Steel for DIY Fire Pit - Advice Needed

[HeLa]

** this might be better in the welding forum but it looks like i can't delete this one **


we've been through a few commercially-produced cheap fire pits - they're junk and just don't last. i'm looking for something bigger and a bit more utilitarian for the next round. after doing some shopping around i found that there does seem to be a niche market for heavy duty fire pits but they are expensive and for obvious reasons need to be found locally.

so, *considering* building my own. i like the idea of something like this built to about 4 ft. square.



so the first obvious question is: what to build it from? (type/thickness of steel) what can withstand the temperatures of a fire and being left outside? stainless is out for cost reasons and i really don't mind the look of the rust patina.

access to plasma/welding equipment and expertise can be assumed available. i'm an amateur but know my way around a bit.

help from those with experience greatly appreciated. thanks!

 

[2458n]

Get yourself a tractor tire rim-go round. If the rim is to tall bury part of it or get your plasma out. Paint it with high temp paint and your grandkids will enjoy it after you are gone.

 

[SPIKER]

Semi Truck rims are really popular as well. Anything thicker than 1/4" is probably way overkill, A36 hot rolled steel is kind of what that pic looks like it is made from. A36 is good & should last for long time as long as water can drain out of it quickly. Water and ashes together forms acid which will eat the steel up no matter what type you use. The boiler plate steels are a bit different harder material & rated for higher heat/pressures vs A36 (sa36 in some places) & they (boiler plate) may need a bit different welding practices (for certifications but not req for outdoor fire pit.)

The 1/4" stuff would be HEAVY and something as shown in 4'x4' would need 2 people to move or tractor. Lighter weight 10gauge or 3/16 should work without with a small amount of reinforcing a top edges to keep warping at a minimum with a good long or hot fire, (angle iron or bent top edge.)

The "hot roll" slag can be left on but in fires will usually chip off taking any paint or coatings you put on with it. Boiled/Pickled steel in similar materials is going to have very little rust resistance however it will take a high temp coating & hold it longer.

Anyhow anything you build for holding a fire and setting outside is not going to last for ever build with what you have and once it wears, rust or burns thru haul it to scrap yard and make a new one

Mark

 

[HeLa]

Semi Truck rims are really popular as well. Anything thicker than 1/4" is probably way overkill, A36 hot rolled steel is kind of what that pic looks like it is made from. A36 is good & should last for long time as long as water can drain out of it quickly. Water and ashes together forms acid which will eat the steel up no matter what type you use. The boiler plate steels are a bit different harder material & rated for higher heat/pressures vs A36 (sa36 in some places) & they (boiler plate) may need a bit different welding practices (for certifications but not req for outdoor fire pit.)

The 1/4" stuff would be HEAVY and something as shown in 4'x4' would need 2 people to move or tractor. Lighter weight 10gauge or 3/16 should work without with a small amount of reinforcing a top edges to keep warping at a minimum with a good long or hot fire, (angle iron or bent top edge.)

The "hot roll" slag can be left on but in fires will usually chip off taking any paint or coatings you put on with it. Boiled/Pickled steel in similar materials is going to have very little rust resistance however it will take a high temp coating & hold it longer.

Anyhow anything you build for holding a fire and setting outside is not going to last for ever build with what you have and once it wears, rust or burns thru haul it to scrap yard and make a new one

Mark

thanks mark.

a36 hot rolled is pretty readily available so this is what i was looking at so long as no one tells me to stay away.

i don't mind heavy. it won't move often and as long as the tractor can move it, it's not too heavy.

i was thinking of running a piece of flat stock around the top lip for just the reason you mentioned, to keep the top edge from warping. this is probably where the pit would most easily warp and also where the warp would be most unsightly.

good info re: the slag and finishes. right now i'm thinking to just leave it unfinished and hope it lasts a while! appreciate the input.

 

[Pete Judd]

I use 2 of the semi wheels stacked. Will take years to rust out.

 

[dragoneggs]

thanks mark.

a36 hot rolled is pretty readily available so this is what i was looking at so long as no one tells me to stay away.

i don't mind heavy. it won't move often and as long as the tractor can move it, it's not too heavy.

i was thinking of running a piece of flat stock around the top lip for just the reason you mentioned, to keep the top edge from warping. this is probably where the pit would most easily warp and also where the warp would be most unsightly.

good info re: the slag and finishes. right now i'm thinking to just leave it unfinished and hope it lasts a while! appreciate the input.

I like where you are going... I want to do almost exactly the same. Excuse to get a plasma cutter for xmas? I am thinking 3/16 with a rim. I am also thinking square so I could inset in a brick or block surround. I like the way the brick/stone absorbs and radiates heat as you sit around it and it looks finished too.

 

[Mace Canute]

A friend has a firepit made from an old culvert cutoff and it looks kinda crappy. Hiding it would improve it a 1000% so I was thinking something along the lines of what these people did would be easily doable.

 

[dragoneggs]

A friend has a firepit made from an old culvert cutoff and it looks kinda crappy. Hiding it would improve it a 1000% so I was thinking something along the lines of what these people did would be easily doable.

There you go, Mace... this is what I am talking about whether round or square. More ideas please!

 

[Larry Caldwell]

https://www.facebook.com/willowhave...4164593265079/981371361877728/?type=1&theater

 

[boggen]

firepit back at the cabin, and then a firepit at my mom's house. both i took a shovel and dug down about a foot. and then sat down some 16x8x8 concrete blocks. and then fill the holes with largerish rocks say 0.5" to 1.5". primarily for "water drainage" these pits get used for twigs / branches that fall out of the tree, maybe some grass clippings, or like. along with just tossing some firewood in, and having a cook out, getting a grill and tossing over things. and cooking right over the fire.

the drainage has helped out to point, some of the old coals that were put out from last use, start to burn again after about 2 to 4 hours of starting up another burning in it. vs being water log from a recent rain. it doesn't completely dry the stuff out, but it does help burning everything completely down. so ashes do not need to be cleaned out as often.

for a long time a large i don't know 2 to 3 foot diameter grill was used (from a old charcoal grill sent to scrap long ago). then a tripod grill has been recently used. lower and raised via a chain. works nice being able to adjust based on heat coming from the fire / coals. every now and then the tripod stand and grill combo show up at various stores.

never have used an actual metal grate to hold firewood off the bottom of a fire pit, logs just rest on the ground and burn. about as basic as things could possibly get, without any fancy shuts / ash trays, etc... that you might see in a wood burning fireplace for heating up a home or like.

==========
cabin has pretty much a metal ring i am guessing 1/8" steel. pretty much a old rim from something.
my mom's house just stacked limestone rocks around in a circle much like above pictures. and never put a metal ring in. kinda of a pain to clean out but works.

==========
cooking over fire, is nice to open a few cans of stuff (beans, corn, vegetables) just leave everything in the can, toss a grill down and set can on the grill, along with what ever meats or like. some stuff wrapped in aluminum foil.

==========
one thing to note. do not get fancy brick for the fire pit, it will all get smudge up with black ash / smoke. and some of that brick can be rather dangerous, as in it can "explode" and send little pieces of sharpnal errr concrete shooting across the yard.