newps

Hi Mark, I would be interested to give that a go as well. Don't know how MS OneDrive works (i'm on a mac) Newps

Hi Ken, My first thoughts are that the issue is really due to the Max31856 controller not getting set up by the program properly. but that will depend if you have the Adafruit_GPIO module installed and it was working. I can't get it on a totally new build SD card as that module is deprecated. My other thoughts are that as you are using a K type thermocouple the Max31855 tc amplifier would be better, mainly because I believe many more of the kiln-controller users are using the K-type and max31855 set up and the problems with it have been resolved. I have to use the 31856 because I am stuck with a S type thermocouple in my kiln. It is an interesting thought to use this program for lost wax casting of silver, I would be interested to know more of how you do it. my experience was a small domestic oven to melt the wax out and then heating the casting flask with a blowtorch before pouring the molten silver into it.

Hi Mark, Like you I have been using the max31856 with S type thermocouples for about a year, I did have a problem before christmas when during a firing the temperature appeared to drop drastically, over 200C and at one point was suggesting the kiln was at 250C but it was glowing redhot through the peephole. Investigation showed that the max31856 was reporting a cold junction fault, but for a range of reasons that was not being picked up by the pi with the code I was using. Are you using the version of max31856.py that is on Jason's GitHub? If so where did you get the Adafruit_GPIO from as its deprecated now ? I tried to download a copy but could only get a version for Python 2.7, and it did not seem to work with Python 3.7 or 3.9 which is why I have resorted back to my old code and the 2015 Stephen P. Smith version of max31856 rather than the 2109 version by John Robinson. Part of my earlier problems seems to be my thermocouple offset was -8C which apparently is a problem for the max31856, my understanding of the chips data suggested the offset should be between +7C and -7C

Don't know why I used the :8081 to start with, possibly just because I saw it in "Client Access Click http://127.0.0.1:8081 for local development or the IP of your PI and the port defined in config.py (default 8081)." It would appear that you could choose another value if you wanted. Let us know how you get on with the Adafruit 3263 (MAX31856) on the current code as I would like to update to the newer version . What type of thermocouple are you using?

I assume that when you say it works fine on local ras.pi you mean that you can control it from a keyboard, mouse and screen attached to the actual RasPi. To work remotely you need to know the local IP address of the Pi . Heres how to do that If you have a Raspberry Pi OS with Desktop installed on your Pi, you can easily find your Pi's IP address by hovering your mouse over the network icon (two arrows) in the top-right corner, next to the clock. An information panel will appear showing your Raspberry Pi's network connections. Mine is on a ethernet link and comes up with eth0: configured 192.168.0.199 To remotely access the pi from a web browser on another computer/phone/tablet the other device must be on the same network as the Pi and you just type i the appropriate local IP address into the browsers address bar. So in my case i put in http://192.168.0.199:8081 and it comes back with http://192.168.0.199:8081/picoreflow/index.html in the address and the display below.

Hi, the Adafruit 3263 uses the Max31856 chip, which in their infinite wisdom Adafruit have deprecated the Adafruit_GPIO software module, to introduce their Blinka software module. That would require quite a large rewrite of the code. see this link https://github.com/jbruce12000/kiln-controller/issues/55 I have been using the same Adafruit chip for a while and used an earlier version of this program, but I had to find my own software module for the Max 31856. I recently tried upgrading to the newest version of the RPi OS and of the kiln software and it wouldn't run. No error messages or anything on the screen when I tried to connect to the Pi. I am using one of the early Pi model B (GPIO pinouts are slightly different) I have gone back to the Buster version of RPiOS and my old code and it appears to be working.

prior to this rebuild i only had the python 3 version and that worked (python 3.7) the rebuild with Bullseye is Python 3.9. I have gone back to the legacy Raspberry Pi OS (Buster) and now have my system back up and running. It appears that it was an issue with a gmail account on the Pi that caused everything to crash. Its currently an older version of kiln-controller that I am using. Thanks for everyones help and comments. Now to get organised for a firing

Just had some feedback about this Suggested that I look at https://github.com/jbruce12000/kiln-controller/issues/55 lt appears that RPi.Gpio has been depreciated, and there will be a new library at some time that will require major changes to the code. One of the suggestions in the article is ".... until that happens you should use something like a raspberry 3 with older code, I.e. buster." And it appears that that solved their problem - hope it will solve mine

Having looked at the discussions on " ModuleNotFoundError: No module named 'RPi' " and some of the solutions I have followed the suggestions for ensuring it is installed, and also tried the code looking for rpi rather than RPi to no avail. I may have to resort to the manual firing, but even for a manual firing the kiln-controller software was good for remotely monitoring the temperature - the old manual controller is very crude and does not show the current temperature

Hi all, I have just done a rebuild of my system, and couldn't get the backup of my older version to run, some issue with permissions, I think because I saved it on a mac and that messed up the permissions. I have therefore just done a complete rebuild following all the instructions on GitHub (copy and paste) when I come to reboot the Pi it was not running the kiln- controller , checking daemon.log I found the code below suggesting a file is missing. Should it be part of the Github cloning, or do I need to get it from elsewhere and if so where. I should point out that I am using a max31856 and s type thermocouple and have uncommented the appropriate lines - are there some other lines I should comment out? Would appreciate a quick response as I need to get bisque and glaze firings done in the next couple of days for a special Christmas present Dec 11 14:22:43 raspberrypi python[250]: Traceback (most recent call last): Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/kiln-controller.py", line 44, in <module> Dec 11 14:22:43 raspberrypi python[250]: oven = RealOven() Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/lib/oven.py", line 381, in __init__ Dec 11 14:22:43 raspberrypi python[250]: self.board = Board() Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/lib/oven.py", line 47, in __init__ Dec 11 14:22:43 raspberrypi python[250]: self.create_temp_sensor() Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/lib/oven.py", line 75, in create_temp_sensor Dec 11 14:22:43 raspberrypi python[250]: self.temp_sensor = TempSensorReal() Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/lib/oven.py", line 107, in __init__ Dec 11 14:22:43 raspberrypi python[250]: from max31855 import MAX31855, MAX31855Error Dec 11 14:22:43 raspberrypi python[250]: File "/home/pi/kiln-controller/lib/max31855.py", line 2, in <module> Dec 11 14:22:43 raspberrypi python[250]: import RPi.GPIO as GPIO Dec 11 14:22:43 raspberrypi python[250]: ModuleNotFoundError: No module named 'RPi' Dec 11 14:22:43 raspberrypi systemd[504]: Queued start job for default target Main User Target. Dec 11 14:22:52 raspberrypi systemd[504]: Created slice User Application Slice.

@Bill Kielb, I really appreciated the explanation and wish I had been given one like that in the past. If I understand your explanation correctly if my kiln struggles to do 60C per hour at the high temperatures but can manage 15C per hour should I use 1185 rather than 1222 for a cone 6 firing?

Can we have some feedback on how your 1260C stoneware burn has gone

Its interesting to hear your comments about thermocouple accuracy, even if the Pi results are a few degrees out they still allow me better control. With my original controller, you set the max temperature with the dial switch that only gave 20 degree centigrade divisions, and regulated the heating with a 4 position energy regulator. There was no way of finding the current temperature other than backing the controller off until you heard the controller click off. Yes I could have got a new controller, but the Pi route allowed me to cheaply and quickly work out if the kiln was worth keeping.

Thinking about it, whilst it may seem excessive to set up a Pi on each kiln, I had to calibrate the PID values for my kiln experimentally, as, if you have 2 kilns unless they are both the same you would may find the settings for one do not work well for the other. 2 Pi's would allow each one to be calibrated separately. You also have to consider that many people appear to be using type K thermocouples, I believe that you are using a platinum/rhodium thermocouple (type R or S) like me, in which case the voltage produced from the thermocouple hot junction is about 1/3 of that for a K type , so I think Bills comments about all the extra junctions affecting the reading are very valid. It is possible to add a few lines of extra code to the Pi so that it automatically will produce a CSV file with all the firing details, and this can also include the kiln details, so 2 Pi's would allow you to have better firing logs.

Thats essentially what I have, partly so that I can quickly restore the kiln and controller back to original. However my controller is a based on a device like that shown below, but calibrated to about 1400C with an S type thermocouple I am still using the contactor rather than a SSR. I am told its a no-no . Give me a bit of time and I will try and do some circuit diagrams and photos. for me there didn't seem to be any problems, but the old controller seemed to be about 40C between switch off and switch on. it may actually have been less than that . In my case the original controller is about 1m from the kiln, and then the wires to the Max31856 are about 300mm long screened cable attached onto the back of the original controller.

What is the range of the wifi like?, with my old Pi I am using a TP link to get the ethernet back to my wifi router, but then the kiln is in the garage at the end of the garden.

That's 2 of us have got a Max31856 version of the code up and running in the last 24hours. Mine is based on a much older version of @jbrucecode, and in my case the culprit turned out to be a log.info statement added to track progress that was incorrect and prevented the oven code running, frustrating how long it took to track down as the error messages were suggesting the problem was with geventwebsocket, ERROR ovenWatcher: could not write to socket <geventwebsocket.websocket.WebSocket object at 0xb4c50880> @MarkTilleswhat type of Pi are you using?

I used the following for my Max31856 https://github.com/steve71/MAX31856/blob/master/max31856.py to prove I could communicate with the Max31856, but I am on an old Model B Raspberry Pi, os the pins are slightly different. I found this worked standalone to check I could measure the temperatures, I then altered the old oven code to accept this module. I thought @jbrucewas going to use this when I sent him my modified code .

Looks like when the code was revised from the original MAX31856 code I used @jbrucehas gone for consistent/better ways of returning error messages from the T/C modules. However the value for returning the error (MAX31856Error) has not been defined within the code max31856. I think its an issue for @jbruceas he will know best which bits to tweek.

For what its worth I soldered the terminal block to the Max31856 board. The purists will say I am working totally wrong because I have the Max31856 wired in parallel with the original analogue controller which I am using as my over temperature protection. But I am taking the view that the modern electronics has a much higher input impedance than the analogue unit so it will hardly affect it. In practice that seemed to be the case. My current issue is more with the basic Pi operating system having lost some of the background files (Gevent) that I need. Possibly a corrupt memory card, so when I click on the start button the Pi doesn't recognise I have told it to start. However with house moves fixing this is low on my list of priorities

I have started to put together a word document to explain some of my choices and the reasons behind them together with how I achieved the result and will share it when done. It needs some photos to help explain how it all fits together. Then will share it as a PDF on here

Hi Mark, @jbrucehas just been updating the code and added support for the Max31856, I haven't studied it fully but I sent him parts of my code so that he could see how I did it. I tried to send a full dump of my system but google wouldn't allow the attachments and there were some executable bits in it. It may be worth relooking at https://github.com/jbruce12000/kiln-controller and giving it a try. @jbrucehas done a lot of reworking of the code so that configuring is better than my haphazard way. For the record I was using a type R themocouple, rather than an S.

I was new to python coding at the time, and there are parts of the tweaks that possibly could be better coded else where in the different parts of code. As I am not using solid state relays but controlling using the original contactor I probably need to do a document explaining my setup and part of the reason for the revisions to different parts of the code. I must say it was great to be able to sit in the living room and monitor the firing in comfort all by having the pi connected to the home network, so a big thanks to J Bruce and the other people who helped developed the code

Hi Mark, I did get the J Bruce's code up and running tweaked to use the 31856, I am using an Adafruit Universal Thermocouple Amplifier MAX31856 Breakout, unfortunately as we are moving house, the kiln, pi and SD card with the latest working code are all in storage. I did add some other tweaks to the code to email at various stages of the boot up and also the firing. First stage would be to look at Stephen P Smith's MAX31856 driver (https://github.com/steve71/MAX31856) When I get the Pi back from storage I will try and dig out the rest of the code

@jbruce I have found this an interesting project and an excuse to see what I can do with an old Raspberry Pi, at the moment all I have is the Pi running the software emulation and I created a profile to roughly match the manually set temperatures and times for a bisque firing. I was surprised at the estimated cost for the firing but then looked at some of the config settings, they were for a 5.5kW kiln mine is only 3kW, but then there are the other parameters im_c_heat = 100.0 # J/K heat capacity of heat element sim_c_oven = 5000.0 # J/K heat capacity of oven sim_p_heat = 5450.0 # W heating power of oven sim_R_o_nocool = 1.0 # K/W thermal resistance oven -> environment sim_R_o_cool = 0.05 # K/W " with cooling sim_R_ho_noair = 0.1 # K/W thermal resistance heat element -> oven sim_R_ho_air = 0.05 # K/W " with internal air circulation Where can I find estimates for these? its only a small 40l kiln. (Cromartie Hobbycraft KLN40) Thanks Newps