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Found 5 results

  1. The facility in which I am working is currently awaiting the prolonged install of a replacement gas reduction kiln. In the meantime they have been firing cone 10 oxidation in a Paragon Viking 28, single phase, with a max temp of 2350F. It is hard wired to what I've been told is the appropriate amperage. When I was brought on board the kiln was failing to reach cone 10 and giving the FTL (Fired Too Long) code. At that juncture when we opened up the switch box the top segment of elements were slightly brown, we tightened the brass bits and the pigtails, all the elements were testing okay, as well as the relays. We fired the kiln with a load of only furniture and it reached temperature. So we fired it again, it didn't reach temperature and displayed the FAIL code. Replaced the thermocouple, and opted for a Type S model because it is rated for porcelain and stoneware temperatures. Reset the controller to the Type S model. Fired the kiln twice and FTL'd on the second firing, then replaced all the elements. The kiln fired perfectly to cone 10 for the next 7 firings. The alarm sounded at around 2100F on the 8th firing even though the alarm was maxed out and set to 9999. We hit enter on the kiln, stopped the alarm, the firing continued but did not reach temperature according the guard cones, but didn't give an error message. After it was unloaded the temperature was giving sporadic readings. Checked the wire connections, then tested the controller with a paper clip and it gave a room temperature reading. Opened the switch box and discovered that a fuse had blown. Replaced the fuse and the kiln fired perfectly for another 4 firings. On the 5th firing the alarm sounded around 2100F again, pressed enter, continued to fire and it failed to reach temperature. Turned the kiln off to run tests and check wire connections which everything appeared to be okay. Turned the power back on and now is showing TC2- (code for a failed thermocouple in the center two terminals of a multi-zone kiln, although can appear in a single zone kiln apparently) . The thermocouple is only 6 months old and has been through less than 15 firings. I have personally loaded and unloaded 90% of the firings since the thermocouple was replaced and I am highly cautious about staying clear of the thermocouple. I know that it is a very fragile thermocouple. It ultimately could be broken. Replacement has been ordered and its on its way. We are in the midst of an extremely busy term, with high volume, glaze ware is stacking up and I have a deep seated fear that the thermocouple may not fix the ongoing problems. If a mercury relay goes out can the kiln still run? Is there another major component of this model of kiln that could be perpetuating the alarm sounding, under-firing, causing a fuse to blow, ruining a fairly new thermocouple? What could have caused the wires connecting to the elements to brown? Could their be a connection between the browning of those wires and a bigger issue? I'm at a complete loss, and would like to get some preemptive feedback in case the thermocouple does not fix the issue, or the errors persist even once the thermocouple is in place. ~Worried Clay Worker -M. Williams
  2. Some advice please...... My thermocouple blew on my last glaze, so we had it replaced. I ran a glaze yesterday and the results are disasterous. My kiln does not have a programmer attached so I watch and set temperature and the other thingy manually. I fired to 1200oC watching the temp gauge and manually stopped at 1200oc with a 30min soak. Shut down the kiln, temp guage 0, the other thingy (heat ramp) to 0, switched the power off at the electrical connection (3 phase) and then went to bed. Went out at 5am to see the temp. Switched on at the plug and the temp indicated 500oC. I could not see the cones and assumed that the kiln had overfired a bit. When the kiln came down to 200oC I opened the peep hole and saw two pots welded and one off kilter. Never quessing that everything had melted. 3 out the 4 shelves have cracked into pieces. The top shelve has slumped down. The thermocouple is about 30cm higher than the ware on the top shelf. I haven't been able to remove anything yet but it seems as if the elements on the side are ok, I don't know about the element on the bottom Can anyone help me with the checking of the temp and how should I conduct the next fire. Andrea
  3. I've been reading Clay and Glazes for the Potter by Daniel Rhodes as well as Mastering Cone 6 Glazes by Hesselberth. Reading these and watching my own firings got me to thinking... How long do thermocouples last? Mine has been fired 125 times. I think it's (I don't have my kiln log in front of me for exact numbers) 55 cone 04 slow bisque, 55 cone 6 slow glaze, 15 cone 05 fast glaze (transfers). And How do you know when your thermocouple is starting to have issues? In my last couple of firings I have had a couple of pieces develop pinholes. I'm trying to remedy this issue since I have never had it before these 2 firings. I am using the same glazes as I have been. I know it might be my bisque firing as well. To fix pinholes at what temperature should I add a hold to burn out the issue? Just a hold at the end temperature? It could also be that my thermocouple is drifting because it needs to be replaced. The cone 6 before this load did not look over fired but this cone looks a little towards the over fired range. It could just be where it was placed or something. If I run a test load through at cone 5 should I add a hold at the end temp? If so for how long? In this last load I also had a couple Amaco Blue Rutile pieces in there and they seem more brown than blue than they usually are. This can also happen if I have the glaze too thin so am not sure if Blue rutile runs brown if over fired. Thank you for helping me answer these questions.
  4. my new kiln has jusr been delivered, not out of the bubblewrap yet. However as my supplier was also squeezing in some underglaze I was waiting for , I took out a couple of little boxes from under the kiln. I had ordered a kiln with a Harco controller attached to the kiln. there was a choice of controller a Harco or SHi something. In one of the boxes there was a free standing, well it isn't attached, but 4 pronged plug Stafford controller... Now before I ring the dealer, does anyone know both to compare the quality for me? On the outside of the bubblewrap is the label...kiln with Stafford Controller... I live on an Island, I have left the delivery of this kiln for a few weeks as I was away initially and then up to my eyeballs with no time to prepare for the delivery. From factory to dealer then to me on Island, nearly $1000 freight so.... Advice on the quality of the cocntrollers would be good. Advice on whether to go further with this would be good. Harco Type r thermocouple, over $2000 here, but haven't isolated the price from the quote yet, but in that ballpark. Babs, bit anxious about the whole thing.. Not contacted by factory or dealer re. different controller to what was ordered.
  5. I need to widen the hole for the thermocouple in my kiln, since I want to replace the old thermocouple with a thicker one (the original is 3mm in diameter, but local pottery supply place only has 13mm ones). Any advice on how to drill without chipping the brick or creating more than the minimum amount of dust? The existing hole in the metal jacket is large enough to accommodate the new thermocouple, so I don't need to drill through the jacket. Am I right that a slow drill speed is best? Should I wet the brick and drill from the inside out? My kiln is a 3.3 cubic foot toploader, so drilling from the inside may be a little awkward.
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