[Danno]

I have read most of the posts here on this subject, but the more I read, the more I get confused.
First let me say that my table will be 5X5, and will be powered by a Hypertherm 45. I plan on cutting steel and aluminum sheets mainly between
.125 and .375 thick.
I have the pan to hold the water already made, but I now have to figure out how high or low I should mount it to the table. The pan will have aprox 3 1/2 inches of water deep in it.
Jim Colt wrote a great article on this, and he claimed that the water should be about 4 inches away from the work, but it seems that any video I watch has the water almost touching the work.
I'm even now thinking about making my water tray adjustable !!
Any clarification would be appreciated

[DirtBound]

I have about 3/4 - 1" from the bottom of the material.

[Danno]

I have about 3/4 - 1" from the bottom of the material.

How's the dust in the air ??

[DirtBound]

How's the dust in the air ??

none at all, I get a very little bit of smoke depending on what I am cutting.

[jimcolt]

Water level with a water table. If you submerge the plate....you will get no smoke whatsoever, however the cut quality will have more dross, and the cut edges will often be rougher. Most plasma torch manufacturers that have blowback style torches do not recommend submerged cutting with this style torch....however many users are succesfully doing this.

As the water is lowered....the cut quality will improve, the smoke will increase, and the splashing will be reduced.

It is a balancing act between the desired cut quality, the acceptable fume levels, and the issues (staining, rusting) associated with water splash that will help each individual user determine the best water level. Many water table designs have a raise lower mechanism that can quickly and easily adjust water levels for each cutting situation....using low pressure compressed air to displace water from a lower chamber into the tray.

There also are differences in plasma jet velocity from one plasma system model to the next, as well as different velocities between different power levels (FineCut, 45 amps, 65 amps, 85 amps use different consumables and different air flow rates) that will affect splashing differently.


Jim Colt Hypertherm

[Danno]

My problem is that I want a perfect cut, zero dross, zero smoke and zero dust !!

I already have the water pan built, and I was planning to mount it solid to the frame of the table. It tapers 1 inch from front to back, with the "deep end" being 4 1/2 " deep at water level.
If I mount the pan so that the water level is flush with my work, it would be possible for me to lower the level , say 2", but I'm concerned that the remaining water (2 1/2") will not be deep enough, and the air blast from the torch will blow right to the bottom of the pan.
Another option is to make the whole pan go up and down, but that will be a PITA to do.
One thing I am planning on doing is to have side drafts in addition to the water. This table is being placed on the second floor of my shop. The shop is drywalled and clean, so I cannot afford to build a table that will spew crap everywhere.
Dan

[jimcolt]

If you want the best of everything you have listed...then you may want to consider a downdraft table....which, properly designed will provide for best cut quality and zero fumes, with no splashing. On precision industrial plasma machines...over 95% of them use downdraft fume control for these reasons.

Water tables are easier and lower cost to build, usually are easier to maintain...but are not the perfect solution for all applications.

A solution that I have used succesfully in the past is a combination of a water tray that is about 12" to 16" below the plate, with a downdraft above the water. The water traps about 60% of the heavier particles....so the downdraft had less work to do. This was important at a trade show as we had to use filtration systems that were noisy and took up too much space. A concern here is that the downdraft would be pulling some very humid fumes....which could be a problem if your were filtering the fumes...but probably not an issue if it was just exhausted outside.

Jim Colt Hypertherm

My problem is that I want a perfect cut, zero dross, zero smoke and zero dust !!

I already have the water pan built, and I was planning to mount it solid to the frame of the table. It tapers 1 inch from front to back, with the "deep end" being 4 1/2 " deep at water level.
If I mount the pan so that the water level is flush with my work, it would be possible for me to lower the level , say 2", but I'm concerned that the remaining water (2 1/2") will not be deep enough, and the air blast from the torch will blow right to the bottom of the pan.
Another option is to make the whole pan go up and down, but that will be a PITA to do.
One thing I am planning on doing is to have side drafts in addition to the water. This table is being placed on the second floor of my shop. The shop is drywalled and clean, so I cannot afford to build a table that will spew crap everywhere.
Dan