Super Kiln adjustments

The Super Kiln is getting some special attention after running into some issues. The concepts of this project are new so some adaptation is required. After a great first run we pushed the envelope a little to far and ended up breaking a couple blanks of glass. These set backs pointed out several key issues and hinted to others that may arise in the future. The design of the kiln is to allow for these changes with a minimal fuss.

Randall you cant hear him but he is calmly requesting his other glove while I take a couple pictures. At 1200 degrees and up the glass came loose from the chuck and out the kiln, fortunately no one was hurt and no damage was taken. Excessive heat on the one inch thick blank caused a increase in decent speed and took us both by surprise.
Heat distribution is a crucial element with all the heat rising to the top, going to far or to fast ends in disastrous results. The controller that we have is capable of running three zones although some fancy programming may be required. Unfortunately the controller is only able to accept one thermocouple so heat sensing only comes from one point. Additional thermocouples may be used to tell temperature in other areas of the kiln but wont provide the info to the controller only to us for calibration. Other methods are also being explored but a quick re wiring of the kiln and an additional mercury contactor give us three zones, The top two sets of heating coils are the same size in electrical load and the bottom set is the combined load. The new enclosures are far simpler and mounted closer to the coil attachment. They will double as an attachment point for a arch shield to protect users and wiring.

Wobbling on a high note has been all but eliminated by two things, one a reduced speed motor going from 64 RPM to 9 RPM and still using only half the speed and two the reinforcing bearings at the top of the kiln. The bearings that were added worked at high speed but torque and poor speed control were still issues at high speed.

The info that we collected led us to many improvements it is nice that the first one worked out but learning from failure is perhaps more productive than getting a bunch of four foot ......tube socks.

First glass dropped in the Super Kiln

The first test piece of glass has been dropped in the kiln. The results are impressive with all things working as they should. The temperature, fall control, air pressure and chucking mechanism worked perfectly with only minor adjustments required for the next test tomorrow!

With the thermocouple reading around twelve hundred degrees Fahrenheit the temperature is just about right at the top of the kiln to start the glass moving. Temperature control will need to be further studied and regulated but works just fine for now. In the image below you can just make out the glass bubble coming down I didn't want to get to close its hot in there.

The chucking mechanism worked well holding the glass securely and allowing easy removal. The first one does not look to appealing but it was only a test and the fact that it even survived after the extremes we put to it is a testament in of itself. The next test scheduled for tomorrow will turn out better.

The vessel itself is about eighteen inches in diameter and almost four feet tall. Uneven heating do to the doors and lack of rotation caused some undesirable affects but should be easily fixed, Definitely a successful first run!

The wobble in the rotating chuck proved to not be tolerable even with the additional down force of the glass, this led me to develop and build a simple solution to hold us until the Iris s built. The kilns heating elements only line two thirds of the inside circumference of the kiln creating a hot and cold side, even a slow rotation will prevent problems but slow is a relative term and at even five RPM a big piece of molten glass is scary. The new clamping bearing system works around the existing setup and should hold the chuck drive pipe securely, allowing consistent rotation and maybe some playing with the glass!

I also built a set of big tongs so Randall could try to squeeze the glass since when we tried before we found even molten glass is really hard. The iris is the real solution to this shaping stuff but is also more complicated than everything combined to this point so it may take a while. While I build it maybe this will keep Randall entertained. Holes drilled in the working end of the tongs provides attachment points for different substances to work the glass.

This is an ongoing project melding design and development, ultimately this prototype will provide the knowledge necessary for a big kiln. Yea I said BIG and fancy, we are talking about an entire setup and process to support making massive elaborate vessels. Fun stuff.