Pictured below is the catenary arch form. For pictures on the forming of the arch shape
please take a look about half way down this page. I formed it with a chain. The dimensions of
the arch are 120 cm tall by 120 cm wide at the base by 180 cm long. The height and width
match as catenary arches usually do. The length I decided on to match the "skin" material.
The skin is 180 cm long. I can attach one piece of to the form and not have to cut it. In the
picture below I have just fastened the top and both side length support boards.
please take a look about half way down this page. I formed it with a chain. The dimensions of
the arch are 120 cm tall by 120 cm wide at the base by 180 cm long. The height and width
match as catenary arches usually do. The length I decided on to match the "skin" material.
The skin is 180 cm long. I can attach one piece of to the form and not have to cut it. In the
picture below I have just fastened the top and both side length support boards.
attached three main pieces, one on either side and one at the top and then moved the entire
form to the kiln as it is seen below. I would like to have put the whole unit together on a flatter
One of the problems with a form of this size is it is too heavy to move. I cut the side forms and
surface but it weighs in at 40-50 kilos and would have been very difficult to move. I have to
add a number of cross supports to the form below. In building what amounts to a free standing
form one thing to look out for is twisting along the long axis. I am not an engineer so I deal with
it by constantly checking measurements and making small adjustments.
form to the kiln as it is seen below. I would like to have put the whole unit together on a flatter
One of the problems with a form of this size is it is too heavy to move. I cut the side forms and
surface but it weighs in at 40-50 kilos and would have been very difficult to move. I have to
add a number of cross supports to the form below. In building what amounts to a free standing
form one thing to look out for is twisting along the long axis. I am not an engineer so I deal with
it by constantly checking measurements and making small adjustments.
Pictured below is a triangular support for lateral stability. Largely ineffective. The long board it
is attached to has a large face that abuts the plywood and that supplies far more lateral
strength than having small diagonal supports. I have two screws per side per long piece of
wood and that, through having a number of long cross boards, provides plenty of strength. If I
was using a piece of wood that had a smaller surface area abutting the plywood I think these
small wooden diagonals would have been necessary and added a lot of strength. As it is I will
disassemble the arch form after the kiln is completed and use it for other projects so building it
as cheap as possible is also a consideration.
is attached to has a large face that abuts the plywood and that supplies far more lateral
strength than having small diagonal supports. I have two screws per side per long piece of
wood and that, through having a number of long cross boards, provides plenty of strength. If I
was using a piece of wood that had a smaller surface area abutting the plywood I think these
small wooden diagonals would have been necessary and added a lot of strength. As it is I will
disassemble the arch form after the kiln is completed and use it for other projects so building it
as cheap as possible is also a consideration.
The size of the arch required I use more than one piece of plywood for width. I actually only
used one piece per side of the form. I was able to cut extra from the opposite side of the form
and attach it as pictured below. I then continued tracing the form onto the enlarged piece of
plywood and then cut it to its final shape. I transferred the cardboard shape from a hanging
chain onto a piece of cardboard. It is easier to move a light piece of cardboard around
compared to trying to secure a heavy piece of plywood to where ever I have my chain hanging.
When attaching the two boards together be careful not to put screws where you will cut.
used one piece per side of the form. I was able to cut extra from the opposite side of the form
and attach it as pictured below. I then continued tracing the form onto the enlarged piece of
plywood and then cut it to its final shape. I transferred the cardboard shape from a hanging
chain onto a piece of cardboard. It is easier to move a light piece of cardboard around
compared to trying to secure a heavy piece of plywood to where ever I have my chain hanging.
When attaching the two boards together be careful not to put screws where you will cut.
This picture shows the form with a few more long support boards in place and two triangular
pieces attached. There is a cut out in the top board on the right of the picture. It is there
because I am reusing wood from previous parts of the project. That piece is recycled from the
leveling forms stage. I have placed a piece of the "skin" on the far side at the bottom. I will,
before considering the form complete, put in four more long cross support boards to support
the skin. It is in theory possible to use fewer of these long support boards if using thicker skin
material. The problem is getting the skin material to bend properly to fit the form.
pieces attached. There is a cut out in the top board on the right of the picture. It is there
because I am reusing wood from previous parts of the project. That piece is recycled from the
leveling forms stage. I have placed a piece of the "skin" on the far side at the bottom. I will,
before considering the form complete, put in four more long cross support boards to support
the skin. It is in theory possible to use fewer of these long support boards if using thicker skin
material. The problem is getting the skin material to bend properly to fit the form.
In most forms I have seen there is a cut-out so the inside of the form can be seen. I don't have
one on this form and am thinking about cutting the plywood ends to make one or two. The
advantages are many. It is easier to get a hand hold on the form when removing it for
movement. It makes it easier to see if there is anything going wrong as you start to place the
bricks against the form. The bricks are heavy. This form will have about 350 bricks worth of
weight when I have finished placing them, just prior to removal. It is tempting to think of the
form as mainly a shape giving device but it is actually a support that has to hold a significant
amount of weight.
one on this form and am thinking about cutting the plywood ends to make one or two. The
advantages are many. It is easier to get a hand hold on the form when removing it for
movement. It makes it easier to see if there is anything going wrong as you start to place the
bricks against the form. The bricks are heavy. This form will have about 350 bricks worth of
weight when I have finished placing them, just prior to removal. It is tempting to think of the
form as mainly a shape giving device but it is actually a support that has to hold a significant
amount of weight.
There are about 375 bricks that are loaded on the form just prior to removal. One brick weighs
about 3.5 kilograms so together they weigh roughly 1275 kilograms. It is important to build a
form that will support that load. In the case of the catenary arch form the actual load is less as
some of the weight is supported by the bricks themselves but there is still significant weight on
the structure.
It is very important to space the support boards taking into account the covering material you
plan on using. You need to have one at the correct place to nail into.
about 3.5 kilograms so together they weigh roughly 1275 kilograms. It is important to build a
form that will support that load. In the case of the catenary arch form the actual load is less as
some of the weight is supported by the bricks themselves but there is still significant weight on
the structure.
It is very important to space the support boards taking into account the covering material you
plan on using. You need to have one at the correct place to nail into.
The skin is attached by any number of methods. I initially fastened it using staples from a The
nails don't have to be long, one inch is more than sufficient. The main issue to look out for in
the form is that you have your internal support structures spaced close enough to do a The
skin is attached by any number of methods. I initially fastened it using staples from a The skin
is attached by any number of methods. I initially fastened it using staples from a staple gun.
They weren't strong enough so I removed them all and re-attached it with nails. staple gun.
They weren't strong enough so I removed them all and re-attached it with nails. The nails don't
have to be long, one inch is more than sufficient. The main issue to look out for in the form is
that you have your internal support structures spaced close enough to do a proper job of
supporting. If they are spaced too far apart the skin will sag as the bricks are placed against
the form. This will cause a deformed arch structure. I have added two more support pieces
that aren't visible in these photos. I think I should have added two more.
nails don't have to be long, one inch is more than sufficient. The main issue to look out for in
the form is that you have your internal support structures spaced close enough to do a The
skin is attached by any number of methods. I initially fastened it using staples from a The skin
is attached by any number of methods. I initially fastened it using staples from a staple gun.
They weren't strong enough so I removed them all and re-attached it with nails. staple gun.
They weren't strong enough so I removed them all and re-attached it with nails. The nails don't
have to be long, one inch is more than sufficient. The main issue to look out for in the form is
that you have your internal support structures spaced close enough to do a proper job of
supporting. If they are spaced too far apart the skin will sag as the bricks are placed against
the form. This will cause a deformed arch structure. I have added two more support pieces
that aren't visible in these photos. I think I should have added two more.
This shows the skin on one side of the form. I actually took the covering back off after this
photo was taken in order to use a stronger fastening system. I also changed the way I laid out
the covering. I first attached one whole board, aligning it from the bottom as in this photo. I
then did the same on the other side, aligning it from the bottom. I then put the next board on
top of the first board, cutting it at the top of the arch. I did the same on the other so I have a
seam running along the top. When making the form make sure you space your support
boards so you have one at the proper height to nail the edge of the skin wood into.
photo was taken in order to use a stronger fastening system. I also changed the way I laid out
the covering. I first attached one whole board, aligning it from the bottom as in this photo. I
then did the same on the other side, aligning it from the bottom. I then put the next board on
top of the first board, cutting it at the top of the arch. I did the same on the other so I have a
seam running along the top. When making the form make sure you space your support
boards so you have one at the proper height to nail the edge of the skin wood into.
This shows the covering with nails in it. I kept the nails close together. I also have a chalk line
that I was going to use to help start my bricks. Instead I just started placing them. If you look at
the bottom of the photo the space between the second row of nails from the bottom and the
bottom row is about twice as wide as the other rows. Since there are going to be bricks
pressing in every 6 cm. it is important to have enough support pieces of wood underneath the
wood. I may add an extra piece after I remove the form in order to move it. I will look at the
finished arch and see if the pressure of the bricks caused a bow in the wall.
that I was going to use to help start my bricks. Instead I just started placing them. If you look at
the bottom of the photo the space between the second row of nails from the bottom and the
bottom row is about twice as wide as the other rows. Since there are going to be bricks
pressing in every 6 cm. it is important to have enough support pieces of wood underneath the
wood. I may add an extra piece after I remove the form in order to move it. I will look at the
finished arch and see if the pressure of the bricks caused a bow in the wall.
The picture below shows the method I use to set the arch. It is necessary to prop the arch up
slightly during the placement of the bricks. After the last row of bricks is placed at the top the
wooden arch form will have to be removed from the newly formed brick arch. The setting
wedges are then removed which lets the form drop down for removal. It is only necessary to
have the drop be an inch or so. In my kiln there is a stepped floor that took some extra
consideration. I had to prop the arch about 3 inches in order to have enough clearance when I
try to remove it. There isn't any way around getting the arch form out unless you disassemble
it.
slightly during the placement of the bricks. After the last row of bricks is placed at the top the
wooden arch form will have to be removed from the newly formed brick arch. The setting
wedges are then removed which lets the form drop down for removal. It is only necessary to
have the drop be an inch or so. In my kiln there is a stepped floor that took some extra
consideration. I had to prop the arch about 3 inches in order to have enough clearance when I
try to remove it. There isn't any way around getting the arch form out unless you disassemble
it.
There are many ways to set the arch. Using car jacks is an easier way in some ways. If there is
a strong base available jacks work fine. When setting and deciding on the method remember
the weight of the arch at peak load is over one ton. A board set on bare earth with a jack on
top of that might not work. It isn't necessary to lay a concrete foundation. If the arch sinks after
it is partially loaded up what is required is a complete removal of all the bricks placed up to
that point and a redoing of the process. It is much simpler to set the arch correctly at the
beginning. In a catenary arch type kiln my method will work well. If you are building a sprung
arch kiln this method or other methods will work.
a strong base available jacks work fine. When setting and deciding on the method remember
the weight of the arch at peak load is over one ton. A board set on bare earth with a jack on
top of that might not work. It isn't necessary to lay a concrete foundation. If the arch sinks after
it is partially loaded up what is required is a complete removal of all the bricks placed up to
that point and a redoing of the process. It is much simpler to set the arch correctly at the
beginning. In a catenary arch type kiln my method will work well. If you are building a sprung
arch kiln this method or other methods will work.
If jacks are used it is necessary to get four of them. I have never seen only two, one on each
side, being used although I guess it would be possible but there are risks involved. I don't
have four jacks at hand which is one reason I didn't consider that method. Another reason is if
jacks are in use it is easy to apply too much pressure to an existing arch and damage it in
some way. In my kiln I will remove and re-set the arch form 5 times, each time aligning it with
the previously built section. If I was trying to jack up the form whilst attempting to see what
clearance I have at the top my money goes on making a mistake. I also have the problem of
no clearance for the jacks at the bottom.
side, being used although I guess it would be possible but there are risks involved. I don't
have four jacks at hand which is one reason I didn't consider that method. Another reason is if
jacks are in use it is easy to apply too much pressure to an existing arch and damage it in
some way. In my kiln I will remove and re-set the arch form 5 times, each time aligning it with
the previously built section. If I was trying to jack up the form whilst attempting to see what
clearance I have at the top my money goes on making a mistake. I also have the problem of
no clearance for the jacks at the bottom.
When setting the wedge piece that does the actual height adjustment for the last couple of
millimeters it is important to take into consideration a couple of things. The wedge will have to
be removed under peak load so if you slip it in almost to where there isn't any of it visible you
will have a very difficult time removing it. Very difficult means it won't be possible with out
breaking or damaging something in the process. If you set it into position flush to a side wall or
something else that will hinder its sideways movement it will also make it more difficult to
remove. It is best to think of it as a wedge shaped lever. Leave plenty showing to facilitate
applying sideways force.
millimeters it is important to take into consideration a couple of things. The wedge will have to
be removed under peak load so if you slip it in almost to where there isn't any of it visible you
will have a very difficult time removing it. Very difficult means it won't be possible with out
breaking or damaging something in the process. If you set it into position flush to a side wall or
something else that will hinder its sideways movement it will also make it more difficult to
remove. It is best to think of it as a wedge shaped lever. Leave plenty showing to facilitate
applying sideways force.
The brick in the picture above and below has been placed sufficiently beyond the line of the of
the brick so it doesn't extend a small portion into the arch form it will be taking all the pressure
on the edge. The edge is weak on most types of materials so it is important to push the brick
into the form at least a couple of inches or centimeters. If I were to make the arch again I might
make it a little narrower. This form is exactly the width of the ramps which makes it difficult to
adjust even a little if I wanted to.
the brick so it doesn't extend a small portion into the arch form it will be taking all the pressure
on the edge. The edge is weak on most types of materials so it is important to push the brick
into the form at least a couple of inches or centimeters. If I were to make the arch again I might
make it a little narrower. This form is exactly the width of the ramps which makes it difficult to
adjust even a little if I wanted to.
call to the guy I buy bricks from. I found out the bricks I had used as a model are manufacturer
specific and not available. I had to recalculate, guess, on the fly as I talked to him. I ordered
one third regular bricks, one third Y-1 and the remaining Y-2. When they were delivered I then
did a trial stack to see if I had guessed correctly. The picture below is of the first stack. I
haven't put in spacers to represent the mortar. My main objective was to try to keep the hot
face matching the arch curve as closely as possible.
specific and not available. I had to recalculate, guess, on the fly as I talked to him. I ordered
one third regular bricks, one third Y-1 and the remaining Y-2. When they were delivered I then
did a trial stack to see if I had guessed correctly. The picture below is of the first stack. I
haven't put in spacers to represent the mortar. My main objective was to try to keep the hot
face matching the arch curve as closely as possible.
The pictures above and below show the hot face matching very closely to the arch form. Y-1
and Y-2 are self explanatory. R means a regular brick, not an arch brick. As the process
developed I kept on hearing the words I had read concerning the plans the Pentagon makes
before going into battle. The plan never survives beyond the first contact with the enemy.
After this initial stack I then went to the other side of the arch and re-did the stack on the
opposite side but using spacers to take into account mortar. The first contact with the enemy,
reality, showed I couldn't repeat the mortar-less arch beyond the first 2 bricks from the bottom.
and Y-2 are self explanatory. R means a regular brick, not an arch brick. As the process
developed I kept on hearing the words I had read concerning the plans the Pentagon makes
before going into battle. The plan never survives beyond the first contact with the enemy.
After this initial stack I then went to the other side of the arch and re-did the stack on the
opposite side but using spacers to take into account mortar. The first contact with the enemy,
reality, showed I couldn't repeat the mortar-less arch beyond the first 2 bricks from the bottom.
I first used cardboard inserts as a replacement for mortar in the designing stage. I used the
same when I was designing my climbing kiln. The difference is I designed the climbing kiln on a
flat surface as a cross section. I took bricks and laid them on the ground to mimic a cross
section of the kiln, fire box, step up to the floor of the kiln, the small step to the exit flue, and
then the wall and onto the arch. The weight of the bricks was supported by the ground, not by
the mortar replacement as it was in designing the snake kiln. After I had re-stacked the arch
below using cardboard as a spacer I noticed the space had completely disappeared after one
day.
same when I was designing my climbing kiln. The difference is I designed the climbing kiln on a
flat surface as a cross section. I took bricks and laid them on the ground to mimic a cross
section of the kiln, fire box, step up to the floor of the kiln, the small step to the exit flue, and
then the wall and onto the arch. The weight of the bricks was supported by the ground, not by
the mortar replacement as it was in designing the snake kiln. After I had re-stacked the arch
below using cardboard as a spacer I noticed the space had completely disappeared after one
day.
It might not sound like a big difference, having mortar spacers or not but in brick terms the
spacers amount to at least one brick worth of space. More importantly they represent angle
changes in the way the arch bricks lay on each other and in relation to the arch form. In the
picture below the form and bricks match up extremely well. As I write this I am in the process of
setting the bricks for the second section of the kiln. That is to say I have already completed
one whole arch section including casting stoking holes, moved the arch form and have gotten
75% through with the next section. I have found the reality on the ground in no way matches
my calculations.
spacers amount to at least one brick worth of space. More importantly they represent angle
changes in the way the arch bricks lay on each other and in relation to the arch form. In the
picture below the form and bricks match up extremely well. As I write this I am in the process of
setting the bricks for the second section of the kiln. That is to say I have already completed
one whole arch section including casting stoking holes, moved the arch form and have gotten
75% through with the next section. I have found the reality on the ground in no way matches
my calculations.
In the designing phase there are a number of ways to calculate the arch and brick usage. One
is to sit down with a pencil and paper with a mathematical formula and work it out. I have never
drawn plans for any of my projects including my large studio so don't feel that is the best way
can be detailed and often involves writing down a number of requirements such as overall
length or number of stoking holes. In deciding on the size of the arch for this kiln I did a kind of
reverse engineering in that I know which shelves I want to use as I have almost 200 of them.
is to sit down with a pencil and paper with a mathematical formula and work it out. I have never
drawn plans for any of my projects including my large studio so don't feel that is the best way
can be detailed and often involves writing down a number of requirements such as overall
length or number of stoking holes. In deciding on the size of the arch for this kiln I did a kind of
reverse engineering in that I know which shelves I want to use as I have almost 200 of them.
I then decided how large I wanted each level to be, how many stacks of ware I wanted to have
for each level and then added in the particulars for the firing style this kiln is specialized for.
Since the catenary arch is equal in proportions regarding height by width it is easy to
determine how large it has to be. The only difference I had in this kiln is I saw I needed a little
more height in order to get sufficient volume as far as the curve of the arch was concerned.
That is to say if I had stuck to a strict minimum size requirement parameter I would have ended
up with a kiln that, because of the way the arch curves, would have been a little too small.
for each level and then added in the particulars for the firing style this kiln is specialized for.
Since the catenary arch is equal in proportions regarding height by width it is easy to
determine how large it has to be. The only difference I had in this kiln is I saw I needed a little
more height in order to get sufficient volume as far as the curve of the arch was concerned.
That is to say if I had stuck to a strict minimum size requirement parameter I would have ended
up with a kiln that, because of the way the arch curves, would have been a little too small.
I added an additional 20 cm to the sides and therefore to the height to get a more efficient
use of the top of the kiln in relation to the curve of the roof. I had another restriction in that I
am putting in what amounts to a triple floor. The floor is going to take up roughly 20 cm of
space from the vertical. One of my requirements in design is that I can put in pieces that are
one meter in height. I will now have that capacity since I made the arch 120 cm. The arch as it
appears now in its partially completed stage seems too large. It is too late to change it and I
am not sure it is in fact too large until I complete it and load it a couple of times.
use of the top of the kiln in relation to the curve of the roof. I had another restriction in that I
am putting in what amounts to a triple floor. The floor is going to take up roughly 20 cm of
space from the vertical. One of my requirements in design is that I can put in pieces that are
one meter in height. I will now have that capacity since I made the arch 120 cm. The arch as it
appears now in its partially completed stage seems too large. It is too late to change it and I
am not sure it is in fact too large until I complete it and load it a couple of times.
Most of the particulars can be changed as you build the kiln. One of the items that can't be
easily changed is the placement of the castable material once it has been placed and set. In
order to change it you need to remove the unit that was cast and replace it. It is expensive and
takes a lot of time. The bricks can be moved relatively easily, they only require the scrapping
off of the mortar that can be reused. Removing bricks takes time but far less than removing
cast parts. I am keeping a set distance between the repeating features in the kiln. I have a
series of 6 stoking holes on both sides of the kiln and a cast hole for a probe in each section.
easily changed is the placement of the castable material once it has been placed and set. In
order to change it you need to remove the unit that was cast and replace it. It is expensive and
takes a lot of time. The bricks can be moved relatively easily, they only require the scrapping
off of the mortar that can be reused. Removing bricks takes time but far less than removing
cast parts. I am keeping a set distance between the repeating features in the kiln. I have a
series of 6 stoking holes on both sides of the kiln and a cast hole for a probe in each section.
I made sure the first of the stoking holes is in the right place and have used it as a control
start and stop below the arch form. It is also important to have the stoking holes in the correct
place. I have measured from the "control" stoking hole to set each of the next holes. It is
important understand what the measurement if for. If you measure from the left side of the
stoke hole make sure your measurement runs to the left side of the next stoke hole. My
openings are 100 cm. apart. So if I measure 100 cm. from the left side of one hole I have
start and stop below the arch form. It is also important to have the stoking holes in the correct
place. I have measured from the "control" stoking hole to set each of the next holes. It is
important understand what the measurement if for. If you measure from the left side of the
stoke hole make sure your measurement runs to the left side of the next stoke hole. My
openings are 100 cm. apart. So if I measure 100 cm. from the left side of one hole I have
to make sure the 100 cm. marks the left side of the adjoining opening. For the next opening in
the wall I then do two measurements. One from the "control" point and then another from the
opening that is next to the controlling opening. Even though I try to assure the openings fall in
the correct place I did place one about 10 cm. off. It happened because the hole falls right at
the arch break. That is the place where I have to join the next arch to the already completed
section. The opening fell in that area and I missed placed the opening. To avoid these kinds
of mistakes I guess an overall blueprint would help but there is still the problem with control.
the wall I then do two measurements. One from the "control" point and then another from the
opening that is next to the controlling opening. Even though I try to assure the openings fall in
the correct place I did place one about 10 cm. off. It happened because the hole falls right at
the arch break. That is the place where I have to join the next arch to the already completed
section. The opening fell in that area and I missed placed the opening. To avoid these kinds
of mistakes I guess an overall blueprint would help but there is still the problem with control.
The picture below shows how I made the arch form. It is possible to calculate out the form and
transfer it to your physical material that way. I have found doing as much work as possible in
conditions that meet those close to what I will be working in is the easiest way to get results
that require little adjustment. The chain is hung from two screws that are 120 cm. apart. It is
draped to a depth that is 120 cm. from the line between the two screws. I now have a form that
is 120 cm. tall by 120 cm wide. The form that results is an arch that will support itself. There
are many types of arches. On my noborigama I have a sprung arch.
transfer it to your physical material that way. I have found doing as much work as possible in
conditions that meet those close to what I will be working in is the easiest way to get results
that require little adjustment. The chain is hung from two screws that are 120 cm. apart. It is
draped to a depth that is 120 cm. from the line between the two screws. I now have a form that
is 120 cm. tall by 120 cm wide. The form that results is an arch that will support itself. There
are many types of arches. On my noborigama I have a sprung arch.
A sprung arch is basically a half circle that needs strong side support. The catenary arch, in
theory, needs no side support. In theory that is the case but it looks like I will need side
support after all. At any rate this type of arch should be stronger than the arch on the
noborigama. I tried two types of arch size. 100 cm. and 120 cm. I choose the 120 cm. size
mainly because there is significant loss in the way the arch curves on the 100 cm. As I stack
started to hit the sides of the kiln. A 120 cm. arch will give me far more vertical stacking room.
theory, needs no side support. In theory that is the case but it looks like I will need side
support after all. At any rate this type of arch should be stronger than the arch on the
noborigama. I tried two types of arch size. 100 cm. and 120 cm. I choose the 120 cm. size
mainly because there is significant loss in the way the arch curves on the 100 cm. As I stack
started to hit the sides of the kiln. A 120 cm. arch will give me far more vertical stacking room.
After letting the chain form an arch it is necessary to transfer the pattern to your form material.
I used plywood for the side pieces. It is the side pieces that form the shape that will ultimately
become your arch. It is difficult to suspend a piece of plywood in the air to transfer the shape
of the chain to. It is possible but there are some details to consider if planning to do so. The
shape needs to be transferred as accurately as possible. To suspend the plywood you need
to screw it into the wood the chain is hanging from. The bottom of the plywood should be
aligned to the same line as the line the chain is hanging from. If the bottom of the plywood
I used plywood for the side pieces. It is the side pieces that form the shape that will ultimately
become your arch. It is difficult to suspend a piece of plywood in the air to transfer the shape
of the chain to. It is possible but there are some details to consider if planning to do so. The
shape needs to be transferred as accurately as possible. To suspend the plywood you need
to screw it into the wood the chain is hanging from. The bottom of the plywood should be
aligned to the same line as the line the chain is hanging from. If the bottom of the plywood
is not attached at the same line as the chain line you will need to cut the portion that extends
past the chain line to make the two shapes line up. I didn't want to deal with the problems of
transferring to plywood so I transferred to cardboard instead. I had to tape a couple of
flattened boxes together to get a piece large enough to fit the whole shape on. I then stapled
that to the wood holding the chain using a staple gun. It was then easy to trace the chain line
onto the cardboard. I just put a mark through the chain link to give an outline of the chain. I
then took the cardboard down and connected the dots to get the shape.
past the chain line to make the two shapes line up. I didn't want to deal with the problems of
transferring to plywood so I transferred to cardboard instead. I had to tape a couple of
flattened boxes together to get a piece large enough to fit the whole shape on. I then stapled
that to the wood holding the chain using a staple gun. It was then easy to trace the chain line
onto the cardboard. I just put a mark through the chain link to give an outline of the chain. I
then took the cardboard down and connected the dots to get the shape.
For someone that is more concerned with accuracy it would be better to mark a half way point
in the arch. The half way point would be at the peak. Then mark quarter, eighth and sixteenth
points to make sure the curve hits the points just right. I am not that concerned with symmetry
so I just marked the chain out. I can see by my arch that I do have some areas that don't follow
a perfect symmetrical arch. I don't think that should affect the firing or loading of the kiln. It will
give the whole a more organic feel. The other item to watch out for is that both sides of the
arch form are the same size. Error can creep in when transferring the shape from cardboard.
in the arch. The half way point would be at the peak. Then mark quarter, eighth and sixteenth
points to make sure the curve hits the points just right. I am not that concerned with symmetry
so I just marked the chain out. I can see by my arch that I do have some areas that don't follow
a perfect symmetrical arch. I don't think that should affect the firing or loading of the kiln. It will
give the whole a more organic feel. The other item to watch out for is that both sides of the
arch form are the same size. Error can creep in when transferring the shape from cardboard.
After marking out the points on the cardboard I then took the cardboard, connected the dots
and then marked the outline on to a piece of plywood. My arch is larger than a standard piece
of plywood so I laid the cardboard on the plywood and then cut out a piece that fell outside of
the arch shape. I attached the cutout to the main piece of plywood to fill in the area that was
missing on the arch form. You can see the filled in area in both the pictures above and below.
I attached the extra piece by putting a piece of wood over the two pieces of plywood and using
screws to hold it on. I then marked the form onto the plywood using a marker. In a best
and then marked the outline on to a piece of plywood. My arch is larger than a standard piece
of plywood so I laid the cardboard on the plywood and then cut out a piece that fell outside of
the arch shape. I attached the cutout to the main piece of plywood to fill in the area that was
missing on the arch form. You can see the filled in area in both the pictures above and below.
I attached the extra piece by putting a piece of wood over the two pieces of plywood and using
screws to hold it on. I then marked the form onto the plywood using a marker. In a best
practices scenario it would be better to mark both end pieces of plywood with the arch form
and then cut them together to ensure they match in size. There is error that can creep in if
you mark both separately. In my arch I cut them one by one and some error crept in. It isn't
critical error. An arch is a robust form that will tolerate a lot of variance. It doesn't look perfect
but the whole theory in the arch is to have a tight structure that isn't able to widen out because
that will lead to collapse. If there is an inch or so difference in the height or width from one end
to the other in the form won't matter.
and then cut them together to ensure they match in size. There is error that can creep in if
you mark both separately. In my arch I cut them one by one and some error crept in. It isn't
critical error. An arch is a robust form that will tolerate a lot of variance. It doesn't look perfect
but the whole theory in the arch is to have a tight structure that isn't able to widen out because
that will lead to collapse. If there is an inch or so difference in the height or width from one end
to the other in the form won't matter.
I cut the form using a regular power saw. I don't have a jigsaw. I don't think it is necessary to
use one to get the precision it gives. The form will be covered by a thin skin of veneer that lets
its own irregularities creep in. It is possible to get a very good curve with a regular saw. It is
important to watch out for placement of screws if you have a piece of extra wood attached like
I do. I work out in the area around the kiln, not in a proper workshop. I did the cutting and
tracing of the form on the pavement out by the kiln area. It is a very uneven surface. Even with
these "problems" it is possible to get a very good cut. If you cut both pieces together it is best
use one to get the precision it gives. The form will be covered by a thin skin of veneer that lets
its own irregularities creep in. It is possible to get a very good curve with a regular saw. It is
important to watch out for placement of screws if you have a piece of extra wood attached like
I do. I work out in the area around the kiln, not in a proper workshop. I did the cutting and
tracing of the form on the pavement out by the kiln area. It is a very uneven surface. Even with
these "problems" it is possible to get a very good cut. If you cut both pieces together it is best
that you don't have a form that requires extra wood attached like the one I used. The that you
don't have a form that requires extra wood attached like the one I used. The attaching of the
extra wood creates an uneven work surface that isn't easily attached to another piece. The
other piece in this case would be the mirror image piece you want to cut. It would make a
situation wherein you are trying to cut two pieces of wood that have some dead air space in
between. Difficult to explain but if using a form that fits on one piece of wood without extra
attachments it is best to cut both sides at the same time. If the arch is too big for one piece
and you need an extra attachment, cut the arch form separately.
don't have a form that requires extra wood attached like the one I used. The attaching of the
extra wood creates an uneven work surface that isn't easily attached to another piece. The
other piece in this case would be the mirror image piece you want to cut. It would make a
situation wherein you are trying to cut two pieces of wood that have some dead air space in
between. Difficult to explain but if using a form that fits on one piece of wood without extra
attachments it is best to cut both sides at the same time. If the arch is too big for one piece
and you need an extra attachment, cut the arch form separately.
After getting the form cut out the next step is attaching the two sides together. This is done by
using strong wood that is the length you want your form to be. I have a form that is roughly
180 cm. long so my internal wood supports are about 178.3 cm to allow for the width of the
plywood on both sides that bring it up to 180 cm. The considerations to take into account in
the length of the form are many. Of course if the kiln only requires an arch that is 100 cm. long
your form will be that length. In my kiln I have an arch that will measure out at about 9 meters
long so I need the longest length I can get that I will be able to move. I did have
using strong wood that is the length you want your form to be. I have a form that is roughly
180 cm. long so my internal wood supports are about 178.3 cm to allow for the width of the
plywood on both sides that bring it up to 180 cm. The considerations to take into account in
the length of the form are many. Of course if the kiln only requires an arch that is 100 cm. long
your form will be that length. In my kiln I have an arch that will measure out at about 9 meters
long so I need the longest length I can get that I will be able to move. I did have
the option of forming the entire length of the kiln, making a number of forms and then doing
the whole kiln at the same time. This would require more arch form making materials. I chose
the whole kiln at the same time. This would require more arch form making materials. I chose
subtle adjustments in the height of the arch in relation to my foundation. It has some one form
that was the length of my "skin" material. This gives me more flexibility as far as drawbacks
such as a more organic form that has a number of areas that have been joined. The join
areas are the places where I finished one arch and then moved the form to start the new arch.
As my arch form isn't perfectly symmetrical I have some slight variations in the wall. Not a firing
problem
the whole kiln at the same time. This would require more arch form making materials. I chose
the whole kiln at the same time. This would require more arch form making materials. I chose
subtle adjustments in the height of the arch in relation to my foundation. It has some one form
that was the length of my "skin" material. This gives me more flexibility as far as drawbacks
such as a more organic form that has a number of areas that have been joined. The join
areas are the places where I finished one arch and then moved the form to start the new arch.
As my arch form isn't perfectly symmetrical I have some slight variations in the wall. Not a firing
problem
but for those that like a level of perfection it could be the cause of stress. I will make the form a
little longer than 180 cm, about 200 cm. next time. This will help me get around the problem of
the casting of the side stoking areas. I have a stoking area every 100 cm. on center. The
problem with a 180 cm. long form is almost invariably the stoking area falls in a join or close to
one. A longer form might help me around that problem. The drawbacks might be it is much
heavier or more difficult to move. A longer form would also require more "wasteful" use of
building materials as the skin material would have to be cut in ways that leave a lot of waste.
little longer than 180 cm, about 200 cm. next time. This will help me get around the problem of
the casting of the side stoking areas. I have a stoking area every 100 cm. on center. The
problem with a 180 cm. long form is almost invariably the stoking area falls in a join or close to
one. A longer form might help me around that problem. The drawbacks might be it is much
heavier or more difficult to move. A longer form would also require more "wasteful" use of
building materials as the skin material would have to be cut in ways that leave a lot of waste.
I have used about 10 or so cross support pieces of wood to attach the two end pieces
together. That would seem to be the minimum. The skin is thin so you can't have the
underlying support too spread out. After attaching three supports I then moved the whole form
to the kiln site from my "workspace" out on the road. It gets heavier and heavier as the
supports are added. After the supports are in place it is time to attach the skin. The skin
should be as thick as possible while still being bendable. I used a veneer that is 2 mm thick.
The next grade up isn't bendable and would have been impractical to use. I initially attached it
with
together. That would seem to be the minimum. The skin is thin so you can't have the
underlying support too spread out. After attaching three supports I then moved the whole form
to the kiln site from my "workspace" out on the road. It gets heavier and heavier as the
supports are added. After the supports are in place it is time to attach the skin. The skin
should be as thick as possible while still being bendable. I used a veneer that is 2 mm thick.
The next grade up isn't bendable and would have been impractical to use. I initially attached it
with
staples. The staples came out over night so I reattached it with nails. The nails are roughly 20
cm on center. That is more than sufficient. The stress on the form is downward so in effect the
bricks press the skin onto the form. My form, like all my construction, isn't perfectly square so
there was some trimming I had to do to make the edges fit. One final caution is to make sure
you have an underlying support board in the right place so you will be able to join your skins.
That is to say where two pieces of veneer meet there needs to be a nailing board to nail into.
Other wise you will have a very weak point if you leave the edge unsupported.
cm on center. That is more than sufficient. The stress on the form is downward so in effect the
bricks press the skin onto the form. My form, like all my construction, isn't perfectly square so
there was some trimming I had to do to make the edges fit. One final caution is to make sure
you have an underlying support board in the right place so you will be able to join your skins.
That is to say where two pieces of veneer meet there needs to be a nailing board to nail into.
Other wise you will have a very weak point if you leave the edge unsupported.
How many bricks does it take to make a 9 meter long snake kiln. I will post a final count when I
finish the kiln but to start out with I bought the load in the picture below. That pile has 600
regular bricks, 660 Y-1 bricks and 660 Y-2 bricks. Odd numbers but that is the calculation I
came up with. Now the story behind the total is far more interesting. I bought the bricks from a
guy who is well known throughout Japan for both his low prices and being cantankerous. So
surly I had promised myself I wouldn't use him after dealing with him while building my first kiln.
It is hard to turn down his price of 90 yen for used bricks compared to 360 yen for bricks from
finish the kiln but to start out with I bought the load in the picture below. That pile has 600
regular bricks, 660 Y-1 bricks and 660 Y-2 bricks. Odd numbers but that is the calculation I
came up with. Now the story behind the total is far more interesting. I bought the bricks from a
guy who is well known throughout Japan for both his low prices and being cantankerous. So
surly I had promised myself I wouldn't use him after dealing with him while building my first kiln.
It is hard to turn down his price of 90 yen for used bricks compared to 360 yen for bricks from
a guy just down the street. So.... When I bought the bricks for my first kiln I called the surly
brick guy and told him how big I was planning to build and let him do the calculations. The
result is I still have about 1,000 bricks left over from his calc. to use on this kiln. So this time I
laid it out using arch bricks I had laying around from my last arch and extrapolated it all out
and came up with a number. My wife called the brick guy with the numbers and found out the
bricks I had used to plan were specific to a manufacturer and aren't available. I had to
reconsider in the space of a few minutes and came up with the numbers above. As I proceed
brick guy and told him how big I was planning to build and let him do the calculations. The
result is I still have about 1,000 bricks left over from his calc. to use on this kiln. So this time I
laid it out using arch bricks I had laying around from my last arch and extrapolated it all out
and came up with a number. My wife called the brick guy with the numbers and found out the
bricks I had used to plan were specific to a manufacturer and aren't available. I had to
reconsider in the space of a few minutes and came up with the numbers above. As I proceed
with the building of the kiln it looks like I have really over estimated the brick count. I did leave
the mortar estimate to the brick seller and it looks like he really over estimated. He figured 25
25 kilo bags. I am now about 1/2 done with the brick laying part of the kiln and have only used
3 or 4 bags. It looks like I will be selling a lot of materials on Yahoo Japan. In the pictures the
bricks I have marked with a "R" are the regular type, the Y-2 are Y-2. Almost all of them are
new. I only was able to get 260 regular bricks used. Mr. Tsuchimoto, the brick guy, doesn't
take reservations for the used bricks he sells so if you call today and he doesn't have any you
don't get any. The price difference is small, 90 yen for used, 125 for new.
the mortar estimate to the brick seller and it looks like he really over estimated. He figured 25
25 kilo bags. I am now about 1/2 done with the brick laying part of the kiln and have only used
3 or 4 bags. It looks like I will be selling a lot of materials on Yahoo Japan. In the pictures the
bricks I have marked with a "R" are the regular type, the Y-2 are Y-2. Almost all of them are
new. I only was able to get 260 regular bricks used. Mr. Tsuchimoto, the brick guy, doesn't
take reservations for the used bricks he sells so if you call today and he doesn't have any you
don't get any. The price difference is small, 90 yen for used, 125 for new.
The bricks were delivered by the brother of the brick guy. When he pulled up he had 4 or so
pallets of bricks, plastic wrapped and ready to be unloaded in ten minutes with a fork lift. I
offered to go get the nearest one, located about 5 minutes away. See note above for family
characteristic. We unloaded the whole load by hand in about 4 hours. In building my last kiln I
used all used arch bricks gathered from my teachers kiln. I was given the bricks, all I had to do
was collapse the kiln and transport them. I found collapsing an arch on a kiln that has been
fired a number of times isn't as easy as one imagines. At certain points I had to smack the
arch with a sledge even
pallets of bricks, plastic wrapped and ready to be unloaded in ten minutes with a fork lift. I
offered to go get the nearest one, located about 5 minutes away. See note above for family
characteristic. We unloaded the whole load by hand in about 4 hours. In building my last kiln I
used all used arch bricks gathered from my teachers kiln. I was given the bricks, all I had to do
was collapse the kiln and transport them. I found collapsing an arch on a kiln that has been
fired a number of times isn't as easy as one imagines. At certain points I had to smack the
arch with a sledge even
though I had removed the keystone brick. I transported the bricks using my Toyota Corolla
station wagon. I am finding using these new arch bricks is a little easier than using used. My
experience with my last arch depended on how well I cleaned the used bricks. This time I can
just grab a brick and go, no cleaning or checking to see if it is chipped or not. Having 3
shapes to choose from, regular, Y-1 and Y-2, has been my biggest headache, mostly at the
beginning. I have only made one mistake so far in putting in the wrong type of brick and that
only required the removal of about 7 bricks.
station wagon. I am finding using these new arch bricks is a little easier than using used. My
experience with my last arch depended on how well I cleaned the used bricks. This time I can
just grab a brick and go, no cleaning or checking to see if it is chipped or not. Having 3
shapes to choose from, regular, Y-1 and Y-2, has been my biggest headache, mostly at the
beginning. I have only made one mistake so far in putting in the wrong type of brick and that
only required the removal of about 7 bricks.
The picture below and the next couple of pictures are of different supplies I ordered at the
same time. The boxes below contain, in the parlance of this area, 3-5-6 saikoro. Kiln furniture.
81 to a box, 10,450 yen per box, 3cm*5cm*6cm. During my apprenticeship I often marveled at
the amount of money my teacher had invested in his equipment. I guess I am moving towards
that kind of investment. I how have 5 or 6 boxes of these rectangular stilts. I also have piles of
cut bricks that I use for stilts. I guess cutting bricks is cheaper than buying saikoro if the cost
of the brick is the only measure of cost. If the cutting blade, time and other small expenses are
factored in they come out to about the same.
same time. The boxes below contain, in the parlance of this area, 3-5-6 saikoro. Kiln furniture.
81 to a box, 10,450 yen per box, 3cm*5cm*6cm. During my apprenticeship I often marveled at
the amount of money my teacher had invested in his equipment. I guess I am moving towards
that kind of investment. I how have 5 or 6 boxes of these rectangular stilts. I also have piles of
cut bricks that I use for stilts. I guess cutting bricks is cheaper than buying saikoro if the cost
of the brick is the only measure of cost. If the cutting blade, time and other small expenses are
factored in they come out to about the same.
A picture of some of the twenty five bags of mortar. I placed them on long wooden runners so
they wouldn't sit directly on the ground. I have found that when I use the bag on the bottom,
they are stacked two high, the paper on the side touching the wood is completely soggy and
the inner layer of plastic is exposed. I don't understand if this is from condensation from the
wood or what. These bags, from the brick guy, go for 800 yen per bag. Very cheap compared
to other places. My wife asked him why he sells so cheap. He said his prices aren't cheap but
that others prices are too high.
they wouldn't sit directly on the ground. I have found that when I use the bag on the bottom,
they are stacked two high, the paper on the side touching the wood is completely soggy and
the inner layer of plastic is exposed. I don't understand if this is from condensation from the
wood or what. These bags, from the brick guy, go for 800 yen per bag. Very cheap compared
to other places. My wife asked him why he sells so cheap. He said his prices aren't cheap but
that others prices are too high.
SK 34 mortar. It is nice to use because I can mix a large load of it and don't have to worry
about it starting to set before I use it. It will set only after firing. I am able to add water to it if it
gets too firm. I am building this kiln with a very thin application of mortar. Basically only enough
to "lubricate" the two brick surfaces. When I tap the brick into place the little amount of mortar I
have used only acts as a slippery material for the brick to slide on. I am doing this to try to
avoid having spaces in the roof where the mortar falls out under the natural wear and tear of
the kiln. In this kiln that is especially important as the whole thing is a roof.
about it starting to set before I use it. It will set only after firing. I am able to add water to it if it
gets too firm. I am building this kiln with a very thin application of mortar. Basically only enough
to "lubricate" the two brick surfaces. When I tap the brick into place the little amount of mortar I
have used only acts as a slippery material for the brick to slide on. I am doing this to try to
avoid having spaces in the roof where the mortar falls out under the natural wear and tear of
the kiln. In this kiln that is especially important as the whole thing is a roof.
These are a few of the 100 shelves I bought. They are roughly 35cm by 40cm. 800 yen per
shelf used. The guy down the street from me sells the same size for 1,600 yen per shelf. Can't
beat the brick man on prices. I choose the same shelves I use for my noborigama for the sake
of keeping things simple. It will make kiln loading that much easier even though larger shelves
would have been useful in some applications. These shelves are the size easiest to get used.
They come from tile makers. I now have about 180 of these. I think I will be short about 200 to
do a full load in this new kiln. I will probably try to do a kiln load with what I have on hand and
then order some more if I am short.
shelf used. The guy down the street from me sells the same size for 1,600 yen per shelf. Can't
beat the brick man on prices. I choose the same shelves I use for my noborigama for the sake
of keeping things simple. It will make kiln loading that much easier even though larger shelves
would have been useful in some applications. These shelves are the size easiest to get used.
They come from tile makers. I now have about 180 of these. I think I will be short about 200 to
do a full load in this new kiln. I will probably try to do a kiln load with what I have on hand and
then order some more if I am short.
The picture below shows the arch again during the planning stage. In the picture I have used
a spacer to take into account the space the mortar will take up. In some earlier pictures I had
spacers in place but they were made from cardboard and flattened down to nothing. The
spacers below are made from bamboo and won't smash. A comparison of the first stack of the
bricks and this more accurate stacking will show the number of bricks used is one or two less
in this picture. It will also show the brick type used is different. Y-2 and Y-1 are used almost
evenly in this stack. The bricks used in the actual arch are different from this mock up still.
a spacer to take into account the space the mortar will take up. In some earlier pictures I had
spacers in place but they were made from cardboard and flattened down to nothing. The
spacers below are made from bamboo and won't smash. A comparison of the first stack of the
bricks and this more accurate stacking will show the number of bricks used is one or two less
in this picture. It will also show the brick type used is different. Y-2 and Y-1 are used almost
evenly in this stack. The bricks used in the actual arch are different from this mock up still.