A neophyte makes a downdraft plasma cutter table

[DrReid]

Last year when I wanted to fabricate some metal and wood furniture, I had to figure out how to cut curves in metal plate. I stumbled across something called a plasma cutter. I had no idea what it was. Then I learned what one could do, and I had to have one, and I wound up with a PrimeWeld Cut60.
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First I needed a plasma cutting table, and so I bought a very inexpensive model from JEGS. I need to move things around my shop, and so I attached plates and casters to the legs. This was my very first stab at welding anything. Ever.
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I also learned that plasma cutting generates a lot of sparks, fumes, and slag. And that's when I jumped down the rabbit hole. The first order of business was to fabricate a sparks and slag collecting system, so I started with a sheet of 18G stainless sheet:
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After much measuring and 3D modeling, I cut the four sides:
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...and, using a new brake, and in my first time welding sheet metal, put together the collecting funnel, which I thought bore remarkable resemblance to a kitchen stove fume hood:
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I attached it with screws, and added an internal bottom shelf of 3/4" ply covered with a piece of 18G SS sheet:
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This is where the project got very difficult for me because I had to modify a commercial table that wasn't designed for modification to turn it into a downdraft table. I enclosed all four sides with mild sheet, cut an opening for a door (to remove the slag bucket), and cut a hole for fume extraction.
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By this point, I was already using the plasma cutter to make all the cuts...to make the table for the plasma cutter. A nice symmetry. After a coat of Rust-Oleum Farm & Implement paint, this project was done:
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Fume extraction is handled by a HF ventilation fan that I installed inline into some 8" ductwork directed out of my shop:
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I made numerous test cuts in everything from 18G sheet to 1/2" mild plate, using the whole surface of the table in some instances, and covering a portion of the table in other instances. In all, the downdraft works perfectly. No fumes in my shop.

 

[dogdog]

hmmm nice... have been wanting to make one for a while... where do you source those 18G SS sheets.

 

[Dumber than lumber]

Thanks for posting this. AMAZING!
Looking at that table I am reminded of how similar the frame is to a cabinet for rack mount data servers. I guess it all starts with “I had to have one”.

 

[OldNeons]

Very nice work! I’ve been thinking about one of the water table kits from 911 Motorsports.... wonder how the water compares to the funnel/fan?

 

[akalian]

You did good, no question about it.
Don't worry about the welds.
You will get better with more practice. And you look like your are well on your way.

As the old guy that taught me how to weld would say..."A half inch weld is good as a half inch bolt."

.

 

[tarmy]

Looks good...but careful with hot slag. Plasma cutting generates a lot of material that is flying around...and that flex pipe you have does not appear to be metal nor fire proof. You could have some issues with hot material finding it’s way into that duct and causing issues...or even making it to your vacuum machine.

A safe welding/plasma tool to have VERY handy...is a good fire extinguisher...just sayin’...

Keep on with the welding projects...great start...

 

[DrReid]

hmmm nice... have been wanting to make one for a while... where do you source those 18G SS sheets.

Thank you. I bought the SS sheet at a local metal scrap yard. The sheet wasn’t scrap, in the sense that it still had poly film on one side. SS was total overkill, but the yard has no mild sheet, and I don’t have to worry about rust.

 

[DrReid]

Thanks for posting this. AMAZING!
Looking at that table I am reminded of how similar the frame is to a cabinet for rack mount data servers. I guess it all starts with “I had to have one”.

Thank you.

 

[DrReid]

You did good, no question about it.
Don't worry about the welds.
You will get better with more practice. And you look like your are well on your way.

As the old guy that taught me how to weld would say..."A half inch weld is good as a half inch bolt."

.

Appreciate the encouragement. I’ve welded a lot more since this project’s inception, and my work indeed improved. Love the quote. I’ll have to remember that one.

 

[DrReid]

Looks good...but careful with hot slag. Plasma cutting generates a lot of material that is flying around...and that flex pipe you have does not appear to be metal nor fire proof. You could have some issues with hot material finding it’s way into that duct and causing issues...or even making it to your vacuum machine.

A safe welding/plasma tool to have VERY handy...is a good fire extinguisher...just sayin’...

Keep on with the welding projects...great start...

You know, that was my only serious hesitation with the downdraft feature. I figured that the convoluted path slag would take from cut metal to exhaust port would allow minimal if any slag or spark escape. Just in case I would ever be wrong about that, I have two fire extinguishers within 2 or 3 steps from my fab area.

 

[dogdog]

they do sell those aluminum kitchen grease filters for kitchen exhaust you can use as spark arrestor at the exhaust port outlets... that way if any tiny hot molten metal goes there it hits the aluminum screen first. or ... double / triple up a few of those metal lath mesh

or something like these. I had plans for these for a kitchen exhaust box.. but should serve the same purpose.

https://www.amazon.com/dp/B07QZRQHZS/?tag=atomicindus08-20

 

[DrReid]

they do sell those aluminum kitchen grease filters for kitchen exhaust you can use as spark arrestor at the exhaust port outlets... that way if any tiny hot molten metal goes there it hits the aluminum screen first. or ... double / triple up a few of those metal lath mesh

or something like these. I had plans for these for a kitchen exhaust box.. but should serve the same purpose.

https://www.amazon.com/dp/B07QZRQHZS/?tag=atomicindus08-20

After looking at the spark arrestor on a generator I used during a power outage, I was beginning to arrive at the same idea. Thanks!

 

[PugetDude]

Great job on the table; I may have to plagiarize your idea.

 

[DrReid]

Great job on the table; I may have to plagiarize your idea.

Thank you. I stood on the shoulders of others to arrive at my table. Plagiarize away.

 

[Lwel9226]

What part of Oregon are you in????

LynnW

 

[DrReid]

What part of Oregon are you in????

LynnW

Salem.

 

[Mandres]

Looks really nice! I think downdraft is the way to go but a lot of folks use a water table instead. I think that would be very messy.
Does it do a good job keeping the smoke and fumes out of the shop?

 

[DrReid]

Looks really nice! I think downdraft is the way to go but a lot of folks use a water table instead. I think that would be very messy.
Does it do a good job keeping the smoke and fumes out of the shop?

Thanks a lot. Yes, my table essentially eliminates the fumes. As I noted above, the exhaust fan is just a cheap HF, but that does surprisingly well. It is too small to handle fumes from the longest cuts on thick plate. However, I tend to screen (block) non-used areas of the table for shorter cuts in order to maximize air flow down. That kind of economizing works very well. All of these compromises and obvious shortcomings of my project should be viewed against my role as hobbyist.

 

[kwb]

This has me rethinking my watertable and waterproofing I was planning around my machine.

Nice work.