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Everything posted by Patrick

  1. Have a particular model/type/source in mind? I ain't above tryin' anything once.
  2. My second thought regarding the oxygen sensor was to use a IFB and a stainless steel tube on the rear wall, removing it from the chimney equation. If I do that, I'll probably just set up some kind of "Don't go near here or you'll die like Liambesaw said" kind of barrier and let it exhaust straight out of the wall.
  3. Thanks for the pointers. Stainless did cross my mind. Good to hear about you being back at it!
  4. First ... You are absolutely correct and I appreciate your vision! LOL!!! Second. Slowly running out of brick (180 or so left out of 1000), and I'm milking the "forced air burners don't need a chimney" ideology. ... Jabba the Hut. ... That's rich.
  5. Mark, you never did answer me way back when. ... Did your arm heal up ok? You broke it. Remember?
  6. Thanks for the food for thought Russ. Been chewing on it, and here's where I am at. Any additional thought would be appreciated. Let's say you're right and my cone 6 firings would soften it up enough to where it would sag - a possibility since it will be sticking out at about a 45 degree angle from the kiln, and not standing up straight. I would be willing to bet a couple of pieces of 1" angle iron welded to the bottom corners running the entire length and supporting the chimney from those pieces would keep it stable. It seems to me that the piece of angle iron surrounded by air would not get close enough to temps high enough to soften. I could be wrong, but I think that might keep it in one functional piece. I initially thought about cutting small holes in the bottom to introduce cooler air, and then I remembered I would be mounting an oxygen sensor in there. Duh. See image below and keep snide remarks private. ... I know. Just don't say it. Red = sheet. Green = supports/mounting points attached to not-yet-existing steel frame. Blue = O2 sensor. PITA? Maybe. Functional? I think so.
  7. Wow, you guys are awesome. If I ever think nobody in the world cares whether or not I run around with my head on fire, I'll just re-read this post (and gracefully overlook Liambesaw's you-should've-taken-responsibility-for-yourself leanings! LOL!) I'll see if I can't address everyone's concerns topically here: Why 4 burners when you only need 2 for the size of the kiln? Heat placement according to Abernathy kiln theory. Rumor has it the 2 extra burners placed on opposite and higher levels of the kiln led to a 30% decrease in fuel usage. It wasn't how many BTUs, but where are you putting those BTUs in the kiln. I will eat the costs of 2 extra burners upfront (which aren't that bad when you throw sweat equity at it) to get a possible savings in fuel, especially since I've used a lot of hard fire brick (AND see just how fast I can go from 70 degrees to 2300 degrees!). Damper, or lack there of. Since I'll be using forced air burners, I'll have a positive pressure in the kiln anyway. If I understand it correctly, the game of turn down the air/turn up the gas will create all the reduction I could use. If that is not the case, the answer below will provide a solution... Lots of holes where you don't want a lot of heat right next to a big hole with nothing but heat coming out of it. My thinking right now is (1) I need a place to mount my oxygen sensor that is going to stay at or below about 1000 degrees Fahrenheit - or risk damaging the sensor. (2) As much as Liambesaw is, in some ways, a person after my own heart, I very well could be the idiot who burns himself up (by sticking my face in places that weren't designed with face-sticking in mind). So, I am planning on welding a long 16 gauge (1/16th inch) steel chimney and angle it up and out of the SHED (!!! LOL) thingy. A few probe holes where I can insert a thermocouple will give me max temps at different locations in the square tube, and I can then know where to mount my oxygen sensor inside the metal, slanting, don't-touch-it, chimney-kinda, thingy. This should also get most of the heat away from places I want to stick my face, AND give me a good place to rig up a metal damper if I need one. Peep hole locations You are absolutely right, Rae. I will move them out at least one more brick. Thanks for looking out for me y'all!
  8. No chimney. The hole where the tape measure is will be the exhaust. I'll be using 4 forced air burners, ergo... just need a hole and something to deflect it from guilty bystanders.
  9. An update: we had a dry day here (finally!) and I welded the steel for the rear wall and stacked the front wall so I could get a game plan for the steel on it. I originally was thinking about making 2 small walls up the front sides and then stack a door in the middle, but the kiln is too narrow - or the door would be too narrow once I got side-front walls of any substance built. Soooo, for now I'll stack the whole darned thing whenever I fire. It'll keep me young ... or make me old. Regrading the steel for the front wall: I still want to put some steel around the 3 layered floor as a frame to attach supports to, and then it hit me, I'll make 2 or 3 removable, vertical steel frame sections for the front wall that (1) bolt to each other (2) attach to the yet-to-exist floor framing to keep the bottom in place, and (3) attach to the rear wall over the kiln. I'm also going to attach the rear wall to the floor braces to I don't have to worry about it going anywhere. I think that will work for now. It will definitely give me something to fiddle with if I get bored, and it will help me not forget how to embrace the suck. Lastly, I have been nostalgically building a monitoring system out of a raspberry pi 3 b+, an arduino uno, two adafruit max31855 thermocouple boards, two 18.5" K-type thermocouples, and a bosch 12028 automotive oxygen sensor. That's been fun. The RPi provides some pretty descent file saving, graphing, and network availability options. The arduino is pretty much just the sensor workhorse and serial data sender. Man, coding has changed A LOT since I quit banging keys. In chewing on downfiring, reduction times and durations, etc. I decided to give it a shot and see how useful it could be. I can also use it on my other kilns if I want to. If nothing else, I will have csv files of every firing I do with it for learning, changing, etc. I mean I can always still unplug the darn thing, buy a gallon of wine, crank up the burners, and hope for the best ... if that's what I'm in the mood for. Here's some eye candy (LOL! That's funny!)
  10. Here is my game plan for steel (1.5" and 2" angle iron - donated by a friend today from his pile o' stuff) on the back wall. What are your thoughts? What am I not getting? I will be putting angle iron on the floor corners also and attaching it to the walls - just didn't draw it in the picture. I will also be pulling the front and back walls toward each other with rods (weld a bolt onto rod) and springs a la Marcia's numerous descriptions.
  11. More progress. Got the back wall put in. Have a few gaps to mortar up, but I'm satisfied. Hope everyone is well.
  12. Thank you. Are you thinking out of necessity, or just for a door frame? Been scratching my head about the bricks walking over time and supporting the back wall.
  13. Thank you. Actually, it's just under 5 feet tall. Must be the camera angle. Hopefully loading/unloading won't be too bad. But then again, who ever got into ceramics because it was easy?!
  14. Progress. One foot in front of the other. Thank you guys again for not being okay with me keeping that plastic keystone. I am in your collective debt. Will continue to update as more progress is made.
  15. Nice. The above photo wasn't mine though. Mine is a page back with the arch frame still in it - minus the castable keystone (Thanks again er'body.).
  16. Is that what you're talking about? Won't have the iron work to support such a door. (Image from Medalta's website) Currently thinking about a double-layered, puzzle-piece-like, insulated, castable door - maybe each door layer in 5 or 6 pieces. ... ... I have enough IFBs from scrapped electric kilns to maybe incorporate them somehow. Haven't made it to that bridge yet, but it's on the horizon. ... And the plot thickens.
  17. Have a few options in mind, but haven't decided yet. What would your recommendation be?
  18. Holy smokes! I'm in the wrong dang business! If I ever want to become an electrician, I'm moving there! Sorry I'm not in your neck of the woods, or else I'd try to help.
  19. Done. Jerked out the keystone before it hardened up. There are certain times when I don't mind being wrong. But the cost/benefit of this one became pretty obvious after I stepped back and thought about what everyone was saying. If my hunch was right and it worked - not too much gained. If my hunch was wrong - holy cow, that would not have been good - not even a little bit. I don't think I was fully considering the extent to which the keystone wouldn't harden up and what would happen if it only partially hardened. Thanks for the offer to cut some brick, Mark. Won't be working on it this weekend. My honey-do list is longer than I like letting it get. I'll throw up some pics when I get the brick keystone in. Thanks for watching out for me y'all.
  20. Hmm. Not sure how to respond except by sharing my deliberations. I am no physicist or engineer - so pardon the slaughtering of certain concepts if I screw this up. Every row holds the arch together - which is ultimately held together by gravity, being a catenary arch. And if gravity quits working, well... that'll be an interesting time. There are several types of forces that can affect the keystone: tensile (pulling apart - doesn't apply here), flexure (bending/twisting - negligible), and compression (crushing - here is where the money is, I think). Abrasion is a concern also with the expansion/contraction of each firing, (which I think what Mark was getting at by "weakens"). I can't say I understand how a soft brick keystone would be better than a castable keystone if the forces we are dealing with are either primarily compression or abrasive. Cold crushing strength of hard fire brick (approximate) = 3500 pounds per square inch Cold crushing strength of a Morgan K25 insulating fire brick = 200 pounds per square inch To be conservative, let's say my fire clay/epk/sand keystone mixture (which is solid - not insulating) is right in between the two previous examples = 1650 pounds per square inch cold crushing strength The entire arch consists of 216 hard bricks. At 8 lbs a brick, if I were to stack the entire pile of bricks one on top of the other, it would ONLY weigh 1728 pounds. The area on EACH SIDE of the keystone that comes in contact with HALF of the kiln is about 182 square inches (364 total square inches in contact with all bricks on both sides). If we could flip the entire arch upside down without it falling apart and put all the weight on just the keystone, we're talking LESS THAN 5 pounds per square inch on the surfaces that contacts another arch brick and ONLY 9.5 pounds per square inch on the part of the keystone that would be sitting on the ground (if you grant the silliness of a catenary arch not falling apart when you flip it upside down.) And I know I have assumed uniform distribution of forces AND I used COLD crushing strength - not 2300 degrees crushing strength - etc., but still, the numbers seem on the "it's gonna be just fine" side of it. Now, here's what I AM concerned about: The clay/sand (no cement, proper) mixture is not yet fired (vitrified), so I will admit I am interested in what will happen through the first firing, it being just bone-dry. If it makes the first firing okay, I will have tons more confidence. But... People have been making castable kilns for a while. I guess what I am saying is I don't understand whence comes the concern. (I haven't used "whence" in forever. Viva la archaic language!)
  21. Here's a pic of the brick on the form. To help anyone messing around with the idea of a similar project, here's a few things I learned/settled for: (1) In using old (as opposed to new) fire brick, there was a lot of culling of not-good-enough bricks. Lot's of beating old mortar off so bricks would lay somewhat flat and/or flush. Some brick were unusable, some were ok, and a few were great. Had I purchased new fire brick, I imagine this part of the process would have been a entirely different type of satisfying. (2) It didn't take long before I realized keeping my lines "straight" was going to be a concern. 1/16th of an inch off x 4 times of that = a lot - for some. Perfect lines would have taken a lot more mortar (1 part fire clay/1 part sand) than what I was wanting to mix up or a lot more scraping and beating. So I adjusted my rows with a little mortar where needed to keep everything pretty level. Once at the top of the kiln, it wasn't that big of a deal because more mortar was being used anyway - just made sure the inside edges of the bricks were in contact with the brick below. Didn't want any floating only on mortar. The front and rear faces of the arch are a whole different story - my thoughts here were "It'll be getting a layer of insulating clay anyway..." (3) Hand splitting brick versus saw cutting brick. I hadn't run across many who recommended hand splitting brick as opposed to cutting with a tile/brick saw. I don't own said saw, and was thinking about purchasing one, and then I recalled all the talk of going through diamond blades (not cheap), so I settled for hand splitting. A mason's chisel is about $5, and I have an angle grinder with masonry cut off wheels. This left an imprecise, jagged face, which I made sure was placed to the outside (toward front or rear of kiln). No biggie. If I had had new brick, I would guess this eye-soar would have been aesthetically more problematic for me. To hand split, I simply scored the brick all the way around where I wanted the split to occur with an angle grinder about 1/8 - 1/4 inch deep (I was just cutting bricks in half), laid half of the brick on a solid surface (another brick) leaving the score to overhang a smidgen, stuck a 4" mason's chisel in the score, and smacked it a couple of times. They all fell apart nicely. Worked better than what I was expecting, but again, it leaves a jagged, uneven face. (4) Keystone. I thought about splitting brick for the keystone. After about 20 minutes of considering that, I decided to use a castable. I used fire clay/EPK/sand. I went a little lighter on the sand than in the mortar, remembering Rae Reich's lamentations of crunchy additions to her glazes from falling crumbles. Might make a difference, might not. I may just end up having to create a crunchy line of porcelain something-or-others. That's about it for right now. Gonna let everything set up until dry and pull the form out. I'll probably fire it a time or two before I put the insulating layer on, if for nothing else to see where my gaps are that need some attention.
  22. Fabbed up one burner and will test it next week. If it is ok, I'll make burner #2 and get them on the kiln. My plan is 2 burners on the front flat wall at floor level and 2 on rear flat wall a little more than half way up. It's more of an even-heating/fuel-saving issue as opposed to hitting required btu's. If I read the (albeit, limited) studies correctly, Abernathy-style kilns experienced about a 30% fuel cost savings on 3 different kilns by spreading the btu's around (read: thinking about convection and chamber flow) as opposed to just worrying about getting the required btu's into the kiln. The image in my head makes sense - blower on bottom and another blower opposite and higher up would create (in my mind) a circulation on the side wall. Would that not equate to more even heating? Again, it makes sense in my head, but whether that will correspond to reality...? I'll start with 2 on the front wall on the floor and see what happens. Do a few firings with cone packs around the kiln. My guess is I'll get a temp differences between top and bottom - but I may not. We'll see. ... And I am open to ideas/input. +1 on larger blowers and orifices. On each burner I've got a 50 cfm blower (at a 10:1 air to nat gas ratio) can support a max of 300k btu's wide open on a good day. I am planning 172K btu's (7/32" orifice at 7" WC) per burner. That will give me plenty of wiggle room and room to play with oxidation/reduction. If I need need more heat, it's there. If I wanted to max out the blower (which I don't see why I would), I'd go with (2) 13/64" orifices per burner and that would give me around 300k. ... ... But I quit doing burn-outs in my car when I was about 25 years old. Tires cost money! LOL! What are your thoughts?
  23. How long or until what event should I leave the arch form in place? I am at least thinking until the mortar is dry. ... The last batch I mixed up was a little too wet, thinking about getting the propane weed burner after it to speed things up just a tad - nothing crazy. Just warm it up a bit.
  24. We're on the same page. Brick angle mortar is fire clay + sand. The insulating layer will have the burn out material. Hard brick walls are stacked 4.5 thick. I have about 500 lbs of dry fire clay, so I'm planning on using that up on the insulating layer before I go buy anything else (fiber).
  25. I am too tight ... cheap ... stingy ... broke ... conscientious to shell out for commercial insulating castable. I have found several recipes and am planning on a fire clay/sand/sawdust (wood flour, actually) mixture. I plan on forming blocks up along the arch about 4" x 4" x (how ever long I need them) with corresponding V grooves so the expansion and contraction can happen, and they will stay well-behaved (hopefully).
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