Bed PID

I was wanting to try using PID on my bed since bang-bang is giving me about a 15 degree range (5 under, 10 over target temp). I have read some about manual PID turning but I have no idea of some good values to start with. My bed is a 300x200x6mm plate with a 400W heater.

First note the default values are given in this thread : [groups.google.com]

My own parameters (just done that yesterday), for a BED diam 300mm, 280W, with 5mm ceramic fiber insulation below.
I have a printbite surface, which creates an insulation on top and significantly modify the behaviour, so your parameters WILL be different, but that may help. Overshoot 3°C, stability within 0.3°C. Not used any math method, as I had bad experiences with them on hotend.
[edit proportional coef - W coefficient]

M301 H0 P90 I0.2 D750 T1.3 S1.0 W500 B8

Your heater is more powerful, so you have to modify the T parameter, see this thread : [forums.reprap.org]

Have a look on this page [reprap.org] for PID tuning and there [robotics.stackexchange.com]

Edited 3 time(s). Last edit at 05/01/2016 06:28PM by PRZ.

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

Quote
PRZ
First note the default values are given in this thread : [groups.google.com]

My own parameters (just done that yesterday), for a BED diam 300mm, 280W, with 5mm ceramic fiber insulation below.
I have a printbite surface, which creates an insulation on top and significantly modify the behaviour, so your parameters WILL be different, but that may help. Overshoot 3°C, stability within 0.3°C. Not used any math method, as I had bad experiences with them on hotend.

M301 H0 P900 I0.2 D750 T1.3 S1.0 W500 B8

Your heater is more powerful, so you have to modify the T parameter, see this thread : [forums.reprap.org]

Have a look on this page [reprap.org] for PID tuning and there [robotics.stackexchange.com]

Thanks for the info. There are so many places the information is scattered around it is almost impossible to find the stuff.

If you have no experience of tuning, a method may anyway help, even if the results are not the best for the purpose, so the Ziegler-Nichols is here :
[en.wikipedia.org]

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

zn tuning of heating/cooling processes sucks it just takes too long to analyse that your in a stable oscillation before you can obtain a time constant.

---

RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD

Warning!
I made a mistake in proportional coefficient in my first post, which shall be 90 and not 900. I edited the inital post.

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

I added on the wiki page most used default values (including PID ) here : [reprap.org]

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

Quote
PRZ
I added on the wiki page most used default values (including PID ) here : [reprap.org]

Using the defaults from that line (M304 P85 I5 D500 T2.7 W255 B5), I went from a 15C swing to a 1.4C swing. That's close enough for me. Thanks.

Cancelled - confusion

Edited 1 time(s). Last edit at 05/01/2016 06:28PM by PRZ.

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]