neilestrick

I use Medex bats. They've lasted for 20 years and they're still going strong. Medex is an exterior grade MDF, absorbent but wont' degrade like masonite. I got mine from Northstar, but there are others on the market now.

Every decision the controller makes is based on information from the thermocouple. If it's not reading correctly then the firing can't progress normally. I would change it, it's cheap and easy. Typically when kilns stall out at 1850-1950 degrees it's because an element is out or a relay has died or is sticking. I know you said you replaced the relays, but did you replace the wiring in the control box? If the power wires going into and out of the relays are worn then they can cause a relay to overheat and stick or fail. I've seen brand new relays die on their first firing due to the wiring.

Hi @Art By Iggy. Welcome to the forum! Have you double checked the voltage of your electrical service? What firing schedule are you using? Have you replaced the thermocouple? What size wiring did you run, and what size breaker is it on? Are the power cord and plug in good condition? Does the plug get hot when firing?

There's a reversing switch somewhere on the motor. It's a 3 position toggle, clockwise-off-counterclockwise. Make sure the power is off when you switch it.

You can probably make it go clockwise by reversing the power wires going to the motor.

That old Amaco is a cone drive. Under the wheelhead there's a large metal cone, and a small rubber wheel runs along the outside of the cone. The speed of the wheelhead is determined by the location of the wheel on the cone. Pretty simple design, and yes, they are heavy and noisy. The old Shimpo wheels were made the same way. They last forever, but if you get a flat spot on the rubber wheel it'll thunk every rotation, which is super annoying. If you want a heavy modern wheel get a Skutt with the built-in splashpan. They weight a ton and will run a lot smoother than the old Amaco, and they have a much larger splashpan and better speed control than Brent wheels.

Sounds like maybe the thermocouple is too close to some metal. Make sure there's plenty of clearance between the thermocouple and the metal jacket of the kiln. Could also be that the controller is dying, which wouldn't be all that surprising given its age. Humming of the elements is normal. Relays should be quiet. FYI, the DTC100C can be replaced with a modern controller no problem. The Bartlett RTC100 is a direct replacement, and the Genesis or V6-CF can be made to fit with minor modifications to the kiln panel.

Coil spacing varies greatly from kiln to kiln, and yet they all work. There's a lot of leeway in the math. If you're using the same thickness wire and the same size winding mandrel as the original element then you're good to go. Wind it up and stretch it till it fits. Easiest way to do it is to lay out a length of wire on the floor that gives you the correct resistance (measure from ends with a meter) and just wind that up.

Have you confirmed with cones that your kiln is firing accurately?

@Jill Smolkin I did cut work at a glass shop for about 3 years after grad school, and we would regularly have people come in needing a new top for their patio table that blew over and exploded. Back then (25 years ago) a tempered 48" circle with a 2" hole for the patio umbrella was about $500. People would freak because they bought the entire patio set for $400, so they would just go buy a new set. Nowadays glass is much more expensive, but the internet has saved the day and you can get cheap patio table tops online. So you may want to check online and see if there's something pre-made that will work for you. You'll probably also want a polished edge of some sort, and depending on the design you might need something thicker than standard plate, like 3/8" or 1/2".

Solid would be a bad choice. There's a limit to how thick the clay can be before you get cracking and explosion problems.

Firing to cone 10 is really the worst thing you can do to your kiln in terms of longevity. Elements in the US are currently about $350 a set (6 elements, sale price) so you could save $3-4 per firing on element costs. Relays will last longer since they'll cycle less and be exposed to a lot less heat. The bricks will definitely last longer since you won't be firing them past their actual temp rating (2300F).

There are other cost savings with firing to lower temps besides just the cost of electricity, big time if you're firing to cone 10 in the electric kiln. - Extended element life. Firing just 04 will give you 2-3x the element life versus glazing at 5/6, double that vs cone 10. - Longer kiln life - Longer kiln furniture life - Less energy removing excess heat from the studio (if you're running AC or fans) Plus you can increase output with shorter firing schedules, and it's better for the planet.

How do you plan to connect the legs to the top?

If you make them kinda thick they should be plenty string without any additional support structure needed. With a glass top nobody's going to be sitting on it anyway.

Drops can be weird, and are often an issue. If you try to drop at too fast a rate, like 600F/hr, and the kiln can't actually drop that fast, then you'll get an error code. If you drop at 9999 it should, in theory, not have any problems because it's not trying to maintain at a specific rate. However, if it's dropping really fast like it does right after the peak temp, it can sometimes have trouble when it reaches its hold point because it takes a certain amount of time for the elements to get going again, and it can end up dropping too far and putting up an error code. The hotter the kiln is when it tries to hold the more difficulty it'll have. In multi zone kilns the 9999 rate can be a problem because the zones don't drop evenly in an uncontrolled drop, and then you get an error code due to the unevenness if they're too far out of whack. I see a lot of published cooling cycles, including from respected sources and books, that don't really understand these issues, and also don't take into account all the different factors that affect cooling like load density, kiln size, and kiln power. In general, the kiln will always be happiest if it's controlling the cooling rather than using the 9999 rate. The key is to find a rate that's fast but not so fast that it can't keep up, that makes the elements work a little bit but is still quick enough to achieve the desired results. In a short drop that's easy enough, but in a long drop you have to be aware that the rate of natural drop decreases as the kiln gets cooler. So while it may be able to maintain a 600F/hr drop at 2230F, it can't drop that fast at 1950F. In most kilns a rate of 300-400F/hr seems to be a good balance for high temp drops.

Where specifically is the sound coming from? There are lots of places for a wheel to make noise, so you may need to turn it over and remove the cover (if there is one) to pinpoint where the noise is coming from.

Would it be possible to just label the front of each tray?

No, it won't hurt anything. It's so far below the peak temp that you won't get any additional heatwork from it.

Are the hazardous waste regulations so strict that they would care about the 7.5 grams of cobalt in the 5kg?

I agree with Mark. One layer of hard brick is too inefficient, even with the layer of fiber over it. There are relatively inexpensive ways to add insulation to the arch, like a mixes of sand, fireclay, cement, and sawdust. The cost of the materials will probably be less than the savings in fuel.

I will never, ever, ever, ever own a minivan, but we rented one for a road trip once and I absolutely loved it!

I also found a lot of discussions about this exact same issue happening with home charging stations for electric cars. Apparently they have a 14-50 outlet (50 amps), but to be able to charge at their peak power of 48 amps they have to be on a 60 amp breaker since they're continuous draw like kilns.

This is the big question, and one I haven't been able to find an answer to. 15 amp outlets have the same internal parts as 20 amp outlets, but that may or may not be true for the larger stuff. A lot of the 30 amp replacement plugs are sold as a 30/50 amp plug depending on how you put them together, so in that case I think it may be true that it's just a configuration issue. But I cannot find anything that says what amperage would actually melt a 50 amp outlet. I found a few electrical forums where folks said it would likely take at least 50-60 amps to melt a 30, and someone said about 100 to melt a 50, but that's all just opinion. I also found electricians who said that it doesn't matter what UL says, it can't be hooked up to a 60 amp breaker with that cord because it violates code, and others who said it absolutely matters what UL says because they wouldn't list that setup if it did violate code. In most cases an inspector will defer to the manufacturer's recommendations, which in this case are that it has to be on a 60 amp breaker, and it can be done with the 50 amp cord. I am of the opinion that the manufacturer's wouldn't be doing it that way if it was a safety issue, because that would put an awful lot of liability on them. And honestly, there would have been houses catching fire from that setup for the last 75 years if it wasn't safe.

Arrowmont in TN has a lot of great several-day workshops.