Some of you may have noticed big temp changes in your hot end when monitoring your prints and controller software (Pronterface/Repetier Host) while printing.
There are settings in the firmware that are supposed to keep this at bay. Some miniscule temp swings are normal. If you are noticing 7-10 degree drops in the middle of the print, chances are you will do yourself a favor by running the autotune function associated with MARLIN.
I've been autotuned for a few days now, and it worked well.
This requires the latest Marlin. It does not work with stock Revb Firmware, as far as I can tell, it will just endlessly cycle without giving a "Finished!" prompt.
Check my signature links, for the firmware I have created for single extruder Series 1 machines.
Goal of this tip/trick:
To help minimize big temperature swings throughout a print.
Tune your hotend according to your fan, power resistor, heater block.
First let me start of by saying that the firmware has settings placed inside Called PID (Proportional, Integral and Derivative) that control the overall heating of the hot end.
Some of you may also have gcode placed in your slic3r/kisslicer programs Gcode "Prefix" area that sets this every time before a print. (TAMS provided settings)
It looks like this, or similar
M301 P24.72 I0.88 D231.1
If this is in your gcode prefix, you have it in two places, which is fine. The code in your slicers gcode prefix area takes precedence.
The actual Tip/Trick:
So if you have temp swings, or just want to fine tune your hot end, simply follow the below steps.
1. BACK UP YOUR SETTINGS! ALWAYS BACK UP YOUR SETTINGS BEFORE MAKING ANY TYPE OF CHANGE, SO THAT YOU CAN EASILY SWITCH RIGHT BACK IN CASE SOMETHING GOES AWRY.
2. Open Pronterface, and connect your machine.
3. Click on the checkbox that states "Monitor Printer"
4. Load some type of filament to simulate hotend being occupied while printing (this will not be extruded, it just needs to sit there)
5. If you normally run your fan at 100%, Type "M106 S255" (Without quotes) In the lower right hand corner of pronterface. Hit "Send"
If you normally run your fan at 80%, Type "M106 S204" instead, and hit send. The formla for finding your percentage is as follows.
(Percentage Wanted) "Divided By" (100) "Times" 255 = S(Value). If 70% is wanted:
70/100*255=178.5 (Round up to 179) so the code would be "M106 S179" Hit Send
6. Now that your fan is running, and you have filament in the extruder to simulate normal printing, you will type in "M303 C5 S185" and hit "Send"
This will cycle the extruder a bunch of times, looking for those magic PID numbers that will make your printing experience even more rock solid.
When its finished, it will say something similar to "Autotune has Finished!"
Once the autotune function is done, it will spit out new PID numbers. You will see a bunch of pid numbers, wait for it to say its actually finished, those will be the numbers you need.
Once you have the new numbers you simply change the code in your slicer programs "Gcode Prefix" Area
M301 Pxx.xx Ix.xx Dxxx.x
Additionally, you can also change this value in your Configuration.h firmware files if you already know how to do that (Simple google search should point you in the right direction for that). This will also allow you to forgo any Gcode Prefix for PID altogether.
Links of Interest: