To taper or not to taper?

[wesslock]

Re: To taper or not to taper?

Todd ,

I dont know how attach spread sheets , wont let me do a xls wants a different extension.

[david s]

Re: To taper or not to taper?

If you make yourself a bunch of wooden wedges to the appropriate angle you can use them on the outside, removing them as you go, then filling the spaces left over with mortar. However the higher you go the bigger the horizontal spaces will be so you will probably still need to do some brick cutting, but an angle grinder with a diamond blade does a pretty fair job.

[mrchipster]

Re: To taper or not to taper?

Todd,

The bottom board is a piece of 2 x 10 I only used that because it gave me more clamping space. I clamped the board directly to the sliding table you could easily use a thinner piece of wood and either bolt or screw it to your sliding table.

My saw is a commercial 14 inch that I picked up on craigslist the head is adjustable vertically similar to the ten inch Harbor freight brick saw. The major difference between my saw and the Harbor freight saw is that the clearance side on the Harbor freight saw is to the right, and clearance side on my saw is left. So your jig will need to be exactly opposite of mine if you decide to purchase the Harbor freight saw.

The angle of the brick is fixed but the slope increases as you go up on each chain, take a look at the pictures and will become clear.

Every brick on a particular chain is identical except for the keys and the smaller bricks to prevent lining up to joints vertically. but the angles and settings of the jig remain the same.

Your last question regarding the back cut; or better described as cutting the top off the brick; yes I did that; I made a jig to hold the brick vertically, and cut through the top face. I did this after cutting the sides. I never took any photos of that jig but it was just an L shaped support at I believe a 5 degree angle. That angle remained consistent until I reached the last couple of chains. Those last few chains throw out all the rules. The bricks get very narrow and are cut at very severe angles.

####BIG HINT HERE#####

Make sure you keep the top slope of the brick pointed at the center of the floor of the oven, My bricks started to point down to much at some point (think... got to steep) because I was always trying to keep a tight joint on the inside and did not pay enough attention to the slope and I got a little steep as about chain 5 or 6. Pay attention to what the ID tool is telling you about the slope and if I were to do another oven I would make the slope cut on the brick 4 degrees so I had more room or mortar on the outer part of the brick.

## end of big hint ##

I do not regret cutting the tops of my bricks, I believe my oven will outlast me by many decades.

Because you would have less reach than my 14 inch saw provides you would have to make a partial cut on the top should you decide to do that; refer to the drawing I provided in this posting. It will allow you to cut off some of the brick. and use the cut off piece to fill the void on the outside of the oven. The angles are exaggerated in this example.

Chip

[mrchipster]

Re: To taper or not to taper?

Chip,
How did you lift the outside of the brick to achieve your vertical, I assume just shims & mortar?
Tks again.

Todd B.

I made great use of a chart done by JCG31 to aid in setting up my cuts. and I used my Ipod touch and a level application to aid in positioning the table.

Chip

[mrchipster]

Re: To taper or not to taper?

I came to the same thought as chip relative to a cutting jig. see..

http://www.fornobravo.com/forum/f28/my-brick-cutting-tool-12478.html

Chip, a 14" saw would have made things easier..

Chris

Chris,

I should actually give you some credit for my jig table as I read your post before developing my table.

Thanks again for the inspiration.

Chip

[SCChris]

Re: To taper or not to taper?

Thanks Chip, no worries!..

I took the idea from a roman who found the idea in Athens, after it had come from a Phoenician who knew a mesopotamian who stole the idea from someone in the Hindus valley, who took it from.....

Leveraging ideas makes this site and our ovens better and better..

Anyway, I sure wish I'd found a 14" saw, it would have made the cutting slick.

Chris

[Amac]

Re: To taper or not to taper?

Chip

Make sure you keep the top slope of the brick pointed and the center of the floor of the oven

I take it the "and" is a typo and should be "at".
One maybe small point is that if you point the top of the brick at the floor then an IT as designed by JCG31 with a 90? angle will not grip the brick correctly. JCGs IT - which I believe is the best - is designed so that a line through the center of the brick points at the centre of the dome. To fit properly you would need to change the angle of the IT to match the angle of the brick with the top shaved off.

David S

However the higher you go the bigger the horizontal spaces will be

I'm pretty sure you have something in mind here but I didn't notice this - and it doesn't sound right - could you clarify what you mean here? Unless you are not making a hemisphere I would have thought the spaces should be the same.

[mrchipster]

Re: To taper or not to taper?

I take it the "and" is a typo and should be "at".

Sorry about that it is fixed.

One maybe small point is that if you point the top of the brick at the floor then an IT as designed by JCG31 with a 90? angle will not grip the brick correctly. JCGs IT - which I believe is the best - is designed so that a line through the center of the brick points at the centre of the dome. To fit properly you would need to change the angle of the IT to match the angle of the brick with the top shaved off.

That is a very good point and I was always fighting with my ID and that is the reason. I should have shaved off the bottoms of the bricks and that would have fixed the minor misalignment.
You are very observant. Great catch.

Chip

[Amac]

Re: To taper or not to taper?

I should have shaved off the bottoms of the bricks and that would have fixed the minor misalignment.

That will probably work fine - if the cut is substantial to be really precise the shaft should be repositioned centrally or there might be a small overhanging "lip" inside at each row. Having said all that it is hard to be so precise.

That IT if it is built accurately grips the top of an uncut brick with it's 90? angle. The top of the brick is then pointing over the dome centre - the bottom of the brick under the dome centre and the centre of the brick directly at the dome centre. So the closest point to the dome centre is the middle of the brick. The top and bottom shold be a little further - the hypoteneuse if you like -so they should be the same.

[mrchipster]

Re: To taper or not to taper?

I remember doing the math on this and for true precision both the top and bottom of the brick would need to be cut. And I also remember saying to myself ..... Close enough for government work.....

Chip

[GianniFocaccia]

Re: To taper or not to taper?

That will probably work fine - if the cut is substantial to be really precise the shaft should be repositioned centrally or there might be a small overhanging "lip" inside at each row. Having said all that it is hard to be so precise.

I ended up tapering the tops and bottoms of each brick in order to maintain a small outside mortar gap. The overhanging lip I couldn't live with so a couple of passes across the edge of the diamond blade took care of that quite easily.

I'm wondering if just using a dome template may be easier than using an IT?

[Amac]

Re: To taper or not to taper?

Chip

Close enough for government work....

Jeez Chip - I had a look at your build thread and I see you actually ground the top layers into rounded bricks - some government work that - very impressive.
Gianni

I'm wondering if just using a dome template may be easier than using an IT?

I'd say some hybrid kinda like what Dejayoh is using would be good. I found the IT good - I see Chip used two at once. I wasn't working fast enough to use two. Also I guess the fact that you had a "compressed" dome would have involved readjustments

[david s]

Re: To taper or not to taper?

Chip




David S


I'm pretty sure you have something in mind here but I didn't notice this - and it doesn't sound right - could you clarify what you mean here? Unless you are not making a hemisphere I would have thought the spaces should be the same.

Amac,
The horizontal spaces between each chain of bricks will be the same, but the spaces between adjascent bricks ( vertical spaces ) will get larger because the radius gets smaller as you get closer to the top.Therfore you have to cutmore angle off the side of each brick.

[GianniFocaccia]

Re: To taper or not to taper?

Also I guess the fact that you had a "compressed" dome would have involved readjustments

This is true. After I cut my dome template I didn't have the patience to design and build an adjustable IT so just went without. It was easy to periodically (every 4-5th brick) stand my dome template up to ensure the next brick was keeping the course in-round. After doing this for a course or two, matching each brick face angle flush against the curvature of the template went fairly quickly.

I think an IT works better if one doesn't need to be fussy about each vertical joint and wants to go fast.
John

[Amac]

Re: To taper or not to taper?

OK David - that makes more sense - I guess the word "horizontal" threw me