Shorty Core gets a bell

Gerry and Thomas,

That is a stellar project - congratulations!

It appears that the riser on Shorty is square (or at least rectangular).
Did you consider making it round or octagonal to encourage better mixing?
Or do the aspects of a short riser with 90 degree bend make the mixing sufficient for the efficient burns that Peter VDB aims for?

Again, great job! And thanks for documenting it so well.

Hey Randy;
Shorty's riser is actually 6"x 6" for the first 10.5", and then it becomes a 9" x 6" rectangle.
A double-rams horn at the bottom of the riser that slows down at the expansion until it reaches the "roof" of the riser and then is forced to turn and go down to exit the riser.
This creates the "casual" burn that is quickly becoming Shorty's trademark, and it allows the bell roof to be made with clay brick rather than fire brick

With this core being the first one built in the USA, I would not change a thing about the riser's shape at this time.
This design is currently Peter's crowning glory for a very good reason: it works exactly as it was intended.
Besides, as a  Journeyman, by changing "challenging" a Master's design, I could find my license revoked! :)

Without the proper test equipment, it would be a mystery whether any changes had improved efficacy or harmed it.

Much appreciate the response Thomas.

Unfortunately, your answer may well get you LOTS more questions!

Based on what you've built, I think my intended design of tall riser 6.5" BB is now morphing into a Shorty!

And although you did a stellar job at documenting the build, I'm likely to miss a few salient points and will be looking for clarification.

My tall riser BB dry mockup seemed to work really well, even though everything was completely dry stacked with no mortar or gasket between bricks.

But the idea of not requiring bricks cut to fit the octagonal riser (as I did in my test model) makes the Shorty even more enticing.

It's still cold and snowy here in Maine, so build season is at least a month away. But I have more hope!

Thanks again,

Randy

Glad to help, Randy;
A square riser works just as well as round or octagonal risers.
The 5-minute riser is as good as a brick riser with no cutting involved.
If you can locate and afford them, 2600F+ insulated firebricks are the Cadillac of them all. (Stacked square)

You will need to build forms and pour three refractory slabs to build a Shorty.

I have local access to Calcium Silicate Board 3”x24”x36”.
I don't have a price yet, but would that work for a top slab?
Or is there a strength issue to address?

Thanks

Hey Randy;
I had to look it up.
Usable range is 1200F; max temp is 1832F
The other thing is how abrasion resistant is it?
Particularly after being heated to max?
I recommend building forms and pouring refractory slabs.
Once you seal a core inside a bell, even if it is built using proper clay mortar, you really will not want to open it anytime soon.

See?  I told you I'd become a pest  ; )

Thank you!

I've found, as confirmed by Peter, that kiln shelves work for the "roof" slabs -- making them a viable alternative to casting your own from refractory cement. Sourcing kiln shelves can be an issue though. I'm in a rural part of Ottawa, Canada, a city of over a million, but I had to order them from the Toronto area, which added a hefty shipping charge.
I used refractory in an earlier stove and was glad to not have to mess with that again. Knowing that thermal expansion stresses materials, including kiln shelves and other high alumina refractory, I used strips of a Superwool type of ceramic fiber blanket instead of mortar to seal the gaps between the slabs and the sides.

Indeed, Peter does use kiln shelves on all his test builds.
But I believe that on his more permanent builds, he uses slabs.
What size (thickness) shelf did you use to roof your Batchbox?

Randy Butler wrote:I have local access to Calcium Silicate Board 3”x24”x36”.
I don't have a price yet, but would that work for a top slab?
Or is there a strength issue to address?

They are quite soft and eventually will get destroyed by hitting with wood pieces and by heat. I don't think they can be used in the flame path.

You can buy fire brick tiles. They sell them in 18x18" size and various thicknesses (for example 2'). Then you can rip them into 4" width pieces to relieve the tension of the slab and build the ceiling.

thomas rubino wrote:Indeed, Peter does use kiln shelves on all his test builds.
But I believe that on his more permanent builds, he uses slabs.
What size (thickness) shelf did you use to roof your Batchbox?

For the firebox: 12" x 24" x 3/4" (305 mm x 610 mm x 19 mm)  cut down to firebox length, because no 12" x 18" shelf was available
  https://psh.ca/collections/high-alumina-kiln-shelves/products/12-x-24-kiln-shelf-pizza-stone
For the riser top: 12" x 12" x 1/2" (305 mm square x 12.7 mm)
  https://psh.ca/collections/high-alumina-kiln-shelves/products/12-x-12-kiln-shelf-pizza-stone
A firebrick thickness strip cut from the large slab spans the top of the riser outlet.
With taxes and shipping, the two shelves cost me C$174, but they saved a lot of time and didn't require warm curing -- important because the cold weather had already begun

I can't tell that there's been any deterioration so far, and I've run some very hot fires to warm the greenhouse bench on the really cold nights we've had sometimes this winter. It's predicted to drop to -26C tonight, the coldest yet, so I'm really stoking the stove this evening. After the heating season, I'll remove the lid and document the condition.

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.

Correction, my mistake.
Of course, Peter is correct; the riser increases to 9" x 9" not 9" x 6"

David Wieland wrote:
For the firebox: 12" x 24" x 3/4" (305 mm x 610 mm x 19 mm)  cut down to firebox length, because no 12" x 18" shelf was available
  https://psh.ca/collections/high-alumina-kiln-shelves/products/12-x-24-kiln-shelf-pizza-stone
For the riser top: 12" x 12" x 1/2" (305 mm square x 12.7 mm)
  https://psh.ca/collections/high-alumina-kiln-shelves/products/12-x-12-kiln-shelf-pizza-stone
A firebrick thickness strip cut from the large slab spans the top of the riser outlet.
With taxes and shipping, the two shelves cost me C$174, but they saved a lot of time and didn't require warm curing -- important because the cold weather had already begun.

Omg, that are serious prices. There is a shop not too far away from me where they make tiled stoves and handcrafted refractory slabs and bricks, at numerous dimensions. The largest slab is 50x21x3cm for the price of about 8 dollars. They follow the traditional craftsmanship and recipes. Maybe I should start exporting them🙈

Matthias Hacker wrote:...Maybe I should start exporting them🙈

Bear in mind that the currently wimpy Canadian dollar is worth only about 70% of the US dollar. Also, shipping breakable things requires extra packaging, which increases the cost. The shipping charge in my case was about C$70, from a place only a 4 hour drive away.

Matthias Hacker wrote:

Omg, that are serious prices. There is a shop not too far away from me where they make tiled stoves and handcrafted refractory slabs and bricks, at numerous dimensions. The largest slab is 50x21x3cm for the price of about 8 dollars. They follow the traditional craftsmanship and recipes. Maybe I should start exporting them🙈

$ 8.00 would seem to be a good price indeed.  19" x 8" x 1.18"  but if very fragile?
Where are you located?

Well I don‘t have any long term experience with them, but they survived my rather excessive cutting with ease. On the pictures you can see the grooves that I cuttend for stripes of metal. And keep in mind they are handcrafted, while being quite precise, there are seldom perfect right angles nor are they perfect plan.

Yes, packaging would be a challenge. Plus taxes and shipping costs…

I'm located in northern Serbia, southeast Europe, a region that was under Austrian-Hungarian influence, some of the craftsmanship they brought has survived, like for example building tiled stove, which is not a Serbian tradition.

Attached pictures of my recently build DSR3 core. I did cut the edges to perfect angles for dry stacking them, but if mortar is used, that wouldn’t be necessary.

Well if there is interest, we could try that out.

This is their website
http://kaljevepecimb.com/Kontakt.html

Translated link https://kaljevepecimb-com.translate.goog/index.html?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=de&_x_tr_pto=wapp&_x_tr_sch=http

And a picture of available Dimensions attached.

…but why not ask them, if they can export their products themselves. I was taking a look at their website once again and read, that they have experience with exporting at least to EU countries.

One discussion I haven't found yet regarding Shorty - can the dimensions be scaled as the PvdB BatchBox can?

I know it is a very new design, but has anyone tried to build one or two sizes up or down from the standard 6"?

I ask 'cuz my chimney is lined with 8" flue tiles.

Thanks!

Yes, I know of a pending 7" Shorty being built this summer in Iowa.
Peter has built larger Shorty's in Europe
Peter can supply you with dimensions for a 5",7" or 8" Shorty.

Regarding the Shorty upscaled, yes it has been done with success, you might want to take a look at this thread on donkeys, all dimensions have been discussed with Peter, as well as a Sidewinder construction. All the dimensions for scaling are there, you only need to convert from mm to inch.
https://donkey32.proboards.com/thread/4091/shorty-batch-160mm-system-brick

Another run
Scott, looking at your image presented I have some questions;
- are aqua coloured parts  tension roods?
- brown coloured sections are angle iron steel frame?
- are the green coloured bricks are held in place by friction created by the aqua rods?
Thanks

Good Evening Thomas.

I've looked at a ton of threads on the Shorty 2 core. But I probably haven't found them all.

I'm attempting to use the 6" metric Sketchup and sizing calculations from PvdB as a guide to create a 7" SAE version.
It's a little tricky since:
  1) the brick sizes don't translate perfectly
  2)  I'm trying to keep dimensions very close to the ideal numbers
  3) I'm designing the firebox with HD firebrick splits as a liner surrounded by K-26 IFBs.

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?

Making the three square box forms for the FB top, RP lintel and Riser cap is easy.
A form combining the latter two wouldn't be much more work, and would eliminate one seam.

Any thoughts?  Would I be making extra work for myself, or would the pieces be more prone to failure?

Thanks for your insights (and feline fotos!)

Hi Randy;
If you tell Peter your brick dimensions, he will happily give you the numbers for a 7" Shorty.
I guess you could cast the cap and lintel in one piece. I have not heard of anyone trying this, but you could be the first!
Sometimes being first can lead to unexpected repairs... Myself, I'll pour three boxes.

John C Daley wrote:Another run
Scott, looking at your image presented I have some questions;
- are aqua coloured parts  tension roods?
- brown coloured sections are angle iron steel frame?
- are the green coloured bricks are held in place by friction created by the aqua rods?
Thanks

I looked back, and did not see, but easily could have missed a posting by "Scott"  showing any of the above items?  

When I do CAD work for designs of this nature, I indeed do a different color for each different part, it simply makes the observation of the finished unit easier for all to understand what is pieced together.  I.e. Full bricks might be Tan, bricks cut to half length a different color, 1/3 length a 3rd color.   Equally tension frames of metal can be another color.

As far as tension frames go, I am not sure the word "friction" would be the right indication of what the frame is doing. As friction would indicate that something is be rubbed against something else. All the time.

By having a frame simply holding brick where it is wanted, both lengthwise and sideways, we accomplish a lot. When one steps back and looks at almost all structures in the world, nearly everything is in one way or another held together by some form of tension. Be it nails, rods, adhesives and the list goes on. Almost always used to keep something together and prevent spreading apart. Frames for Rocket type stoves can do this as well.  Externally of course. not in the  fire path.

I would caution that any proposed designs may look good, unless tested to the level that Peter V. does, are simply proposed, not yet proven.

Thomas -

Thanks for the response.  I'll forward my query to Peter.

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.

John C Daley wrote:Scott, looking at your image presented I have some questions;
- aqua parts are tension rods?
- brown sections are angle iron frame?
- green bricks are held in place by friction created by the aqua rods?
Thanks

Aqua rods in the photo,  keeps bricks from sliding aft, or sideways Finger tight is plenty, or spring tension maybe better, if you have a mind to, and it will NOT get hot enough on the exterior to take the temper out.

Brown corner pieces, if they look like angle iron, then that is what they are. by extending tabs, there is enough room to slid in hi temp insulation, if desired.

Green bricks- cut right,  will support the bridge action of a roof top, You just have to keep them from sliding off the top.  You would have the tension rods already there. NO friction is counted on, If you rely on "friction" of the green bricks, they will/could/would slide off and you would have a mess.

Good Afternoon Thomas.

As you are one of the more experienced Dragon Breathing Builders, I thought I'd run a question by you.

My conversations with Peter vdB have yielded wonderful results, and of course generated a few questions.

But I know he is swamped and you have built a bunch of heaters so - some questions for the experts:

     7 1/2" system: Base  = 5.43  (Chimney is 8" square clay flue tile lined)
  The Riser Exhaust - if I can maintain the height and total width per specs, can I divide the exhaust in 2?
  Lower Riser Bay - Width and Depth both system size (so 7 1/2")
  Upper Riser Bay - Width and Depth both 2*Base (2 * 5.43 = 10.86, pretty close to 10 7/8")

  BUT in one of Peters notes, he says the riser depth should be less than riser width to establish a good "double ram's horn."
  I did not find any specifics on just what the difference should be.

He also expressed concerns about minimizing the number of brick cuts required for any layout.
Other than ease of assembly, do you find that to be any issue? Mine will be done on a chop saw with abrasive blade.

Based on the numbers I have, plus PvdBs input, I made a stab at a 7.5" core in SketchUp.
Suggestions on how to post the skp file?
I'd love any feedback if you have a chance.

Thanks!

Randy Butler wrote:




     7 1/2" system: Base  = 5.43  (Chimney is 8" square clay flue tile lined)
  The Riser Exhaust - if I can maintain the height and total width per specs, can I divide the exhaust in 2?
  Lower Riser Bay - Width and Depth both system size (so 7 1/2")
  Upper Riser Bay - Width and Depth both 2*Base (2 * 5.43 = 10.86, pretty close to 10 7/8")

  BUT in one of Peters notes, he says the riser depth should be less than riser width to establish a good "double ram's horn."
  I did not find any specifics on just what the difference should be.

He also expressed concerns about minimizing the number of brick cuts required for any layout.
Other than ease of assembly, do you find that to be any issue? Mine will be done on a chop saw with abrasive blade.

Based on the numbers I have, plus PvdBs input, I made a stab at a 7.5" core in SketchUp.
Suggestions on how to post the skp file?
I'd love any feedback if you have a chance.

Thanks!

Randy
Are you asking if you can have two smaller exhaust instead one, and I presume you mean if you have the same square inches?  if I am reading this correctly, what is the perceived gain?  what friction loss calculation do you intend to use?

When you say "riser depth" and "riser width" where are you measuring for these numbers?  The first part and the second part of the riser are square each. to the best of my calculations. Left to right and front to back.

Minimal brick cuts.     it takes great planning for the least amount of cutting,  with the general rule, lesser amount of cuts equals lessor amounts of waste, thus far less cost.  I have cut 1000's of pieces, brick-marble-granite-tile, and this " least amount of cutting" is always important.

I may not have answered any of your questions, but did ask some more of you.

cheers
Scott of Iron Design.

Hey Randy,
I second Scott's reply. The riser is square in both locations.
With its deep port, Shorty makes a fine double ram's horn.

My Question is, why did you develop a 7.5" batch rather than a 6", 7", or 8"?

I can see no benefits to splitting the riser. Peter did a pretty good job on this design, so there is no need to redesign it.

I find cutting bricks to be fast and easy.
Toss your abrasive blade aside and get a diamond blade for your chop saw; they are well worth the 20-30 bucks.
Use a masonry abrasive blade on a side grinder for trimming.
Always soak bricks before cutting.

Sorry, I can hardly use SketchUp, much less know how to post it.

Gentlemen - thanks for the quick response.

It will take me a while to find it, but I'm sure I saw a note from PvdB that the double rams horns will develop easier if the riser is slightly rectangular instead of square.
Lord, I do miss my mind, wherever I left it!
As to the size reason - turn out that the FB dimensions and port are very close to full brick dimensions when adding a FB Split liner.
With the chimney being 8", I don't want to crowd my limits, and since the place has cathedral ceilings and almost no insulation, it seemed logical to go as big as possible.

The divided exhaust port means I can have a center (IFB) "post" to support the middle ends of the two IFBs above and no lintel.
Castable refractory isn't cheap here, and I have more than enough K26 IFBs.

Hi Randy;
I suspect you may have seen that in Peter's Shorty development thread.
He tries a variety of things during development and then uses the testo to see the changes in output.
He only keeps the improvements that consistently produce a clean exhaust throughout the burn.

I recall him using Superwool to modify the riser dimensions.
He may have had some promising initial results with a rectangle creating a strong ram's horn.
A nice ram's horn (that you can not view) is much less critical than a consistently clean burn.

Perhaps 1" of superwool wrapped around an angle iron tee would be a better option for holding up the riser roof.
Or, create an angled ifb roof and utilize a tension frame to keep it in place.
Adding a column inside the riser is sure to have an effect, probably not a good one.
What was your plan for the core roof?
 
 

Randy Butler wrote:Gentlemen - thanks for the quick response.


As to the size reason - turn out that the FB dimensions and port are very close to full brick dimensions when adding a FB Split liner.  

The divided exhaust port means I can have a center (IFB) "post" to support the middle ends of the two IFBs above and no lintel.
Castable refractory isn't cheap here, and I have more than enough K26 IFBs.

Randy, Please take the time, to consider that building a 7" shorty will require NO splits.  Enclosed is a photo up to the top of the port, thus showing only the lower burn chamber ( lower riser)  There are NO splits in this, all of 2.5" thick x 4.5"wide x  9"Long or cut derivatives of this brick, The light tans are full bricks, any other color is cut to a smaller size.

As Tom pointed out, using a tension frame, and correct cuts of brick  ( full bricks - think 22.5 and 45 degree cuts, nothing else)  will allow you to avoid the surface tension drag in the riser as  you have proposed with a split riser roof support. Adding resistance opens up a huge can of worms.

I know the casting material is expensive, but sometimes it is simply un avoidable,  a case in point might very well be the extra long cross piece at the exit port.   another area where an obstruction could have detrimental effects.    

Tom showed how he made his "castings" with the sawzall vibrator, and there are other ways as well.  All far beyond a hammer and help greatly for a finished product. While I have not looked,  Amazon Prime with free shipping (in a sense $12 to $16 a month or find a neighbor with it)  can really open up the door for a cost effective solution.

Gentlemen -

The reason for my plan - I have some 400 K26 IFBs.
It seemed (to me) that using those, along with a lining of split FB for abrasion resistance, would provide a solid, long-lasting core.
I would, of course, maintain the internal dimensions of the firebox, port and riser.
Being able to easily replace a piece of the lining seemed logical. Perhaps not?
I do plan to cast both the firebox roof and that for the riser with refractory.
Guess I'll add lintel to that list as well.

Thanks!

thomas rubino wrote:Hi Pablo;
Those bricks are called new clay bricks at Home Depot.
They cost.58 cents apiece. I used apx 400+ in this build.

Hi Thomas,

Could you please provide a link to the item on the Home Depot website? I have been scouring the internet all day for "clay brick" and I cannot find anything remotely similar. What I am finding is no less than $3 a brick and either seem to be concrete or extra thin so I am getting pretty confused and would appreciate some guidance.

Would something like this work? Since I'm seeing a lot of posts around permies about dirt cheap bricks, I'm hoping I won't have to spend this much if I don't have to.

Thank you very much.

Edit: An hour after posting this, I finally figured out that I can find similar bricks if I look at Home Depots in other states. I will have to do more research to figure out which one is the closest to me and has the best price.

Here is a link, Hal
https://www.homedepot.com/p/8-in-x-2-1-4-in-x-4-in-Clay-Solid-Brick-RED0126MCO/100323015
Unfortunately, not many HDs carry them.

Thank you so much! I really appreciate it. And your heaters look awesome!

I swear the hardest part of doing any DIY construction is figuring out what materials you need and where to get them.