So I have been taking the stove apart and cleaning it for restoration and my question is this. What is the best way to patch this... I was thinking of getting some screen and using metal epoxy to glue it on the back and use the screen as a base to hold some kind of material but what... Bondo, jb weld putty...? I also saw a listing on facebook market place for the correct Estate stove for sale a little over 3 hours away for $250 alas I am broke and lack a pickup truck.

I'm not sure epoxy can be relied upon to hold to the stove casting, that inside surface has got to be nasty. I think I'd fit a piece of sheet steel (as heavy gauge as can be formed to fit, 16 ga. at least) and drill some holes in the casting for flat head machine screws with the nuts inside the sheet metal. Once that is done and solid, any auto body filler should work to build up the missing part of the casting and fill over the screw heads, and should stick well to the sheet steel. Of course you realize that this makes the stove non-operative...

If it was me, I would get a piece of cast iron bar kinda like this McMaster Carr part number;

8928K76 (it comes in different sizes/thickness) See here;

https://www.mcmaster.com/iron

And shape it to fit, cuts easy enough with a hacksaw, grinding wheels and files.

Then I would bevel the joints to the old material and oxy-accetylene braze it all back together. This repair method would allow the stove to continue to be used.

This repair method would last another 50 years (if done correctly).

But it is the "hard" way to repair it.

I wager any kind of "filler" (JB Weld, Bondo. etc) that is not the same thermally (expansion/contraction) will eventually show cracks where the joints are.

My two cents, your mileage may vary.

Also, if there are any remaining cracks that are heading "into" good solid metal you should "end stop" them. You find the end of the crack (sometime squirting kerosene on the metal works, the liquid in the crack evaporates last) and then drill a small ~ 1/8" hole through the end of the crack. This distributes the stress around the perimeter of the hole and will help keep the crack from progressing over time. The hole can be filled in with braze metal.

Good luck, Kevin.

Looks like the stove tried to tilt with a rough couple or slack action. Cracks are visible at the corners of the lost piece. If this will be in an operating caboose I would also separately support the hold down bolt holes. May be some over-sized nuts as washers under as not to open the cracks when bolting it down. I would not like to light a fire in this without a replacement base.

Why will the stove be non-operative the base should be getting next to no heat.

Back when I was overhauling locomotives, General Electric sent us some damaged blocks with big holes punched through them from rod damage. They supplied these kits called "Lock and stitch"(you can buy these kits). It's a time consuming process that involves clamping the damaged pieces to where they broke off from, then drilling a hole in the center of the crack, then you tap it with a special tap, then you tighten a special screw until the head twists off, and finally you sand it flush. It really is a incredible kit as when you are done it is just as strong as before and there is no lines showing any damage. The only downside is the kits are expensive and work can be tedious depending on how many pieces you have. Here is a one such repair http://www.jswl.co.uk/metal-stitching.htm

In your case you really need a donor part to cut the broken section out of. You would cut it out in a rectangle pattern on both in the donor piece and the replacement piece. This would make fitting easier. You could weld it in place but welding cast iron typically needs to be heated to 1500 degrees, welded, and then gradually cooled to prevent cracking. If you had a lot of time on your hands you could just keep welding on the edges until you filled the whole thing up. You would need to have a good eye and a lot of grinding disks to get the curves right.

Here's a video for Lock-N-Stitch, I have no clue if it would work in your situation with a piece detached: https://www.youtube.com/watch?v=Pq0wfU4ZaKk
http://www.locknstitch.com

To get back on track, here are my thoughts. (Disclaimer - I'm not a cast iron expert and have had only a half cup of coffee so far...)

Drill a hole at the end of each crack to help stop them from spreading.

If you have the broken out piece, brazing it back in from the back would work. If brazing is out of the question, use a high temperature epoxy though it won't be as strong. Use the epoxy as filler for any gaps. Block sand to blend it in. Spray paint with flat black high temp paint.

If I'm barking up the wrong tree, I'm sure someone will point out the right one to bark at.

I don't have the peace just a hole that needs filling.

The base will get plenty of heat, via conduction from the firepot above, especially if someone leaves the damper open and the stove goes cherry red. The polyester body filler is only good to 150 deg. F or so, epoxies not much more. If you want to fire the stove, drill the holes to stop the cracks and assemble it with the broken side of the base toward the wall.

Hi RCD

By your post, I see you are located in Massachusetts, there is a place in Littleton, Mass, called Woodstove Fireplace & Patio Shop.
They are located at 60 white street, the last time I was there, they did refurbish stoves like yours.
As you said you don't have a lot of money to spend, but it wouldn't hurt to call them, or send them an email, showing your problem, this is just a suggestion.
Their phone number is the 978-707-4168 email Barry@stoveshop.com
Again this is just a suggestion, hopefully, they can either advise you on how to fix your problem with the stove, or they can make the repair?

For the amount of time and money you are going to sink into it you can likely just find a replacement stove.

In addition to the stitching pins they manufacture, Lock-N-Stitch also does furnace brazing of cast-iron pieces at their shop in Turlock, CA.

They could probably make a replacement part out of cast iron and furnace-braze it in place.

Many years ago I watched a guy repair a large pot belly stove which was also missing a piece. In that case, he found an old cast iron bath tub at the local junk yard, beat the finish off it with a hammer, cut the piece out he needed (with the proper curve already in it), then welded that in to place (pretty sure it was a cast iron weld, not brazed). Worked like a champ for many years and I was always impressed with the bath tub angle to getting the piece he needed with the right radius.

I have a PRR stove with that base the I'd sell you... there's some other parts that make my stove an outside wood stove only.