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Lars 06-06-2009 10:12 AM

Tapering bricks with a chisel.
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I thought I would explain how I am doing my tapering, and perhaps ( if this is not posted in the right place, just move or delete)

By cutting each standard fire brick at a 11 to 13 degree angle down the center, you end up with two pieces that taper in either a clockwise or counter clockwise 'swirl', so to speak.

Since I see many images on straight cut half bricks making up a dome, I figured, with this small taper, at least the bricks might stay in place when/if the mortar were to fail. Hopefully, that won't happen, but I just don't know.

Meantime, you also do not want the mortar joints to line up, so on each chain, I 'swirl' the opposite direction!

Now, I KNOW this is not perfect like some of those cool perfectly tapered bricks, or like those cool guys who make each brick taper with a diamond saw, but the joy of making it fit together a little nicer, with no dust, no noise but the plink of a chisel, really makes the building process kind of timeless for me.

I am attaching a photo. ( perhaps...)

Well, that's all for now... Thanks for all the suggestions and interesting pictures I have seen on this forum!!

cynon767 06-06-2009 10:28 AM

Re: Tapering bricks with a chisel.
I'm very interested in seeing how this comes out... I have been working with the chisel on my garden bed project in preparation for doing this as well, and have found that it is possible (at least with standard red brick) to cut a crude compound bevel. I have not yet perfected this, but wondered if you had tried it and if so what your results were.

Lars 06-06-2009 10:29 AM

Re: Tapering bricks with a chisel.
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ps. My 16 year old daughter had gotten quite good at marking and cutting the bricks. I use a 1/2" block of pine ( 1/2" x1 1/2" x 1 1/2" ) to lift the back side of the brick piece, and I am up 7 chains with no forms and, as far as I am concerned, the inside of my oven will probably not ever get the kind of scrutiny that would demand a perfect dome shape.

Oh, and another thing. Rather than measuring, or laying out the bricks in advance, I just cut them and lay them up. To mark, I carefully cut a piece of masonite with the right (not a right angle, mind you, the correct angle) angle on it and draw a line on both sides.

My 2" chisel taps gently along the line on one side, then on the 2.5" side, aiming toward the cut face ( tilting the chisel at about 12 degrees) then along the other face ( straight down) then on the other 2.5" side. After one, maybe three times around the brick, it snaps.

Another thing. To get thinner joints, I rub the cut face against a concrete block on the base to take off and highly erose bumps. This becomes less critical as you go higher because the mortar joints will all be tapered unless you totally taper your bricks ( on all 4 joint faces)

Sorry for all this verbosity... I am a complete brick novice, so please let me know if this method may be problematic down the road.

Frances 06-07-2009 02:53 AM

Re: Tapering bricks with a chisel.
I think it sounds fascinating, thank you for explaining in detail!

In fact, if I'd read this post before building my oven I think I would have tried your method. Probably in a lot of cases you're just as fast with a chisel as if you had to get out the extension cable, angle grinder (change the blade like as not), ear plugs, protective gloves, mask, and goggles (many of which will have been put somewhere unexpected by other members of the family)....

Lars 07-13-2009 03:57 AM

Re: Tapering bricks with a chisel.
Ah, here we go...

My filter made this post lapse... Obviously it was so good that no one needed to comment on it!!!


Food With Legs 06-10-2010 08:42 AM

Re: Tapering bricks with a chisel.

This strikes me as a great idea. I'd also like to cut as many firebricks as possible by chisel. After using the angle grinder on the concrete blocks to grind the channel for the angle iron I know how noisy, uncomfortable, and wasteful it can be.

My ability to visualise things in three dimensions isn't always perfect so just to clarify which way do the cut faces go? Am I correct in assuming that they face towards the next brick in a particular course (moving clockwise in one course and counterclockwise in the next)? And therefore the face with two 5" edges always faces the outside and the face with two 4" edges always faces inwards?

Did you stick with this system for the uppermost courses or did you have to modify it?


Lars 06-10-2010 09:25 AM

Re: Tapering bricks with a chisel.
Sounds like you have the picture right. Cut edges abut the factory end of the next piece. Alternating clockwise/counterclockwise with each 'chain'. Yes...

I started bridging over the top with a triple arch ( may be some photos in my profile) and I would recommend doing the really pretty method that most everyone else does. My oven works okay, but it got kind of uneven with the 'arching over' and having to fill in four 'key' areas. I am fairly certain the heat stays in the bricks and my oven works okay, it's just that when I show people the inside when the temp gets them to 'whiten up' , it's not a cool looking.


cynon767 06-10-2010 10:28 AM

Re: Tapering bricks with a chisel.
I did the same basic thing, starting off the first couple courses with a chisel before moving on to a borrowed tile saw. It was one of those simple ones with the blade coming up through the flat table, which took two passes per brick (and still had to snap them in half at the cut line) rather than one of the nice ones so many people here seem to use. Both methods encouraged me to keep cuts to a minimum, and I continued with the single angled cut up until about the 8th ring. After that, I went to a 1/3 brick setup where I made 2 slightly angled cuts per brick.

I discussed it on my thread here.

I should mention that, as I went up, I had to adjust the angle somewhat from chain to chain; it was relatively easy to eyeball, though.

Lars 06-10-2010 10:31 AM

Re: Tapering bricks with a chisel.
It's so easy to cut bricks with a chisel, I really did not use a single power tool for the entire build. I think I only had about 2 cuts break the wrong way ( out of hundreds of cuts)

Food With Legs 06-10-2010 11:23 AM

Re: Tapering bricks with a chisel.
Thanks, Lars and Jamie. You both have the sort of great oven builds that I'm hoping to emulate.

I was planning to use an indispensable tool but noticed that neither of you used one. Any thoughts on if it would be possible to use on with the single-taper half bricks? Do the "swirls" cause the internal faces of the bricks to not face exactly squarely towards the centerpoint in the middle of the oven floor or are my spatial visualisation skills just failing me again?

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