Simple Baffle Solution for your old FISHER ! More Heat Less Smoke under $25

Welcome to the Forum Tom;

Yes, you have a Grandma there. Measurements for the box are correct, your height is 3 inches higher than normal. Possibly longer legs?

3/8" shouldn't warp like this 5/16 factory baffle in an XL;


This is far wider than your Grandma. Goldilocks is the same width, and the 5/16 factory baffle stayed straight.

Notice the factory smoke shelf has 2" X 3" notches in the front corners. Not sure of the purpose, but it would allow more heat to the top at the sides, as far as possible from the vent. This was designed during smoke reduction testing, so it must be beneficial. The Goldilocks plate is the same design.
By putting a bend in the plate at the rear and front edge, (so the front and back edge is horizontal) about 1 1/2 inch from the edge, may keep it straight. Probably have to take it to a fabricator with a large enough brake.

The round baffle plate was only in the Honey Bear. That model is about half the size of a Grandma, so a smoke shelf baffle would have taken too much room in the firebox. It's more of a diverter than a baffle.

Here's my latest baffle for a Mama Bear that the owner was rough loading and kept knocking the support bricks out from under it. This 5/16 plate has been in use a season and a half with no warpage.
1 1/2" angle iron welded to the sides will prevent the upright bricks from falling into the fire. I never knocked mine down, but some people aren't careful loading; (Baffle is shown upside down on flat stove top, angle iron is at baffle front edge)




If only the stoves had welds that look like that..........

If you draw with chalk on the side of the stove, start with a line from the rear just below the outlet pipe. (or from the top of firebrick if there is only one course to set it on. I measure it inside, and transpose the line to the outside so you can get a good idea of plate size. Width is about 1/2" narrower than stove to be able to get it in and out. This can vary with stoves) Angle the line upwards towards the top bend. Smoke space square inch area at top edge of plate varies with draft. Just don't make it smaller than the cross sectional area of the outlet. (50 sq in.) 2 to 3" below the top is fine. The factory original on later stoves was about half that size, since they didn't know how well of a drafting chimney some customers would have.

Here's a pic inside an XL rear vent that shows the plate angle; This was the shape of factory baffle sitting on angle iron. If you bolt or weld short pieces of angle iron on the plate sides, near front, you can stand bricks upright to set the plate on without fear of the larger plate and bricks falling in. I don't have a pic of one inside a Grandpa.

Yes, the flat plates are upside down to show the angle iron welded to the plate. It's 1 1/2" angle iron on 5/16 plate. 3/8 is better for your larger size, but factory used 5/16. (And warped in wider stoves as shown in XL photo) Plate size is fine, factory was only 8". But again they had to err on the small side in case of a poorly drafting chimney to avoid smoke roll in problems with doors open.

If you have one course of bricks around bottom of stove, stand a brick on each side on top of the first row to raise the front edge of plate. I wedge a piece of wood across the two bricks to hold them tight to the stove sides while I set the baffle on top. Angle baffle through door, and set plate level on top of bricks. Then slide it towards the back letting the back drop onto the rear brick ledge. Remove wood wedge holding bricks tight, and you can slide the bricks fore and aft to change the plate angle.
It should sit on the bricks as shown; (no angle iron on plate in photo)


The baffle plate shown rests on a welded tab under the outlet in this Mama Bear. If you don't have anything in your stove to set it on, use the top of the bricks. If you feel this is too low and takes away from loading area, set one brick sideways across the back in center to raise the plate just under the outlet. They cut clean and easy when scored with masonry blade in circular saw.