Picking a layer cooler fan



  • I am working on getting a FolgerTech FT-5 R2 printer going that still has the stock hot end (MK-8 style). I'm using the standard 0.4 mm nozzle for normal printing with PLA at the moment.

    I downloaded and printed a fan shroud that came from Thingiverse. It has a mounting point for a 40mm fan, and it ducts the air to three outlets around the nozzle.

    My question is simply this: What sort of fan should I buy. In other words, what would be about the right max CFM rating so that it would provide a reasonable amount of air flow for this application.

    I suppose another way to ask the question is "about how much current would an appropriately sized fan draw?".

    I did research here and learned the fan outputs on the control board can source 2 amps, but I'm pretty sure that I neither need nor want a fan that powerful. I'm expecting the slicer to control the fan speed most of the time.


  • Moderator

    Can you link to the duct you printed?



  • you will be very hard pressed to find a 40mm 10mm wide fan that draws close to 1 amp.

    even insane ones like Delta FFB0412SHN draw only 0.6 A.

    but pla for a layer cooler fan duct is not advisable. as its close to the hotend and it will warp.



  • From the testing that I and others have done, most fan duct designs completely destroy the air flow at the exit point. I've even heard some people reporting negative air flow! My advice would be to forget about CFM but use a fan with the highest static pressure that you can find. This usually means a blower type fan. Such a fan is likely to be noisy.



  • @Veti said in Picking a layer cooler fan:

    but pla for a layer cooler fan duct is not advisable. as its close to the hotend and it will warp.

    I wonder why mine haven't.

    Frederick



  • @Phaedrux

    Yes, I printed this one.

    www.thingiverse.com/thing:3030440

    Veti remarked about a thought I'd also had, that being how well would the device survive its proximity to the hot end block.

    I did adhere some aluminum foil to the surfaces that are closest the the hot end block in an effort to reflect away some of the heat. Another thing I will find out is whether that foil will remain in place.

    During times that the layer fan is running, the air moving through it will have a cooling effect that could mitigate warping, but I can't predict yet how this will work out.

    It occurred to me that ABS might be a better choice for making this part, but I'm not that far enough along yet; i.e. I don't even have any ABS filament, and no experience using it.

    The fan I have placed on the duct for now is a 40mm fan that's 28 mm thick. The nameplate current draw is 0.195 Amp. Here are the specs.

    San Ace 40 109P0412H3D053
    Dimensions: 40x40x28 MM
    Voltage: DC 12V
    Current: 0.195A
    Input Power: 2.34W
    Speed: 8700 RPM
    Air Flow: 11.3 CFM
    Noise: 37 dBA
    Bearing: Ball
    Feature: Locked Rotor Sensor
    Termination: 3-Pin / 3-Wire / 9-Inch

    This is a 12 volt fan, although I think there are 24 volt versions available. Since the board is putting out 24 volts, I placed a 68 ohm resistor is series with the fan to divide the voltage approximately in half.

    The resistor is large enough to dissipate the heating, but clearly when I go to buy something, I'll get a 24 volt fan.



  • you can try petg instead of abs. its easier to print



  • @Veti said in Picking a layer cooler fan:

    you can try petg instead of abs. its easier to print

    Thank you for that; I was about to ask for a recommendation for something a little more suitable, but within my current capabilities. Is PETG particularly hygroscopic?

    I did have a little issue with warping of one of the fan shroud arms, but I think I know why, and I think I fixed it. Time will tell I guess. The problem was on the left side only, and I think it was because the wires for the heater block element and thermistor came out and were pressing just slightly on the arm, thus making it twist slightly and descend too.

    I took the heater block apart and re-oriented the wires a bit so that they don't press on the arm. I used heat gun to soften the arm just bit, and then put a block under it so it would harden up again in the desired shape. So far, so good.



  • @bjackson said in Picking a layer cooler fan:

    Is PETG particularly hygroscopic?

    you want to store petg in a dry place when you are not printing with it.



  • @Veti said in Picking a layer cooler fan:

    you want to store petg in a dry place when you are not printing with it.

    I have a storage box from Staples that forms a decent seal around the lid. Inside are some bags of silica dessicant. I also have a food dehydrator that can hold a 1 kg spool.

    That gives rise to a question about using a dehydrator. If you've had some filament out in the open for a few days, and you think it might need to be made dryer, what's a reasonable time in the dehydrator?

    I printed the Benchy Boat test using my newly installed layer cooler. The difference was dramatic on the overhang when printing the hull of the boat. I wonder why FolgerTech sold a kit that didn't have a layer cooler? It looks to me like it's an essential component.

    The improvement I saw with that fan I listed above tells me it must be decently close to the right specs for this application or it would not have had such a positive effect.


  • Moderator

    @bjackson said in Picking a layer cooler fan:

    If you've had some filament out in the open for a few days, and you think it might need to be made dryer, what's a reasonable time in the dehydrator?

    Not for PLA or PETG. Nylon, yes.


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