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hi the temperature that my sapphire pro reports for the hot end varies widely even though I have "tuned" the PID system several times has any body got a system using PIOD control rather ths Bang-Bang that works say staying within about 5C of the set temp.
Possibly not too useful, but I did have a printer that had a firmware bug that would screw up the PID if the X and Y axis steps/mm were adjusted.
This may be similar, where the wrong variables are being changed. Do you know what firmware it's based on, and is it running a custom interface over the top? E.g., is it Marlin underneath, with a touchscreen and a custom interface firmware on top? If so, can you connect via computer and find out what the real values are using something like Pronterface?
Hi Thanks Martin The firmware is based on Marlin as you say and I have been examining it with Prontaface and changing the PID settings directly on the basis of what little I know about the workings of PID. It looks like the hotend heater is not man enough for the job it is only 38 watts ie 15ohms at 24 volts. At low temps as per P say 220C it is not too bad but at 250 C it swings madly low and really gets to the target temp. Too bad as I have to use a lot of exotic filaments!!
I have ordered a couple of 50 Watt heaters in the hope that will help but they are coming from china - so it will take a while.
I understand that two trees don't respond to a request for the firmware source code as they should under the GPL open source license of Marlin. As the semi-retired MD of a software company \i could the find someone who could at least take a look at the problem.
38 watts shouldn’t be a problem. E3d actually switched to 30w so they don’t melt the aluminium heatblock in case of runaway, and they’ll still cruise past 300°C.
What happens if you run the autopid from pronterface (maybe m303. Can’t remember).