More efficient brick cuts

[Majic31]

Re: More efficient brick cuts

I have already bought the bricks and they are 9"x 4 1/2"x 2.5". I didn't purchase any tapered bricks.

What my thoughts were - I cut the 9" length as you described creating two halves (being 5" on what will become the outside and 4" on the inside). That will take me around the chain horizontally.
Then to get the vertical rise, replacing the wedge with a tapered brick... I cut the 2.5" of each half brick, so that I have 2.5" on the outside and 2" on the inside.(example only - not actual measurements)
I don't plan on cutting or shaping the sides, other than to get the 4"/5" split.
I only see it as one extra cut on the top surface. What am I missing here?
Majic31

[splatgirl]

Re: More efficient brick cuts

with the indispensible tool, or at least with my version of it, the angle bracket provides the proper elevation/angle for the brick. When the top face of the brick is flush with the top surface of the angle bracket, the angle is correct. I would just put the cut brick against the bracket and set it into place in the chain, and then stuff mortar into the gap at the back until it was held in place flush with the top face of the bracket. Some people use clamps to hold the brick in the bracket, but I found that unnecessary because the brick stayed put immediately if my mortar was nice and stiff.

[kebwi]

Re: More efficient brick cuts

Majic31: I'm not sure if I understand your description. Bottom line is that it is very difficult to taper a brick "across" the face because the 10" brick saws most FB users have don't cut 4.5" deep, which would be required to cut through the brick from the edge.

Not that I would know. I haven't cut a single brick yet...but the geometry is pretty easy to conceptualize.

One thing I am considering, only for my entry arch mind you, is shaving a brick down from 4.5" to 3" wide and then tapering "across" the face because a 10" blade will reach 3". For reasons of my arch design whose details aren't important here, the much easier alternative of tapering my arch bricks on the standard 2.5" axis is less feasible.

[Majic31]

Re: More efficient brick cuts

Kebwi - thank you for the info - you have understood exactly what I thought I'd be doing.... I have the same 10" HF bricksaw you mention, and was unaware it wouldn't cut 4.5"
(I thought 10" blade - must cut almost half the radius - 5" right?). I just went out to the garage and the PVC tray is only 3" deep... so there goes that idea..
Looks like I'm either cutting wedges or attempting to build an indispensible tool to get my lift angles....
Splatgirl - I understand what you're saying, and I'm giving it serious thought..thanks

[kebwi]

Re: More efficient brick cuts

You have to account for a saw blade's "axle", which would have to be of infinitely small diameter to cut as deep as the blade's radius. I believe this is sometimes referred to as the blade's "arbor". Therefore, a blade's cut-depth is always less than the radius, for the same reason that a vehicle's ground clearance is always less than the wheel's radius.

[jmhepworth]

Re: More efficient brick cuts

Don't overlook the possibility of just using the string method. Following Ken's example, I took a piece of 1/4 inch plywood about 15 inches wide and long enough to go from the front of the oven to the back, found what would be the center point in the oven and poked a hole through that. I pushed a string through the hole and tied a washer to the string. Then I laid the plywood down on the floor of the oven, making sure the string was centered and tied a knot at 21 inches (for a 42 inch oven). I put some heavy pavers on the plywood to hold it in place. Then for each course I pulled the string tight. The knot told me where the top of the front of the brick was supposed to be, and the string told me what the angle of the brick was supposed to be. I used wedges at first to keep the bricks in place but quickly figured out that the mortar was both stiff and sticky enough to hold the bricks in place without the wedges. I used Heat Stop 50, so someone who used another mortar might have a different opinion. I was surprised that I never needed to support any of the bricks. In the ebook, James says finishing the oven without a form or without support is hard. I didn't find it to be. As the bricks got closer to vertical I went down to 1/3s instead of halfs, so they didn't slide as much, and I held them in place for a bit longer (sometimes as much as a minute) until the mortar set up enough to hold them. When I build my next oven I will probably use the string method again, although I readily admit to intense jealousy over the really clean, symmetrical look that the indispensable tool gives.

For me the bigger challenge was trimming the inside edges of the bricks to avoid those tall isosceles triangles between the bricks. I used the HF wet saw to trim almost all of the bricks, nipping off the edge at an angle to make the face of the brick into more of a trapezoid. I wish I had pictures of that to share, but I was busy cutting and only took pictures after I got things done.

The most important thing I could stress is that if I could do this anyone can. I make my living on my butt, and have very little experience with masonry. But I'm willing to read and learn. There's no better place to learn than on this site, and by diving in and making mistakes.

Joe

[Majic31]

Re: More efficient brick cuts

kebwi -
No, I knew I couldn't cut the same distance as 1/2 the radius because of what you describe - but the blade is 10" and I thought I met get away cutting 4 1/2"...but it appears the tank is only 3" deep... I'll have to mock up a firebrick and try it just to see how far it will cut...

Joe -
thanks for the info.... I've been impressed with Ken's "Old Kentucky Dome" since I first started lurking here on this forum.... and will definitely consider the string method... I'm just not sure at this point which method I'll use....
I also love the look you get with bricks properly set using the indispensible tool...but I love the simplicity you've described... (I believe in the K.I.S.S. theory - keep it simple stupid)
Oh well.... it's getting too cold here to build my dome, (unless we run into a spell of warmer "Indian Summer" weather), so I guess I'll have some time to make a decision...
I'm off now to research the problem of the isosceles triangles you mention.. I've noticed it in some posts... but am not fully aware of what it is, or how to deal with it...
Thanks

Bob

[Lars]

Re: More efficient brick cuts

Bob,
We are talking about the mortar joint, on the inside face ( either side) of each brick, as you get higher up the dome, say around the 8th chain.

Your first few 'chains' are nearly flat, and the bricks your place for the next chain sit pretty snugly on the sides with one another ( practically touching). As you get higher up, the circle ( surface) for the next chain is smaller and more tilted.

As you lay bricks side by side on the smaller and more tilted ring, the bricks which have a 'perpendicular' to the bottom edge, tend to meet at the top corner to the next brick with a triangular gap for mortar. This triangular gap is more pronounced the higher up you go. It becomes most noticeable around the 8th chain and beyond .That is where people tend to want to taper the sides to avoid that.

I took a different tack and arched over the top back and forth. It was not a perfect solution by any stretch, but it still will cook a pizza.

L.

[arren]

Re: More efficient brick cuts

Hello,

Special shapes that tend to disrupt the production line can now be made without slowing the manufacturing process and still increase output of specials. The automatic brick saw will greatly increase the output of sample slabs, which is a must in the brick industry.

For small-scale brickmakers perhaps the easiest step to improve efficiency and save money is to make sure bricks are dry going to the kiln. Then it's possible, without too great an investment, to work on kiln control: following a good firing regime and controlling air flow. Increasing insulation, particularly of clamps which can be scoved with a thicker layer of mud, offers a potential saving without a big cash outlay. Substitution of wastes for part of the primary fuel, and incorporating some fine fuel into the body of bricks can be done on a small, experimental scale to minimise the cost of any failures. Keeping good records costs only a little time and effort.

A radical way to save all the energy used to fire bricks is not to fire them at all! Where fuel is very scarce or very expensive, unfired, sun-baked bricks can be used for many applications provided good architectural design protects them from rain, floods, ground and splash water. The same is true of rammed earth construction. Stabilising soil with cement, lime or bitumen is another option.

Have a nice day