Electricals

There are many approaches to making a successful annealer. Keep in mind the true scope of the project: We are annealing beads, the maximum diameter is generally no bigger than 1 inch. Though for those expressive types lets say it is 2 inches. If you are capable of making a distinction here we can save you a lot of money, because the division line is somewhere between the 1 and 2 inch size. Simply put, the smaller ones don't need great annealing, the bigger ones do. Here great annealing is the difference between a sensitive turndown and a casual one. Or put another way it is the difference between careful annealing vs casual annealing.

The original 50 mailbox annealers I built were equipped with a 650 watt element controlled with a 1000 watt dimmer switch. (I now equip the kilns with a 750 watt element and use an infinite switch. Both are fine, but as the kiln is expected to go higher/faster, it needed a little more zip. The kiln will get to 950°F in about 10 minutes.) If you are careful and fastidious you can carve a great annealing curve on the downside. Matched with an add on timer switch this is suitable for annealing even the two inch "mongoes." But this approach takes time and care.

To a great many people time is not a plentiful commodity and for these busy folks an automatic turndown seems appealing. To my way of thinking this was fine for them, but in my shop, for most of my thirty five years of annealing things I have used the old tried and true method of "careful turndowns." So for those who wanted the automatic version they had to go elsewhere. Stubborn of me.

Today, after numerous experiments in the programables I own many such devices that I use on our many experimental kilns and furnaces. I have changed my tune. I love these units. I really like the ease of setting a known turndown and leaving the work to the computer chip. For more information please read pages 86, 89, 97, and 126 (under "controlling pyrometers") in my book, A Glassblower's Companion.Please link to our programables section of our site. Today I am an avid proponent of controlling pyrometers. It's a brave new world.

Here is the element in place as seen through the end door looking up:

The element (Joppa element number #E120-06-205) is shown entering the kiln cavity in the rear through two lead tubes. The element proceeds through the kiln space in a "U" shape supported on 1/4" mulite rods that are 15" long. Each mulite rod is supported with two donuts, and those donuts are held in place by a wire that is wrapped around the groove in the middle of the donut. This support wire is pulled through the insulation using a donut needle and attached to the outside of the kiln in much the same way as the frax pigtails are attached.

Next, is the switch end of the kiln. Here is a general overview shot of the project.
On the right is a view of the wiring in the 4" box, with the cover removed. For a more detailed view of this component study figure 19-8 on page 96 of A Glassblower's Companion. Figure 19-8 is an in-depth schematic of the situation here at hand.
Here is the simple electrical diagram of the mailbox project.