Bill Kielb

It’s been several months since this project was complete. You might want to Direct message the ras pi guys above or search the board with the oven control program.

I use the automatic for most normal firing as I believe the default speeds are fine and special programmability for custom firings when there is a real reason to go a different speed. I must say I never use the fast schedules as they are a bit on the edge for even firings and the mix of wares that might exist in many kilns. Cone 5 with a fifteen minute hold is not really all that custom but I will use the combination when temperature sensitive glazes are present. I also never really use the fast schedules, too fast for me and tend to be uneven unless in the test kiln for which many of my glazes are just fine fast fired but it’s such a small kiln it fires even at high speed. I never really fast bisque as well, with the variety of clays, it’s just not worth being unsure everything is burned out. I will say a -40 degree offset seems very high to me though. It makes me wonder how much is due to the fast speed.

Yes it is ought to be just fine. Wax burns off at around 800 degree f so in the range of let’s say 450 degrees to maybe 850 degrees folks often smell the wax. Use a lot of wax, lots of smell. You should not see any signs of carbon as it will burn away in the rest of the firing. Any kiln vent will help this but downdraft vents are often not capable of removing the smell completely …… and they are not really designed to get all the wax smell. So a downdraft will help but not likely to capture all of the wax smell. The smell will however disappear above 800 degrees. As far as refiring, a simple general way to think of this would be: for a glaze firing, if you have not fired within 300-400 degrees of you finish temperature then you have not done much real heatwork. Silica and alumina don’t melt less than 3000 degrees so they need flux and enough kiln energy to help them melt earlier. Until your kiln reaches this melting temperature (often called a eutectic) not much is done in the way of useful work on the glaze. So refiring is generally just fine for most. Technically (Per the Orton cone chart) most of the relevant heatwork to maturity is done in the last 200 - 250 degrees of the firing. For bisque firing, generally it’s not a concern, just rebisque to your proper cone. Generally It’s ok to bisque more than once and often done when multiple layers of decoration are desired.

If I could give you multiple likes I would! Thanks for sharing. This has affected many folks over the years.

Might help finding off : You really ought to feel the off detent where the low point of the cam is. Even if the on/off contacts are stuck together so it stays on 100%. The low spot on the cam should be the only place it’s intended to turn off and you ought to be able to feel this flat spot. Common infinite switch shaft shape is an H shaft I believe to try and avoid this very issue.

Might line up some way, either perpendicular or parallel. Definitely not arbitrary. Neil makes a good point, if the pilot light is not connected to the switch, it will only indicate what is powering it. The inside of this switch typically looks like below which provides a spot to turn off the power. Most devices that use these have a need to be able to go full off. Might be just so worn though that it won’t anymore.

May be just be a bit too worn, most infinite switches have an off location and detent where the switch wants to stop, your pilot light ought to extinguish as it passes through the off location if set up to indicate from the pilot output of the switch.

Makes sense. When your new line drawn on the switch is at 12:00 is the kiln off? If so, then it appears you indexed it correctly with your line.

I am starting to think Dal-tile as part of a business move to eliminate outside sales also did this to increase their near term demand

All else fails, McMaster likely carries them. Gotta spend some time measuring though.

@Dikka Rian The electrical information tag should be stamped with a maximum firing temperature. For longevity reasons folks firing to cone 6 generally make sure their kiln goes to cone 10 ( 2345f) if your kiln is marked cone 8 (2280 f) then it will fire to cone 6 but the wear on the elements will shorten their life. Take a look at the equipment tag and tell us the info on it or post a clear picture of it.

As far as operation, It’s really not necessarily supposed to have stopping points. It is supposed to be an infinite switch which usually have two stopping points, off and fully on. My suggestion - It really is supposed to operate like a volume control, so maybe that is the confusion. At this point find the off position if it still exists and is not totally worn out and index this spot on top as off. From there use it as if the knob was numbered zero to ten, turning it anti clockwise. Picture the numbering on the stove knob above. Forget about trying to land on some specific spots, it’s just a volume control that goes from low to high while turning it anti clockwise. Check out Duncan’s own instructions below

If you stuck this knob on there would it make more sense with respect to turning from low to high over time? This control should work exactly like an electric stove switch so maybe two hours at setting 2 - 2 hours at setting 4 - two hours at setting six and finally full power to the end of firing. When these are on a stove the knob is marked and the index is on the stove. On this kiln they labeled the kiln instead of the knob which makes this less than intuitive for most. Fully clockwise should be off, fully counterclockwise should be full on or high. zThe index will be the top dot on the kiln, disregard all the other labels.

To test the theory out I would temporarily seal the plaster perimeter so no air escapes along the edge of the mold. Then before releasing my next trial tile I would take a thin blade and score the clay along the perimeter so it is no longer adhered to the side of the mold before turning on my air.

Yes, It appears much of your release air is along the perimeter which reduces the air pressure in the middle so no lifting force in the middle. You could just seal the perimeter of this mold to try and confirm. The air under the slab will migrate to the perimeter on its own anyway. Score the edgeline all around before applying air.

Hard to tell in the video but it looks like a bunch of release air along the perimeter and maybe little to none in the decorative relief lines. My thought - I think it would be preferential to release center out to overcome the roughly 14.7 PSI on the effectively evacuated interface plus any adhesive forces if you will, or at least uniformly from center out before the pressure escapes along the perimeter. For the local adhesion issue, a suitable mold release seems likely a decent easy fix.

We use Frost for its whiteness but it is finicky. Compressing was key to solving these issues but how it was compressed became critical, especially around handle joints. Here is an old bad video about compressing https://youtu.be/jVNJELUpclk. Once we started being religious about our compression the cracks disappeared. Same for joints, which often we clear glaze, so any crack shows up. Best idea, re-evaluate how things are compressed and whether they are truly denser when you are done. The bowl below is frost, the mug Is frost, just warm lighting, it reveals the type of handle joint which deserves lots of compression at attachment time when it is clear glazed. Hope that helps! Threw in a bisqued version below before spraying the clear glaze. Frost is very white.

Peroxide ends up as water so it could thin the slip. If I google oxiclean the ingredients appear to be sodium percarbonate, sodium carbonate, surfactants (detergent) .... polymer ...... water etc.... which decomposes to water and soda ash So the oxiclean could change things a bit. Probably ends up to be more about proportions.

I guess I always determine the load so I always try and choose the stacking as appropriate. Seems like I am solely responsible. I never infill a kiln with things that don’t need firing, It does serve a purpose for many though. I will maximize the space available as practical. I just see it as using more electric so I see little value in that unless attempting to simulate a condition.

http://www.ktrefractories.com/hightemp_coating.cfm https://www.ceramaterials.com/fiber-glue-rigidizers/ Suggest: Search refractory coatings rigidizer..

Wow, that’s gotta be on the Genesis control then. Good to know.

Wow, seems sort of excessively off. So I wonder if similar applies to bisque? Any chance the operating voltage is low by 10%, maybe worn breaker? Just seems a lot for a new kiln.

Yeah, measured on a two kiln setup, they end up starved. They work, just not able to move near their design air because of the high losses on the suction side. This is fine for their design, since all the production motors are externally cooled just generally not good for a fan that cools itself such as an in-line fan. If you hook up a 100 cfm in-line fan, it will not discharge 100 cfm drawing through a few 1” holes. The dual Orton setup was measured at 14 cfm total discharge on a 100 + cfm rated fan. The inlet size was 3 - 1” holes on each kiln so six 1” holes or about 4.5 square inches. A 4” diameter pipe is about 12.5 square inches so no surprise, a big restriction. In their defense, they don’t need anymore since airflow through the kiln is way less given a 1/4” diameter hole or two into the kiln. They are starved because of the inlet restriction, which is fine for their use and design. Not necessarily for a quiet in-line fan that gets cooling by the air through it though.

If you swap for an in-line fan and use the same kiln pickup, the existing mixing box is usually very undersized to let the proper amount of air through the fan. In-line fans are self cooled, you could try an in-line fan rated for dryer booster service to deal with the starved condition, but these are often rated in the 200 Cfm rangę, so nosie and overkill become your issues. This type of fan can be enclosed for noise, but it must cool itself with enough exhaust air. When we actually MEASURE the air that can make it through the commercial units its generally on the order of 1/10 th the fan rating. No surprise since the pickup area is usually a fraction of the 4” diameter it would need for full flow.. The mixing manifolds on the commercial units are generally too small and therefore do not allow much room air to enter. This is fine with an externally cooled motor, but an in-line fan needs this to cool itself. Not an issue as long as you pay attention to temperature of the units and folks often find a goof proof easy way to let more room air in. I have seen folks simply install a 4” open T fitting above the kiln and still get enough suction at the kiln connection to perform as originally designed.

@kristinanoel Just an FYI - this motor has a separate cooling fan built into it (Notice the slots on the rear of the motor) so if you cover this with a box to reduce the noise you will need to let cooling air in and out of the box and motor else this motor will very likely overheat fairly quickly.