jbruce Posted January 19 Report Share Posted January 19 I'm the author of an open source kiln controller project. A recent feature request is Cone Firing Mode which most private companies offer in their controllers. I need some help in understanding cones and my mental model of them. I know very little about cones other than reading what manufacturers [like orton] make available for public consumption. Here's what I've done so far: I've used python to simulate a cone such that for a cone with the 3 rates and corresponding maturation temps as input, I can find the maturation temp for any heating rate [within reason 10C/hr through 300C/hr]. I use some math libraries to curve fit the three points. The fitted curve equation can be used to get the maturation temp for any rate. When I iterate over all the reasonable rates [like 15C/hr to 250C/hr] by 1 degree C for a given cone [like cone6]... for each rate, if I calculate the total heat work using a 2s cycle time [so that's 2 seconds X temp for that 2 secs] iterating every 2s from 1 hour in the past to maturation [to get the total heat work for those 1800 samples], I get a deviation of just a few percent across that for total heat work comparing different rates. This few percent equates to a minute or less actual firing time. As an example, here are two different heat rates for a cone6 cone... name,heating rate in C/hr, maturation temp, temp to start measuring, total heat work to bend cone (in degrees C X secs) cone6,30,1203.09,1173.09,4277147 cone6,89,1230.61,1141.61,4270090 So this data says when I heat at 30C/hr from 1173C to 1203C [cone fully bent], the cone6 cone absorbs the same energy as when I heat at 89C/hr from 1141C to 1230C [cone fully bent]. I can get these stats for any rate. The difference in total heat work (4277147 and 4270090) represents just a few seconds in kiln run time for these two examples. I think having total heat work numbers so close validates the model. Using this ability, I think I can examine a profile and estimate the spot in the profile when a specific cone would bend. A proper estimate requires only a constant heat rate during the last hour. Does all of this sound valid? or way off base? Quote Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 19 Report Share Posted January 19 2 hours ago, jbruce said: As an example, here are two different heat rates for a cone6 cone... Just an idea I would suggest following the Orton model. Heatwork prior to the last 100c / 200f is not relevant. Cones have been tested and derived for the final segment at a certain firing speed. This should be easier to code and maybe allow for offsets or a cone table that could be tweaked per application as needed. Work done prior to the fluxed reactions begin is basically reversible and not nearly as important to where the cone will melt. Quote Link to comment Share on other sites More sharing options...
Dick White Posted January 19 Report Share Posted January 19 The Bartlett and Orton controllers have an algorithm (designed by Orton, licensed to Bartlett, so both have it) built into the cone-fire mode that senses actual heating rate (which may or may not be what was programmed) and adjusts the final temperature for the intended cone bend. As @Bill Kielb notes, the Orton tables focus on the last 100C/200F, and the published cone-fire firing schedules for Bartlett controllers all start the final segment at 250F below target temperature regardless of cone or rate. In my kilns which are all performing well, the Genesis logs show this happening as programmed; the final ramp at medium speed is a straight line at 120F per hour. What I do not know is, if the kiln were faltering in the final segment, does the controller average the achieved rate over the segment, or adjust incrementally as the segment progresses. In some of my diagnostic work with others' failing kilns, the rate of increase may be reasonable at the beginning of the final segment, but slows down significantly by the end of the segment (i.e., the graphed temperature is a curve, not a straight line) so how does it calculate the appropriate end point? What does this mean for your programming? I don't know, just throwing it out there that many potters think that if the controller finished without an error code, their kiln is in good shape, when it is not. The controller is working around the kiln failure. You'd like to mimic that, which is awesome. Quote Link to comment Share on other sites More sharing options...
PeterH Posted January 19 Report Share Posted January 19 It's just possible that the work mentioned here has some relevance. ... but I've never been able to find more details. It doesn't seem to be mentioned here: https://sure.sunderland.ac.uk/id/eprint/2824/1/NCECA_2012_Program.pdf https://issuu.com/nceca/docs/2012journal Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.