Richard Gralnik on wed 29 oct 97
What do you do if the span of your arch is between the exact dimensions
in the AP Green charts. My arch is 37" wide but the book jumps from
36" (18 #1's and 1 straight 9) to 38" (18 #1's and 2 straight 9's).
I'm loose stacking so just slapping in extra mortar isn't a solution I
want to use. Would you recommend cutting a second straight 9 down to
take up the slack (it would be pretty thin)?
Thanks,
Richard
WardBurner@aol.com on thu 30 oct 97
Richard wrote:
<<<in the AP Green charts. My arch is 37" wide but the book jumps from
36" (18 #1's and 1 straight 9) to 38" (18 #1's and 2 straight 9's).
I'm loose stacking so just slapping in extra mortar isn't a solution I
want to use. Would you recommend cutting a second straight 9 down to
take up the slack (it would be pretty thin)?>>>>
To begin with, is your total rise 6"?... Just making sure your using the
right chart.
Next question; If your using 9" series bricks, how did your span get to be
37"? It should be 36" (four bricks wide). I don't know where the extra inch
came from. (That's why the chart skips like it does from 36" to 39". Maybe
your walls slowly crept out as you were going up. Your angle iron corners and
tie rods might bring everything back into line. If you do decide to cut a
thin brick, stick in the arch near the wall and not as the key brick. Feel
free to give me a call if you have any other questions.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
Tadeusz Westawic on thu 30 oct 97
Richard Gralnik wrote:
>
> ----------------------------Original message----------------------------
> What do you do if the span of your arch is between the exact dimensions
> in the AP Green charts. My arch is 37" wide but the book jumps from
> 36" (18 #1's and 1 straight 9) to 38" (18 #1's and 2 straight 9's).
> I'm loose stacking so just slapping in extra mortar isn't a solution I
> want to use. Would you recommend cutting a second straight 9 down to
> take up the slack (it would be pretty thin)?
>
> Thanks,
> Richard
Cut full-scale end profiles of arches and straights out of paper or
posterboard and start laying them out on flat surface with drawn in
endpoints. Adjust arch height if necessary. You only have to plan half
the arch. This will work for you.
If you've already ordered the brick, then I think you'll want to crush
some-up and mix with cast set (castable refractory). But I've never done
the castable thing myself and have always used other solutions.
Otherwise, better to have several rows af arch slightly shaved-down than
one row cut very thin.
Cutting brick: I used a bandsaw once and went through two blades, also
very dusty. I went to lumber co and bought a piece of expanded metal
lath. I cut it down and attached it to plywood sheet and used it like a
grater or washboard. Had a lot of brick to do so I made a box that
enclosed the brick shape I needed. Then put the too big arch brick in
box and grated it on the metal lath "washboard" grater. I knew I was
down to right size when nothing but the wood from box was rubbing the
metal lath. Make sure you attach lath to plywood with "cutting angle"
upwards so that grating occurs on your downstroke when you use it. If
you do a lot of brick this way you will go through more than one
"grater", amazing how the softbrick wears away metal in friction.
Good luck
Tadzu -- Sunny and mild at 6000 ft in SW New Mexico.
Cameron Harman on thu 30 oct 97
To Richard Gralnik,
In the first place the arch figures in the book are correct
only if you set dry (without mortar). They forgot to take
into account the thickness of mortar.
When you lay the arch you simply cut the last brick to fit.
You can duplicate this cut for the other rings. Be sure that
you reinforce the sides well since there is a *lot* of force
trying to pus the ends of the arch apart as the temperature
rises. Also be sure to use a skewback to rest the end briks
of each arch ring. If you do not have a skewback you can
make it by cutting brick to fit. If you don't know what I
mean by skewback just look in your A.P. Green book, they
will have pictures of it.
Write if you have questions.
Cameron Harman
--
**********************************************************
Cameron G. Harman, Jr. 215-245-4040 fax 215-638-1812
e-mail kilns@kilnman.com
Ceramic Services, Inc 1060 Park Ave. Bensalem, PA 19020
see our web site at http://www.kilnman.com
THE place for solutions to ALL your kiln and drier problems
**********************************************************
Marcia Selsor on thu 30 oct 97
I don't understand how your arch dimension is not divisible by 9".
Bricks are usually 9x4 1/2. The AP Green book goes by those dimensions.
Have you cut your form to the right dimensions. Is the radius what you
are suppose to have. Need more info to help.
Marcia in Montana
Rafael Molina-Rodriguez (Rafael Molina-Rodriguez) on thu 30 oct 97
Richard :
My suggestion is to modify your skewbacks. You can make one from a
straight (9"x 4 1/2" x 2 1/2") to fit the span in the AP Green book.
In fact, I just made my own skewbacks yesterday for a small sprung
arch kiln I'm completing. I used a diamond tip saw blade with a little bit of
water for lubrication and it cut right through the length of an Empire with
little problem.
I would caution against mortaring the arch or for that matter any part of
the kiln. I prefer to drystack.
This leads me to a question for the group. What are the
advantages/disadvantages of mortaring versus drystacking?
Rafael
>>> Richard Gralnik 10/29/97 06:49am >>>
----------------------------Original message----------------------------
What do you do if the span of your arch is between the exact
dimensions
in the AP Green charts. My arch is 37" wide but the book jumps from
36" (18 #1's and 1 straight 9) to 38" (18 #1's and 2 straight 9's).
I'm loose stacking so just slapping in extra mortar isn't a solution I
want to use. Would you recommend cutting a second straight 9 down to
take up the slack (it would be pretty thin)?
Thanks,
Richard
Vince Pitelka on thu 30 oct 97
At 07:49 AM 10/29/97 -0500, you wrote:
>----------------------------Original message----------------------------
>What do you do if the span of your arch is between the exact dimensions
>in the AP Green charts. My arch is 37" wide but the book jumps from
>36" (18 #1's and 1 straight 9) to 38" (18 #1's and 2 straight 9's).
>I'm loose stacking so just slapping in extra mortar isn't a solution I
>want to use. Would you recommend cutting a second straight 9 down to
>take up the slack (it would be pretty thin)?
>
>Thanks,
>Richard
Richard -
I cannot remember from your earlier comments on your kiln project whether
you are building an IFB kiln, but I assume you are. I have NEVER had the
arch come out perfect using the APGreen Pocket Handbook charts. With IFBs I
have always had to cut the key bricks at the top. As you no doubt know, one
always builds the arch up from both sides, slipping the key brick in last at
the top before springing the arch. It will not matter if you have to trim
the key brick down quite a bit, as long as it is still an inch thick or so.
With hardbrick arches, when the APGreen configuration does not fit, I simply
mark off a cross section of the arch on the ground, and experiment with
different configurations of arch and straight bricks until I get a perfect
fit. In our recently completed salt kiln our skews were placed absolutely
perfectly, and our arch form was very accurate, and when we went with the
APGreen configuration it was half a brick off at the top. As described
above, we did a bit of experimenting, and came up with a perfect arch with a
different configuration of bricks.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
paul m wilmoth on thu 30 oct 97
Richard,
You should be able to move the dimension of your arch out to 38
inches which will allow the bricks to be supported by the wall if for
some reason they slip. That extension is only 1/2 inch per side.
The other bit of advice is to lay your bricks on a sheet of
plywood in the order which they will be laid , with the dimensions that
you need. Use these bricks as a template to scribe your arch form onto
the plywood, this will give you a more accurate form to the bricks that
you are using (especially if the are used) and an idea of which bricks
you really need to use in the form. The APGREEN book is great, but in the
field it is just a good starting point, adjustments always need to be
made.
good luck -- Paul
Marcia Selsor on fri 31 oct 97
On the last arch I set in 1994 my class and I adjusted the fit using a
tie rod with the car valve spring on each end. Setting the form on shims
and 2x4 the arch bricks/straights combo according to the APGreen book
were placed into position. The fit became perfect and lifted off the
form when we tightened the nuts on the tie rods at each end.
The bricks did not all go into place until we adjusted the walls with
the tie rod which
loosens or compresses the angle iron on the corners.
I always use this and my arches work.
In response to Raphael, I prefer dry stack. Curt Weiser pointed out
that you can always
turn the bricks inside out on the next construction. At a low budget
institution, reuse of materials is a must.
Marcia in Montana
Richard Gralnik on mon 3 nov 97
Everyone,
I'm off to Johannesburg, South Africa for 3 weeks on business so I'm
signing off clayart temporarily. No way I'll have time to go through
+/- 1000 messages when I get back.
I spent today laying the floor of my kiln. It took the day because I
added sheet metal to the inside of my frame to protect outside face of
the 1" thick layer of K-FAC1900 board that backs up my bricks. That
addition and the way the sheet metal took up the slack in some not quite
straight angle iron in my frame left me cutting and shaping too many bricks
despite the care I took to make my inside dimensions work out the full
brick lengths.
For the people who wondered how I ended up with a 37" span, take my 36"
inside width, add 5 1/2" for each wall (4.5" brick + 1" board). Now
take a pair of 2.5" thick bricks to form the skew brick and backing brick
which gives a 5" thick skew on each side. The .5" by which the skews
are thinner than the wall+board gives a 37" span.
I will be laying out the bricks to get the curve of the span, but I will
use the 2.5" thickness of the skew brick backed by a pair of bricks layed
flat and cut to width to give me the span I need.
Off to pack. See everyone around turkey day.
Richard
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