Bill Kielb
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Posts posted by Bill Kielb
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3 hours ago, Chalkie76 said:
I’m Still tempted by the PID controller - in your opinion are they as straightforwards as they are marketed?).
PID programming (proportional, integral, differential) can be extremely challenging. Now days most are auto tune so that can help. Segment programming is a bit of a haseł as well for each firing but doable for many. SSR’s not exactly the miracle devices either but generally reliable. There are nuances though, for instance generally a definite purpose contactor needs to be installed ahead of the SSR’s to ensure potential leakage does not cause electric shock while loading the kiln. To that, there needs to be some safety circuit that drives that contactor such as a lid switch …….
If you are electrically savvy, then maybe a nice project with a temperature controller. For simplicity I usually suggest getting a bare - bones Bartlett controller and building upon it. It allows one touch cone fire programming so the simplicity is great and all that underlying setup and tuning is virtually done for you already.
I would suggest download any temperature controller install and configuration guide and see if it appeals to you or it reads like another language.
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38 minutes ago, Chalkie76 said:
now I have to hold at 60% for several hours to keep the temperature from sky rocketing
These switches traditionally last a long time, but making sure they are not overloaded is important to their longevity. Hopefully you are not at maximum amperage. If so, one solution - this can drive a more robust relay which then power your elements.
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11 hours ago, Hyn Patty said:
So, looks like I'll order a spool of Radix 200C like I was planning to do anyway.
Just some things you might want to double check-
Not familiar with Radix brand. You might want to double check the olympic which very well might have been wired with MG (mica glass 450c). For connection to elements some of the silicon HT wire will char and burn to ash well above 200c. Also might double check the voltage rating (basically insulation thickness) and get 600v rather than 300v. For longevity sake. -
4 hours ago, VermontPotter said:
There must be a compatibility issue or my bisque firing didn't entirely burn off stuff.
Possibly true but often a function of a glazes fired viscosity and surface tension (oddly enough) and ability to heal. Search for drop and hold firing schedule, glaze pinholes, etc…. I would agree - glaze pinholes in wares intended for food, or even if potentially could be used for food, Certainly not a ware I would consider keeping -ever. I usually destroy the piece always worried someone at some point in the future might unknowingly use it for food service. I actually don’t know of any experienced potters who would consider filling the pinholes in their wares for food service with a chemical fix.
Epoxy viscosity
Epoxy comes in many forms, the typical household stuff is about the viscosity of maple syrup. Not super low, like water but not super high either. Epoxy also comes in a putty form - semi solid and stays where you put it so super high viscosity I guess. Epoxy even comes in a uv curable form so the viscosity of that - not necessarily relevant. Epoxy also comes in food grade compositions. An example: https://www.permabond.com/industries_served/food-safe-epoxy-adhesive/
Not many potters I know would risk this repair on any food surface. Instead they would bisque longer or solve the glaze issue or only use tested durable defect free glazes as a liner for their food service stuff.
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my thoughts
Renewing the wiring harness is a great idea. Making your own great too, but high quality crimp and crimp work is key. If you make your own, please buy a decent locking crimper and good quality welded seam crimps, else the premade harnesses likely a best choice. When I rewire, I use #12 and #10 MG (mica glass) rated wire good to 450c all in an overkill fashion so I can identify with make it better.Low voltage harness
The current low voltage harness likely is ok and should currently experience less than 1/2 amp of load …….. but 18 gauge stranded is plenty sufficient. You should be able to read the side of the existing wire harness to determine what gauge and what temperature it is rated at. Again the crimp work is the important part with respect to longevity and kiln manufactures rarely seem to use high temp insulation on these.Again I strongly suggest Measuring the resistance at these element circuits ….. at the relay, would definitely be helpful, possibly for knowledge useful by others but now will also give you a real idea of how much over designed you would want to pursue by knowing your current amperage and looking in an open air amoacity of wire table. Lots of tables here is one https://up.codes/s/ampacities-of-single-insulated-conductors-in-free-air
Since you are exploring rewiring general insulation and it’s typical ratings in order of temperature tolerance:
- Mg (Mica Glass) - 450c
- Teflon products - 200c - 250c (fep, etfe, pef, And others with f in them)
- Silicone Products 150c-200c (srg, srk, smrl - silicone motor lead developed for small motors vibration and temperature)
All the above though generally is a decent reason to just buy a premade harness that fits perfectly though. Most wiring begins to fail at their connections which overheat, anneal the copper and continue to overheat more as the conductivity decreases. The physics says this will decrease the electric load on the relays, but a harness that overheats also adds heat to an already confined space. The latter being bad for the relays as well so replacing a harness not a bad thing, replacing with a better harness, even better, but does take some diligent work, good crimps and good crimpers to achieve this.
Airflow and cooling helps everything regardless of gauge and insulation, so making sure there are no obstructions or the kiln is not enclosed in an overheated area with no way to get relatively cool air is a no cost best practice for all the electrical components inside. The control box depends heavily on stack effect which means relatively cool room air can freely flow from bottom to top and out of the louvers.
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On 11/17/2023 at 1:01 PM, Lauren F said:
final segment was set to 1200F.
My question is—would I be able to tell if the tiles were fired to 1200F instead of 1860F?
Just a couple thoughts
1200 f is about cone 020 ( likely not very sintered), folks who intentionally carve soft bisque end up around cone 012. 1860f is cone 05 / 06 so you likely would notice a big difference between the products including: look, touch, size, firmness, absorption, tongue test …… from 1220 f - 1860 f lots of things burnout including sulphur, calcium carbonate, etc… but they don’t burnout necessarily because of peak temperature. It’s rather time at elevated temperatures so bisque firings are generally slower than glaze.- You could bisque something to 1200 and compare
- You could re-bisque the pieces in question to let’s say cone 06 to be sure
- You could slow your glaze firing schedule through 1200 - 1860 as sort of a modified once fire schedule. Slow bisque schedules generally go about 180 f from 1000f to 1700 f btw.
I do not believe your actual glaze temperature has been referenced yet. What cone do you glaze fire to? Some of the above more or less assumes you glaze to cone 5/6.
Cone 020 is really a China paint type schedule generally designed to just begin softening glaze, I think the bisque would be incredibly soft at this temperature and not very sintered, but easy to test to be sure.
- Kelly in AK and Lauren F
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@Hyn Patty Just curious, can you measure the resistance (unpowered kiln) across the two wires that go directly to the elements and post? Just curious how much load is on these relays and what their current specified rating implies. Also curious what the element insulators look like, basically if they are clean. A picture would be great.
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3 hours ago, neilestrick said:
You've still got the original 20 year old wires connected to the relays
Wires Might be a solution, but the connections and wire we can see look pristine and the copper in the relay overheated, but no signs whatsoever on the wire or connections. Bad wires / connections ought to raise the resistance of the circuit and lower the load on the relay unless they are shorted somewhat. Still - could be downstream of this picture and new wires never a bad idea but I would definitely measure the resistance from the relay terminals just to understand at what load this relay was running at.
Only parallel I have experienced - carbon tracking or something slightly conductive acting as a slight short to ground around element connections etc… If the wires are replaced, also strongly suggest cleaning any coating off the porcelain element bushings and such. A resistance measurement at the relay terminals likely can confirm this.
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7 hours ago, Pyewackette said:
Seriously, I already have trouble telling my right from my left. I also have trouble lining things up like this - what direction the wheel is turning and what direction a "spiral" in wedged clay (ram's head or spiral) is going - I'm not sure I could even do that at all. I get real turned around real fast on these things. TOO COMPLICATED.
In many many years, I have never found proof that one can polarize or directionally align reasonably wedged clay. I have not found that to be credible in my experience.
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While not the expert I’ll offer this thought and suggestion: Both relays appear to have failed due to overheating resulting in the plastic melting enough so the quick connection tipped to one side. The corresponding moveable contact in the relay on the right appears to show signs of overheating as well.
So why so much heat? Electrical load or inability to cool itself with the updraft in the kiln. It failed quickly so, electrically overloaded or just a defective relay that can not tolerate the load …. Or ….. new relays use a thinner moveable contact? First step tell us the model so we can look at the wiring diagram which should allow us to see how closely the relay is to or above the rated load and rated operating temperature. From they’re easy enough to measure the element resistance right at the relay contacts to verify the elements are as expected with respect to loading. Maybe the last piece in the puzzle would be this relay in spec is rated by horsepower. Converting to amps gets the contacts down to prox. 12 amps. Elements (resistance loads) cause significant heating in the controls and wiring, so it will be interesting just to see just how many amps the elements are and if the newest forms of this relay handle less than previous for a resistive load. Table below
Just adding relay specs below - all appear spot on except for the meaning of 2hp @ …… rating.
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2 hours ago, Brett said:
(and sliding a .5mm wire through
Hmmm, pretty small actually I would feel better if it was stamped. .5mm is .0280” which is a number 70 orifice which gets you [5.9 kw] @ 34 Kpa so seems to be a high pressure burner. When burners burn backwards the combustion velocity is greater than the physical velocity so the flame travels back towards the orifice which is counter intuitive to having too much pressure. I assume it backfires in free air, so maybe an easy test I would suggest is to put a hand operating valve upstream of the burner and see if you can stabilize the flame slowly closing the valve ( in free air) - maybe to near zero flow. The primary air needs to be fairly open, don’t close it. Again counter intuitive but nothing makes sense here really. If that works then I think we can safely assume it is low pressure or medium pressure burner and work from there rather than buying a bunch of stuff guessing.
Propane and natural gas have relatively slow combustion velocities which make this issue fairly rare for Venturi burners, stove burners, you name it. I think worth the test and observing the result.
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25 minutes ago, Brett said:
- it back-burns even when right away from the kiln with flaps open.
Can you check orifice size for us. Wonder if one is in there, then what size. 3-5 Kpa would be typical sizing so at 100 Kpa unknown how that would react. We really want to know the orifice size but I am also curious if you drop this pressure down to single digits, does it operate. I think it would be good to see this orifice in a picture as well - any chance a little critter crawled in and made a home? Often spider webs.
The orifice size will tell us its intended operating pressure. Pictures might tell us if someone drilled it out.
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While I don’t use groggy clay, when I did, wet sand the bisque to smooth as much as practical ( rim and foot) and ALL pieces after glaze firing - foot diamond grit ( wet) sanded super smooth.
- Pres, Pyewackette, Rae Reich and 2 others
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Very, very unlikely. Lowfire glazes melt about 2000 degrees. Fired on enameled porcelain is usually a mix of Frits and fires in the range of 1400 degrees. That’s probably the tip temperature of a propane torch, plus if cast iron - you need to heat the whole vessel. My thought is very very unlikely, removing to a restore shop possible but I am guessing replacement probably more economical.
- Hulk, Chilly, Callie Beller Diesel and 1 other
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Atmospheric burners contain orifices sized for a particular range of pressure and the fuel used to produce a certain amount of heat. No new news there, but for all that to work the velocity of the gas has be be greater than the combustion velocity of a fuel air mixture expected to enter let’s say at a 5:1 air fuel ratio or about 50%% of the required air. The remaining 50% of the required air must enter around the side of the burner through a sufficient overcut all the way around.
So:
- Wrong pressure
- wrong orifice
- Too much back pressure from the kiln
- Any chance you are feeding liquid to this?
- Not enough overcut around burner
- Adding a metering valve upstream of the burner and downstream of the main gas valve allows variability, how are you controlling the gas to the burners?
What size orifice, what is the burner rating (kilowatts, btuh - thermal output) , what pressure is this operating at (typically in the 2-3 kilo paschal range) not the maximum pressure ratings on the valves, what size regulator is installed on the tank, pictures of the installed burner, picture of it burning back ….. and never close the primary air 100%, it should likely sit at least 1/2 open or better and not really need adjustment.
Propane boils about -41c so at 21c there will be about 850 Kpa of pressure in the tank. Definitely way higher than your burner rating. So in the end sounds like these might be high pressure burners and need a first stage regulator to operate correctly.
This is fairly easy to solve but often folks, even licensed fitters confuse the pressures and installation requirements for kiln operation. Tell us a bit more
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2 hours ago, Dick White said:
Yes, the Orton table shows 108F/hour for the medium speed. Bartlett programs the cone-fire profiles at 120F/hr.
Yes of course. I thought your explanation spot on. I mention 108f because if all else fails look at the chart and follow it! regardless I have seen kilns wear enough from 120 degree speed to usually over fire and eventually error out. 120 is fine and is part of Bartlett cone fire design. Eventually though many kilns won’t even do 120. Too slow often ends up ugly. 200 is probably pretty hard for most kilns to hit unless new or lightly loaded. 2200 is sort of a cone 5 finish at 200 degrees per hr final segment. Add a 20 minutes hold for good measure. Lots of compensations from Ortons design can lead to reduced consistency.
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you may find this helpful
Just a late add here, @Dick White summed it up well. For the final segment ….. generally folks use the center column of Orton and most kilns can maintain with elements in reasonable condition.. So 108f per hour is a nice final segment speed in the last 180f or so to hit the predicted cone at the corresponding peak temperature within that column. (See chart) The added benefit of reduced speed in the final segment is the tendency for firings to be more even compared to higher speeds.
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6 hours ago, mrdstone said:
Hi, we have a raku kiln that is set up for natural gas that we want to convert to propane. Can you share what the conversion kit is that you have and where it came from?
His conversion kit is for the Geil make and model he is firing. Yours will need to be for your make and model. I suggest calling the manufacture or posting your make and model kiln here for feedback.
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You could close or fill the interior with foam.
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4 hours ago, Jason Schiedel said:
I will be looking into bench top solutions. Might be the most practical for my situation.
Thanks Bill!
Hulks example great above - also can outfit with a multitude of polishing wheels. I would not entirely dismiss vibratory polishing though. You may find a suitable finish, nearly hands free.
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35 minutes ago, Pyewackette said:
but really its just the handles I'm focused on atm
Handle molds and handle forms (2 ideas) forms are only foam and cheap so you can make your own if you find a consistent shape you like. Press mold a bit pricey but very precise consistent handles can be made easily.
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3 hours ago, Pres said:
Several years ago, I built a deck attached to the garage and house. 2 layers, no help building the framing at all. Used one corded hammer drill and two different cordless drills. Charged over night batteries lasted all day. Dad helped me put on composite decking. Don't know how I would have done it using corded drills with cords all over the place.
Unfortunately / fortunately the way of the future. Batteries improving in longevity and weight. ECM motors more efficient. Rare earth magnets replacing wound copper rotors. Brushless! Powered tools improve productivity and non corded site safety a whole bunch. Gone are the days where the tool is holstered, you are tied off of Course dragging around 50 ft of extension cord just waiting to pull off balance, get tangled or stepped upon. Pneumatics also being replaced with battery powered - same issue, maybe worse. Like printer cartridges though everyone has their proprietary battery shape and chargers.
Lithium batteries - game changer in weight and power density. Lithium iron phosphate newest game changer, now battery powered site generators in many ways better than the old fueled. Tesla scheduled to reveal newest next game changer battery soon.For home construction and special needs, corded are still fine. For convenience and improving site safety more than tenfold, cordless can’t be beat and very few sites (if any) are significantly corded anymore. Cord safety in itself a constant OSHA issue. When real contractors build things, as many cordless as practical are in use for many good reasons.
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I am with @Hulk polishing compound, fixed bench polisher allows you to hold the item being polished. Pneumatic tools are great but those cfm and horsepower requirements for home use fairly significant. If you are not going for mirror finish, polishing in a blasting media cabinet with non etching media or light etching or even tumbling (rotary or vibratory) with appropriate media might be a convenient way to get the desired finish or at least close.
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If you stretch it cold it likely will snap. The typical practice to put elements back in grooves, heat it with a propane torch to glow red, anything glowing will gently bend easily. A heat gun won’t get it hot enough to glow red. Once cool though - it’s back to being brittle. So torch would be my minimum suggestion.
Cress Kilnsitter Graded Element question
in Equipment Use and Repair
Posted · Edited by Bill Kielb
The electro sitter expects to turn all the elements on 100% and off 100%. So having other controls interrupting things is just confusion. Normal procedure is to turn all the kiln controls to high or full on and let the electro sitter manage the firing. The firemate should go to maximum or 10 and depending on your model any other kiln control you have turned up to high.
To answer the question of how it works, a timer motor slowly turns up a standard infinite switch. So the infinite switch cycles on and off proportional to its setting (likely starting around 22% and somewhat linearly to 100% power within prox 330 degrees of rotation) ……. and the timer motor ramps this setting upward over some amount of time. Generally the most confusing thing for most folks but an early attempt at semi automation.