metal slat material for water table?

[LureMin]

Hey guys, about finished putting together my CNC table, and im to the point where I need to make the slats for the water table. Here is my question, I need to use 1/8 x 2" flat bar, but was on the fence about using steel VS using aluminum. I know aluminum is a little bit more expensive and they are consumable pieces but the cost difference isnt to bad, and my reasoning for veering to Alum is so they dont look like a rusty mess in a matter of weeks or so. unless there is a downfall to using aluminum im not seeing?

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[curbster]

Hey guys, about finished putting together my CNC table, and im to the point where I need to make the slats for the water table. Here is my question, I need to use 1/8 x 2" flat bar, but was on the fence about using steel VS using aluminum. I know aluminum is a little bit more expensive and they are consumable pieces but the cost difference isnt to bad, and my reasoning for veering to Alum is so they dont look like a rusty mess in a matter of weeks or so. unless there is a downfall to using aluminum im not seeing?

Many would advise against using aluminum in a water table. The hydrogen expands under pressure and when the dross from previously cutting aluminum is under a sheet you are cutting, if there is no air for the aluminum to breath, it will explode.

It will also deteriorate much faster than steel. I use 10ga x 4" for my water table.


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[LureMin]

Yea after looking online a bit more I've decided against aluminum, there had to be a reason why no ones uses it lol.

Now here is the next question, what sort of solution or what have you will cut down/ or pretty much eliminate corosion on the slats from the water? I've seen some things as plasma quench? cant find where they sell it, or as simple as using Washing soda?

[curbster]

There are recipes online to make your own. I typically buy from the company who made my table. $150 for a 5gallon jug. The reason I justify the cost is that their recipe doesn't have nitrite in it, but plasma quench does. I've used plasma quench before, it's cheap, but once the flame hits the water the smoke turns into a carcinogen and smells awful. Be aware of the chemicals people use and how they might affect your health. I'm still looking for the right recipe after 1.5 years of owning


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[LureMin]

Oh damn yea I definitely dont want that as this table will be used in my indoor shop with air conditioning, so fumes will have to be at a very very minimum to zero. For sure dont need carcinogens in the air lol

[flyinwilly]

I use 10GA x 2" steel for the slats in my table. They do look a bit crappy after a while but the water table will look worse with the scraps and junk that burns off the sheets as you cut. If you are worried about the appearance, you'll be spending all your time cleaning instead of cutting.

I use a mixture of sodium nitrite and Physan 20 for my quench. It is very effective in eliminating rust and algae/mold and is quite inexpensive. You use 1/4lb sodium nitrite and a teaspoon of Physan20 to 75 gal of water. As for being a carcinogen, it can't be too bad since it is a major food preservative. If you eat bacon, you've been eating it. As for the smell, I can't smell anything when cutting but my table has both a water table and a downdraft system so I don't get any smoke or fumes off the table. Without some kind of smoke/fume collection system, you will be getting smoke / fumes in the air. That's a bigger worry than the quench. If you use this recipe, be sure to get Sodium Nitrite, not Sodium Nitrate.

Willy

[LureMin]

Thanks Flyin, I will have to set aside my ocd while cutting thats for sure, as I am a clean freak of sorts in my shop area as you can tell by the pictures. I will try out that recipe , and yes I eat bacon lots of bacon... can you post some pics of the water and down draft system? I may try to do both on mine as well.

If I cant however make both work would a down draft system be better than the water table? I can always convert my water table into a down draft if it will get more smoke out. I have an outside wall right near my table and wouldnt be hard to plum multiple 6" vent holes in my water table pan and run through a filter and duct outside.

[flyinwilly]

Plasma is very dirty and if you are running in an enclosed area, you need to do everything you can to minimize the dust. You won't believe how much crap is generated. It will get over and into everything before you realize it's happening. It's also not too good for your health.

Look at my build, A Different Machine - Downdraft/water table, here on the zone. My table is 4 x 2 so the downdraft was fairly easy to do with one large blower. If I doubled the size of the table to 4 x 8, I would have needed 4 times the blower size. With a large table, I think I would use a large overhead hood. You could have so it could be lowered close to the table when you are cutting. I once saw a plan where the hood was about 2 x 4 on a 4 x 8 table (maybe slightly larger) and moved along with the gantry on the X axis.

I don't think that filters are practical for the downdraft / updraft systems. I tried putting filters on the exhaust and they clogged up so quickly they became ineffective and actually reduced the downdraft to the point where it was not functioning. I now use a 12" flexible duct to exhaust outside.

I believe the water table is the most important part of the waste collection system. It will catch 80-90% of the scrap and the dust that the plasma generates when it cuts through the metal. My downdraft system catches most of the remainder. I only get a very light coating of dust on the edges of the table. Most of this is caused by the cutting sparks above the sheet. I did the dual system because my shop is in my cellar and needed to be very clean. It's been 6 years and I run 6-10 hours per week (much less than a few years ago) and my shop is dust free.

Willy

[LureMin]

do you have a link or some pics of the water table and down draft? I think thats what Im going to do as I want zero dust because I have alot of other stuff in my shop I use to make my fishing lures that I do not want dusty at all. and im in about the same boat its a sealed area with air conditioning. My table is a 2x4 also and I was thinking about using a 3200 cfm inline blower for a 12" duct. will that suffice? Also where did you find your 12" duct. I looked all over locally and couldnt find one.

[flyinwilly]

Do a search here for the thread of my build, "A Different Machine - Downdraft/water table". It has a complete description and pictures of my table and how I built the downdraft system (and everything else).

My blower is quite large and is rated for 950-1200 CFM and does the job very well. I would question the CFM capacity of that 12" duct fan. Most fans that size are only good for 800 - 1200 CFM. Also, an inline fan would have the motor exposed to the smoke and dust. Part of the exhaust will be extremely fine particles of metal generated by the plasma. I've found in the past that it is very hard to keep this stuff out of motors (no matter how well sealed) and is why I went with a belt drive fan with the motor mounted outside the table.

You can find the duct at this site, turbineproducts.com , under ventilation. It is a really good, rugged duct and reasonably priced.

Willy