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Controlling 12v fan on original 5v pins
Ive probably mistated something already just by the title, but what Im wanting to do is control a 12v fan, via the pin(s) that are currently controlling the extruder fan on a stock setup. Im getting to the point where Im finished trying to cram a layer fan on the existing carriage. Id like to install 12 v fans where the handle cutouts are, and blow across the bed versus directly on the extrusion. I stood up a small box fan last night, with the side panels off, and I got better results than I ever had with any version of attached fan Ive tried.

Ive seen where the current fan is controlled via pulse width modulation. While I know what that means, i dont know the implication in regards to controlling a 12v fan. Will that affect the machine/code trying to control fan speed, or will I be stuck with a simple on/off config. I think it would still be ok if Im just full on or full off when using a 12v fan, but Im open to stand corrected.

I know this has been discussed several times, Ive probably even commented on the threads, but I cant seem to find them today. If this is covered in detail in another thread please just point me towards a thread title and Ill find it.

Any input is greatly appreciated.
Damn... right now I'm working on a design that blows as close to the nozzle tip as possible... almost done with the model but haven't printed it yet. Anyhow, what calibration model(s) and material did you use to measure the effectiveness of one cooling solution vs the other? I'd like to perform some similar tests. I suppose something with overhangs or bridges will do.

I'm going to install side fans in the handles too, but probably will be additional to the layer cooling fan and turned on/off manually, depending on the needs of the print.
Oscahie, my comparison was with a Buddha statue with significant overhangs and PLA. PETG did a little better but did still have some layers bowing downward on the start of the overhang.

I was also wanting to print out an entirely new carriage and don't want to add another fan to that. So the fan on the sides was a nice surprise when it fixed the overhang I was having issue with.

I'd be happy to give your design a go, but right now it really feels like I'm getting more air out of the tiny 12v e3d fan versus the 50mm 5v I'm running for layer cooling.
Ive got a buddy coming over this evening to wire this up for me. Ill fully detail what he does along with a quick overhang/bridge test, before and after. I wasnt able to fully comprehend what was needed from forum posts, so i took the easy route and bribed an electrical engineer. Judging from the amount of air being pushed by 2 12v fans, looks like my biggest problem will be keeping the print from blowing off the bed. Wink
Ok, so for PLA actually I don't think you'd need to control the side fan(s) with Repetier... at least I always set fan at 100% for PLA (except for the first layer).

What will you be using to hold the side fan(s)? I found this design which looks quite good but haven't printed it yet.
Yes, thats the model i used for the fans. When i had my first layer fan installed i was constantly forgetting to turn it on and now it will be even worse since its on another floor of the house.

Yeah, i think i will be ok with simple off/on as my pla profiles all kick the fan to 100% after the 2nd layer anyway. After turning these things on though, it may be too much air. Ill know more tonight once i get everything installed.
Excellent, please keep us posted on the results, and include some pics Smile

Are you installing the fans on just one of the sides or on both handles? and pushing or pulling air?
Im on the fence whether to just leave the other handle cover off, or to blow a fan out the other side and possibly vent that outside or into a carbon filter to reduce the fumes.
Wasnt able to complete this last night as my buddy didnt show. That gave me some time to think things through, which normally results in me ditching my original plan.

While blowing across the bed versus nozzle does work well, im starting to question whether that will have any adverse impact on the bed as it will be constantly struggling to maintain temp. I will also never be able to use it for abs, since it will be the fast track to delamination and adhesion problems.

So im back to a layer fan attached to the carriage, but a 12v one as the 5v barely cranks out any air.

Oscahie, hows your new fan shroud working out, need a beta tester? Wink
I printed part of it (the print failed for unrelated reasons) and it was not fitting well under the carriage, the dimensions were off, so I have to do some modifications. I do have a working v1 of a simpler design that can be easily attached to the modded carriage (plus it provides additional stability to the mod, as it sort of shims the stepper). The current work is towards tunneling the airflow closer to the nozzle. If you wanna test the v1 in the meanwhile I can sure upload the stl here Smile
Yeah, if you wouldnt mind, Id love to try it out, especially if the output is closer to the nozzle. I still plan on implementing this and doing a few tests, but I think I may be stuck with a carriage fan. I know just enough about electronics to be really dangerous, does it seem like this would work to use a 12v fan on the 5v pin?
Pretty cheap and easy solution if it would work.
Don't ask me, I know just about the same as you do about electronics Smile I do know more or less how a transistor works and it should be a pretty easy circuit to make, but probably that Amazon booster will work as well.

My plan is to continue with the 5v layer cooling fan for now. It seems to me like the airflow is decent, but don't really have another same size but 12v fan to compare with. For the side fans I'll be using 2 x 60cm 12v fans, but controlled manually with an on/off switch. Perhaps I'll also add a simple potentiometer to be able to throttle the RPMs.

I've attached my v1 design. I haven't used it to print anything serious yet, just a few other test prints, but it seems to work well. If you do some testing and comparisons let me know your results!
Thanks, Ill print that out tonight and give it a run.
That voltage converter link my previous post wont work unless Im happy with just on/off, just fyi.
Im trying to have a friend that understands this stuff go through all the posts on the topic and tie them together in one cohesive set of instructions. Ill post it up once hes finished and I understand it.
lol, I posted what you needed earlier... you're making this a lot harder than it needs to be
I thought you were being deliberately vague by posting the word "transistor" then removing it. Didnt understand why you were making it hard on ME, after I claimed electronics ignorance. Wink
You did post along with the word transistor, that you hated repeating yourself, so that clearly blocked any attempt at clarification.

This is the first time Ive spoken on this topic and I cant determine the clear path based on the bits and pieces Ive been able to find.
The post contained two links, guess you didn't read close enough
I've printed the side fans holder pretty much perfectly, with no layer cooling, only the side fans! It does induce warping in the ABS, as expected, but I think that can be fought successfully with ABS juice or hair spray.

Anyway I'm going to tweak the model a little to either improve or completely remove the fan grid in order to get more airflow. I think the current design is lacking a bit in that aspect. I'm also going to attach a potentiometer to be able to manually regulate the RPMs depending on the needs of the print.
Make sure your fan doesn't draw more than 500mA, or you'll need a different transistor

Emitter to ground
Base to the 5V fan positive side
Collector to the 12V fan negative side
Connect 12V fan positive to one of the yellow wires coming directly from the power supply

Can't make it much simpler than that. These are the same two links that I had posted previously IN THIS THREAD. Also:
Thank you. I have to admit I glazed over after I pulled up the DigiKey link, as Im not familiar with most of this or the concepts. Im not familiar at all with electronics aside from making simple connections and following explicit instruction. Was hard to follow along between folks that already knew what they were doing.

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