Jonathan Kaplan on sun 25 apr 99
I'm just wondering if I am the only one who repairs electric kilns and has
found the following to be true.
A caveat:
This perhaps only applies to those of us using 10-14 sided "hobby" type
electric kilns in our studios and facilities. Not to be disrespectful or
discourteous using the word "hobby" even though these kilns are used by
many of us humble professionals.
We have 4 large Paragon kilns (TnF-28-3) in our plant. These are used
daily. They have performed exceedingly well over many years. We, like most
of you, pride ourselves on taking care of all our equipment: proper and
timely maintenance, trying not to overly abuse them, keeping them clean,
etc. etc.
As kilns"deteriorate" over time, components and elements wear out and need
replacing, in order to keep them in top shape and performing up to one's
expectations. I think that any one using equipment of any type understands
this and either performs repairs and maintenance in house, hires someone to
do it, or takes the kiln back to the dealer for repair, whatever and
which-ever.
So like most frugal potters, we do all our repairs and maintenance in
house. Its not rocket science. Armed with a multimeter, some basic hand
tools, comman sense, and even perhaps a working knowledge of basic
electrical concepts, almost any one can take care of any or all of the
following:
1. Replace or repair damaged bricks
2. Replace elements
3. Install connecting wires
4. Replace burned our relays
5. Replace a defective switch or controller
6. Test elements for continuity and correct resistance
7. Replace defective parts in a kiln setter
8. Install a kiln vent
9. Rewire the kiln at a new location
10. Install a circuit breaker
And I am sure there are many more, and we all have our levels of "risk and
reward" and can select from the above list those items which are in our
comfort zone.
So the question is: Do the manufacturers of electric kilns think that no
end user takes care of any repairs and maintenace? Are they the only ones
privy to such work? And if that is true, do they also find that they have
created "non user friendly" equipment that is so poorly designed from a
repair/maintenance
point of view? I don't think so. Perhaps they just cram all that stuff in
there and hope it lasts a life time and no parts need to be replaced.
Friends, to me, this is just bad design. Case in point:
Paragon kilns, and perhaps others that use controllers, have a power
transformer, a series of 3 or more relays, a controller, and an inline
fuse. On 220-240 volt models, there are of course 2 110/120 legs and a
ground. The power transformer steps a portion of one leg to 12 volts or so
to run the board and the relays. There is a fuse on the 12 volt line. The
incoming high voltage legs are wired to each relay so that when the
thermocouple/controller requires/senses a need for heat, the relays are
energized and voltage flows to the elements. A simple binary operation.
Need heat? Power on. Don't need heat? Power off. The controller takes care
of this binary operation and proportions each segment with the user
programmed instructions of rate/hour, end points, holds, etc.
After of course turning off the breaker....
In order to replace, test, or inspect the relays, power transformer and
connecting wires, the entire front panel must be removed. Its about 28
inches in length and 5 inches wide and maybe 3 inches deep. It contains the
controller, relays, power transformer, and is a protective cover for the
wiring and element connections. Real cheesy self tapping screws hold the
panel in place and usually corrode over time. When the screws are removed,
the panel flops down straining all the wiring and must be supported by
something to hold it in a workable, secure position. The connecting wires
are too short to allow proper positioning if this assembly. We have used
over these many years, stacks of bricks, 5 gallon buckets, pile of stacked
2 by 4's, and other constructions. The power transformer and the three
relays are screwed to a small interior panel that is screwed to the big one
we have just removed. These components are crammed into this small space
with virtually no room to use a hand tool. They are secured with small nuts
and bolts that cannot be tightened or loosened with a nut driver not only
because they are in such confined spaces, but their mating screws also
turn when applying pressure to their repsective nuts. No access to the
heads of the screws.
So then the entire small panel needs to be removed to gain access to these
fastening devices
to replace a relay or transformer. But.....the panel can't be removed
because the inline fuse is in the way, as well as four small securing
rivets that hold the specification plate. So by removing the fuse holder,
bending the metal of the panels, and other various contortions, one can
finally expose the kiln's innards and work on them, all at the same time
trying to keep the large long panel steady and secure, while balancing your
coffee, hunched over on your knees.
The wiring is all push on connectors, and is also so crammed in this small
space and the resulting skinned knuckles, bruised digits, provoke a string
of vile or not so vile epethets.
So that is the scenerio. We have all the necesary repair parts in stock so
that the amount of down time needed for repairs and maintenance is kept at
a minimum.
Don't the manufacturers realize that we are not idiots? Do they actually
design this basically unworkable environment consciously?
Here are some very simple, cost effective, and user friendly changes that
would make me a happy camper: ( and perhaps even others)
1. Put one side of the larger panel/cover plate on a piano type hinge. Use
stainless steel self tapping
screws to secure the other side, or a simple latch configuration to
hold that side in place.
2. Provide longer connecting wires so that this panel can be opened and
secured for ease of work.
3. Place the relays and other necessary components in a logical workable
arrangement that doesn't
require a contortionist to work on them. Make them replaceable without
needing to disconnect and/or
disassemble the entire inner workings just to remove/replace one part.
4. Label the zones that the relays control. While this is a pretty easy one
to figure out, it would be
an asset for those who are electrically challenged (or should not work
on kilns?!)
5. Use standard wiring connecting blocks with screw terminals to avoid
using huge wire nuts to connect
the incoming larger gage wiring to that of the kiln wiring.
6. Our newer kiln has a separate connection box to take the incoming line
wires and secures them to
the kiln wiring. But this block is in such closecontact to the kiln
wall and radiant heat.When I inspected
it, the plastic had corroded from this heat exposure and needs to be
replaced.
Thats all for the electrical things.
Ever notice how cheesy and cheap the kiln stands are? That they only
support the entire weight of the kiln on the bottom slab, and mostly on the
center of the bottom slab? And ever notice that your floor slab will
usually crack after one firing?
Why don't they make a stronger stand that supports the weight of the kiln
under the kiln walls and not in the center of the floor? What we have done
to eleviate this design flaw is to have a 1/4" steel plate cut to the
exterior diameter of the kiln, with a center hole for the venting. The kiln
sits on this and the entire assembly then rests on the stand (as cheesy as
it may be).
I also think itis bad design to dismantle the entire kiln to gain easy
access to replace the bottom elements on larger kilns. On our kilns, you
1. remove the lid. 2. remove the front panel 3. remove a metal connecting
plate in the rear. 4 and finally, remove the top ring of the kiln after or
course, disconnecting the elements from their connecting wires in the
panel. Is this logical?
After all of this, we have repaired our kilns this week, replaced the
necessary parts, and we are back on line.
Last January I ordered a large front loading, heavy duty industrial
electric kiln with a three zone controller, element in the floor and door,
fiber roof modules, heavy duty Hoskin elements, and mercury displacement
relays. This kiln will replace 2 of our small Paragons. It also was
manufactured to take the same size rectangular shelves as our gas kiln. Its
interior volume is 26 cubic feet. Next year, we hope to purchase a second
one. Its big. Almost triple the amperage. I am sure it will provide quality
firings.
Am I the only one who has noticed how poorly designed these "hobby" kilns
are? Any one using Skutts, L and L, and others experience similar
situations?
Jonathan
Jonathan Kaplan, president
Ceramic Design Group LTD/Production Services
PO Box 775112
Steamboat Springs CO 80477
plant location
1280 13th Street Unit 13
Steamboat Springs CO 80487
(970) 879-9139 voice and fax
jonathan@csn.net
http://www.sni.net/ceramicdesign/
David Woodin on mon 26 apr 99
All the things you say are correct but these so called hobby kilns were not
meant to be used every day and the solution is to buy the industrial quality
kiln. The hobby kiln is perfectly adequate for most potters and is
affordable. Universities are where you start to see the industrial type
kilns and of course potteries like yours. Euclids showed me at NCECA
pictures of their kilns used by industry which use solid state or mercury
relays and have the controllers mounted away from the heat of the kiln. To
make a long story short price is the reason the kilns are built the way they
are for potters or hobbyest.
David
Fay & Ralph Loewenthal on tue 27 apr 99
Hear, hear to that long rant. I have worked on far smaller
"Hobby" kilns where the control boxes are fixed to the wall
next to the kiln. These boxes are manufactured by an
International company, and guess what I have the same
problems. If I refurbush a kiln, the first thing I mke sure of is
that the wires in that box are long enough so that I can work
comfortably. BTW I use ceramic wire connectors, which makes sense when one is wo
This reminds me when I received my first car, a Ford Anglia.
This car had more than enough engine space to work on
comfortably. Everything was easy to get to and fix. The cars
today need mechanics with either very long fingers or very
thin hands and extremely expensive machinery to tune. I am
convinced that the manufacturers do this to make sure that we
have to make use of their authorized dealers so that they can
make that extra buck out of us.
This only supports Mel's contention, at least that is the way I
perceive (spelling?) it, that we should build our own kilns, and
get to know them well.
I hope that long rant was therapeutic for Jonathan. all the best
Ralph in PE SA.
Jim Brooks on sat 1 may 99
Jonathon.. something you didnt get into..is... Paragon..and maybe others (
but i do not know of them), do have kiln repair classes.. The class at
Paragon is two days. and in depth.. After the class, i felt that i could
rewire a 747...providing someone wanted to fire it as a kiln.. So call and
check with the kiln company close to you.....
Leona Stonebridge Arthen on mon 10 may 99
Skutt, at least, has had the foresight to put the box on piano hinges. And
their lid hinge is supported down the back of the kiln. My little Paragon
has nearly ripped apart the one brick its lid is attached to.
I still see no way to change elements other than taking the whole kiln
apart piece by piece, however.
Leona
---
Leona Stonebridge Arthen
leona@javanet.com
Worthington, Massachusetts/USA
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