WarmGlass.com

Here are a couple of pix of my bell kiln. Unfortunately they are not taken at an optimum angle. My studio does not have a great deal of stand back space.



Instead of rolling my floor as many people have done, I roll my bell. You can't see by the pictures, but the bell is stabilized using 4 chains. 2 are longer, so when the bell is lowered on the chains, it swings over and contacts the A-frame gantry and becomes stabile. I can then roll the whole rig by myself back and forth. I have enough room to walk around the floor 360º

The design features that I like are that my A frame gantry is simpler to build than Nelson's structure, and I don't have to roll my floor with glass set up on it. Another feature is that I have a leveling system that allows me to adjust the height of the kiln floor from many central and perimeter points. This could not be done if the floor moved.

I have a bundle of welding cables that go from the Bell over to my switches that are mounted on the wall nearby. I got these cable holders from the electric supply that clamp on to the cables so that they don't effect the hot connections when the kiln is being moved. My rig is now 13 years old and working very well.

An alternative that I see as being acceptable would be simply lifting the bell up and down in a setting with a high enough ceiling. There needs to be a way to positively support the bell when lifted as one would not like it to fall on your head. If that support system is attached to floor and ceiling, you could avoid needing all of the cross pieces that Nelson has used.

A lively discussion on kiln design would be welcomed by me. I am working on putting together a publication with drawings and pictures. I can viusualize the same essential design working on any size from tiny to gigantic with reasonable engineering modifications.

Bert Weiss wrote:A lively discussion on kiln design would be welcomed by me. I am working on putting together a publication with drawings and pictures. I can viusualize the same essential design working on any size from tiny to gigantic with reasonable engineering modifications.

Great suggestion Bert. If I can fight the customers off long enough I'd like to learn more about insulation properties of various materials and how to do the calculation for element power:kiln volume ratio.

I told Dudley Giberson at Joppa Glass works (http://www.joppaglass.com/index.html) the size of kiln I was building and he told me what elements I needed.

In the meantime it would be interesting to read about the successes of anyone who's built their own. Here's mine; http://www.artemisglass.co.uk/studio5/s ... ninfo.html

Controllers would be another good discussion.

Paul Stevenson wrote:

Bert Weiss wrote:A lively discussion on kiln design would be welcomed by me. I am working on putting together a publication with drawings and pictures. I can viusualize the same essential design working on any size from tiny to gigantic with reasonable engineering modifications.

Great suggestion Bert. If I can fight the customers off long enough I'd like to learn more about insulation properties of various materials and how to do the calculation for element power:kiln volume ratio.

I told Dudley Giberson at Joppa Glass works (http://www.joppaglass.com/index.html) the size of kiln I was building and he told me what elements I needed.

In the meantime it would be interesting to read about the successes of anyone who's built their own. Here's mine; http://www.artemisglass.co.uk/studio5/s ... ninfo.html

Controllers would be another good discussion.

Paul

One of my motivations for writing a book is that Dudley's book has bad information in it as far as I can tell. I believe he underpowers his kiln design.

I am using close to 900 watts per cubic foot. I think that 800 will work and 700 works but is probably under powered enough to cause devit. Since I only have 2 kilns, I'm not rock sure about those numbers. I'd like to hear about other people's experiences. What I do know is that if one of my 3 zones goes out, I will not make 1500ºF.

I don't really know if the critical calculation is watts per cubic foot or square foot. My big bell is 14.5" deep. I am not sure how much it costs to heat that extra 2.5" of air space. It definitely costs more to heat bricks than fiber. I like to cover my brick floor with as much fiber as I have. Right now I think I have about 1.5". I add and subtract layers from time to time.

My refractory supplier has a computer program that gives him hot face /cold face temperatures with different insulation profiles. He tells me that mineral wool, like monoblock, is a cheaper and more efficient backup insulator than Duraback blanket. I have used both materials in my 2 kilns. I am recommending going with the Monoblock as backup to 1" HD board. 2" in the walls and 4" in the roof.

I understand what you mean about underpower resulting in devit because it takes longer to get to fuse temp and more energy to hold it there, hence more time in the devit range.

The floor space of the kiln I built is (in your money) 20" square (1.66 sq. ft.) and 8" deep. Total floor area =2.8 sq. ft.

The element rating is 3520 watts, so that works out at 1257 watts per sq. ft.

At commercial (not residential) rate of electricity, it costs less than US$1.60 to slow fuse two thicknesses of BE and soak for ten minutes. So just over 57 cents per sq. ft.

An idea for securing the bell overhead. If it's winched up, add 2 more chains (one on each side) with hooks on the ends. Then adjust them so the hooks connect under the bell. That will stop the bell from falling if the winch fails. You might want to pad the chain, or use straps instead. But a good idea for safety.

Greg

watershed wrote:An idea for securing the bell overhead. If it's winched up, add 2 more chains (one on each side) with hooks on the ends. Then adjust them so the hooks connect under the bell. That will stop the bell from falling if the winch fails. You might want to pad the chain, or use straps instead. But a good idea for safety.

Greg

Greg

I see the chains and a pinning system. There can be vertical posts and a way to pin the weight in place, relieving the cable.

Does anybody have experience with the $150 - $300 110 volt winches? I have used a worm gear winch powered by a 1/2" drill. After 12 years, my winch failed and I tried fixing it but that didn't work. Currently I'm using a come along which works but is tedious.

Bert Weiss wrote:Does anybody have experience with the $150 - $300 110 volt winches? I have used a worm gear winch powered by a 1/2" drill. After 12 years, my winch failed and I tried fixing it but that didn't work. Currently I'm using a come along which works but is tedious.

try harbor freight. they have a bunch, some with brakes. use a couple of pulleys and you don't need a very large one

charlie wrote:

Bert Weiss wrote:Does anybody have experience with the $150 - $300 110 volt winches? I have used a worm gear winch powered by a 1/2" drill. After 12 years, my winch failed and I tried fixing it but that didn't work. Currently I'm using a come along which works but is tedious.

try harbor freight. they have a bunch, some with brakes. use a couple of pulleys and you don't need a very large one

I know Harbor Freight sells them, I tend to do business with Northern Hydraulics/Tool. They both are selling Chinese crap, which scares me. I also know that the good stuff costs $1000. Before I waste my money on the Chinese crap, I'd at least like to know that somebody else uses one and it has worked for a while.

Bert,

The worm gear winch has worked well for you for a long time, why wouldn't you just replace the broken one with one from Fulton or Dutton for the $70 or $80 it would take to buy new from Grainger or McMaster (respectively)?

http://www.grainger.com/Grainger/wwg/vi ... tPage=2153

http://www.mcmaster.com/ pg 1239

Tony

Bert, It's great that you are encouraging a think tank on this big kiln topic. I'm a heavy earth moving&diesel fitter by trade which is where I get my penchant for making things well. Basically it comes down to what you have access to and how patient you are. I'll hold back at first on all of the concepts, as I tend to think outside of the square & would baffle myself if someone was to repeat it to me. - haydo
(see, I read it & I'm baffled again)

Haydo wrote:Bert, It's great that you are encouraging a think tank on this big kiln topic. I'm a heavy earth moving&diesel fitter by trade which is where I get my penchant for making things well. Basically it comes down to what you have access to and how patient you are. I'll hold back at first on all of the concepts, as I tend to think outside of the square & would baffle myself if someone was to repeat it to me. - haydo
(see, I read it & I'm baffled again)

Haydo

I've gotten my best advice from people in the trades who never saw a big kiln. Now, if those of us who actually use them can put our experiences together, I think we can all learn something.

Dear Bert,

Great design. I like the bell moving instead of the table.

look at this link:
same concept as yours

http://www.wilbartec.com.au/manufacturing/

My kiln is 12" x 88" x 54" inside dimension
three phase 28.5 KW 220V
6" of fiber blanket on top, 4" of fiber blanket on sides. Fire brick table.

elements suspended on ceramic rod. rod is attached to the kiln frame with stainless rod and stainless ring.

I moved to a new warehouse. My previous location has underpowered electricity. I did not know it until I moved to my new location. After moving, my Big Kiln is operating beautifully. More juice here!


Nelson

Nelson Tan wrote:Dear Bert,

Great design. I like the bell moving instead of the table.

look at this link:
same concept as yours

http://www.wilbartec.com.au/manufacturing/

My kiln is 12" x 88" x 54" inside dimension
three phase 28.5 KW 220V
6" of fiber blanket on top, 4" of fiber blanket on sides. Fire brick table.

elements suspended on ceramic rod. rod is attached to the kiln frame with stainless rod and stainless ring.

I moved to a new warehouse. My previous location has underpowered electricity. I did not know it until I moved to my new location. After moving, my Big Kiln is operating beautifully. More juice here!


Nelson

Nelson

Your power is just a hair under mine at 863.63 watts per cubic foot. Looks good to me.

I checked out the link and oddly enough one of their rigs is in Massachusetts at a facility where I have worked. It wasn't there then though.

Bert:
Do you really need 700-800 watts per cubic ft. I'm planning on building a larger kiln after we move, and could use some advice from wiser ones than me.
We like to mix Spectum Baroque,Whispy,Cathedrals (smooth) with SYS96, so I have to pay attention to Devit.

PS: I'm open for a Controller topic. I've built quite a few, mostly Bartlett, Orton, Watlow, some Ogden, one Digitry.
Rich Edelman
(ex-production foreman Crucible Kilns)

KILN-TEC wrote:Bert:
Do you really need 700-800 watts per cubic ft. I'm planning on building a larger kiln after we move, and could use some advice from wiser ones than me.
We like to mix Spectum Baroque,Whispy,Cathedrals (smooth) with SYS96, so I have to pay attention to Devit.

PS: I'm open for a Controller topic. I've built quite a few, mostly Bartlett, Orton, Watlow, some Ogden, one Digitry.
Rich Edelman
(ex-production foreman Crucible Kilns)

Rich

My kiln uses 900 or more watts per cubic foot. Preventing devit can be done by spending less time ramping from 1000 to fuse temp. Underpowered and firebrick kilns are slow and promote devit.

My controller experience is different than probably anybody else on this board. I use Barber Coleman which is now Eurotherm. They make the best and most expensive controllers out there. My late father sold them and among his clients were PPG. They would outfit whole factories with these instruments. I have always had industrial strength control with SCR's and good controllers. Although I started out with set point controllers and an analog ramp generator that was a monster. My next rig will be computer interfaced.

I want to hear from people using the Bartlett computer interface program. Is it a good setup?

Bert:
When determining how much wattage for a kiln, do you look at the amount of mass/volume your fusing?
Eurotherm is an excellent line, I used them from the mid 80's untill early 90's while building controls for marine refrigeration (fishing boats). Eurotherm, Red Lion, Watlow, all pretty much standard industrial lines, a little to pricey for most. Although I see a lot of 981/982 Watlow's on annealing kilns.
Bartlett- my favorite. I actually have the computer software (courtesy Dave Bartlett) and find it easy to use. Mostly, I like to log firings as it shows me when something is going wrong. Check out Bartlett's "other" circuit board the RTC-1000, edit on the fly,edit your ramp, temp., or soak in the segment that's current while your firing. Also has an "add time" key(in 5 minute increments).
Rich Edelman

KILN-TEC wrote:Bert:
When determining how much wattage for a kiln, do you look at the amount of mass/volume your fusing?
Eurotherm is an excellent line, I used them from the mid 80's untill early 90's while building controls for marine refrigeration (fishing boats). Eurotherm, Red Lion, Watlow, all pretty much standard industrial lines, a little to pricey for most. Although I see a lot of 981/982 Watlow's on annealing kilns.
Bartlett- my favorite. I actually have the computer software (courtesy Dave Bartlett) and find it easy to use. Mostly, I like to log firings as it shows me when something is going wrong. Check out Bartlett's "other" circuit board the RTC-1000, edit on the fly,edit your ramp, temp., or soak in the segment that's current while your firing. Also has an "add time" key(in 5 minute increments).
Rich Edelman

Rich

I'm really glad to hear another voice of experience here.

Can the Bartletts be set up to output a 4 - 20 milliamp signal for SCR's? Can they be ganged somehow to run multiple zones on the same program? Most importantly, do they continue after a power outage, and have a stop the clock when not at setpoint feature?

Bert:
No, the Bartlett boards are an unregulated 12vdc, so you cannot use them on SCR's. However, Both the V6-CF & RTC-1000 are one, two, or three zones, easily programmed in the field. This lets us run 1/3 or 2/3 of a large kiln when only partially filled. Check Turner Iron & Glass, take the link off my webpage http://www.kilntec.com. Bart Turner has a 5'x10' Bell Style kiln, I built the custom 3phase, 3zone Bartlett back when I was still with Seattle Pottery Supply (Crucible Kilns). You can partition the kiln and run part of it to save electricity.
Power Outage- If the temp. drops more than 250 degrees the controller will shut down. At close to final temp. a drop of 100 degrees will shut it down. For more info feel free to call Dave or Rob Bartlett toll free at 1-888-404-9026 (Iowa), tell them Kiln-tec sent you.
Rich Edelman

Computer Interfaced controller would be a nice topic.

Multiple kilns that can be controlled from our PC. Ramp down, ramp up, even the opening/ventillating and closing of the kiln would be nice. Graphical representation of our actual firing cycle would be a tremendous help for future reference or corrections.

Somebody posted a computer program that uses the 1980's PC to control kilns. That is very ingenius. I think old PC's are very powerful for our kiln control need only. Much inexpensive than a purpose built controller. Problem is how do we make the two communicate.

KILN-TEC wrote:Bert:
When determining how much wattage for a kiln, do you look at the amount of mass/volume your fusing?

Rich Edelman

Rich

The mass that you are heating certainly does effect the speed at which you can heat up. This is why fiber kilns are easier and less expensive to heat than brick kilns.

For simple calculation purposes, I don't take mass in to account. The watts per cubic feet calculation seems to work. One thing I wonder about is the difference between watts per square feet and cubic feet when air and some insulation are the only differences. I don't know the answer to this.