Steel sizes and Water table considerations

[ClarKent101]

I'm about to start building the water table and bed for an 8 x 4 table. This is my first build, so just wondering a few things before I begin...

1. What size steel do people typically use for the frame, I'm thinking 50x50x3mm all over would be enough to be strong and rigid?

2. For the water table, would you use a stainless steel pan rather than painted steel? What are the baffles or dividers for that I see people use? I've seen mentioned a pump is needed to circulate the water. I was going to build a minimal depth of say 80mm to hold the water.

3. Does the water stay directly below the sheet or does it also sit above the sheet?

Thanks.

[SeanP]

Yes I'm sure that size box is fine, I actually went with 60x60x3.

I just used 2mm mild steel, it's been going nearly every day for the last 8yrs and still seems fine, I don't use any additives in the water.
I did paint it at the start but wouldn't bother again to be honest, the black gunge used to stick like hell at the beginning a lot better now it's just bare metal, just cleaned out this morning took me a hour.
My slats are 75 x 3mm you really want 30mm below slats free I would say, mine is 20 to 25 in middle, it's slower to drain down once it build with gunge under slats, I even have a few 25mm holes in the slats to help drain down and extend cleanup period.

I have my table sides 50mm higher than the slats and it's a godsend, why more don't do that design I don't know.
It's stops a lot of water splashing out, a good base to position spacer stops to place sheet against, but best thing is to have somewhere to use a pry bar to roll a tube under plate for rolling sheet off or to get access for forks, hard to explain but it works really well.
My slat spacings are 80mm, happy enough with that really, some jobs would stand more some less,,,

I'd avoid a pump at all costs, just something else to go wrong and way slower, I started with a 2mm steel tank under the table but it's only lasted 2yrs, some sort of reaction put a end to that plan, I now use a 1000ltr IBC tank, I'm lucky as can have the top same level the table outside, also luck we don't get to much frost!
The 1000ltr is good as well as it can go for 3 months before needing topped up as it does evaporate like hell and that's with draining down every day as well.

A 2'' outlet & plastic ball valve is a must as well for the drain, drain down and refill is very quick.
Have a look at my build in link below

[ClarKent101]

Very nice design, one of the better ones I've seen so far. I've just seen you're in Kerry, I'm in Cork myself, near Macroom so have the same conditions as yourself.

Is that an 8 x 4 table you built?

[SeanP]

Thanks,
Haha small world!!
Yes 8'x4' is max sheet size, need a bit of working area around it.

[ClarKent101]

Yes this could be a problem, I'm building this in a 20ft shipping container so 2.3m across, I'm hoping the footprint will allow me to walk past it, since lockdown though it's been getting harder to squeeze past things so I better draw it up first in SW. Think I'll use your pics as a rough guide though to get started.

When it comes to the water table I'd be folding up the edges and just welding down the 4 corners. For that and the sheets and base plates etc. I'll be looking to buy them. I usually get them from a place cut and folded, seeing as you're a neighbour, if it's something you're interested in you could perhaps quote in a PM?

[SeanP]

When it comes to the water table I'd be folding up the edges and just welding down the 4 corners. For that and the sheets and base plates etc. I'll be looking to buy them. I usually get them from a place cut and folded, seeing as you're a neighbour, if it's something you're interested in you could perhaps quote in a PM?

Sorry only have a 4' box and pan, thanks anyway.

[ClarKent101]

Yes no problem at all, thought I'd mention it anyway!

I'll be starting with just the water table for now and using a MPCNC Primo for the gantry to start with. Later on I'll upgrade the gantry, yours look fairly substantial, will either go with a SHS or Aluminium extrusion with linear rails, undecided on that. How does yours perform in terms of accuracy and speed?

[SeanP]

How does yours perform in terms of accuracy and speed?

It's very good, rapids at 10,000 but max I cut at is 6000.
I'd maybe go with double rails rather than the single on the gantry, be a more solid job.

[ClarKent101]

Hey Sean just having another look at your build for the water table..
Did you weld the water table to the end RHS pieces? Is it just a sheet that lies flat or did you put folds on it?
I think I can see that it tucks under the angle iron that holds the slat locators?
Did you manage to fit the 1000 litre IBC under the table?

[SeanP]

Its a 4 sided tray with the angle bolted to the side rails, clamping it together.
No IBC is outside , about 2' lower than table.
You can call to see it sometime if you want.
https://photos.app.goo.gl/uLZefBzmhnd9SW8CA

[ClarKent101]

Thanks for the offer I might take you up on it depending on how it goes!

I'm going to soldier on for now and see how it goes, probably no harm in spending extra time in design to wait out the steel prices anyway!