[Clayart] controllers/safety

wschran at twc.com wschran at twc.com
Thu Oct 25 09:47:58 EDT 2018

You know that I have used L&L kilns since I bought my first kiln.
Their kilns have had a barrier of ceramic fiber between kiln and controller since they introduced the programmable controller on their kilns.
But even with this insulation it's very important that every kiln with a controller be in an environment with adequate cross ventilation.
There must be a way to bring in fresh air and remove heated air around the kiln.
It is also very important not to position a kiln in a corner of a room - that area traps heat!
You are correct, these controllers do have a operational temperature range that are listed in the instruction manual.
Low temperatures are not as much a problem as high temperatures are to the ability of the controller to function properly.
During warmer weather, garage door and windows open I need to use a small portable fan blowing across the controller box the keep the temperature down.
With the Bartlett controller one can enter a sequence of keys to read the controller board temperature. I would think the Orton controller also has this function.
I have not had my board read higher than 105F.

I completely agree that one must never leave a kiln unattended during a firing.
I have had failures with Kilnsitters and with stuck relays on programmable kilns.
I check firings about every hour and log each firing.

I also use witness cones in EVERY firing, even if I don't view them during the firing.
I don't use the pre-programmed firing schedules, like slow and fast firings, nor do I use "cone" firing schedules.
I enter my own firing schedule and each glaze firing schedule heats up at 500F per hour to 2000F, then slow down to make the magic happen.
I also had upgraded elements and thermocouples in my current kiln as I use schedules that stress the kiln (crystalline glazes) and require accurate temperature readings.
The type "K" thermocouple that is supplied with most all programmable kilns is inaccurate above 2000F.
They also wear rather fast making accuracy even worse.
I have type "S" thermocouples, very accurate and may outlast me.
I also upgraded elements to APM's instead of the usually Kanthal A-1.
The A-1 type element wears down, changing its resistance over time, causing programmed firings to take longer and changing glaze results.
APM elements don't wear down the same, but will simply fail at some point.
I have over 250 firings on my kiln with no change in length of firing schedules.

Yes, the newer Bartlett controller used on Skutt and L&L kilns and others does have a touch screen with more functions.
But as you wrote, still a small computer that must be kept within certain temperature parameters.

During a crystalline glaze conference back in 2005 held in Kansas City the owner of Bartlett controllers gave a presentation.
He noted that the Gemini space capsule was the first to have onboard computer controls.
Mercury space capsules were  sent radio signals from computers on the ground.
He commented that the computer that were being installed in kilns in 2005 had more processing power than the Gemini space capsules!


William Schran
wschran at twc.com

---- mel jacobson <melpots at mail.com> wrote: 
> i had a great deal of mal/function with my controller on my
> small kiln.  i finally ordered a kiln sitter with switch/relay.
> i spent more time messing with the orton controller than i did
> making pots.  and, you learn new swear words.
> i was also of the opinion that a controller screwed to a kiln was a 
> bad system.  it got very hot.
> arnold has been testing controllers now that have kaowool blanket between
> the kiln and controller...he is getting temps of 125F from 170F without the 
> insulation.
> in my mind, it is still too hot.
> my stand off controller works fine. i bet it never gets above room temp. it is
> two feet from the kiln.
> what was one of the first things we learned with our first computers in
> 1990???  keep them cool.  and gamers ran a/c through the machine.
> now we have 170 on the controller???/what the hell is that?  and then
> think of the heat on relay systems and transformer?  
> and, the big one for me was the controller would not let me fire at the
> speed i wanted....why is it set for slow fire?  i don't slow fire.
> i am firing to cone 7 in the kiln in under four hours.  and, i do not
> like machines telling me what to do...gd it.
> skutt now has a touch screen...big whup.  what is the temp of the controller?
> and, my last line is....controlled kilns have to be watched...they can malfunction
> just like any kiln.  don't control kilns from fifty miles away.  be home, be near and
> monitor your firings....try explaining to an insurance investigator that you monitored
> your burned up kiln from your cell phone from a movie.....good luck.
> mel
>  website: www.melpots.com

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