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  2. They work well in industry and have some real drawbacks. For safety they need a mechanical means to positively shut them off as they can fail in the closed position more so than mechanical relays which occasionally fail that way. Common method is a lid switch integrated into a safety loop. All hard wired stuff for reliability. Finally protecting the relays themselves requires proper fuses that quickly blow else the relay itself is not protected. Not really a big deal to add the fuses actually and these are becoming so cheap folks may just accept replacing them if the unlikely short occurs in the kiln. Finally thermal management is super important so the size relay you need is fine but requires a whole lot of heatsink to be proper. As a favor and at request we made a video of some of the things it took to design. They definitely have benefits and mostly only come on expensive kilns at this point. Price point for us as a diy design / install was three hundred bucks for two kilns I believe. At some point I will likely do this as a favor for a trusted studio. It’s just relays are so cheap and easy to change quickly I am not sure when.
  3. Thanks very much - it's extremely helpful to know where to start. We'll take take the cover off of the switch box today and see how the wiring looks. I'll also call Paragon about the resistanace so we can check the elements. There's no kiln sitter so we will definitely look into the external controller. At the very least I'm sure I'll learn a lot from this project. Thanks again for the advice! Holly
  4. Looks great, but a word of caution as when we contemplated the PLC version we scrapped the automation part for reasons of safety and to ensure it would be a tool that folks would learn how to fire from. So some of the safety issues, gas valves needed to be spring return closed as is customary under automation, kiln pressure needed to be redundant fairly high precision devices (very expensive) since the pressure is very difficult to measure in a harsh environment and also needs regular calibration. Linear damper actuators needed to default mechanically to some reasonable open position And Mechanically stopped at some minimum position ( all with position indicators so we knew with certainty the position) all topped off with real high temperature limits and a redundant gas valve. Oh, did I mention that redundant O2 probes were even contemplated just because a single reading at some point likely will not be reliable. Other than that, it was an interesting project that turned into a learning tool instead just because the risk to human life was too much risk and one button Automatic operation did not end up to be very positive with respect to folks learning how to fire. Hats off to all your effort, I know we spent a bunch of time learning and perfecting to touch screen level advanced graphics, WiFi, intranet, text alarms, etc...... It was fun but in the end I am happy with the monitor and never would contemplate the automatic version for liability reasons. Oh, FWIW they make 0-10 volt valve actuators actually, spring return closed and they are tested and certified for the use, just expensive. Best of luck, nice project!
  5. Air drying clay is very different. Suggest you buy a small pack for yourself and have a play before inflicting it on your students - lol.
  6. Today
  7. hi all, i'm writing to share infos about my homemade arduino gas kiln controller. I have an homemade 350 liters downdraft gas kiln with 2 venturi burners (using lpg), the controller setup is an aurduino, a stepper motor for controlling precision valve a type k temperature sensor a sdcard for datalogging and a diplay for realtime infos. this is a basic setup, i will add oxygen probe for reduction and a wifi module for remote monitoring. the controller works very well at the moment arrived at 1100 celsius degrees with several ramps with a real temperature error of maximum 6 celsius degrees on the ideal ramps temperature. the code now is a quick and dirty version but it works, i can share it if you want. what do you think about. (sorry for my english!) stepper motor actuator gas valve
  8. Yes, you can thin it down. It may be insufficiently stirred. I find the best way to "stir" slip, is to pour it from bucket to bucket at least 6 times.
  9. Ahh yes, thanks. Hopefully the schedule we gave her is simple enough to program and it looks like she has solved her over-firing issue and can now experiment.
  10. @Bill Kielb they're not overlaps, they're 3 different firings
  11. Nice work! This probably becomes much easier if you measure the draft in the firebox.
  12. Full list of my tests in case they help anyone in future. I have removed all but two hard bricks on the bagwall at the middle and back of flame trench and left the deflectors in place. All tests are with original chimney height unless noted otherwise. I'm going to do another bisque soon with the setup I've retested a few times which gets to highest temp. Damper full open, 2 brick bagwall Starting temp 100 - 5 mins @ 0.5 bar Original End temp 343 Block chimney opening by 3" X 4.5" (24" long) End temp 366 Block chimney opening by 6" x 4.5" (24" long) End temp 386 Block chimney opening by 6" x 4.5" (24" long) Decrease chimney height by 2 courses End temp 358 Block chimney opening by 6" x 4.5" (24" long). One brick bagwall End temp 363 Retest - Block chimney opening by 6" x 4.5" (24" long) End temp 394 Block chimney opening by 6" x 4.5" (24" long) increase chimney height by 2 courses End temp 348 Retest end temp 383 Retest - Block chimney opening by 6" x 4.5" (24" long) End temp 396
  13. I think this comes down to aesthetics, not about being silly or being paranoid. I don’t like leaving an unglazed ring on the plate part for the lid to sit on, especially when I use a dark glaze on my white clay, it just looks wrong. Yes it takes more kiln space to fire them separately but for me it’s necessary to get the look I want. I use my slab roller and scrap clay to make the wasters, really doesn’t take much effort. If it looks okay for your style of work then great fire them together, if not then the wasters are a solution to warping lids fired on their rims.
  14. This. Seems silly to go through all this extra trouble when you can fire them together and avoid all of these problems entirely. You have to leave the portion making contact with the donut unglazed anyway, might as well fire it on the actual part. Could even suspend it with wadding if you're really paranoid.
  15. Why not leave the gallery unglazed-problem msoved -fire them together like most butterdishes-ytake up 1/2 the space always warp together .No issues-if you have to leave the lid a little unglazed inside no big deal
  16. I think you can either raise the amperage capacity of the relay or raise the cooling to compensate. The higher the amperage being put through it, the hotter it gets, so if it's a 30 amp ssr, and you're putting 30 amps through it, you need to have very active cooling. This means fans and heat sink. If you get an 80 amp ssr, and put 30 amps through it, you may be able to get by with passive.cooling Hope that makes sense...when I was shopping around for SSRs I would see one that says 50 amp, but when looking at the specs it was 50 amps at 25 celsius, which could only exist under ideal circumstances with active cooling.
  17. I started in 1976 with a Brent model C-still have it in use today.
  18. Hi Ron, fwiw, I prefer to make (curved lids - flat is different!) lids upside down as well (off the hump for smalls, one at a time for largers), and fire them in set in the gallery or on the shelf, no problems out of round either way (yet). From there, I'll pull and stick a handle, or throw a knob (usually hollow) and stick that. For a small knob, I'll leave a thicker base and just turn it. Other problems, yes, oops, broke it, a bit too small, bit too big, don't like the profile, don't like the knob, etc. ...which is why I try to follow Bill Van Gilder's advice and always make extra lids and at standard sizes. Will have to move boxes of extra lids to storage soon, else target practice? So, I'm curious what solves the problem for you - doesn't look (to me) that those lids are so big and heavy that they can't drag evenly as they shrink and end up round. Nice shape, btw.
  19. If not big producr of scraps, factor it in to your daily potting schedule. Couple of plaster slabs, couple of buckets. A nice way to get the feel of your clay. Less dependence on going down the shop and buying more. Many posts hete on recycling clay. Have a search
  20. Could use these with the heat sink and mount so the heat sink is outside the control box but they are not a double pole relay.
  21. Go for it! You need to be able to cool them, actively. That means using a fan. If your control box is mounted to the kiln, the interior of the control box is too hot for passive cooling. At least on my kiln. I was thinking about using them but measured my control box at cone 6 and it was a balmy 120 degrees, which would not be ideal for passive cooling (heat sink). To me, adding solid state relays, heat sinks and fans was just adding 3 more points of failure, but done correctly I'm sure they would do really well. I just don't trust myself with that
  22. Kicking around the idea of getting rid of the sitter and build in a Genesis 3 zone controller on my Skutt kiln. Looking into solid state relays for a longer relay life span and less issues. Anyone run these on there kiln? I know they cost 3 -4 times as much but if they last it would be worth it. Looking at maybe using there for each zone.
  23. Once it dries it's done. You can turn it back into sodium Silicate by boiling it in lye, but I highly discourage doing that. Very unsafe!
  24. I was afraid of that. Thank you for your help I appreciate it!
  25. The butter is packed into the bottom and is glazed inside and out except the under side. The top is thrown upside down like a bowl then trimmed and a knob added, It is glazed except for the bottom edge so it can sit on the shelf. I could add a thicker rolled rim on the edge but it is not the look I am trying for.
  26. Time to toss it out. I don't know what you use yours for but mostly I use mine for making magic water. When I get a new jar of sodium silicate I mix up a few gallons of magic water and have found it keeps fine for years, unlike the jar of sodium silicate.
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