Thread: Advise for tempering a BBQ from stainless

Hello.
My mate is a sheet metal worker and built me a lovely BBQ last year from my specs.
he made it from 3mm stainless.

The BBQ buckled and warped after a few uses.

He’s about to make me another, half the size of this one, and I want to avoid the warping.

I’m guessing the warping was because the steel was soft and not treated.
Can anyone please advise on how I can prevent the same happening again.

My mate has no facility/possibility to heat treat the steel at his work place.

Here is a pic of the previous BBQ before being used.

Thanks
Dave

Its not tempering or anything else you can do to stop stainless buckling. Stainless is a poor conductor of heat so with a fire in centre , most of heat will stay there and stainless will expand while outsides will not.
Stainless may look good but it is a bugger to work with sometimes.
How about reusing the one you have but cut out the bottom leaving a 25mm lip around base. Then use another piece of thicker stainless or even mild steel to sit inside. That way the inner section can expand but outside frame will not.

Yea I would use a box-inside-a box design.

Inside box using 3mm sitting inside an inside box of 1 or 1.6mm should do it.

Thanks for both of your replies.
the new BBQ he is making me is for camping, so needs to be made from scratch.
is there a better material to use than stainless?

G'day Dave,
You could stick with the original box design as done previously and make a second layer from expanded mesh with short legs to sit inside the main box. The expanded mash should absorb most of the expansion differential with minimal buckling. Another advantage of expanded mesh is you can use heavier gauge without adding significantly to the weight and it will allow your fire to breath better.
You can also go with plain mild steel mesh if you don't mind the rust.
Cheers,
Greg.

Originally Posted by DaveMK

...the new BBQ he is making me is for camping, so needs to be made from scratch.
is there a better material to use than stainless?

When I was active in scouting, all the BBQ's we used were plain steel. Better conduction than stainless (so not as potential to warp). The grease/ oil from the food being cooked usually was enough to protect the steel parts from rusting (In other words, don't clean it too well).

Michael

For camping we used a SS clothes dryer drum as a fire pit and a removable 6mm mild steel plate for the cook top.
the Stainless is very think <`1mm
A second drum could be placed on top to act as an oven like this
BB2.jpg

We cooked bread, Pizza, slo roasts, scone etc in that oven but never a sign of buckling.

Eventually we decided it took up too much room and switched to a flat packable thing like this - its just mild steel.
The are heaps of similar flat pack deigns out there
I do have 6mm thick SS and MS hotplate top for it.
SWMBO made up a tough canvass bag for it and it takes up much less room in the van.

Screen Shot 2021-02-08 at 4.01.30 pm.png
It doesn't seem to rust that much and any parts that do seem to get burn off in the subsequence use

I made my outdoor fire pit from 3mm Mild steel plate. I heat a 30sq metre outdoor area with it to the point of too hot, and it hasn’t warped yet.

Thanks again for everyone’s suggestions.
I want to keep my design if possible, as it suits our style of cooking, and I already have a grill, skewers, and grill baskets that will fit it perfectly. Also, I like having the charcoals directly under my food in most cases.

how about aluminium?

Originally Posted by kwijibo99

G'day Dave,
You could stick with the original box design as done previously and make a second layer from expanded mesh with short legs to sit inside the main box. The expanded mash should absorb most of the expansion differential with minimal buckling. Another advantage of expanded mesh is you can use heavier gauge without adding significantly to the weight and it will allow your fire to breath better.
You can also go with plain mild steel mesh if you don't mind the rust.
Cheers,
Greg.

Cheers Greg,
this could be a possibility. Kind of a chip basket for a chip pan. Right?

Aluminium might work, but the trouble is that if the fire gets hot enough it could anneal, so go soft on you.

Michael

Originally Posted by Michael G

Aluminium might work, but the trouble is that if the fire gets hot enough it could anneal, so go soft on you.

Michael

Cheers Michael,
That could be embarrassing.

It will eventually burn through

I’ll be really grateful if anyone can come up with a solution that enables me to keep my original design.
Gregs idea was good, but I move my charcoals about during cooking, and the expanded mesh would make that hard.

Thanks
Dave

Would the box be less likely to warp if it was built/welded from separate base and sides, rather than being bent from a single sheet?