Controlling plasma cutting sparks & debris?

[JimGnitecki]

I just received my inexpensive 50 amp "lunchbox" size plasma cutter from Amazon. I have not used it yet - will read the user manual first (despite the universal prohibition among REAL men to never read the instructions first!). But, I have watched a number of videos before even ordering one, so have a question:

How can you control the sparks and debris coming off the material during cutting, when using one of these small portable machines (as opposed to a professional water table setup)?

I am asking because I have seen plenty of "unbox and try" Youtube videos where people just unbox, connect the torch, ground, and air, and proceed to fill the immediate vicinity with lots of sparks and hot fragments.

ONE Youtube poster, Mike Festiva, actually built a small setup that attaches to his welding table. It is a roughly 1 ft x 1 ft homemade mild steel "grate" that bolts to the side of his welding table. It has a pair of rails on the bottom of it that enable him to slide a standard commercial kitchen stainless steel "steam table pan" into position below the grate. He has about 2 inches of water in the pan. He places his workpiece on top of the grate, lines up the proposed cut line with one of the "slots" in the steel grate, so that his plasma stream will not cut the grate, but only the workpiece, and cuts his workpiece. This directs most of the sparks and debris into the pan, rather than into a wide area surrounding the plasma torch. The water extinguishes the sparks, which sounds like a good idea!

Couple of obvious questions:

1. Why would Mike use a grate, rather than just 2 pieces of steel separated by a gap for the plasma torch to run through? That could be a much simpler thign to both build AND use. Just buy a standard size steam table pan (I would think maybe the 12" x 20" size), add water into the pan, place 2 pieces of plate steel on top, separated by a narrow gap, place your workpiece so that the proposed cut line follows the gap between the 2 pieces of steel (table), and cut!

The 2 solid pieces of steel would cover everything but the cut line, so in theory none of the sparks or debris would get out into the air or on the floor.

After the cut is completed, both pieces would stay in place, rather than one falling onto the floor and right into the debris that just preceded it to the floor!

2. Why would Mike make the entire rig so small? By doing so, he limited his maximum length of cut to under 12". By using a 12" x 24" size instead, you would get the ability to do up to a 24" cut. Or, you could crosscut one long piece of metal easier by placing the piece ALONG the 24" axis a lot easier than along the 12" axis. Any reason to limit the size of the rig? (Other than being in a very small shop)

3. WHY is this the very first homemade plasma cutting table I have seen in a Youtube video? Do most owners just cut using the end of a workbench or between 2 workhorses?

Why would people voluntarily allow sparks and debris to go in any uncontrolled direction, when they represent fire danger and personal burn or injury potential?

Or is it just that we men liek to see lots of fire and stuff flying around when we work??

What am I not understanding here?

Jim G

 

[Former Member]

The only question you should be asking, is anything even slightly flammable around and go from there.

 

[trevj]

All the welding shops, and welding areas, that I have been in, were built so there was no flammable crap left laying around waiting to be lit. Either smooth concrete, or dirt floors, steel cabinets, etc.
At least half the time, the most flammable stuff in the area, was the welder's coveralls.

The grate works better on a plasma table because then you don't have to mop up the mess, when 15 pounds of cut-off steel lands in the pan, and either knocks it over, or punctures the bottom of it. And you don't burn yourself on the cut ends, making a wild grab for the part as it bails off the supports. Gravity. Still a useful workholder, after all these years!

Pretty much every CNC plasma table out there uses some variation of the theme. Many even submerge the bottom surface of the sheet to reduce dust in the air. A lot, use a wavy pattern, for the support grate, so as to reduce the chances of a cut through, and to maintain the top surface, on average, fairly flat, despite heavy use. The grate IS a consumable, and must be replaced when no longer serviceable.

Aside from that, a grate is much more useful, for when you are NOT cutting strips off a new sheet of material, you can lay almost any off-cut that will do, on a grate, and cut a gusset or bracket out of it, so you minimize waste.

As case in point, the last use of my plasma cutter, was cutting out wheel clearance arches in the side frame of a welding/flat deck that one of the nephews was building for his 1 ton Dodge truck.

Hard to find a handy place that has a hoist to swing the whole truck over a catch table, so it was done as you say, sparks flying everywhere. "Everywhere" had already had a decent clean up done around it, and there was enough time after the operations, to be reasonably sure there was no fire risk.

 

[phaxtris]

Even with a water pan/box you still need to be aware of the risk of fire, the sparks don't always just go down

Welding, cutting, grinding, all come with inherent fire risks, keeping your work area clear of combustibles, being mindful of where your sparks are heading, and having some means of putting out a fire are all good practice, something you should be doing anyways

And do not let the last thing you do in the garage be hot work, most of the fires don't happen right now, they happen 30.min to an hour later

 

[trevj]

Even with a water pan/box you still need to be aware of the risk of fire, the sparks don't always just go down

Welding, cutting, grinding, all come with inherent fire risks, keeping your work area clear of combustibles, being mindful of where your sparks are heading, and having some means of putting out a fire are all good practice, something you should be doing anyways

And do not let the last thing you do in the garage be hot work, most of the fires don't happen right now, they happen 30.min to an hour later

Ayup.

'Course, not to say i have not looked down to see half my pant leg missing on <cough> at least one occasion.

Handy to have a bucket of water or a hose on hand, when working in less than ideal circumstances, but either planning your work flow around the hot work being over some time before you shut down, or planning around a hot check a time after you have left the work area, are both darn good ideas!

 

[JimGnitecki]

Even with a water pan/box you still need to be aware of the risk of fire, the sparks don't always just go down

Welding, cutting, grinding, all come with inherent fire risks, keeping your work area clear of combustibles, being mindful of where your sparks are heading, and having some means of putting out a fire are all good practice, something you should be doing anyways

And do not let the last thing you do in the garage be hot work, most of the fires don't happen right now, they happen 30.min to an hour later

Yes, Many years ago I was in manufacturing management, and was as a result the chief safety officer in manufacturing plants that had lots of hot processes including MIG welding and lots of flammable liquids and solids, so I am very attuned to keeping a very clean shop in my two retirement home garages.

It is even more challenging given that my rear garage necessarily houses both metalworking and woodworking equipment and processes. As a result, I vacuum a lot, have a dust collection system, use paper towels versus rags for chemicals, throw the used paper towels out same day, and keep a WIDE radius of clean and clear concrete floor all around ANY process that could cause combustible solids, liquids, or gases to ignite. And like you have pointed out, I never leave right after completing hot work. I wait until everything is positively cold. I even have one of those electronic temperature guns that provides a digital display of the temperature of anything you aim it at.

This is why I am asking how best to manage the sparks, debris, and hot outputs from plasma cutting. They are an obvious hazard to mitigate.

I read the user manual for the plasma cutter tonight, and one of the things that struck me was how it emphasized that a big contributor to safety is getting correct and accurate control of the amps being applied (varies with thickness and metalurgy), the DRY and steadily reliable air supply, appropriate torch speed (varies with metal thickness and amps), slight "rearward" arc pattern on the cut metal, and the amount of post air flow. Also, it sounds like drilling a start hole for a non-edge start versus piercing, will prevent a lot of horizontal sparking and debris throw because piercing, like incorrect amps, generates a lot of UPWARD and SIDEWAYS sparking and debris instead of the proper DOWNward spray.

A lot to learn to make plasma cutting simultaneously precise, clean, and safe.

Jim G

 

[JimGnitecki]

Ayup.

'Course, not to say i have not looked down to see half my pant leg missing on <cough> at least one occasion.

Handy to have a bucket of water or a hose on hand, when working in less than ideal circumstances, but either planning your work flow around the hot work being over some time before you shut down, or planning around a hot check a time after you have left the work area, are both darn good ideas!

Yes, I have an A,B,C fire extinguisher on the wall by the exit door, ready to use. I also keep a spray bottle of water right near where I TIG weld and where I will be plasma cutting, not to douse a fire (the fire extinguisher will do that much better), but rather to douse my skin or clothing should either be accidently suddenly heated! Skin burns cna be prevented or at least mitigated by getting water onto the affected skin area FAST. And of course no synthetic fiber clothing which would really add to any burn.

Jim G

 

[phaxtris]

The way to mitigate it is to do it in an area free of things that light on fire and be mindful of where the majority of the sparks are flying, it's not really practical to try and contain all of the sparks from a hand torch, the best you can really hope for is some screens to contain it to an area

As for clean, If you want clean you should use a hacksaw or some other toothed tool...even a water pan is messy...just wait untill you have to clean it out

If you keep a clean work space the worst thing you should have to worry a out is a stray set of drawings or the frays on the bottom of your pant leg, all easily patted or stomped out...but do keep that extinguisher and fire watch just in case

 

[6.5 Fan]

I second all of the above suggestions for welding, stay safe out in the shop. Fire and burns are not fun unless its at a weinie roast. Not your wienie though.

 

[Former Member]

And do not let the last thing you do in the garage be hot work, most of the fires don't happen right now, they happen 30.min to an hour later

This!

 

[Aliva]

Where I used to work anyone that may be doing " hot work " were required to ware Nomex clothing. Fortunately the company provided the clothing. The clothing is very expensive so the average home hobbyist is not likely to buy them.
I believe the shirts were around $100.00 and the pants $250.00 to $300.00. I still have a few shirts and pants but seldom ware them as I don't do much hot work at home. Coveralls were around $400.00. The cheapest alternative for home would be leather welders jacket and chaps. Even grinding can be hazardous I'm sure we've all burnt a shirt or 2 while grinding, I know I have.

 

[Dan Dubeau]

I only use mine outside. I will grind and weld in my shop (with caution), but the plasma is a no go. It's just too small of a space to be throwing that amount of fire babies everywhere.

I did see a neat idea that I'd like to make and that's a 55gal steel drum with a cutout from the top half way (ish) around, and down about a foot to create a backdrop. Then they welded in a grate to do the cutting on. All slag and scraps, and sparks fall into the drum. I might build something like that outside my back door, so I can drag the plasma over for quick stuff to cut outside.