Bill Kielb

For me,I go with mg @ 450c but shop the web. Usually 20-30ft of #12is a lot of replacement though. I just shop the wire suppliers for best price. $28.00 handles a lot of repairs for me.

Complicated question actually. Optimal operation is often considered 40c - 50c (105f x 122f). (For reference - 120f hot water is considered reasonably safe but feels VERY hot to the touch) most circuits are designed around the lowest rated connection in the circuit. Starting with 60c and has grown to 75c and 90c over time as materials improve. 150c rated wire nuts are often categorized as plenum rated. Ceramic wire nuts generally have higher operating temperature ratings. So exceed or meet 60c would likely be a material minimum requirement. Best answer I can give, run everything as cool as practical. As things heat, resistance generally goes up which means a local voltage drop which means some watts locally which means more heat locally …… Proper sizing and proper cooling are the best ways to minimize this. Wires rated higher in temperature will last longer, which is why MG would be better than lesser rated insulation. Passive cooling is dependable so that updraft thing is very useful dependable and free of operating cost but very dependent on ambient temperatures. Kilns are weird animals, the element connections approach 2000f so better convective cooling helps the longevity of this connection and can enable lesser rated wires to operate satisfactorily. Element end connections can often be preserved longer with a bigger heat sink type splice just because of the additional cooling area and of course any improvement in convection helps lower the average temperature of this splice. Old designs 60c, UL now I believe requires 75c for lugs / breakers. So all components can be designed to meet or exceed the lowest design temp in the circuit ….. which is often the lugs and breakers in the US. A nice brief explanation of NEC temperature https://iaeimagazine.org/2009/september2009/where-a-successful-installation-begins-and-ends-understanding-nec-rules-about-wire-temperature-ratings-terminations/ A bit lengthy but the point is, lowest practical temp is generally best for longevity

Separate box great idea!. Cooling from bottom to top still applies. Just a note, if installing wires through holes use appropriate bushing or electrical connector. Never wires through a hole in the steel. Chase nipples are cheap and an electricians safe way of routing machine wiring safely through an opening.

Yes that U shaped piece divides the space it does not need to be heavy, just reflective. Making it heavier will not add to its effectiveness as a reflector. Making sure ventilation air can travel freely from bottom to top will though.

Well ventilated and thermally managed with wiring isolated from kiln infrared, hundreds of degrees above ambient. So most kiln manufactures create a channel adjacent to the kiln that creates an air gap (prox inch or two) where cooling air can rise from bottom to top freely for cooling. The remaining components and majority of the wiring are located on the other side of this partition and are also ventilated bottom to top. Done well, a few hundred degrees over ambient. It’s never been worth my while, so I just always used MG wire which is Mica Glass usually rated continuous at 450C which is upwards of 800 f. I order from wire supply though, McMaster is probably pricey. Definitely overkill by many of todays standards and lesser rated wires will work. Make NO mistake, they are lesser rated so not necessarily better for temperature resistance but adequate. Popular now is silicone. Wiring gauge is chosen by amount of current the wire will carry. So for me, really good ventilation design and my wire is overkill, but my remaining parts can be standard stuff. And all will last a long time. Your control box should be coolest furthest from the kiln wall and lowest where air comes in to ventilate. Ventilation (stack effect) and isolation are key. If your components can “see” the side of the kiln, they are not isolated from the infrared that will be emitted from it..

@davidh4976 I don’t have the Reddit location this was at @colormek8art but assuming you will be working lowfire and / or glass the cone 6 limit likely will be ok. It is a manual kiln though so fusing, slumping, squeezing, annealing can be a bit of a challenge compared with a kiln with an automatic controller. If you were to be using this for midfire clays (cone 6) then you will likely only get several firings from this before you will need an element change. I believe that plate says model 181 so to that end your electrician will likely find the 181 manual handy. You can download here: https://skutt.com/skutt-resources/manuals/kilnsitter/ These kilns often said to be three wire actually required two hot legs and a full sized neutral as well as an earth ground for safety. They were in effect two present day residential 120 v. circuits and an optional ground wire which I would suggest is no longer optional. So having your electrician figure this out in advance is important. See pic below, “if” this is your model. Note the four wire power cord.

Just to suggest, this looks to be a three phase kiln capable of about cone 6. To start maybe post a clearer picture of the equipment tag and possibly the cord end that is on it. If you know, what cone will you be working in: cone 04 (Lowfire) cone 6 ( midrange) and / or cone 10 (Highfire) then add that as well. Your home is single phase, so confirming that this is three phase as well as what cone you plan to work in are probably best first steps before ordering elements.

I likely would not. China paint and lusters are still more durable for my use and as accents. This depends on the conductive paint beneath so likely not as temperature resistant. Having said that, this process is pretty neat for vases and such and solves the mirror finish dilemma, especially when coating an entire surface.

Good trick to know for sure with the mirror for moisture! Bisque firing is also about Sulphur compounds which begin around 600 c and can be corrosive to elements and humans. Also some late off gassers above about 800c. Your mirror may clear before this. So when in doubt, closing the vent later would be a conservative way to try and ensure all the bad stuff is eliminated. As you might have noticed, the earliest Nabertherm suggests is 950c to be conservative I believe.

Nice just some conductive paint and you are on your way! Looks like somewhat non functional stuff (I should probably say non food contact or something like that) though, but nice for its use.

I agree with Neil, however reduction and your visuals likely will change a bit. That nice blue flame is not something you will see so much with propane. Propane literally has double the btu output per cubic foot used, but proper orifices will compensate for this. You should be firing on temperature and rate so manually controlling will compensate for slight faster or slower. For reduction, your visuals will change a bit but not something you will not grow accustom to.

Still a nice look. It’s really difficult to get true mirror like gold. The PVD coating above was actually a pleasant surprise to me.

Dishwashers can be fairly aggressive on non durable glazes. This a soda fired piece so not something designed and tested durable. Looks like the dishwasher dissolved some of the surface of the glaze. It’s soda fired so hard to predict and no guarantee it will end up durable.

Looks better than expected. I wonder if you can buff it, not necessarily to a mirror but glossy smooth?

No, I think my math. Assuming 8”round prox. 20.32 cm so area should by 3.14x((20.33/2)^2 ) = Prox 324 sq cm. So 22W (from above)/ 324= ..068W per sq cm. A bit more than your floor heater ought to melt ice off your mirror as opposed to heating a floor to comfort temps.. I think you are in range and my quick calcs are wrong above. All done flipping back and forth on this iPad, but seems right. Someone should triple check all the calcs if the OP does want to do this in some fashion, I think we can sneak up on a real potential load.

The density of snow varies significantly. I kind of really liked the heated mirrors above for approximate established data. I think we really need more of a description as much as practical as the mounting and what it is mounted to could significantly affect the required energy as well. Gotta start somewhere so maybe size, mounting, materials ….. Maybe a display case in the end is practical.

I think we can tell you more but you will need to tell us how big will this be ……. Tell us as much as practical. To be effective, I believe we are just going to need the potential load in watts which is affected by size and enclosure or lack there of. Sorry, the above is the best thoughts that come to mind to address the potential load. Maybe others will have more insight here. I would suggest describing what you envision as completely as practical though.

Still not sure ….. PVD coating that sticks to ceramic? (See below) it’s definitely not common and lusters have served this function with reasonable durability for potters. Most folks try and keep the lusters away from high wear and direct contact with food as well just to be extra cautious. I see this finish on many other materials such as steel and plastic more so than ceramic. I am not aware of a glaze that can produce the finish nor a traditional spray applied coating either. Spray applied coatings generally lack durability and are often not high temperature tolerant. If you figure it out, maybe you have something folks have been asking for for years. PVD appears a bit expensive unless it scales well to produce thousands of items.

Knowing that, I would suggest a carbon fiber heating element or flexible element often used in heated clothing. 80 meters of Nichrome is a very long distance so not sure what area you plan to heat or how you intend to distribute the heat from a single wire. My first instinct is to enclose or protect from snow, maybe move energy with air, but that may not fit your use. Maybe a full description here will sparks some ideas from others. Just to add a bit to this we are talking about raising some area from -15c to above 0c with only still air (undisturbed layer of air near the fabric) as an insulator. The slightest breeze makes that layer go away. This can become a very large loss of heating in a hurry. Maybe insurmountable wattage actually, when we look at available batteries and storage. I think the more accurately you can describe here it likely will improve your chances of suggestions by others. @Ahmad.khd Just looking at this further, car mirror heaters might give us an idea of the energy required. If my quick math is right - temperature dependent - it looks like on the order of 1-2 watts per square centimeter. Likely not trivial depending on how large an area you are trying to defrost. Cold climate Heat pump technology could produce this at 1/2 to 1/4 the electrical energy vs resistance heat. Assuming the above is correct my thoughts go to dark minimal awning, maybe using the existing sun as practical and a ducted heat pump only when essential. Maybe even automotive heat pump.

My thought is first work out the total heat needed which goes to what are you trying to heat up and what are the losses. Once you know the losses in watts we can figure out how to replace those watts with available nichrome wire (Diameter and resistance using your 80 meter length) and available batteries. It’s actually a very significant problem in my mind where no simple answer comes to mind. Perhaps a bit more description of what you are trying to heat would be helpful here.

Hmm, the machine should generally ought to do it better or at least more consistently than creating a custom program. So when you create your schedules do you follow the last 100c requirements in the Orton chart?

Just curious, since it is a Skutt with the touchscreen controller, why not use the cone fire programs rather than working with holds and various rates? Also - to get a particular Orton cone to fall it’s customary to set the last segment rate to that shown in the chart. Begin that rate 100c before the cone temp. If you follow Orton, just curious if anyone has explained how that chart is intended to work?

Not that it’s not possible for this to work, I would say with this level of cracking, highly unlikely. I am with min wondering about pouring dry.glaze in and out. I am not familiar with this technique from Mayco etc… or the expected look.

Usually cycle off after a test resets it. The interesting point though is to definitely cycle this test switch to make sure it’s not stuck and releases freely. Pretty funny though it’s either “off” or simply turn it to “No”.

Just a late add - Nabertherm does a nice job IMO of explaining a bit about the fresh air and exhaust port. In addition, they suggest when to open and at what temperature to close. Manual https://nabertherm.com/sites/default/files/noindex/2023-07/M01.1089_English_2023-06.pdf Section 5.5.6 - section about how the vent works with reference to piping, slope and height. Section 5.7 - first firing with fresh open 100% of the time to 950 c to season the elements and burnout in a new kiln. Just a good thing to know for future use. 6.5.1.1 - some nice preset program firing charts with reference of suggestions of when to close the fresh air inlet. Their range 950c-1250 c depending on type of firing, Anyway, it may seem confusing but this does give reference to a suggested temperature to close the fresh air vent, and these appear to be me to be relatively conservative numbers. This may help a bit. Perhaps confusing now, but likely will have greater meaning as you fire more and more and gain greater knowledge. sample schedule below with specific closure temperatures. Finally - why are we doing this? Here is a nice article from this web site that could give you an idea of what we are burning out and about when this happens. https://ceramicartsnetwork.org/ceramics-monthly/ceramics-monthly-article/Bisque-Firing-101#