Marcia Selsor on fri 19 feb 10
I prefer to use threaded rod with car valve springs backed with large =3D
washers that allow the arch to expand and contract and can be tightened =3D
over time.
I used this sytem for several decades.
Marcia Selsor
On Feb 19, 2010, at 4:59 PM, Brandon Phillips wrote:
> I have a question about bracing on kilns for anyone in the group who
> thinks they are a kiln expert...
>=3D20
> I am currently teaching a kiln bldg. class and we are finishing up a
> downdraft car kiln before we move onto a salt kiln. My personal
> experience with gas kilns is limited to kilns that were held together =3D
with
> threaded rods. The reasons I assume are limited access to a welder on =
=3D
the
> kiln site and ease of adjustment(though should a properly built kiln =3D
need
> adjusting?) I've been looking at a lot of kilns lately, none of which =
=3D
use
> threaded rods, and those suckers have complete welded frames. I'm
> thinking particularly of Donovan Palmquist's kilns. So my question is
> there an advantage to one over the other? Do you prefer one to the =3D
other?
>=3D20
> I remember reading/hearing somewhere that IFB don't expand/contract as
> much as hardbrick. The car kiln we've built is mostly 2600IFB...hard
> brick in the burner ports, flu, floor, etc. It's a good size kiln and =
=3D
I'm
> leaning towards welding the frame together, I think it's a =3D
structurally
> sound idea and I think it looks cleaner(i'm a sucker for aesthetically
> pleasing kilns.)
>=3D20
> So anyways...feel free to chime in, I'd love to hear your opinion.
>=3D20
> Brandon Phillips
> www.supportyourlocalpotter.com
>=3D20
Marcia Selsor
http://www.marciaselsor.com
Vince Pitelka on fri 19 feb 10
Brandon Phillips wrote:
"I am currently teaching a kiln bldg. class and we are finishing up a
downdraft car kiln before we move onto a salt kiln. My personal experience
with gas kilns is limited to kilns that were held together with threaded
rods. The reasons I assume are limited access to a welder on the kiln site
and ease of adjustment(though should a properly built kiln need adjusting?)
I've been looking at a lot of kilns lately, none of which use threaded rods=
,
and those suckers have complete welded frames. I'm thinking particularly o=
f
Donovan Palmquist's kilns. So my question is there an advantage to one ove=
r
the other? Do you prefer one to the other?"
Brandon -
Be careful asking for advice from anyone who calls themselves an expert. I
ain't no kiln expert, but I have built a lot of kilns and have some
well-considered opinions. You are always much better off with a welded
frame, because kilns tend to shift around a lot over time, and a bolted
frame is not enough to prevent that, especially in an institutional setting
where the kiln is heavily used. As you pointed out, IFB does not need any
expansion joints. You probably already know this, but the best way to
proceed is to just build the kiln up to the level of the skews, and then
build the frame around it before laying and springing the arch. When you d=
o
that, build a temporary spreader in the door opening, stand the four
vertical angles up at the corners, and strap-clamp around the whole thing
while you weld in the cross-members.
I am curious as to what kind of car-seal you are using. The best design is
a taper fit, where the car fits in like a cork, with about 1/2" of overall
taper along its length. That way, it seals tightly when shut, but opens
easily with no scraping/rubbing.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Brandon Phillips on fri 19 feb 10
I have a question about bracing on kilns for anyone in the group who
thinks they are a kiln expert...
I am currently teaching a kiln bldg. class and we are finishing up a
downdraft car kiln before we move onto a salt kiln. My personal
experience with gas kilns is limited to kilns that were held together with
threaded rods. The reasons I assume are limited access to a welder on the
kiln site and ease of adjustment(though should a properly built kiln need
adjusting?) I've been looking at a lot of kilns lately, none of which use
threaded rods, and those suckers have complete welded frames. I'm
thinking particularly of Donovan Palmquist's kilns. So my question is
there an advantage to one over the other? Do you prefer one to the other?
I remember reading/hearing somewhere that IFB don't expand/contract as
much as hardbrick. The car kiln we've built is mostly 2600IFB...hard
brick in the burner ports, flu, floor, etc. It's a good size kiln and I'm
leaning towards welding the frame together, I think it's a structurally
sound idea and I think it looks cleaner(i'm a sucker for aesthetically
pleasing kilns.)
So anyways...feel free to chime in, I'd love to hear your opinion.
Brandon Phillips
www.supportyourlocalpotter.com
shane mickey on sat 20 feb 10
brandon.Great question. I think both ways are acceptable building practices=
=3D
and can result in asethically pleasing or not pleasing kilns.With an all if=
b=3D
kiln that is built very level and very plumb you should have very little e=
x=3D
pansion compared to a hardbrick kiln. That said i would be more accepting o=
f=3D
a welded frame on an ifb kiln vs. a hardbrick kiln. A welded frame is a so=
l=3D
id unit in theory, this theory holds water as long as someone is welding pr=
o=3D
perly. I have seen many welds on kilns pop due to the outward pressure. I h=
a=3D
ve also seen frames bend under said pressure because of too weak metal (2"a=
n=3D
gle iron or 1/8 in angle).=3DC2=3DA0I choose to use 1/2 threaded rod for th=
e fol=3D
lowing reasons; mainly the arch, I like to go around and snug all rods exce=
p=3D
t the ones that tighten down the arch. The rods that tighten the arch are s=
e=3D
t so the final arch brick or keystone has to be hammered in. I will set my =
f=3D
orm in place, lay my arch brick, pound in the last arch brick. I then tight=
e=3D
n down the arch usually about 3/4 turn to 2 turns until the arch rises off =
t=3D
he arch form a bit. This way i know the arch is sprung. I have seen alot of=
=3D
arches start to slump or fail on welded frames. I believe this is due to th=
e=3D
fact that once the frame is welded and the arch is set you are stuck with =
t=3D
hat pressure. I also don't prefer casting a keystone on sprung arch, no pre=
s=3D
sure involved there. Another reason for using rod is adjustability. I agree=
=3D
that adjusting shouldn't be needed. but if you notice a few years into the =
k=3D
ilns life that the walls are walking in or out,all you can do with a welded=
=3D
frame is bang the walls back in. With an adjustable frame you can loosen th=
e=3D
frame and take the extra pressure off, then get the walls back in shape. T=
h=3D
en the pressure should be ok, still may need adjusting after moving the wal=
l=3D
s. The last reason and isn't a good one or that important, is for movabilit=
y=3D
. Say the ifb kiln you are building suddenly needs moved in the next 3-5 ye=
a=3D
rs. Well now you have to cut that frame apart. and when you go to reassembl=
e=3D
you will have to buy some more metal. I like kiln designs to be flexible i=
n=3D
as many aspects as possible. I do have one last reason. I build my kilns f=
a=3D
st, this by no way means they suffer quality. I like to think i am building=
=3D
very structural sound kilns and the ones that are getting up in years are t=
e=3D
stament to that. That said, i like the idea of setting the irons up, thread=
i=3D
ng them together and moving on. I don't like taking half a day to a day to =
w=3D
eld up a frame on site. All my irons are designed and fabricated off site a=
t=3D
home by me so that as much of the fabrication is finished before i get the=
r=3D
e. hope these ideas sound good to you. any questions feel free to call me.s=
h=3D
ane mickeykiln design services828-467-1208http://www.shanemickeypotterslife=
.=3D
blogspot.com/
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Steve Mills on sun 21 feb 10
I'm absolutely with Vince on this. The times when I've used threaded rods o=
r
chains and tensioners, are when I've had to build a frame to be taken to th=
e
build site and assembled there with materials brought in by others,
consequently I've needed to have some flexibility available to cope with
unforeseen variations.
Steve M
On 19 February 2010 22:59, Brandon Phillips <
brandon2@supportyourlocalpotter.com> wrote:
> I have a question about bracing on kilns for anyone in the group who
> thinks they are a kiln expert...
>
> I am currently teaching a kiln bldg. class and we are finishing up a
> downdraft car kiln before we move onto a salt kiln. My personal
> experience with gas kilns is limited to kilns that were held together wit=
h
> threaded rods. The reasons I assume are limited access to a welder on th=
e
> kiln site and ease of adjustment(though should a properly built kiln need
> adjusting?) I've been looking at a lot of kilns lately, none of which us=
e
> threaded rods, and those suckers have complete welded frames. I'm
> thinking particularly of Donovan Palmquist's kilns. So my question is
> there an advantage to one over the other? Do you prefer one to the other=
?
>
> I remember reading/hearing somewhere that IFB don't expand/contract as
> much as hardbrick. The car kiln we've built is mostly 2600IFB...hard
> brick in the burner ports, flu, floor, etc. It's a good size kiln and I'=
m
> leaning towards welding the frame together, I think it's a structurally
> sound idea and I think it looks cleaner(i'm a sucker for aesthetically
> pleasing kilns.)
>
> So anyways...feel free to chime in, I'd love to hear your opinion.
>
> Brandon Phillips
> www.supportyourlocalpotter.com
>
--
Steve
Bath
UK
www.mudslinger.me.uk
Brandon Phillips on sun 21 feb 10
Thanks for the advice everyone. I think I'm going to weld the frame and
then we'll see what happens. I'm(was?) a certified welder(good backup
career by the way) so fabricating it is no issue. I think we'll tie-rod
the other kiln and see which holds up better.
Vince-I'm using a tapered floor. This is my third car kiln to build but
the first time to use the tapered floor. I was surprised at how easy it
is to incorporate. In fact way easier than anything else I've tried.
brandon phillips
www.supportyourlocalpotter.com
> I am curious as to what kind of car-seal you are using. The best design
> is
> a taper fit, where the car fits in like a cork, with about 1/2" of overal=
l
> taper along its length. That way, it seals tightly when shut, but opens
> easily with no scraping/rubbing.
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