Strength vs Simplicity

[BeanAnimal]

Re: Strength vs Simplicity

I have contacted Harbison and requested sizing and pricing information for their medium duty fire bricks. The other local supplier lists their bricks as 8.75 x 4.25 x 2.5 so not ideal, but $1.30 each.

Harbison also carries many blanket and board products so I will get pricing and data sheets to see what is suitable.

I am very excited to get the planning finished and start the foundation (will create a build thread in the proper forum when the work starts).

[Les]

Re: Strength vs Simplicity

For the cost of water jetting 20 different styles of bricks in two planes you could buy multiple modular ovens.

I totally agree with you David. I'm just saying that if you had access to one, it would be a fun project to build an oven that way.

[Millstone Man]

Re: Strength vs Simplicity

As to the brick cutting: I got a used 14'' saw off of craigslist and have not replaced the blade yet after a lot of cutting (oven and kitchen project). As stated here before, the key is to have a good water pump and not force the bricks and your blade should last a very long time.

[BeanAnimal]

Re: Strength vs Simplicity

I think I will buy the $99 14" chop saw and retrofit it with a few water sprays and a diamond blade. That way I can set the 10" HF saw up for the angle cuts and the 14" for the bevel cuts.

[Sharkey]

Re: Strength vs Simplicity

We've learned that the best commercial oven builders in Italy only trim the inner edges of the bricks so that they appear to fit on the visible side, and fill the outer gaps afterword.

I was considering cutting perfectly shaped bricks for minimal joints but after seeing the work of some traditional Italian builders decided it would make negligible difference in the end. If you want a good finish on the inside with minimal joints you only need to taper the bricks vertically.

Actually, I found it harder to get the mortar into the joint if I also tapered the bricks from front to back.

And you will still end up with some flat V-shaped mortar joints on the tighter chains because the circle is not actually a circle but a series of straight lines.

[BeanAnimal]

Re: Strength vs Simplicity

I have no plan to shape the bottoms to eliminate the horizontal vees. That is where the CNC waterjet would come in...

The local harbison distributor has not responded with prices and a catalog yet, so I will call them again Monday. I am anxious to see what tapers the brick come in.

[Les]

Re: Strength vs Simplicity

I have no plan to shape the bottoms to eliminate the horizontal vees.

Bean,

If you stay perfectly off bond - at the 13th course the brick is about 5/8 inch wide (you mentioned you laid this out in CAD so you see the issue). At that width, there would be no gap to speak off. Before I got to that point is where I realized the problem. Although I saw it coming, I had no appreciation of hard it was to hold onto the brick while cutting it. My advice - Make a fixture. The beauty of this forum has been evolution - go for it!

[BeanAnimal]

Re: Strength vs Simplicity

I had started to lay out each brick to ensure a perfect bond patterm, but realise that the real world and autocad will greatly differ due to mortar joints, etc. So the autocad plan is fairly generic with regard to brick widths for each ring and actual widths will need to be cut on the fly.

Autocad has been a very valuable tool for me with regard to laying out things like my arch, vent and dome. The dome will be 42" but only 19" high. I was able to simulate the offset indispinsable tool and how it would shape the dome, etc.

The software may take some of the "art" or "craft" out of the project, but I am not an artists or an old world craftsman by a long shot so I need all of the help I can get.

P.S.

The software is only a tool, the collective knowledge available here on this forum is invaluable. It is amazing to see the progression of ovens over the last several years!

[BeanAnimal]

Re: Strength vs Simplicity

So I have debated wether to start yet another thread or just defer to those who have helped here...

My only local source of fire brick is the Greer LIGHT DUTY product. Prices range from $1.25 to $1.75 each for 9 x 4.5 x 2.5

Harbison Walker quoted a whopping $2.59 each for MEDIUM DUTY brick, adding at least $350 to the cost of the oven. I can find no other lcoal medium duty bricks at supply yards or refractory distributors.

I did find a company (MT. Savage) in Maryland that manufactures MEDIUM DUTY bricks and will sell them for $1.17 each. So if I figure 300 brick to be safe, add $300 (just a guess) freight, plus the $8 pallet fee and a $35 partial pallet fee, I am looking at roughly $750, or $2.31 per brick. That is still fairly spendy but less than the local Harbison by $87!

So LIGHT DUTY $495 or MEDIUM DUTY $700

Is there ANY reason to go with the more expensive option? That is, is it AT ALL worth the extra money for the MEDIUM DUTY brick?

FWIW the tapers and arches only come in HIGH and SUPER duty products from any of the companies I have contacted... So that idea is out the wondow.

[BeanAnimal]

Re: Strength vs Simplicity

Can anybody with knowledge jump in here? I need to get my bricks ordered so that I can get this puppy started.

[Les]

Re: Strength vs Simplicity

I recall the plans suggest medium duty. I know some have used light duty for their build and I haven't heard anything bad going on. If you were to fire it up everyday at crazy temps I would avoid them. If money is tight, I think you are safe.

[dmun]

Re: Strength vs Simplicity

I don't think there is any advantage to medium duty firebricks at the temperatures we run. Don't spend the money, is my advice. Besides, if you are going to be doing a lot of cutting, you want easy to cut bricks.

[das]

Re: Strength vs Simplicity

I believe the reason the Harbison Brick is so expensive is it's made in CA. HW is now part of a larger company that is local to you but the medium duty brick I believe is made in CA. I found out today the freight costs from plants across the nation and Canada adds anywhere from 25-200% to the brick cost.

I have called all around today, except ANH, for medium duty brick. I found the Alsey medium duty bricks I was after, but they were all re-brands They had traveled from IL, to WA or NorCal then to SoCal, by this time a $1.60 brick had turned into a $4.53 brick. I can buy their High-Duty indutrial bricks for $2.90. Either way it looks like freight shipping and fuel surcharges are the biggest factor on these bricks, considering they're 8lb a piece. All the brick made here in CA from Pacific and Muddox etc. are only $1.07-1.45.

Regarding Low vs. Medium Duty. On the surface the difference is temperature limit. But from the reading I did over the weekend the differences that are most relevant to us are the conductivity, and the dimensional stability from heat cycling. According to an Alan Scott book, medium duty have a heat conductivity of 60% and high duty is ~75%, therefore I figure a low duty is <50%. A. Scott said HD bricks for the hearth get too hot for bread baking and may burn the bottoms, and suggests MD, however suggests for strictly pizza a HD brick may be better suited. Jim Buckley of Rumford Fireplaces posted answers to the same question, High duty vs Low Duty firebrick on a Masonry Heater Association board. From his experience he stated that Alsey MD bricks are the best, and then seemed to suggest Whitacre-Greer or I-XL(which I hear is closing down) low-duty bricks as the next best. What he stated was that the ASTM specifications for fire-brick do no include any spec. for thermal expansion/stability which to him is the most important for longevity and reduced cracking/spalling. His suggestion for brick is based off personal experience and years of building fireplaces and fireboxes with all the major firebrick manufacturers on the market.

Considering the self-labor involved is worth much more, and suggestions from people with years of experience I plan to use either ALsey or H-W MD bricks if I can get them under $3.00, else I plan to use W-G low-duty (quasi MD bricks). I was bummed I couldn't find a full stocking Alsey distributor as they make a non-watersoluble mortar, castable refractory, fireclay, firebrick color stains, and large floor tiles as well as arch and key stones. Besides the ceramic insulation it would be a one stop shop with all the products designed to work together.

[Tscarborough]

Re: Strength vs Simplicity

W-G light duty are fine even for commercial pizza oven use.

[Tscarborough]

Re: Strength vs Simplicity

Also, while maintaining bond, do no use any brick that is less than 2" width on the face, and 3-4" is better.