New KJ Firebox Design

Hawg Fan

i saw a post on Facebook today revealing the new Kamafo Joe re-designed firebox.  The five piece design makes sense and should reduce the number of cracks and breaks.  Replacing one piece should be less costly as well.   I'm wondering if BGE will do something similar?

bgebrent

Smart engineering!  

stlcharcoal

More edges/corners = more stress points.  

Worth a shot, time will tell.

bgebrent

stlcharcoal said:

More edges/corners = more stress points.  

Worth a shot, time will tell.

Not more relief points?  Just a chemist so truly asking.

stlcharcoal

bgebrent said:

stlcharcoal said:

More edges/corners = more stress points.  

Worth a shot, time will tell.

Not more relief points?  Just a chemist so truly asking.

That too!  So time will tell.....hope it works.

bigbadben

KJ also announced a new hinge, top vent, and gasket.  

Hawg Fan

Looks like they've upped their quality of gasket material as well.  The post I read said KJ worked with the best gasket company in the world for the new design and KJ is debating whether to offer a lifetime warranty.

DMW

Hawg Fan said:

Looks like they've upped their quality of gasket material as well.  The post I read said KJ worked with the best gasket company in the world for the new design and KJ is debating whether to offer a lifetime warranty.

That gasket looks sexy.

SGH

Love them or hate them, KJ has come up with some cool stuff. 

Ozzie_Isaac

bgebrent said:

stlcharcoal said:

More edges/corners = more stress points.  

Worth a shot, time will tell.

Not more relief points?  Just a chemist so truly asking.

Seems there are a lot more expansion joints which is good.  I wonder what there layout for warranty is and the projected savings with this redrsign.

td66snrf

What type of metal is at the top?

blasting

I sure do appreciate KJ's spirit of innovation.  I'd sure give them a look, if I was in the market.

Hawg Fan

@DMW. - Ha! That's the tequila talking.

Ozzie_Isaac

Btw, I count 7 pieces.  I suspect you assemble it on place.  That will be a pain for cleaning, but neat to see them innovating.

bgebrent

DMW said:

Hawg Fan said:

Looks like they've upped their quality of gasket material as well.  The post I read said KJ worked with the best gasket company in the world for the new design and KJ is debating whether to offer a lifetime warranty.

That gasket looks sexy.

You're easily aroused

Hawg Fan

td66snrf said:

What type of metal is at the top?

The FB post said the ring was stainless steel.

DMW

td66snrf said:

What type of metal is at the top?

Stainless steel. And that's what has me wondering. I don't think the expansion rate of SS is the same as ceramic. However, the ceramic pieces have room between each section, so it might be OK. However, I don't really see the need for a metal piece on top of the ceramics. Why not just set the fire ring on top of the fire bowl sections without the SS piece?

SGH

td66snrf said:

What type of metal is at the top?

If you are asking about the gasket, it's interwoven grapho-glass. 
Same thing that Rutland is made from. 

Edit: After re-reading your question, I realize that you were asking about the band on the fire box. My mistake. 

DMW

Hawg Fan said:

@DMW. - Ha! That's the tequila talking.

Nope, Evan Williams.

Ozzie_Isaac

DMW said:

td66snrf said:

What type of metal is at the top?

Stainless steel. And that's what has me wondering. I don't think the expansion rate of SS is the same as ceramic. However, the ceramic pieces have room between each section, so it might be OK. However, I don't really see the need for a metal piece on top of the ceramics. Why not just set the fire ring on top of the fire bowl sections without the SS piece?

Keeps the piees from falling back against the base.  Looks like a round firebox bottom and 5 petal leaf pieces held in place by the SS ring.

bigbadben

DMW said:

td66snrf said:

What type of metal is at the top?

Stainless steel. And that's what has me wondering. I don't think the expansion rate of SS is the same as ceramic. However, the ceramic pieces have room between each section, so it might be OK. However, I don't really see the need for a metal piece on top of the ceramics. Why not just set the fire ring on top of the fire bowl sections without the SS piece?

My understanding is that the metal ring holds the interlocking pieces together.  

DMW

Ozzie_Isaac said:

DMW said:

td66snrf said:

What type of metal is at the top?

Stainless steel. And that's what has me wondering. I don't think the expansion rate of SS is the same as ceramic. However, the ceramic pieces have room between each section, so it might be OK. However, I don't really see the need for a metal piece on top of the ceramics. Why not just set the fire ring on top of the fire bowl sections without the SS piece?

Keeps the piees from falling back against the base.  Looks like a round firebox bottom and 5 petal leaf pieces held in place by the SS ring.

bigbadben said:

DMW said:

td66snrf said:

What type of metal is at the top?

Stainless steel. And that's what has me wondering. I don't think the expansion rate of SS is the same as ceramic. However, the ceramic pieces have room between each section, so it might be OK. However, I don't really see the need for a metal piece on top of the ceramics. Why not just set the fire ring on top of the fire bowl sections without the SS piece?

My understanding is that the metal ring holds the interlocking pieces together.  

Well, my perception skills might not be all that sharp tonight (thanks Evan), so that makes sense.

HeavyG

I'm guessing they decided not to go with the cast iron fire boxes they had prototypes of a few months ago.

Their new cantilevered hinge is going to be sweet on their Big Joe. Their new vent cap will be nice also. Hopefully all these improvements will be available this summer.

Canugghead

Just thinking out loud here ... wondering if the sides of each petal are slightly concave (at the same height as the hole), thus creating a ventilation gap at each joint, the hole can be eliminated to reduce the chance of cracking around it? 

tikigriller

When I add a second egg, which will be quite some time, I will be hard pressed not to put some red in the back yard. 

I really hope BGE starts to come up with some stuff like this as well. They are going to get left behind if they don't start making some changes to their designs that we all buy things to improve upon. 

Toxarch

Weight reduction lifting parts for cleanout might be good. Though it would be a little more hassle with more parts. I guess it would drop the price of warranty parts replacing and shipping the one piece. I do like that they ship warranty parts direct to the customer. 
The gasket looks almost like what is used in kitchen ovens. Looks more like a metal braid than the stuff Rutland uses 
I wouldn't hesitate to buy red. Already bought a Junior. Is comes with lots of things BGE charges for as optional accessories. 

JohnInCarolina

Maybe next they'll design a forum that doesn't suck.

Photo Egg

JohnInCarolina said:

Maybe next they'll design a forum that doesn't suck.

How many years did it take BGE to take over and run their own forum?

Eggcelsior

Photo Egg said:

JohnInCarolina said:

Maybe next they'll design a forum that doesn't suck.

How many years did it take BGE to take over and run their own forum?

Interesting non-sequitur

JustineCaseyFeldown

Corner stress isn't the issue. Expansion of ceramic (something not very flexible) across a large field/area (especially curving in two directions) is the real problem. Reduce the size of the piece and lessen the complexity of its shape, and there is less stress

They struck a balance between making the pieces smaller to reduce stress, while not making it too much like a jigsaw puzzle

the one piece fire boxes end up splitting almost exactly like this anyway. They just went with it and made them that way in the first place. Makes good sense actually

My original firebox, and fishlessman's too, split horizontally around the 'equator' and then into pie wedges. And enough pics over the years of other broken fireboxes shown pretty much the same thing. 

just not as cleanly as this obviously. They simply followed the lines where it tends to crack and made a hard joint there. 

This is why sidewalks have cracks. Going to crack, typically across the least dimension. So give it a place to crack (the tooled joint) or make the crack in advance (paving stones, for example).
 

JohnInCarolina

JustineCaseyFeldown said:

Corner stress isn't the issue. Expansion of ceramic (something not very flexible) across a large field/area (especially curving in two directions) is the real problem. Reduce the size of the piece and lessen the complexity of its shape, and there is less stress

They struck a balance between making the pieces smaller to reduce stress, while not making it too much like a jigsaw puzzle

the one piece fire boxes end up splitting almost exactly like this anyway. They just went with it and made them that way in the first place. Makes good sense actually

My original firebox, and fishlessman's too, split horizontally around the 'equator' and then into pie wedges. And enough pics over the years of other broken fireboxes shown pretty much the same thing. 

just not as cleanly as this obviously. They simply followed the lines where it tends to crack and made a hard joint there. 

This is why sidewalks have cracks. Going to crack, typically across the least dimension. So give it a place to crack (the tooled joint) or make the crack in advance (paving stones, for example).
 

This is largely correct, except in your last paragraph regarding the "least dimension."  In brittle materials, the direction of fractures is largely dictated by the orientation of the maximum tensile principal stress component.

The complexity of the shape also isn't the issue here so much as the constraint provided in the circumferential direction of a contiguous piece.  That's what gives rise to sufficiently large tensile principal stresses under a thermal gradient.