Permsteading.com

Have you ever tried extending your forms for the casting mold to include the riser?

No, I have not. Be aware that this mix I am making is not that strong. I'm sure it would just break right off. I also wouldn't want to handle either the core or the riser much at all once it's dry. It's just good enough to stay in place, but it is in no way a structurally strong material.

Matt, your videos are great on this build! I'm working on mocking up my core and I'm curious how you join your riser pipe to your core. It looks like your form sticks out a bit on the exhaust end. Then your temporary riser is stuck down into your cast slightly? is your temporary riser slightly bigger than your square exhaust port? I'm just piecing things together and it looks like I would need to trim down the mold for the interior of the core to get an appropriate size pipe to match up.

Thanks Manny, I'm really glad they are helpful. I had so many requests for how I built my home system, it took a while to figure out the best way to share it.

Don't over think the connection there. I use the temporary pipe to help shape the transition from square in section to round, but that's all that is there for, and it's not necessary. The riser just sits on the core, using a bit of mud or fireclay or furnace mortar or whatever to form a base as you set it there so it's level. Once it's on there, and you are forming up the surround, you can seal around the riser drum with mud. It's really very forgiving, once you get into it you'll realize that.

I have little of value to add to this at this time. I am planning to build one of these in my laundry room this summer, which is on a thick slab of several feet deep. It is the only part of my house in which I can do this, as it is an old farmhouse with wood floors and a post foundation and no basement. I have the old Evans book, and that gives some good basic information.

That said, I have never seen anything posted anywhere by anyone that is as valuable as the information on this site, and I do plan to use your core plans for my heater. I will be watching what you post here, and when I get started, I plan to document and post photos and video and share information as much as possible.

Thanks for all the information you have posted, Matt.

Welcome Lucy! Glad to have you here, and thanks so much for the compliments. I am really glad that others are finding this information useful. I would love to follow along on your build, please do document and post as you get going on it.

I put together one of these cast cores over the weekend. I scaled it down to a 6" and built the inner mold of the J-tube from OSB. I cast it yesterday and let it sit inside over night, then I strapped it to a 2-wheel dolly and slid it outside this morning. Nothing special, just a cast block. I did hollow a small area (5" x 1" deep) under the feed tube for an ash catch, and I lined the inlet to the feed tube with orange clay bricks.

Fired it up this morning and she was a rockin!!! Once the clay started to harden around the stove pipe exhaust and the J-tube burned out the exhaust leaked a little and the performance went down. Starting to get a feel for how the wood burns and what size pieces to use. I was a little worried about the 6" system but after using it I cant imagine that having an 8" feed chamber would be much better.

She's been cooking all day. It's got some significant cracks, a bit more than in Matt's video. I used the masonry cement with the perlite and fireclay.... I'm not too worried though. Or should I be? I think it will be ok. About half-way through I was wondering if I should have put some rebar or something in it, but too late now.

I'm going on about 12 hours of constant burning but I'm about to let it go and go to bed. One thing I'm worried about is that we're still seeing some some low temperatures here, and I hope it doesn't freeze and break. I'm guessing there's still a good amount of water in it. We're seeing highs of around 32* and lows of 10-12*. Oops, should have thought of that before. So I figure I've got about $60 in this core right now. I guess if it does fail from freezing it wouldn't be the end of the world, but I'd rather not make it again.

Anyway, thanks again for everyone that posts on here! It was so easy to put this core together after reading all the posts on this site. I'm going to include some pictures of my own at some point here~

Okay, I think I'm getting this picture thing figured out:

Here's the core going together with the bricks around the feed tube.


Here's the finished product, burning clean (aside from the OSB burning away, I still don't really feel good about that.)




Thanks again, Matt!

Hmm, I can't see your photos Manny. Maybe just post them as a link and then we can work on the code from there.

I got really excited on reading your post, that's fantastic that you've got one up and burning! I'm inclined to not worry at all about the cracks. Once the core is in it's final location you will cover it everywhere with cob, so it can't fall apart to the outside, and patch anything major on the inside with the clay/FC. It'll be fine. I think rebar would tear the thing apart even more due to the different rates of expansion/contraction. Don't worry, it will just get stronger and stronger as you burn it. Can't wait to see it Manny!

Manny, I was able to use my moderator powers to see what you posted in your post as an image link. If you click on your photo in Photobucket so it opens it up full size on your screen, on the right of that screen are "Image Links." Use the lower one, "IMG code", and copy and paste the whole IMG code here for each photo. That should do it.