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Tim Allen

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About Tim Allen

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    http://www.thorpeallen.com/

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  • Location
    Keene, NH / Boothbay Harbor, ME
  1. I wasn't there, but two techs from our gas supplier showed up this morning, and Wendy showed them the kiln. Not something they deal with everyday, so they were very interested in it. They observed that the pilot was a "lazy flame," took the assembly apart and noted that it did not appear to have a gas orifice. They called Olympic to find out if it was supposed to have one and to get the specs, then one of them went looking for one in their truck. Meanwhile the other tech looked around on the sheet metal under the kiln and found the one that had somehow fallen out. They installed the orifice in the pilot assembly, and it works! And we don't have to tape the red button down to keep it running, either.... They did recommend some maintenance on the whole pilot bar assembly.... we have a problem with the bar burners getting "coked" up with carbon deposits later in a firing (when the main burners are turned up), which I think might be due to gas density effects changing the mix ratio as the propane tank ices up, and thus the supplied gas is colder.... We should probably get a larger tank or a dual tank set-up to reduce the freeze up.
  2. Update: Swapping thermcouples sounds simple but they have different lead lengths, so the TC from the left side would not work on the right side. Leaving the TC's in place and just swapping them at the valves would require swapping the pilot system gas plumbing at the valves as well.... with already formed tubing cut to length, that would be a lot of work. So we got a new thermocouple, and got that installed (see my other thread on removing the old TC). Started up the left-side pilot system and it was immediately obvious that the pilot flame on the TC was crap. Adjusting the needle valve on the gas TC pilot gas supply offered no improvement. Still had to tape the red button down to keep the pilot burning, but gas was flowing through the valve, so we started the pilot system on the left side (much better pilot flame on that side), and then lit all six main burners to "candle" the kiln for a bit to try to dry things out. Everything was looking good, except for the crappy pilot flame on the left-side TC, but the kiln was running, so we started the firing. We check on it every 15 minutes, and on one of those checks after about two hours, we found the kiln had died. We tried to re-light it, but gas would not flow through the first BASO valve anymore. Wendy took apart the gas supply to the left side TC pilot flame, blew everything out with compressed air to clean it all up, put it back together, but no joy -- the pilot flame was still all yellow, no blue.... So either there is some sort of problem with that pilot "burner" still, or the problem is within the BASO valve -- not supplying the right gas pressure or something. We are still having to tape the red button down to keep the pilot flame burning. Our next step is to get a tech from our gas supplier out to take a look to see if they have any insight (a delivery truck driver from the company was filling a propane tank at our house when we tried firing the kiln last week, and he offered some helpful suggestions then). The kiln is still loaded with "unfired" wares (it only reached about 700F before quitting -- we fire to Cone 10).
  3. I finally figured this out. I pulled and pulled, and not only the thermocouple but the socket into which it is inserted. The socket was press-fit into a hole in the angle-iron mount. It has knurled (ribbed) section that was the press-fit, the other end is internally threaded and has wrench flats. Initially I had thought those wrench flats were a "nut" that was securing the thermocouple in place, and had tried valiantly to unscrew it -- before I figured out that this thermocouple was this snap-in style. It turns out that my wrenching had deformed the socket fitting enough that it was no longer round, so the thermcouple wouldn't come out. I squeezed the socket fitting in a vice to try to get it back to round, go the thermocouple out, made some more adjustments to the shape of the socket fitting so that a new thermocouple could be inserted. Then I devised a screw-press to press the socket fitting back into place (although now it is a bit loose....). Anyway, this part of my problem appears to be solved.
  4. Heh heh. Wendy ordered a new thermocouple from the local distributor -- she'll pick that up on Monday. So we will try again on Tuesday. Re-arranging the order of the valves in the valve train seems like a big job, and if we are going to go to those lengths, I would probably just get a new valve to replace the troublesome one -- if a new thermocouple doesn't resolve the trouble....
  5. Hi Bill, The fuel gas is Propane. I am not sure the photos capture the flame colors accurately. The thermocouple from the troublesome left side gave an open circuit voltage of 30 mV when heated with the distal end of a MAP torch flame, and about 24 mV when heated by the regular pilot flame (red button taped down to allow gas flow to the pilot, end of thermocouple removed from the valve body for voltage measurement). These measurements after some minimal cleaning of the tip. Not sure how I would measure the closed circuit voltage? I guess I would need some kind of connector to insert between the valve body and the end of the thermocouple that would allow me to insert the probes from my mulitmeter?
  6. FWIW, this is an Olympic DD-12 kiln. There are two groups of 3 burners, one on the left side and one on the right. Each group of burners has it's own pilot "bar." Each pilot bar also has associated with it a thermocouple with it's own dedicated pilot flame (separate from the flames that come from the pilot bar to light the burners). All six burners are fed from a single manifold fed through a chain of four valves: (1) electric valve powered by a set point controller; (2) BASO valve for the left side pilot assembly; (3) BASO valve for the right side pilot assembly; (4) manual valve for controlling flow to the burners. Here is a picture of the pilot/burner arrangement on the right side of the kiln (although it is the left side that is giving me trouble right now). The pilot "bar" is the horizontal pipe with all the little holes emitting small flames. The thermocouple and it's own flame are mounted to the angle just to the right of the front-most burner: And here is a picture of the valve chain (in which you can also see some of the left side pilot assembly). The angled venturis are the ones that feed the pilot bars. Each of the BASO valves has two gas leads, one for the pilot bar burner, and one for the separate flame powering the the thermocouple. Both supplies have needle valves for adjustment. It's the first BASO valve (and it's associated thermocouple) that's giving us trouble right now. We first fired this kiln in late March 2014, and have fired it approximately twice a year since then. It's outside in a metal shed, but with a gravel floor (we put the sheet metal down on the ground to try to prevent dust from getting sucked up into the kiln. The kiln legs are resting on steel plates to spread the load over the gravel.
  7. Relatively old. I think the thermocouple is delivering "marginal" voltage -- enough to open the main valve (sometimes), but not enough to keep the pilot flame burning (if that makes any sense).
  8. Thanks for this, which is what I wanted to know, and confirms a hypothesis I had, and helps me focus further troubleshooting efforts.
  9. Hi Fred, thanks for your response. The thermocouple rotates freely inside the spring clip ring which is stationary in the socket. There is just enough of the spring clip ring exposed that I can just see the bases of the spring arms peaking out from the socket in which the thing is inserted, but not really enough for me grab hold of (of just the spring clip ring) with some vice-grip pliers... The socket, by the way, is probably internally threaded for a screw-in fitting.... an identical socket (at least in external appearance) is used to receive the tubing that brings the gas to the pilot flame) Suspect I just have to get a tighter grip on what I can with my vice grips and just tug harder!
  10. The pilot system on our gas kiln is equipped with K15F Snap-In thermocouples, with little spring loaded clips that hold them in place: It looks like I should be able to just pull them backwards out of their holders with a good tug, but they are not coming out easily. Do I have to somehow depress those little spring clips in order to get then out, or just tug harder? Thanks, Tim
  11. Does anyone know where I could find a schematic of the internal workings of a BASO valve? I just want to understand how it it supposed to work, I'm NOT proposing try to repair it myself.... Obviously when you press the red button, that opens up gas flow to the pilot system. But does that also open up flow through the main part of the valve to rest of the system downstream? Or does that part of the valve only open when the thermocouple is sending voltage, and the magnet moves? If the thermocouple IS sending appropriate voltage, why would the pilot system shut down when you release the red button? If you are getting appropriate voltage, isn't the magnet supposed to move and keep the valve open even once you release the red button? I've read about, and tried, "poking" the magnet by spiking the voltage, heating the tip of the thermocouple to red hot. I've cleaned the contacts between the thermocouple and the valve body. I've check the thermocouple for appropriate voltage, and I've done some cleaning of the thermocouple tip (but maybe could do more). Something is still not working right..... So back to my may question: Does holding the red button down open the valve to gas flow through to downstream of the valve (not just to the pilot system)? Thanks for any ideas. Tim
  12. That's where our electric kiln is located, in a detached garage. No vent system in the current installation, we just open the door. We only use it for bisque
  13. If you were to continue monitoring the temperature every 30 minutes during the cooling phase, and then graph your data, it would probably look something like this: Marcia's right on about the lack of thermal mass having a significant role in your case. Also, just in general, smaller kilns will cool more quickly than larger kilns, because the smaller kiln will have a larger surface area to volume (mass) ratio -- cooling is primarily due to radiative and conductive/convective heat losses to the air at the outside surface of the kiln. Leaving the peep holes open will facilitate convection of air through the kiln interior (somewhat), but that will have only a marginal impact on the overall cooling rate, because peep holes tend to be small. Still, if you want slow cooling, leave the peep holes closed. (Leaving the damper and burner ports open on a fuel-fired kiln will have a larger impact on the cooling rate, because those openings are typically much larger.)
  14. We have a business insurance policy for general liability and other business losses (e.g. lost product if in an accident on the way to a show, etc....), but that also covers our detached garage where the studio and electric kiln are located. One thing our independent agent did was to set us up with our business policy, homeowner's policy, auto policy, and umbrella policy all from the same company, so that there would never be a question as to which company was responsible should there ever be a claim. (fwiw, the company is Maine Mutual Group, which does offer coverage in NH and some other states as well as ME).
  15. Ron, 8% apr on $5K over 24 months would result in a total payment of $5427.27 (or only $427.27 in interest, vs. the $2400 mentioned above).
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