PID autotune question. I can't seem to get the printer to develop more than

3D Printing
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1

PID autotune question.

I can’t seem to get the printer to develop more than 225C…which is odd, as there’s otherwise very little load on the power supply.

I want to get it up to about 240 to print PETG with some headroom, but autotune doesn’t get any higher than 225.

Initial PID is M301 P20.19 I1.59 D64.11

I throw M301 P2.19 I1.59 D64.11 at it, and it ramps up a little quicker due to the change in P, but I’m still stuck floating around 225 at the top end.

Thoughts? Pid tuning was always one of my weak points.

2

What firmware?

3

Can you tell if the heater is constantly on? There should be an indicator LED. If it’s not near temp it should be solid on. If it’s solid on and not getting to temp, then it’s a thermal issue, if it’s flashing and not near temp, it’s a PID setting issue.

4

Check the firmware for any max PWM values. Some let you set a maximum PWM value so that even at “fully on” as far as the firmware is concerned, the mosfet is never actually completely on. I’m not sure whether that setting affects auto tuning though.

5

It’s set to the default:
#define HEATER_0_MAXTEMP 275

6

Oh, and it’s a e3d Lite6 on the other end.

7

@Mark_Rehorst , PEEK is safe up to like 250C. And UltiMaker still uses a PEEK isolator on the UltiMaker 2 so…it has legitimate uses.

8

Marlin, RUMBA, Looks like it’s got a good heat ramp (70 degree angle or so), then curves nicely as it approaches 210 degrees or so…

9

Came home tonight, told the printer to fire up…requested it heat to 210…and it’s cooooold. So perhaps it was a bad heat cartridge.

10

I find that a 2mm layer of silicone aquarium sealant on the hot end (but not on the nozzle) works as a good insulator, and improves my thermal profile and reduces my power draw.