheets) ends up being $23 a sheet.

When I bought my current cnc machine about 8 years ago (about $14k with plasma cutter)...I convinced my wife it would pay for itself in about 6 months. I'm 100% positive she did not believe me, but she still went along with the purchase likely to be able to prove a point. I decided to make it come true....and I worked hard on evenings and weekends selling, cutting and delivering plasma cut parts to every small shop within a 30 mile radius. I easily covered 100% of the machine cost in that time.....and now I consider the machine mine and it is used primarily for what I wanted it for.....my hobby cutting needs. I still occasionally take on small paying jobs, however I turn away more than I accept. The height control and the ability to fine tune the plasma allows me to easily profit (after cost of materials, consumables and shop overhead) well over $100 /hour when the machine is running. The more time you spend doing secondary operations (grinding, acid dip, etc) the less goes in your pocket.

I understand the budgetary requirements as I spent a lot of money in my younger days equipping my shop with imported and used equipment. Some worked out well, others were simply making me beat my head against a wall trying to use them. Just keep in mind that there are better ways to do many jobs.....usually it cost more for the equipment.....but the higher purchase price usually results in a better job in less time and lower operating costs.

Wow 14k, that's crazy! I guess I have will have to hustle a little more. My girlfriend has been advertising on facebook for me and seems nobody was biting. Yesterday she found a inbox on facebook called "other" where its' messages from people you don't know. So I hope business picks up that way.

I'm sure you will get yours dialed in.....we are here to help. Lower power, smaller orifice nozzles, tweak the speed and control cut height as accurately as possible....and you will see major improvements in dross and overall cut quality.

If you want....send me the .dxf file, I'll cut that part....with video running and we'll look at the time to cut and look at the top and bottom cut quality and warpage. You may be surprised at what height control and a good cutting process will do.

Jim Colt

Appreciate the offer, but I don't want you to waste material on me.
I sprayed the front and back with nozzle spray. Helped with some dross, but the smell sucks. Ideally it's not the end solution I want but it works in a pinch.
I did a line test and found that 60IPM netted zero dross, so I didn't change the torch height, just put on new material and 60ipm and TA DA! Still had dross lol. How does that happen!?

I shrunk this to fit 2 on a sheet and at 60ipm, 35amps, and nozzle spray it only took 1 flap wheel and 20 minutes to clean up. I guess it's a step in the right direction.

And of course I ruined the first piece, it warped (tried no water) and threw everything off about 1/2". I wondering if I should build a clamp that attaches to the slate and holes the workpiece down.

I really still don't see how no warping is possible even with height control and say 100Ipm. it just seems like the overall heat input would make it warp regardless?

I very much appreciate the help Jim!

14k wow! I guess I have to start to hustle a little more. I had my girl advertise on FB and such

[gamble]

14 gauge steel cut at correct height and speed with a Powermax plasma at 45 amps.

https://www.youtube.com/watch?v=0f9KBbnZfpE

WOW
Can my torchmate even go 250IPM!?

I would have never thought about that much amperage for such a thin piece.

[Brand X]

Can my torchmate even go 250IPM!?

I would have never thought about that much amperage for such a thin piece.

You can cut many ways, and get low distortion. You don't need absolute speed to get it done. You need range in your cutter, and nozzles. I cut .035 MS with about zero distortion/dross at lower then 150 IPM Key is my machine has 20-30 amp nozzles, and my cutter can go down to 15 amps. (don't use it that low, but 20 amps works just fine, even 25) I cut with a non shielded nozzle in those amp ranges, and the THC follows the plate Perfect. Never get blow-back from the tip, and end up with a very tiny kerf. Just a awesome for me, and would not change machines ever. !4 GA. would be like cutting 1 inch as far a distortion. It's all about a good thc, and low amp nozzles/ machine to get a Torch-mate to work correctly.

I would be tempted to try a 30XP with the finecut nozzles. Not rated that high in duty-cycle,(talking 14 ga here) but I bet it would give you the exactly what you are looking for in a low distortion/zero dross, and slower cut speeds to maximize your plasma table.You would end up almost with a laser like kerf in your hobby CNC table. Don't discount the little machines, because if you think out of the box, cool things happen..

[davek0974]

I'm running a 30xp on my small CNC table and I love it. I was cutting 3mm Ms today, 30A and 1800mm/min very little dross, it was all scroll work and the only dross was where the system slowed a little on som of the tight curves.

I was running the finecut consumables.

I get great results on 1.2mm stainless at 25A too, excellent little machine.

[matze-atze-sch]

Hey Gamble,

if you want a THC,
you can look at this:
http://www.ebay.com/itm/Proma-Compact-t ... 19f3893520

If you can connect this to your machine, its in my oppinion a good one, who I used by my self!

Greets from Germany,
Marcel

[gamble]

Did some testing this weekend. was cutting from 38-48IPM on 14 and 16g metal. Some good and some bad results.
Went to cut the blackhawk again at 180IPM and about 40amps and it warped fast. Did the face and 1 feather and it warped so bad the plate moved all over.

Which brings me to my next question. Do you guys clamp the material down or just let it sit there? I've always just let mine sit there but never had to do anything with this much detail.

[davek0974]

If I'm cutting thinner stuff i dump a lump of heavy metal in the non-cut area to keep it down, if there is no safe area I just put in a few pauses and let it cool between cuts, I'm in no rush.

[mike 1948]

I spent a few hours modifing this file to work for me, then 20minutes or so of cut time, then I burned up 4 flap wheels and about an hour of grinding.
I'm tired. lol
This is about 20"x20"
How can I speed up the clean up process?

Smaller parts I have in a small plastic bin of muriatic acid and water. Weather is getting colder and grinding in the garage with the door closed makes a lot of dust and debris I rather not breathe in. And rather not keep the acid in the garage. I hate how strong that stuff is. Would like something equally as strong just not harmful to the skin.


On a side note: I still have dross to remove when it sits in acid for awhile. That normal?

An hour of grinding eats up any profit you might have left in your $75.00. I cut a lot of Bucky Badgers(14 ga.), I have included a pic in this post, but I use cold rolled sheet. I have no scale to remove just the light dross which "usually" comes off fairly easy. It takes approx. 10-15 minutes to grind both sides and get it ready for clear coat and paint. The time savings I would think pay for the increased material cost plus you don't have to deal with acid and scale.
Here is the flap disk I use, very thick and last for 3-6 Bucky's: http://www.ebay.com/itm/10-4-5x7-8-Jumb ... 3f0d41afe2.
I use a Cutmaster 52 at 40 amps and 100 IPM. with THC. I also see some minimal warpage, but use some 1/2 thick pieces to hold it in place. A 0.09 dia. tip seems large, my 40 amp tip is approx. .040-.050 dia. approx.
Have you tried reversing the direction of your cut, sometimes the dross will accumulate more on one side than another, get it to stick to the scrap side.
Here is where I get my material, cut to size and delivered to the door: http://metalsupermarkets.com/
Don't order online, you get better pricing when you call.

Good Luck getting dialed in,
Mike

[Brand X]

One point, factory 9-8208 victor tips are closer to .035 maybe a bit less Esab 40 amps are .032/ 20-30 amps are .028 (from memory there)

[gamble]

That looks great! I wondered what was up with that. It seems to cut better in one direction than the other. I"ll look into reversing it and see what happens.
I may have just got a hook up. My friend works at a place and gets a discount, but i have to cut them myself.
It will bring my cost down from $23 a sheet of hot rolled to about $8 a sheet of cold rolled.