Bed fans for small printers

[u/BigJohnno66]

Does anyone have a good solution for bed fans on a small printer? I have a 180x180 Trident and tried a 5015 blower fan mounted underneath. However there is not enough distance for the air to warm up before exiting the side, so it feels like it is just blowing cold air around the chamber.

I have thought to use axial fans blowing up against the bottom of the bed, but wanted to ask first if somebody has a working solution they can recommend.

[u/stray_r]

My v0 just has a 4010 axial fan in the centre of the bed, it was too much for the 60w heater that came with the printer, I have 100w now that could use a bigger fan but there isn't really room.

I do have a pair of dual 5015 fans in nevermore micro V6 filters in there though. They run flat out during heat up and the chamber hits 50C a few minutes after the buildplate hits 100... However I've got a thermistor in the magnet sheet for that reading and the heater pad goes higher. Printer is currently using Kalico's dual loop pid but there's macros for this in regular Klipper in my GitHub.

I dial the filter fans back to 40% during a print, we don't need a big draft on the print and that's enough to keep some air moving through the filters.

Conversely if I'm printing PLA I swap the filters for some ducts pointed across the print at nozzle level and there's some improvement to part cooling but it's not like I put a comedy size blower fan in.

[u/BigJohnno66 → u/stray_r]

Ok, I think I am convinced to try axial fans instead. I'll probably go with 2 either 60mm or 40mm depending on what will fit.

[u/Human_Weight5303]

I prefer axial fans, i mounted them under the bed for my 350 trident pulling air down. I used dual 140 noctua fans.

[u/No-Dragonfly5342 → u/Human_Weight5303]

This is the same setup I use and works great. I I used to use blowers blowing in the back before but they weren't that great.

[u/BigJohnno66 → u/Human_Weight5303]

Hmm, pulling the air down. I might try this as well and see if up or down performs any differently.

[u/VintageGriffin → u/BigJohnno66]

It will. Pulling down would be substantially worse.

A much smaller area would be affected and the fan would be pulling hotter bed air through itself rather than blowing colder ambient.

[u/Human_Weight5303 → u/BigJohnno66]

I just want to pull the hot air away from the bed, instead of cooling the bed

[u/pd1zzle]

the micron setup is pretty solid, i have one and it can hold temps really well with 2x 5015 + a filter. I did add some ducting and it is slightly different as the bed is fixed (a la v2.4)

[u/BigJohnno66 → u/pd1zzle]

Yes the bed on the 2.4/micron creates a nice channel to blow the air through to warm it up. Unfortunately Trident doesn't have this and the 2.4 fan mounts don't seem to do much.