Stainless steel sheet work - What thickness + sheet size?

[Stickmaister]

Hi everyone ,
I'm here to ask for some expert advice, I'm doing a job for an old friend. A garden water feature..
He wants a stainless steel sheet, made into a sort of trough, that will have water pumped into it. The water will then flow through the trough and out of an opening the other end and drop into a pond.
Here are some photos to help me explain..

The slate slabs will be removed from the concrete walls and the trough will sit on top of the walls. (walls 100mm thick at the top) 1700mm width overall

Here's a simple sketch.

Two main questions I have and what I need help with is..

-What thickness sheet can we get away with? Bearing in mind I would like the sides folded. we were guessing around 4mm? Would that be strong enough without bowing? The water should just flow through the trough and not be held in there.
I would like to avoid welding any strengtheners , would like it just a folded sheet.

- Is it possible to get a single sheet this size? And have it folded?

Here are more drawings and dimensions..

I would like to avoid welding on this as much as possible due to only having a mig welder and although I can weld stainless there not the cleanest welds.
If there isn't a sheet size big enough it will have to be welded together and I'll have to figure out the best way around that.
Obviously there are areas that will need welding and I hope I can dress the welds down nicely. I'm concerned about distortion and rusting on the welds.

Many thanks for your time if you've read this and any advice will be much appreciated.
Thank you,

 

[hotponyshoes]

You can't fold the shape shown in picture 5 full stop. So at least some welding will be needed (or you could use metal glue and some angle strips for the bits that do need doing.

Other problems,
Sheets that size are available but hard to source as a one-off (so expensive)

Next problem will be finding someone to fold that size. The biggest I can go locally to me is 3mm on 1500mm. 4mm would be around 1000mm.

I expect, if you can find a place to fold it then they will be best placed to supply the sheet as well.
You could try one of the online places for a quote and if they offer a price it shows at least one place in the country can handle it and will do one-offs.

If you use 3mm or thicker sheet it will weld nicely very easily.
It will be a lot of time spend welding and cleaning up but might be easier than driving all over the country fetching the sheet then taking it somewhere to have it folded then having to take it home and still need to weld part of it anyway.

 

[bricol]

You can fold that shape - but not in that size. Biggest sheet I'm aware of is 3mx1.5m

Put a return fold on the sides to keep the tops straight, assuming they are something like 100 tall, they will be stiff enough. but across the 1500 gap - you are going to need something under it to stiffen - it will bow. It's it only carrying a few mm of water, then a x-crease across it might be enough.

If you can add stiffeners under it, give the sides some depth with a top fold/return fold, then 2mm would be fine, 3mm, you probably don't need the return fold.

If you can't see it from above, or even if you can, make it from two halves , in effect have a double thickness central divider - might not need the underside stiffeners then - any welding is then on the radius of the folds on the underside, or on the top edges of the adjoining sides in the middle. Unless you shorten the tapered overhang by 300, then that bit will need welding to the main section(s) - unless you get creative with end folds and bolt them together.

 

[Stickmaister]

You can't fold the shape shown in picture 5 full stop. So at least some welding will be needed (or you could use metal glue and some angle strips for the bits that do need doing.

Other problems,
Sheets that size are available but hard to source as a one-off (so expensive)

Next problem will be finding someone to fold that size. The biggest I can go locally to me is 3mm on 1500mm. 4mm would be around 1000mm.

I expect, if you can find a place to fold it then they will be best placed to supply the sheet as well.
You could try one of the online places for a quote and if they offer a price it shows at least one place in the country can handle it and will do one-offs.

If you use 3mm or thicker sheet it will weld nicely very easily.
It will be a lot of time spend welding and cleaning up but might be easier than driving all over the country fetching the sheet then taking it somewhere to have it folded then having to take it home and still need to weld part of it anyway.

Got it!
Very useful information mate, thanks!
Will 3 or 4 mm sheet weld nice and come up clean with mig? If I were to make it out of say, 3 sheets , welded together, would there be any distortion in the sheets at the joints? Will the areas welded rust over time ?

Really appreciate the info!

 

[BrokenBiker]

Personally, I'd cut and weld it rather than trying to fold 4mm stainless...it's not for the faint hearted ...if you haven't got Tig then get some suitable stainless wire and some very low co2 content gas...I've welded stainless with 5% but it was never going to be on show, I believe you want less than 2% ideally

 

[Stickmaister]

You can fold that shape - but not in that size. Biggest sheet I'm aware of is 3mx1.5m

Put a return fold on the sides to keep the tops straight, assuming they are something like 100 tall, they will be stiff enough. but across the 1500 gap - you are going to need something under it to stiffen - it will bow. It's it only carrying a few mm of water, then a x-crease across it might be enough.

If you can add stiffeners under it, give the sides some depth with a top fold/return fold, then 2mm would be fine, 3mm, you probably don't need the return fold.

If you can't see it from above, or even if you can, make it from two halves , in effect have a double thickness central divider - might not need the underside stiffeners then - any welding is then on the radius of the folds on the underside, or on the top edges of the adjoining sides in the middle. Unless you shorten the tapered overhang by 300, then that bit will need welding to the main section(s) - unless you get creative with end folds and bolt them together.

He did mention he would rather not have any stiffeners underneath. Yes the sides will only 100mm high.
Won't really be seen from above. I don't mind welding it up and cleaning etc. as long as it will look nice, not obvious distortion and the welds don't rust over time.
hmmm.. some thinking to do!

Thanks for your input mate , much appreciated

 

[Stickmaister]

Personally, I'd cut and weld it rather than trying to fold 4mm stainless...it's not for the faint hearted ...if you haven't got Tig then get some suitable stainless wire and some very low co2 content gas...I've welded stainless with 5% but it was never going to be on show, I believe you want less than 2% ideally

Yes, this looks like the more realistic option now. I have welded stainless recently, and the welds looked ok, I'm just thinking will the welds rust in the long run and how to avoid this?
Last time I used normal argosheild, decent results, but for this I will probably buy a specific low co2 gas for the job.

Will 4mm stainless distort much when welding? Will 4mm be strong enough across that span without stiffeners?

thanks for your help brokenbiker

 

[hotponyshoes]

Yes. It will try to distort like mad.

I'd aim for 0 gap and do it with the tig.

3 or 4 mm will weld fine with mig. If you have pulse mig you'll cut down a fair bit on the distortion. If you can leave a gap of half the material thickness and use a purge backer it will fill in lovely. That's a lot of moving around with the backer though. Might be easier on something that size to bevell both edges run the first with a clay backer then do the other side when cold with a wet backer.

If you use matching filler wire then either clean up with a stainless wire brush (or ideally electro polish) then passivate it the welds won't rust any more than the rest of it.

Do you want the welds ground and polished out or are you happy for them to be visible?

 

[Stickmaister]

Yes. It will try to distort like mad.

I'd aim for 0 gap and do it with the tig.

3 or 4 mm will weld fine with mig. If you have pulse mig you'll cut down a fair bit on the distortion. If you can leave a gap of half the material thickness and use a purge backer it will fill in lovely. That's a lot of moving around with the backer though. Might be easier on something that size to bevell both edges run the first with a clay backer then do the other side when cold with a wet backer.

If you use matching filler wire then either clean up with a stainless wire brush (or ideally electro polish) then passivate it the welds won't rust any more than the rest of it.

Do you want the welds ground and polished out or are you happy for them to be visible?

I think mig is my only option to be honest mate.
I used 0.8mm wire last time, will that be ok on say 4mm or even 5mm sheet?
Im worried about distortion because there is such a big span, 1.7m joint.

I've only got a basic set up for stainless, don't have purging or backing stuff, I'll have to look up on that backing things you mentioned.

I will want the welds ground down and polished as much as possible.

Thanks for your help!

 

[gaz1]

just to point out here a 1m wide opening is going to need one hell of a water pump to feed it and a good amount of water stored under it to feed the water fall feature

id go with 2 2mx 1 metre sheets and join in the middle as the sides and the rear can be folded

3mm can be folded with just a vice and rewelded with a cut marker and bent then welded

this 3mm stainless steel done as above the sheet was 1m wide before folding

 

[knighty]

it's too big to not need stiffeners

but you could put them inside, so they're in/uder water?

 

[Stickmaister]

it's too big to not need stiffeners

but you could put them inside, so they're in/uder water?

What thickness sheet do you think would be needed to be able to go without stiffeners?
I was thinking about stiffeners on the top in the water but dont want to disrupt the water flow and have it splashing on the stiffeners.
Thanks for your reply

 

[Stickmaister]

just to point out here a 1m wide opening is going to need one hell of a water pump to feed it and a good amount of water stored under it to feed the water fall feature

id go with 2 2mx 1 metre sheets and join in the middle as the sides and the rear can be folded

3mm can be folded with just a vice and rewelded with a cut marker and bent then welded

this 3mm stainless steel done as above the sheet was 1m wide before folding

View attachment 540286View attachment 540287

I’ll leave the water issue for him to sort out but i will mention that to hom , thanks
Ok, that makes sence , i will need 4off 2x1 sheet for this!
So that would be x3 1700mm joining welds along the width!
I cant see that being neat? what do you think?
That looks tidy mate good work

 

[Hitch]

You could cut from a single sheet, 4x2m are available.
Depends on the height of the upstand, and where you went, it could be folded in one too, using sectional top and bottom tooling- although would be a pain at those sizes.

Consider what sheet finish you need too, that could affect your sheet sizing. 2B would be the simple choice for 3mm or under.

I hope he has deep pockets!

 

[TEO]

Profold in Thatcham have been very helpful in the past & can deal with these sizes https://www.facebook.com/share/18mvNYXMSw/
Bit of a trek but the logistics will be part of the job.

 

[Stickmaister]

You could cut from a single sheet, 4x2m are available.
Depends on the height of the upstand, and where you went, it could be folded in one too, using sectional top and bottom tooling- although would be a pain at those sizes.

Consider what sheet finish you need too, that could affect your sheet sizing. 2B would be the simple choice for 3mm or under.

I hope he has deep pockets!

4x2 would be ideal!
Do you know where I might be able to get a quote on a sheet that size? Say 4mm?
And maybe a quote to get it folded too?
Many thanks Hitch , much appreciated

 

[Hitch]

Aalco, Richard Austin Alloys, Righton Blacburns.. all worth a call.

As for folding, I guess that depends where you are.

 

[piman]

Stickmaister,

3mm, to me, is far too thick, 1.6 mm will do that job quite adequately, and if you can shorten the 'spout' and use a standard 2 x 2.5 M sheet.
I made a tank for our cask washer in 1.6, 2M long and has cleaning solution 200 mm deep in it all the time, no stiffeners.

Alec

 

[gaz1]

this shows an over shot of water over a water wheel

 

[Stickmaister]

Profold in Thatcham have been very helpful in the past & can deal with these sizes https://www.facebook.com/share/18mvNYXMSw/
Bit of a trek but the logistics will be part of the job.

Thats great TEP thanks, I’ll have a look today and get in contact with them today!