::EDIT::
Now Fixed, Thermistor wasn’t tight into the Block, E3D v6, bolt was slightly loose.
Here’s something that’s got me confused. Bed and Hot End are both PID controlled. Both are PID tuned with 10 cycles. No matter how much I PID tune the Hot End it’s bouncing around by roughly +/- 1°c as you can see on the graph. This is on a the FB2020 Plus, which has transplanted hardware, with the exception of the board and Stepper drivers. Now this was happening on the MKS, and I’d just put it down to crappy hardware, however, the RAMPS I know is fine and holds temps as it was used on the original FB2020 for a while. The only thing I can think is it’s the PSU as it’s allegedly 20A over the 35A on the Original FB2020, or the Heater Cartridge. All connections are solid and tight. Just want opinions before I go and rip things apart again.
Did you PID Tune without fan and then turn on a fan? Thats the simptom mostly. Or you have a thermistor that stands of (like the ones in the M3 distancebolts which are cemented in). Maybe youll make yourself a silikonehousing for the hotend or you buy one. Or just test it by wrapping kapton tape around it.
It’s an insignificant variation.
+/- 1 °C is OK. There is not so big thermal inertia in hot end like in heated bed (aluminium especially) so heater is in on and off cycles all the time.
@VolksTrieb - That wasn’t printing, I’d got distracted and left it, but it was bugging me. It’s an E3Dv6, so should be solid.
@Andre_Kjellstrup , @Tomas_Vit - It really isn’t. 0.4-0.5, yes 1°c, no. 1°c can make all the difference between a good print and a bad print. The actual temp line on that should be barely visible behind the temp set, which on the original FB2020 it is. ::Edit: Sorry, little aggressive there. I will say I’m a perfectionist, so if it isn’t how I want it, then I get a little narked,
More info: I’ve swapped out the Cartridge, it’s brought the PID values down, but no effect. Made sure the Voltage on the PSU was correct, and re-tuned, same. I’ve just discovered the Thermistor was loose, so I’m checking that, if not, I’m swapping the Thermistor as a check.
Edit: sorry I didn’t see the note that it was solved.
I agree that you should shoot for tighter. I think I get ±0.2° regularly. I rarely see that kind of cycling. You might want to make manual adjustments.
- if it overshoots a lot and oscillates, either the integral gain needs to be increased or all gains should be reduced
- Too much overshoot? Increase D, decrease P.
- Response too damped? Increase P.
- Ramps up quickly to a value below target temperature (0-160 fast) and then slows down as it approaches target (160-170 slow, 170-180 really slow, etc) temperature? Try increasing the I constant.
Source: http://reprap.org/wiki/PID_Tuning
@Jeff_DeMaagd - yeah, I’m still seeing about +/-0.4-0.6 ish. seems the wiring is a bit dodgy too, when I moved one of the wires near the hot end, it throws the temps out a little bit more. I’m going to strip it out when the new spiral wrap comes in and switch it for a new thermistor, which the one in there is, but the wire’s cheap and the connection probably has enough resistance to throw things out.
