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I Forge Iron

fire grate stock advice


RogueRugger

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My first fire grate; just something quick for a neighbor.  I'm not sure what size stock to would work best in this case.  The fire box is about 19"W x 17"H x 12"Depth.  FWIW - 'Customer' has requested a distance of about 1.5" grate-to-floor distance.  

The box is relatively small, and obviously I don't want the material to take up the entire space, but I want it to hold up for a few years at least. This is the main heat source for their home so it's going to be used regularly. All of the grates that I've found on the web have been for much larger boxes.  Hopefully that's enough background. 

I'd appreciate any thoughts anyone would have for basic stock width to start with (or a link where this might have been discussed before).  

Thanks in advance 

 

 

 

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I am a little confused by your description.

Not quite sure what your dimensions describe. Width Height and depth is not a standard group...Both Height and Depth often refer to vertical dimensions. Are you using "width" to describe the dimension across the fire place, and depth for the dimension front to back? 

Is the plan view longest dimension (the Length) 19" the plan view Width 12" and the Height of the box from grate to top 17"?

What fuel is going to be burnt? Wood or Coal?

I think you use the word "grate' initially to describe the project but then later you appear to use it to describe the grid the fire sits on. Which stock sizes are you after. Those for the whole project or those for the actual grate/grid?

If coal, and you cannot buy a readymade cast iron grid (which can be replaced when it burns out) I have made them from individual fire bars forged from 30mm x12mm (11/4"x 1/2"). I set them so the 30mm is vertical and forged the ends to give me a 25mm wide offset spread TEE. They rested on a ledge front and back the spreads creating a 12mm gap between the bars. Making them from individual elements meant that as the middle ones burnt out they could be shuffled to the outside edges for overall longevity.

Wood can either be burnt on a similar grate...but it burns better if allowed to build up a layer of ash underneath, and if so insulated will quite happily burn on a plate or thick sheet base, air entry from underneath is not necessary.

A start for you.

Alan

 

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9 minutes ago, Alan Evans said:

 

Apologies for the confusion.  The dimensions are right off the manual for the unit and is the same way my own fireplace is described by the designer/builder.  

19"W = distance across the front of the firebox

17"H = distance from bottom of box to top of the firebox

12"D = distance from the front of the box to the back of the firebox.

Wood is the fuel of choice.  

I'm looking for suggestions for bar stock size for the grate on which the wood would rest inside the firebox.  

Again, thanks for any thoughts

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You will need air space between the ash and the bottom of the grate that holds the fuel. The heat from the fire on top and the ash/embers on the bottom will burn out the metal of the grate otherwise. This happens with coal also.

I have a wood burning stove to rebuild that the fire burned through 1 inch round stock grate due to no one cleaning out the ash. The customer wants a shovel and ash rake to clean out the ash and prevent the problem in the future.

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5 hours ago, RogueRugger said:

Apologies for the confusion.  The dimensions are right off the manual for the unit and is the same way my own fireplace is described by the designer/builder.  

19"W = distance across the front of the firebox

17"H = distance from bottom of box to top of the firebox

12"D = distance from the front of the box to the back of the firebox.

Wood is the fuel of choice.  

I'm looking for suggestions for bar stock size for the grate on which the wood would rest inside the firebox.  

Again, thanks for any thoughts

If you have a manual for the unit...do you have the unit? Are you just replacing it? If so can you just match the existing grate?

The usual form of fire bars is as I described my forged ones above. They are set on edge so that the narrow edge faces the heat and their bulk below acts as a heat sink. They have wide lumps on either end and sometimes in the middle which create spaces between them. Even the more resistant cast iron ones are this way...although the cheap knick-and-snap-to-length grids usually are square section bars and rely on the material properties rather than their cross section for longevity.

I did make up some wooden patterns which mirrored my forged bars, and had them cast by a local foundry. They worked out very expensive, over three times the cost of the mild steel and I did not think they would last three times longer. I offered them to customers who invariably went for the forged steel option. I have not had any requests for replacements...so they evidently outlasted the clients at least.

But if its for wood just a plate will work and be easy clean, Cast iron would be traditional, Stainless Steel will last longer than mild, mild will last fine, and be cheaper initially. But the time they have burnt out a few times over one hundred years a bespoke Cast iron plate would probably work out cheapest but there is not a lot in it.

Cheapest and simplest as I said above is buy a readymade cast iron drop-in grid and make shelf supports in the box to suit.

Allow clearance for the grate/fire bars/floor plate to freely expand and contract with the heat.

I am maybe also at cross purposes. Using the word box frequently, are you talking about an enclosed wood burner / wood furnace rather than an open fire basket? My comments were from the assumption it was an open fire basket.

Alan

 

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We have a wood or coal burning stove with a couple of glazed doors for heat in the sitting room. It is welded from 4 and 5mm mild steel plate. the floor and part way up the sides is lined lined with 20mm thick fire brick tiles.  In coal burning mode it has a free standing cast iron grid with riddling device which is set about 50mm (2") above the floor. In wood burning mode, as we use it, you take out the grid and just burn it on a bed of ash on the fire brick.

Maybe it would be helpful if you posted an image of your unit, just in order to stop me rambling about every possible form of fire box.... :) 

Alan

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Hate to be a party pooper, but usualy wood dosnt require a grate, nor dose it benifit from one, either in a wood stove or fire place. Air coming in under the wood makes it difficult to controls the air, and therefore the burn rate. So it's ny on impossible to "bank the fire" overnight. In a fire place, the fire will burn longer, just not so energetically on the ash bed. Once an ash bed develops large peices will take a longe time to burn up. Grates and anderacks allow air to get underneath, this leads to a  brite energetic fire, good for light, fast heat and reflector ovens. 

Coal needs the additional air, so one has to put it on a grate.

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13 hours ago, Charles R. Stevens said:

Hate to be a party pooper, but usualy wood dosnt require a grate, nor dose it benifit from one, either in a wood stove or fire place. Air coming in under the wood makes it difficult to controls the air, and therefore the burn rate. So it's ny on impossible to "bank the fire" overnight. In a fire place, the fire will burn longer, just not so energetically on the ash bed. Once an ash bed develops large peices will take a longe time to burn up. Grates and anderacks allow air to get underneath, this leads to a  brite energetic fire, good for light, fast heat and reflector ovens. 

Coal needs the additional air, so one has to put it on a grate.

Not a party pooper...more a curious sort of echo! :)

Alan

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  • 3 weeks later...

I'm probably too late to offer timely advice, ... but will try anyway.

In my opinion, ... 1/2" square mild steel, will not hold it's shape, when buried in hardwood coals.

As mentioned above, 1/4" x 1" flat bar, ( or larger ) set on edge, with about 1" spacing between bars, will serve much better.

If there's room for something heavier, 1/4" x 1 1/2" flat bar, would do a fine job.

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