Peter van den Berg

Randy Butler wrote:Any chance you have a link to the spreadsheet (or even a jpg version) so I can confirm what I have found so far?

At the moment, no spreadsheet has been made yet. The firebox itself is according to the spreadsheet of the original batchrocket though. If you scale the whole of the thing up in Sketchup, until the width of the firebox reach the correct value then you're done.

Randy Butler wrote:Can you please tell me if the Shorty 2 core is as scalable as the earlier offerings?

Affirmative. The development model was a 5" version, during one year after finalizing the design there are a handful of 6" versions done, including at least one sidewinder. And a 7" version even more than a year ago. I am unsure what you mean with Shorty 2, as far as I know there's only one design (apart from the sidewinders).

Randy Butler wrote:Do you have a SketchUp of the 7" Shorty 2 with standard US brick sizes (FB 4.5 x 9 x 2.5, splits are 1.25 thick)?

There's no 7" Shorty core design in US brick sizes yet, but I can draw you one. Don't hold your breath though, I am awfully busy at the moment. Will have time in about two weeks, is that OK to you?

Randy Butler wrote:Or can I just scale up from the 6" and re-arrange bricks to meet the up-sized dimensions?

You could try that as well, it's always a learning curve how to arrange things in such a way that minimal cutting is involved while keeping a running bond.

Randy Butler wrote:As I "build" and assemble bricks in Sketchup, I wondered - has anyone tried casting the Riser cap and Riser Port lintel in a single piece?

As it happens, I am working on a newly designed small(ish) mass heater, housing a Shorty core. There were two bags of refractory castable lying around, a lot of pieces of laminated spinboard and a pile of extruded polystyrene plates in three sizes. So I decided to use that instead of buying new materials. Here's one of the larger cast pieces and three smaller ones.



Thomas will probably recognize where in the core the above is situated.

Yes, I am participating in a workshop during the AFPMA (French mass heater builders association) annual gathering, held from 14th through 18th of May. The venue is a campsite close to the village of Montendre, north of Bordeaux. I did the design, a Shorty core coupled directly to a voluminous (although not very long) bench. It will be a quick build, meant as a proof of concept as opposed to a finished heater.

OK, you don't have the Sketchup application. By the way, the Shorty core isn't published on the site as yet, so much to do before I am getting too darn old...
But I can provide you with jpegs, of every layer of the core and you can work with that. I understand you are in Australia, the firebrick sizes might be different.
So, what are the firebrick measurements you are able to buy?
Is a Shorty sidewinder core the type that you want, or just the straight one like Thomas has built?

thomas rubino wrote:Shorty's riser is actually 6"x 6" for the first 10.5", and then it becomes a 9" x 6" rectangle.

Thomas, are you sure about that rectangle? As far as I know, you've built the thing to specs, which means the upper part of the riser box is also square.

Madeleine Innocent wrote:I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

What size do you want to build? Straight one or sidewinder? I am able to provide you with the core drawing in ISO or Imperial measurements. What do you prefer, pictures of every layer, drawn out brick by brick, or the original SketchUp file? Free to use, no charge.

Small donations are appreciated, although not mandatory in any way.

The design of the bell is done  by Thomas Rubino and Gerry Parent, ask them for guidelines.

Regarding the development of the Shorty and DSR3 cores: both were done for a large part with kiln shelves. The top of the riser box and firebox were as thin as 10 mm (0.394"). Sidewalls of the firebox were mostly 15 mm (0.591") and the rest was a hotchpotch of 30 mm (1.18") slabs and thinner leftovers that were laying around. The core that was in the EU approved DSR3 was done entirely in kiln shelves, bar the riser tube, of course.

I don't know about the DSR3 development model, but the Shorty one is in daily use since the last week of November. The top of the Shorty's riser box is still closed with three strips of 10 mm shelve material.



All shelve parts are still in one piece as far as I know, have seen it Januari 31rst last time.

The neighbors of a friend living in a yurt were complaining about the smoke of his steel box heater. The development model of the Shorty core was lent out to him in December. We did some repairs on it lately, the thing wasn't meant to be in use all winter anyway. He's now getting the hang of it, the upper barrel has a bypass now, and the liner inside the riser box was replaced by a sound refractory one.

This evening he sent me a short video, showing the Shorty running like mad after starting with really dry fuel and the bypass open. The video was shot 10 minutes after startup, the chimney is just a bare pipe of 4 yards long, rising two yards above the yurt. Not much wind, about 4 degrees C above freezing point.

https://pberg0.home.xs4all.nl/pictures/dev2023-2024/VID-20250209.mp4

Pretty hefty for a mere 5" ish core, I'd think!