Hi, I installed 40mm fan on my prusa last night and did a hollow cube test; material abs walls 3 bottom 0 top 1 infill 0 auto fan enabled fan on at layer 5 min fan 35% max fan 100% To my concern was that, when the fan turned on, the bed temp suddenly dropped as low as 95'c when it was originally 110'c and my heated bed unable to go up again, only around 100'c max when using the fan and the cube already peeled from the bed but still printing though. One improvement I saw by using fan is the outer surface has finer finish compared to not using fan, looks perfectly aligned. Correct me on this one if I'm wrong Another thing is, the air blowing out of the fan duct are dispersed like a spray, the fan duct I attached is from here [www.thingiverse.com] Here are my setup [imgur.com] My question is, is it normal to have the bed temp goes down during fan blowing on to the prints? https://reprap.org/forum/read.php?262,572038,572038#msg-572038 Sat, 11 Jul 2026 01:48:09 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?262,572038,579086#msg-579086 https://reprap.org/forum/read.php?262,572038,579086#msg-579086
100'c is quite low for abs and will come off anytime below that point]]> sarf2k4 Printing Mon, 02 Nov 2015 21:38:39 -0500 https://reprap.org/forum/read.php?262,572038,577162#msg-577162 https://reprap.org/forum/read.php?262,572038,577162#msg-577162 deaconfrost Printing Thu, 29 Oct 2015 14:30:11 -0400 https://reprap.org/forum/read.php?262,572038,576457#msg-576457 https://reprap.org/forum/read.php?262,572038,576457#msg-576457 Montiey Printing Wed, 28 Oct 2015 06:55:01 -0400 https://reprap.org/forum/read.php?262,572038,576337#msg-576337 https://reprap.org/forum/read.php?262,572038,576337#msg-576337 sarf2k4 Printing Tue, 27 Oct 2015 22:27:46 -0400 https://reprap.org/forum/read.php?262,572038,576335#msg-576335 https://reprap.org/forum/read.php?262,572038,576335#msg-576335 Montiey Printing Tue, 27 Oct 2015 21:20:20 -0400 https://reprap.org/forum/read.php?262,572038,576334#msg-576334 https://reprap.org/forum/read.php?262,572038,576334#msg-576334
I did try to put cardboard underneath it, having the bed positioned at y max, but that time I didn't turn on the bed pid yet and it still struggling. I was considering to wrap the cardboard with aluminum foil but somewhat scared I might short the bed wires together]]> sarf2k4 Printing Tue, 27 Oct 2015 21:10:46 -0400 https://reprap.org/forum/read.php?262,572038,576310#msg-576310 https://reprap.org/forum/read.php?262,572038,576310#msg-576310 From your photo, it looks as though the heat bed is installed with the actual heating element underneath. Have you considered turning it upside down so the heated side is making contact with the glass? The way (I think) you have it, the heat bed pcb is actually acting as an insulator between the heating element on one side of the heat bed and the glass surface you print on.
Another thing you could try is putting some insulation under the heat bed. I see a lot of people put cork board underneath. I have just used some cardboard and taped it under.
Getting the heat up around 100 degrees or higher is something a lot of people struggle with. And when you put a fan on it, it will struggle further.]]> blabbersnitch Printing Tue, 27 Oct 2015 19:13:36 -0400 https://reprap.org/forum/read.php?262,572038,575867#msg-575867 https://reprap.org/forum/read.php?262,572038,575867#msg-575867
When I try to print one of the small objects, with auto cooling + always on at 25% min, the bed drops as low as around 100'c, the fan turned on at 1mm height or at 10th layer based on 0.2mm layer height]]> sarf2k4 Printing Tue, 27 Oct 2015 00:47:04 -0400 https://reprap.org/forum/read.php?262,572038,573304#msg-573304 https://reprap.org/forum/read.php?262,572038,573304#msg-573304 sarf2k4 Printing Tue, 20 Oct 2015 21:37:37 -0400 https://reprap.org/forum/read.php?262,572038,573181#msg-573181 https://reprap.org/forum/read.php?262,572038,573181#msg-573181
Just ignore the output during the tuning. If you've set bed pwm to 255 you're good.]]> imqqmi Printing Tue, 20 Oct 2015 14:44:35 -0400 https://reprap.org/forum/read.php?262,572038,572818#msg-572818 https://reprap.org/forum/read.php?262,572038,572818#msg-572818
@Putzer, I last night tried to print another of my printer parts but decided to increase to 260'c, the results were great this morning, the fan mostly were disabled so I guess I should disable the fan from what you said. furthermore, with fan actually, on a 20mm test cube, the surface somewhat aligned much better than without fan, this also what troubles me either to use or not to use the fan due to appearance quality improvement

in addition, during the autotune upon starting the first cycle, it state something like 34'c @ 127, from what I understand is the '127' is the amount of power driven to the bed, is this normal?

So let's say the pwm is 255 to drive the bed, does the current drawn by the bed would be the same as pwm at 127?]]> sarf2k4 Printing Mon, 19 Oct 2015 22:58:19 -0400 https://reprap.org/forum/read.php?262,572038,572595#msg-572595 https://reprap.org/forum/read.php?262,572038,572595#msg-572595 Putzer Printing Mon, 19 Oct 2015 11:18:43 -0400 https://reprap.org/forum/read.php?262,572038,572487#msg-572487 https://reprap.org/forum/read.php?262,572038,572487#msg-572487
These instructions are for Marlin, other firmwares may differ.

Run pid tuning, with S indicating your preferred heated bed temperature, C the number of cycles:
M303 E-1 S60 C8

The last PID values needs to be set using, replacing the values 1 2 and 3 with the corresponding values found above:
M304 P1 I2 D3

Depending on if you've enabled the EEPROM, you need to enter the values in the firmware and recompile or use M500 to store the settings in EEPROM.]]> imqqmi Printing Mon, 19 Oct 2015 05:47:27 -0400 https://reprap.org/forum/read.php?262,572038,572379#msg-572379 https://reprap.org/forum/read.php?262,572038,572379#msg-572379
If after, what initial pid value should I use for autotune?

The pid value there were the autotune value returned but with bed pid disabled (I think) in the past. Seeing how the value were, it looked like somewhat extremely high value.

I'm not an electrical and electronic proficient person :(]]> sarf2k4 Printing Sun, 18 Oct 2015 23:45:02 -0400 https://reprap.org/forum/read.php?262,572038,572358#msg-572358 https://reprap.org/forum/read.php?262,572038,572358#msg-572358
Also, do a M303 to autotune the bed. for example, M303 E-1 S60 C8 will target extruder -1 (the bed) and run autotune at 60 degrees 8 times (to make sure that the heat has time to disperse).

:)]]> Montiey Printing Sun, 18 Oct 2015 22:34:18 -0400 https://reprap.org/forum/read.php?262,572038,572354#msg-572354 https://reprap.org/forum/read.php?262,572038,572354#msg-572354
Here is my config.h [pastebin.com] hope someone can guide me on this]]> sarf2k4 Printing Sun, 18 Oct 2015 21:55:58 -0400 https://reprap.org/forum/read.php?262,572038,572338#msg-572338 https://reprap.org/forum/read.php?262,572038,572338#msg-572338 Montiey Printing Sun, 18 Oct 2015 20:31:22 -0400 https://reprap.org/forum/read.php?262,572038,572335#msg-572335 https://reprap.org/forum/read.php?262,572038,572335#msg-572335
electronic
29A 12V psu
ramps 1.4
e3d v6
tower pro sg9 servo
2004 lcd panel

My printer placed on living room, underneath the ceiling (not directly under it).

Last night I tried turning off the ceiling fan, nozzle is 2mm above bed positioned at the center, fan were set to full while bed heating up, it couldn't reach to 110'c. I tried using a small cardboard covering it diagonally from the front, still couldn't reach the target temp. Last night was quite cold actually probably around 25'c

I guess I need to run the bed pid?

I've been having delamination issues on attempting printing my printer's parts]]> sarf2k4 Printing Sun, 18 Oct 2015 20:24:32 -0400 https://reprap.org/forum/read.php?262,572038,572131#msg-572131 https://reprap.org/forum/read.php?262,572038,572131#msg-572131 Montiey Printing Sun, 18 Oct 2015 10:08:20 -0400 https://reprap.org/forum/read.php?262,572038,572038#msg-572038 https://reprap.org/forum/read.php?262,572038,572038#msg-572038
material abs
walls 3
bottom 0
top 1
infill 0
auto fan enabled
fan on at layer 5
min fan 35%
max fan 100%

To my concern was that, when the fan turned on, the bed temp suddenly dropped as low as 95'c when it was originally 110'c and my heated bed unable to go up again, only around 100'c max when using the fan and the cube already peeled from the bed but still printing though.

One improvement I saw by using fan is the outer surface has finer finish compared to not using fan, looks perfectly aligned. Correct me on this one if I'm wrong

Another thing is, the air blowing out of the fan duct are dispersed like a spray, the fan duct I attached is from here [www.thingiverse.com]

Here are my setup [imgur.com]

My question is, is it normal to have the bed temp goes down during fan blowing on to the prints?]]> sarf2k4 Printing Sun, 18 Oct 2015 05:04:29 -0400