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High Bridge Pottery

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Posts posted by High Bridge Pottery

  1. G0026 is a weird one, doesn't even really look like the same glaze? Maybe the ink is throwing me off.

    Did you dip them at the same time?  Not sure why the worse clay is a lot better.

    G0027 seems like the one to go with. I would try reducing the silica and/or alumina and see if that reduces the orange peel texture.  The high SiAl is probably doing a lot for how it fits though so may start crazing again. If it does it would be interesting to try your spodumene again and see if adding a little makes it worse or better.



  2. What's the problem with having high LOI? I never found it causes any problems, especially in cone10 glazes. Always found whiting the best CaO flux source. I hate trying to sieve wollastonite so don't use it, clogs up the mesh. and takes me 10x longer.

    The Silica and Alumina look too high for me but interesting to see what results you get. 

  3. Why do you think adding say 0.1 Li2O and 0.1-0.2 B2O3 decreases durability? I think a good mix chemistry is better for durability in most cases. Too much of any oxide is bad for this so it seems a good option. Sure you can make a nice glaze with only Na2O and CaO but why not add some more flux into the dance that can also lower COE.

    I don't know how adding silica or clay is any easier or less complicated than using spodumene and a frit.

    Why ignore the calculated COE values when they line up with tests? The 6.5 crazed less than the 6.7. Even if the numbers are for a theoretical final melt they still have value in relation to each other.  

  4. The last thing I was working on is a bubble free transparent. It's a slightly odd recipe as I was trying to remove any silica or clay. I was also removing zinc because I hear it is bad with some colours, and I don't know how well it reacts in reduction firings. Fired to cone10 oxidation on the tile.


    It is true that you don't need boron at cone10 but I see no negative reasons not to include it. I think your observation that a lot of the recipes are probably more a cone11 is a good one. 

  5. A lot to me is just more than my old commercial kiln would click the relays. I am using mechanical relays so I guess it is much easier to hear it. Do you think as long as you can keep it cool then there is not much to worry about with SSR's?

    In this picture you can see my test, it does wobble a little on the climb so could be much better but it is pretty close. It does get worse as it goes up and I have never tested past 900c so some tuning is needed. I just had no idea how so bodged this way. The big rise/drop is because I didn't code going from on for 60's to off for 60's right and it stuck on so I pulled the control wire. That setup was one big safety issue in the corner of my bedroom. Only tried once, it gave me a headache. 

    421632263_Screenshotfrom2018-05-0122-43-12.png.235ddac7ab5a222379496a4b907f53ab.png IMG_0938.JPG.c68ff783b004f28603bfcf6beac61acc.JPG


  6. On 1/11/2019 at 3:52 PM, jbruce said:

    @High Bridge Pottery Are you deciding if you should turn the relay off or on every 2 seconds?

    Yes.  This is a configurable parameter. The code originally made this decision every .5s and that duty cycle was too high for kilns.  I have heard some folks going as high as 10s.  Since it is configurable, you decide the value that works best for your kiln.

    How did you come up with the PID values to use?

    I read many articles discussing PID tuning.  Some were complex algorithms, some simple.  I tried to find the simplest method that could be done in a few hours.  The process I used is described here... https://github.com/jbruce12000/kiln-controller/blob/master/docs/pid_tuning.md

    The tuning it provided the first time around is good for my use.  If you find a simpler, better tact, post a PR and I'll check it out.

    I read a few things on pid tuning and was very confused on what to do, the one you posted looks a little easier for kilns specifically. I just ended up using the pid code to read the temperature difference from setpoint + actualtemp with  p=1 i=0 d=0. 

    Does 2 seconds not get the relay to cycle on and off a lot? Maybe that has a lot to do with my pid use :lol: I ended up deciding every 60 seconds if the power should be on for 1/6th of the 60 seconds up to 6/6th. That got things to work pretty well and only turn on and off once in 60 seconds.


  7. 14 hours ago, neilestrick said:

     I agree that this is a great thread. No denying that seeing someone build their own controller is very cool. But I do have a responsibility as a moderator to point out things that could be dangerous to others who would copy what's being done here (it's actually in the rules), and for the safety of the person posting.

    The only rule I can find says information is presented at your own risk.

    On 3/11/2014 at 5:49 PM, Jennifer Harnetty said:

    All information is presented as is, and your reliance on any information presented on this site or its forums is at your own risk. Although Ceramic Publications Company may monitor discussions, postings and other user generated content from time to time, we are under no obligation to review material on the web site, and you agree to hold us harmless from any actions based on content that you post or read on these sites.

  8. Ok, if it is saying 10psi input I guess that should be for propane. I don't think natural gas ever comes at 10psi. The only reason I was worries is if you are supplying the burners with a low pressure they wont get 60,000BTU as that is related to the size of the burner orifice and the pressure of gas you are supplying.


    I had no issue using a single control valve before a flat regulator on a 4x burner gas kiln. Actually found it much harder to get an even turn/twist on each burner.

  9. On 7/23/2018 at 6:28 PM, Linda A said:

    I have a 100 pound propane tank that was over three quarters full.  It has a pressure regulator which is set for 4  when tank is turned on.  There is also a further flat regulator between the valve to turn the propane on and before the piping branches out to each burner. Not sure what or why that is there.

    I am still not convinced that regulator is for propane pressure instead of natural gas. I think you need to find out what pressure that regulator is outputting. Whatever it is saying on the gauge wont matter once you hit the constant pressure the flat regulator is outputting.  


    I may be completely wrong as nobody else seems to be worried and it's not a constant pressure regulator.

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