MakerGear Forum

There have been a number of discussions about the best way to position the bed fan on the M2, and a number of brackets can be found on Thingiverse, including ones from Jim and Dale and others who frequent this forum. I've never found a strong need to reposition my bed fan, although I'm pretty sure that the original design is sub-optimal. Especially since I added the Z-probe to my dual extruder, the probe is partially blocking the space between the bed fan and the nozzle, and I'm clearly not getting as much air blowing on the nozzle as before.

However, as some of you forum readers may know, I've been working on a new and hopefully-improved dual extruder design, and the design basically looks like two single V4 extruders side-by-side, with independent movement. The independent movement means that the two extruders can't share either the extruder fan or the bed fan. The V4 single-extruder design already uses a 40mm x 40mm extruder fan instead of the 50mm x 50mm fan used by the V3b and the MakerGear dual V4 design. But I think I will need to use a 40mm x 40mm fan for the bed fan as well, since the 50mm fan is either going to run into the frame, or into the other extruder. And it will need to be mounted directly in front, not to the side ([edit] see below).

So what is the consensus on putting the fan in front? ([edit] For the dual, that is. I think the dual extruder is the only configuration with the fan on the side at an angle. If you didn't know that, the question would sound rather strange.) Has anybody tried a front-mount design for the dual extruder bed fan, and does it work better? And has anybody tried using a 40mm x 40mm fan for the bed fan, and if so, how does it compare against the larger fan? For that matter, how does the smaller extruder fan compare? I have noticed that the V4 single extruder does not use a fan duct like the dual V4, which redirects some of the airflow directly down onto the mount plate. But that was likely overkill on the dual.

I made a front mounted fan shroud (http://www.thingiverse.com/thing:724933). I think the front mount position is better than the diagonal mount, as it gives symmetric flow to both nozzles. Ducting also improves air flow quite a lot, and is necessary for a front mount as there is not much vertical distance to work in. With high CFM/low static pressure fans, it is better to have as little actual restriction as possible, so it's just directing the stream.

I was thinking about messing with something, but the holidays snuck up on me, and that gets to be a really busy time.....

My idea would look something like the image below - it would just be a replacement fan guard for the 50mm extruder fan (on the dual), but with a bump-out to hold the bed fan at an angle so that it pointed directly at both nozzles. (Tried attaching it directly and it causes the fan to extend down too far - it hits the bed before the nozzles do.)
So anyway - something like that.....i'd like to balance the air flow across the front of the print, because when using both of them, the left nozzle really oozes (air flow is blocked by the print).

I dont know if my mount can help but i use this i designed it because i wanted a more sturdy piece and that would be easier to remove removing just 1 screw both fans

https://www.thingiverse.com/thing:1083655

Yeah, well you guys are great for getting me off my bum......

Went ahead and designed the replacement fan guard - it actually works, and the design of this particular guard opens up the air flow to the stepper motors as well. (So win-win.)

It's not going to keep you from sticking filament into the fan as efficiently though....
Loaded the file here if anyone wants to try it - it's a quick print. You'll need one extra M3x16 screw to attach the second fan.

http://www.thingiverse.com/thing:1163035

Ooh, very nice, Jules!

So apparently MakerGear put the bed fan at an angle to the side on the dual extruder so that it woud not touch the plate and so that it would minimize the extent to which the extruder fan blocks the flow? So with your new orientation, do you think it's getting less air to the nozzle, because the extruder fan is blocking it, or more, because it's closer to the nozzle (especially the left nozzle, which is the one I use if I'm not using both extruders)?

Haven't printed anything with it yet, but i turned on the fan and stuck my finger under the left nozzle......Based on this highly scientific test, ( ) it definitely gets a lot more air flow to the left nozzle. (That's the one that i use primarily too.)

Only the very top portion of the fan is blocked at the angle that i used, the rest blasts away at the nozzle, and more air hits it because it's a lot closer. (It looks like more is blocked because of the angle of those top pictures.)
I'd like someone else to try it though - the angle needed to point the bulk of the fan towards the nozzles doesn't leave a whole lot of clearance for the fan - just about 3 or 4 mm above the nozzle touch point. I might have to rework it at the expense of air flow to get more clearance for other people's setups. (Going to have to be careful to lift that setup enough when clearing the clips in the startup routines too.)

Thank you, everyone, for your input.

Due to tight space constraints, I'm going to have to give a 40 x 40 mm bed fan a try. I'll report how it goes.