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David Woodin

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Everything posted by David Woodin

  1. The figures I gave you are for self supporting cones or large cones mounted @1 3/4 ". Large cones mounted with 2" mounting height deform approximately 2 deg C lower. As to your other question All the figures are based on the last 100 deg C of firing, a 40 deg C ramp to 1159 deg C should bring cone 4 down Its starting point is 1059 deg C. A 30 minute hold means you subtract 25 deg C from the 1159 deg C = 1134 deg C is its top temp., its starting point is 1034 deg C. So with a hold you fire longer at a lower temperature. David
  2. I usually make a 20 grid but 35 grid would work fine. A = base glaze + 8% Iron Oxide: B same base glaze + 8% Iron Ox.& 10% rutile; C same base glaze no colorant: D 10% Rutile. This gives a line blend from A to C for iron; A to B iron stays at same value but it cross blends with Rutile :C to D line blend for Rutile: This line blend cross blends with iron B to D. This is impossible to explain but the top row 1 thru 4 Iron is 8%, but 2 to 4 rutile is #2 = 3.33%R + 8% Fe,# 3= 6.67% Rutile + 8% Fe, # 4= 10% Rutile + 8% Fe. Anyway it is a good method for testing 2 colorants and depending on your base glaze you may get some rutile blue. take a look at www.matrix2000.co.nz David
  3. Have you ever tried taking a glaze that you use and run the Currie method on it? You may be surprised that there are many more good glazes in the grid. Also there are some other very good ways to test colorants. David
  4. cone 4 @72 deg F ramp is 2118 deg F top temp. a 30 minute hold is -45 deg F. ( reduce the top temp by this much) or 40 deg C ramp to 1159 deg C top temp. 30 minute hold -25 deg C cone 4 down 90 deg. David
  5. If cone 5 is down or 90 deg bend than Cone 6 shouldn't have deformed at all. Cone 6 at a ramp rate of 108 deg F/hr would start to soften at around 2195 deg F but cone 5 would have been down to 90 deg bend at 2167 deg F. As far as your glaze goes it probably doesn't care, probably cone 5 1/2. David
  6. Before changing to zone control you could try a slower ramp rate for the last 200 degree's of firing. If interested I could give you the top temperature you would fire to if using say 75 deg F/hr. You would need to make your own user program. David
  7. If the cone is down the cone is down right? and the heat work has been reached. I thought the slow down was because orton know that going 150deg/h till X temp or 60 deg/h to X temp for the last two hours achieves the cone/heatwork. On the Orton chart it says "heating rate deg F/hour (last 200 degF of firing)" or" Heating rate deg C/hour ( last 100 degC of firing)" I decide on what user ramp I want to use, usually less than 108 deg F/ Hour and as long as I use this ramp for the last 200 deg of the firing than the results are very close to what the cone calc. program says it should be, this also allows me to forget about a cool down firing unless I want to enhance a matt glaze surface David
  8. Yes it is almost impossible to glaze vitrified pieces properly. But you need to fix the sitter first. You didn't mention how you shut off the glaze firing. The sitter is suppose to be a safety device. Did you use witness cones to shut off the glaze firing? You could google Dawson kiln sitter and get information about the sitter and how to adjust it, plus repair parts. David
  9. 200 deg F below the final top temperature is what most controllers use as the starting point for the last ramp of 108 F/hr ramp to final temperature. For example Cone 6 down is 2230 F, so you start that last ramp of 108 F/hr at 2030 F. But suppose you wanted the final ramp for cone 6 down to be 80 F/hr? My original post was asking if anyone considered using a different ramp. There is a cone calc. cd that tells you. A 80 F ramp for cone 6 down is A TOP TEMPERATURE OF 2218 F therefore the last ramp starts at 2018 F. I find that this enhances the fired surface and seldom am bothered with pinholes, also it is easier on the kiln to be using a slower ramp rate. David
  10. I think you might want to slow down between 600 F and 1200 F for the bisque firing David
  11. Does anyone try to use ramps other than 27 F/hr, 108F/hr and 270 F/hr? when programing to cone 6. I am sorry I didn't ask this question very well. There are times I want to go slower than 108 deg F for the last 200 deg F. Recently I contacted Orton and they sent me a CD of their Cone Calc. program so now I know what to put in as a top temperature. The feature Neil mentioned is great but only puts in the values for 108 F/Hr, but it will be like a regular cone program. A vary fire program doesn't sense how fast the kiln is going etc. So I guess if anyone wants to know what the end temp is for various ramps, either ask Orton for the CD or I can put in the information you want to know. David
  12. One half cone difference top and bottom is considered quite good so you must be doing things right. Do you use the cone program or have you made your own program? David
  13. Hi Marvin, You can add T/C's and rerout the wires to the relays from the board, you also need some type K extension wire for the new TC's You will need the code to get in deep enough to reprogram for zone control, unless that has allready been done and single zone was chosen for your kiln. Look at the posts on metal spitting from thermocouple, I am not in agreement about using a mullite protection tube and the offset you have to put in the controller. I don't have any offset on mine, and get great results. My thermocouple is in a metal Omegaclad tube. David
  14. If you are in need of a kiln, get one of the manual kilns that is in good shape and add a controller to it, or make your own on the wall box with a Barlett V6-CF controller and with some creativity make a 2 or 3 zone controller for your kiln. David
  15. I think rather than taking up the forum's time it would be better to contact me off line hdwoodin@gmail.com The kilns I have didn't have a controller so I decided to buy one controller and use it to control three different kilns. I also would need a picture of the inside of the control panel. David
  16. The model I suggested and use doesn't need a protecting tube and therefore has a high response time and needs no offset for the lag of a large mullite protecting tube. If you were to go with the Omega you need a way to mount it and I can tell you what I use. The DH-1-8-K-12 is a replacement thermocouple for what you now have except it is 12 inches long you would have to cut it shorter. The other web page I couldn't open and probably shows a complete assy. with protecting tube. So yes you are getting into deep waters. If you want the mullite protecting tube, you might ask Olympic about it and tell them of the problems you are having. As to how long does the one I use last, I have some in use since 2009 but I am not a production potter. David
  17. It is not that expensive, 1 or 2 thermocouples some wiring, the relays are already there so reconfigure controller to zone control , If it is a Skutt talk to Mike. David
  18. Euclids recommends firing to 1922 F peep holes open hold for 8 hours. That is what I have been doing and it is almost as good as coating with ITC 100, a lot cheaper too. David
  19. I am glad to see that L & L has addressed this situation. There tests didn't mention if they tested Omegaclad which is not Inconel. It would be a lot easier to use what L&L or some of the other kiln mfg use that have protecting tubes, because of trying to adapt connections to the various controllers. One big plus for me with the Omega is the rapid response of these 1/4 inch diameter thermocouples and 150 firings is a very conservative estimate. David
  20. Go to Omega.com type in part # KQXL-14U-6. This is 1/4 inch diameter by 6" long and enclosed in a high temp.sheath I usually get between 120 and 150 firings out of this. When it fails it fails fast so the accuracy stays stable with no drift until a pinhole develops in the sheath. I use them in gas or electric kilns. Your spare from Olympic costs $45.00 this costs $38.00. As far as flaking goes you will eventually see some black area under the probe on the shelf but you normally don't but a pot under the thermocouple, and it is only into the kiln about 1 1/2 inches. You may not like the quick connect junction they have another transition junction with extension wire. I use the ungrounded just in case there is electrical noise being picked up. You can always talk to someone about it at Omega. David
  21. Your thermocouple is contaminated and that is what happens to a type K exposed to the atmosphere in a kiln. You need to replace the thermocouple. The T/C mounted in the top of the kiln is going to flake all over the kiln like it has. If you are only firing in oxidation you might consider using a protecting tube, but that tends to slow down its response. You don't have to be using a 8 gauge T/C. You can get a 14 gauge element in a protecting tube that would be about the same size and last longer because of the protecting tube.. Check www.omega.com Almost all kiln manufacturer's use open thermocouples and they are prone to this problem. If you want to respond to me directly hdwoodin@gmail.com I use a high response type K in a protecting tube. Is this a gas or electric kiln ? What is the model number maybe the thermocouple can be relocated? David
  22. I asked Skutt if there is a kit to upgrade a Skutt KM1027 240 vac to zone control. Mike Sievers, mike@skutt.com answered, and yes there is. David
  23. The kiln sitter was designed as a safety device and never meant to be the primary method to shut off the kiln. That is why kilns have peep holes so you are suppose to set cones so you can see them and manually shut off the kiln when the cones are where you want them. Unfortunately it is not easy to see the cones but a high power halogen flashlight will help. David
  24. Wouldn't it be easier to add zone control to the kilns that don't fire evenly enough? I have 3 electric kilns and have made them into zone control myself and am very pleased with the way they fire. The Bartlett V6-CF series 700 controller has the capability for up to 3 zone control built into it, you need the code to change to zone control, plus parts. Euclids sells everything you need. Another control problem is due to the open end type K thermocouple which is getting contaminated, it may be cheap but not that reliable. Omega makes a much better high temperature enclosed high response type K T/C, I get at least 125 or more firings from this type. David
  25. Before the vent you had stagnent air now you have some air movement. If you want to continue to use your program, change the last hold time to 15 minutes with vent on. This doesn't explain why the cone fire mode didn't work all though you could add some hold time to it, like 10 minutes. There maybe something the Skutt tech can see from this latest information. It looks like the T/C is reading correct but there may be a problem with the cone 04 offset if the number starts with 9 it is negative, if it start with 0 it is positive. David
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