Fixing warped grates

Hey all, warped my grates a few weeks back, had gotten used to a low slow ash build up from burning wood and let the ash box get too full after I stated burning real fuel.

The weather has been pretty warm here so I've been burning wood for the past couple of weeks but with the colder mornings I'm about ready to switch back to black diamonds. A buddy of mine has cast iron grates in his outside wood burner, he said that you can use a shop press to SLOWLY bring the warped grates back into shape. Since they are just sagging in the middle this makes sense but I have to ask the forum, has anybody had any success in doing this? My grates are about $50 each and I need 4, add another $50 for shipping and I'm up to the price of a cheap press but I don't want to snap the first one that I try and end up spending more money.

Possibly, most cast iron you see is brittle but if its heated to a high temp for a long time the irons crystal structure reforms and when it cools it will be a little more workable.

I have also worked on iron exhaust manifolds that have gotten hard as a carbide cutter on one end and soft and gummy at the other

Well the grates warped from heat, so it makes sense to me if you could get them glowing hot then you should be able to warp them back maybe with some kind of vise? I dunno... But I would definitely try getting one orange hot and bending it back to straight.

Nothing ventured, nothing gained,mn, I've played with a few old tractor exhaust manifolds & all I can suggest is--start saving some money up--will they not shake at all? Enough to get you by for this season--if so, leave it---if you break one playing, you'll be in trouble me thinks.

Hope you can find a way to get the grates real hot. I tried to braze my busted grate but I also tried to cut corners and ended up just emptying my oxy-acetylene tanks. I think it was Carl that educated me after the fact that the cast iron has to be uniformly heated before it will accept a solid braze. Great explanation; it expands in 3 dimensions, so I was brazing 4 breaks in vain, getting one part of the grate mad hot while the other parts were relatively cool.

Maybe you could put them in a small bonfire and get it real hot with a leaf blower or something. I bet if they were uniformly hot enough, you could coerce them back into flat. Good luck!

cast iron repair

I have heard good result from using an old weber round style charcoal grill with the cooking grates removed and heating the part on or in the coals. Then repairing them on a small bed off sugar sand then putting them back in the weber grill to cook at 500 plus for hour or so then bury them back in the dry sugar sand for 12 plus hours this process i am told allow the cast iron to accept the weld ( oxy acetylene or nickel arc weld ) then to cool slowly this minimizes the likely hood of cracking. this has been done to fix broken pieces not so much to unwarp. I second the position of if they still function use em as is then when u have new ones you can play with the warped ones

From my experience you usually only get one good chance with cast iron,take all necessary steps to get the odds in your favor.Nothing is worse than to hear that breaking "pinkk" sound when the cast is cooling a little too fast after all the work has been done. Good Luck. Mike

Yep, lot of good advice here, heat & cool slow both if a weld is attempted then just a bit & pink lightly & long which also cools slowly then a little more & so on. I would really doubt a press would work unless really hot & then if you could hold the pressure until cool. I've done a tractor exhaust that is still in use two years later but he has a new one on hand, good luck but I would look around for replacements, in these parts there are quite a few Amish stores that carry several different grates.

Ok while 4 of the 5 are sagging they will still work, I'll end up losing a little more coal than I would like during shake down but that's much better than breaking one or more of these things and being screwed. I'll replace them after this season. Temps are falling here so I'll burn wood tonight and get a fire going for coals tomorrow, once all that is left are the hot embers I'll start tossing in some nut and get the black diamonds going again. No more 2 AM feedings LOL.

Thanks guys gang

Kevin

Can you turn the grates upside down, so that maybe gravity will take out some of the sag??

And later in the season, you could try to repeat the scenario that caused the sagging: let the ash pan get too full, and see if they will straighten out,
Greg L

Hey Greg

Afraid flipping them over won't work, the acuter rod would have nothing to attach to so no way to shake ash with them flipped over... nice idea though.

Merry Christmas all!!

If the grates will install upside down, even without the actuator rod hooked up, later in the season, I'd try to get a good hot fire going on the grates, with a close to full ashpan,, and see if they sag back some.. If you can see the grates through the ashpan door, you might be able to gauge the amount of sag or 'hump [when upside down] the grates have..

So you could use the stove as your foundry,, get it hot, look at the grates, if they are red, either let 'em sag or GENTLY ! from above push down on each grate with a strong poker or crowbar. If gravity sagged them it shouldn't take too much pressure.

Since you are probably going to break them anyway, unless you find a foundry furnace to put them in, ad slwoly cool them down in,, it will be a good experiment and you will be repeating the conditions of the original sagging.

just a thought..

Greg l

Greg, you really think that will work? Cause I got some original sagging going on right here on the farm. I just thopught it was me getting old. Merry Christmas all

LOL,, Fred I've got plenty of the sagging going on here too! But I'm pretty sure it's from over work, not over heating !

Yeah, I think it could work, nothing ventured nothing gained.

I know for sure that unless the sagged grates are heated to red-hot, then slowly cooled over several hours, they will NOT survive a straightening job.

So a furnace is needed.

greg L

Agreed, it's probably the only way without screwin them all up.