Chubby warped grate

Re: Chubby warped grate

PostBy: dcrane On: Tue Feb 19, 2013 6:28 am

In theory you would think the more times you can heat up evenly cast iron grates and cool down slowly the stronger the grate would become and the place to do this would be an electric oven (because attempting it with a wood or coal fire would not heat the entire surface as "evenly"). The problem is... ive tried this with pizza ovens and it never seems to prevent the possible damage that occurs with over firing. With firebrick it well worth this investment in time (ive seen first hand how durable and long lasting and wear resistant firebrick can get if its "cured" in this fashion. Cast Iron is seemingly not that easy and if it were... manufacturers would be doing it prior to shipping. Clearly doing this with cast iron can only help (it will not hurt to be sure) but dont have high expectations for this (I've been their and done that, as im sure many have) and I could never stop warpage from an abused stove or increase the life expectancy. The solution was making a grate system that was not one piece but rather many smaller/shorter pieces that no not lay flat/horizontal but rather lay vertically (very expensive to do but proven to never fail and never require replacing).

Oddly enough I will say their IS a drastic difference between castings and foundry's, Im not so tech savoy that I can understand or know why this occurs BUT the fact is some grates made by some foundry's are vastly more durable than other grates made at other foundry's... I would say this is also the reason why antique cast iron most of time is better then new cast iron. I don't know if our forfathers used a different method of firing or cooling or if they used different mixtures in their castings but their IS a difference!
dcrane
 
Hand Fed Coal Stove: Crane 404

Re: Chubby warped grate

PostBy: ONEDOLLAR On: Tue Feb 19, 2013 4:37 pm

I forget but at what temp does cast iron become pliable?
ONEDOLLAR
 
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Re: Chubby warped grate

PostBy: carlherrnstein On: Tue Feb 19, 2013 4:47 pm

I would not try to bend it back. I would mark where it rubs and grind the high spots down.
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Re: Chubby warped grate

PostBy: tcalo On: Tue Feb 19, 2013 5:28 pm

carlherrnstein wrote:I would not try to bend it back. I would mark where it rubs and grind the high spots down.


Excellent idea, I didn't think of doing this... :oops:. The advice I got from Larry was to place a 1 1/2" washer with a 1 1/8" hole on the center pin under the grate to raise the grate off the support tabs. Hmmm, which idea to go with?
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Chubby warped grate

PostBy: dcrane On: Tue Feb 19, 2013 6:55 pm

tcalo wrote:
carlherrnstein wrote:I would not try to bend it back. I would mark where it rubs and grind the high spots down.


Excellent idea, I didn't think of doing this... :oops:. The advice I got from Larry was to place a 1 1/2" washer with a 1 1/8" hole on the center pin under the grate to raise the grate off the support tabs. Hmmm, which idea to go with?


Its hard to argue a point with the maker of the unit... rest assured Larry has done, seen, tested it all 1000x over, go with what he say's over any of us and tell him to get his ass on the forum! :mad:
dcrane
 
Hand Fed Coal Stove: Crane 404

Re: Chubby warped grate

PostBy: dlj On: Tue Feb 19, 2013 9:58 pm

ONEDOLLAR wrote:I forget but at what temp does cast iron become pliable?


Doesn't really happen with grey iron. That's one of it's great advantages as a material for grates. You can get it up to 1000*F and it doesn't want to move...

Dcrane wrote:In theory you would think the more times you can heat up evenly cast iron grates and cool down slowly the stronger the grate would become and the place to do this would be an electric oven (because attempting it with a wood or coal fire would not heat the entire surface as "evenly"). The problem is... ive tried this with pizza ovens and it never seems to prevent the possible damage that occurs with over firing. With firebrick it well worth this investment in time (ive seen first hand how durable and long lasting and wear resistant firebrick can get if its "cured" in this fashion. Cast Iron is seemingly not that easy and if it were... manufacturers would be doing it prior to shipping. Clearly doing this with cast iron can only help (it will not hurt to be sure) but dont have high expectations for this (I've been their and done that, as im sure many have) and I could never stop warpage from an abused stove or increase the life expectancy. The solution was making a grate system that was not one piece but rather many smaller/shorter pieces that no not lay flat/horizontal but rather lay vertically (very expensive to do but proven to never fail and never require replacing).

Oddly enough I will say their IS a drastic difference between castings and foundry's, Im not so tech savoy that I can understand or know why this occurs BUT the fact is some grates made by some foundry's are vastly more durable than other grates made at other foundry's... I would say this is also the reason why antique cast iron most of time is better then new cast iron. I don't know if our forfathers used a different method of firing or cooling or if they used different mixtures in their castings but their IS a difference!


It doesn't quite work that way. You can probably heat up a grey iron casting in a home electric oven hundreds of times and it likely wouldn't do much of anything after the first few hours of cycling and that's only if there was some kind of tempering taking place. . Unless you have an oven capable of running up in the 1000*F to 2000*F range, you aren't doing much to the microstructure of grey cast iron. Of course, running in a wood or coal stove within the firepot can get up there.

I don't really know because I've never had the opportunity to study it, but from what I've seen, warpage in grates seems to come mostly from 2 separate sources: 1) the grates were either the wrong alloy or weren't stress relieved. 2) Running the grates in the stove, ash got built up on the side away from the fire. This makes the bottom of the grate notably colder than the top side of the grate that is against the fire causing thermal stresses resulting in warpage.

As far as old cast iron being better than new cast iron, I have to strongly disagree. World War II and after saw tremendous advances in our knowledge of cast irons. Grey iron metallurgy is very complex. If you want a good casting, you have to know how to specify it for the foundry to produce the alloy needed. There are many grey iron alloys...

dj
dlj
 
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Re: Chubby warped grate

PostBy: wsherrick On: Tue Feb 19, 2013 11:14 pm

One simple solution, get a new grate.
wsherrick
 
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Re: Chubby warped grate

PostBy: dcrane On: Wed Feb 20, 2013 5:36 am

wsherrick wrote:One simple solution, get a new grate.


now there's a piece of absolute genius! :lol: Larry is pretty reasonable compared to those rip off places like woodman's (if i had a Chubby id just walk down the street and ask Larry for a new grate (he smartly saved all his patterns and its a very simple process for him to have more made at any time).
dcrane
 
Hand Fed Coal Stove: Crane 404

Re: Chubby warped grate

PostBy: carlherrnstein On: Wed Feb 20, 2013 11:53 am

If you can get away with just shiming it you should. Chances are it had some internal stress that made it warp but, if the stress is relived it will be stable and not move anymore. whereas if you force it back to shape somehow without breaking it you will put a stress back in your grate and it will probably warp again if not break.
carlherrnstein
 
Hot Air Coal Stoker Stove: combustioneer model 77B
Coal Size/Type: pea stoker/Ohio bituminous

Re: Chubby warped grate

PostBy: dcrane On: Wed Feb 20, 2013 12:00 pm

lets all tell Larry to join the forum every time we talk to him or communicate with him :P
dcrane
 
Hand Fed Coal Stove: Crane 404

Re: Chubby warped grate

PostBy: tcalo On: Fri Jul 26, 2013 11:56 am

Just an update. I did what Larry suggested and placed 2 washers under the warped grate, just like new! I used two 2 1/2" x 1/8" thick washers. They had a 1" hole punched in them, fit perfectly around the pin that the grate sits on. Now only if the weather would cooperate and get cold... :)
tcalo
 
Hand Fed Coal Stove: Chubby Coal Stove
Coal Size/Type: Nut Anthracite

Re: Chubby warped grate

PostBy: ONEDOLLAR On: Fri Jul 26, 2013 6:10 pm

Glad to hear everything worked out... Don't rush in the cold weather yet. It is coming soon enough! :P
ONEDOLLAR
 
Hand Fed Coal Stove: 2014 Chubby Prototype
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Re: Chubby warped grate

PostBy: tcalo On: Thu Feb 06, 2014 11:32 am

What am I doing wrong!!! My new grate only lasted 1 year, almost to the day. I went to shake down the stove last night and the shaker handle got jammed, I couldn't budge it. Upon further inspection I noticed the grate was cracked. I had to make the gut wrenching decision to let the oil burner pick up the slack while the stove cooled down. Luckily I have another grate I could use. It's a little warped but should work fine. So I don't know what I'm doing wrong. I usually run the stove around 450*-500*. According to the specs it doesn't max out until about 650*. It has seen just north of 600* occasionally, but not very often. Temps rarely dip low enough for the stove to get run hard. When I shake down I usually leave the ash in the pan until the next 12 hour shake down. I have been getting a lot of ash this season. I don't let the ash get above the pan, but it does fill it to the top. With the ash pan filled there is about a 3" gap to the bottom of the grate, this should be sufficient air flow. Could it be poor metal quality? Maybe I should dump the ash right after shaking the stove down? I've followed Larry's advice exactly. I'm getting frustrated with this stove! Any suggestions would be appreciated.

Tom
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tcalo
 
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Re: Chubby warped grate

PostBy: Carbon12 On: Thu Feb 06, 2014 11:35 am

I don't know the answer but emptying the ash right away couldn't hurt.
Carbon12
 
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Re: Chubby warped grate

PostBy: McGiever On: Thu Feb 06, 2014 11:45 am

Grate metal too hot = sag and break.
Ash pan level not problem...rageing fire on bare grate = hot metal forge temps.
Might just shake less and let some ash behind on grate or be more conservative of raging fire.
Likely you are rushing when you do reloads. ;)
McGiever
 
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