Extruder Cooling Fan Mods

A number of posts have talked about the need for a better extruder cooling fan arrangement.

The stock 40mm fan at the back of the extruder assembly can provide general cooling but can not be focussed and is a bit of a hit and miss affair. Also, when the stock fan is running more than about 25-30%, the heated bed can not hold temperature at 100c. For example, if the fan is set to 100% for an ABS print, the bed temperature will drop to 85c or less even if the heated bed is set to 100c.

So I thought it would be useful to start a thread to collect some ideas for improved cooling fan designs.



Here is one example of an alternative cooling fan I am using.

The design is a simple ducted blower style and uses:

- A 50mm x 15mm 12v blower fan like this :http://www.ebay.com.au/itm/301003641233?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

- A short length (about 80mm) of flexible tubing cut from this :http://www.ebay.com.au/itm/310808936994?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

- A short length (about 70mm) of heavy gauge copper wire (ie about 1.8mm thick from some scrap house power cable)

- A couple of small printed ABS parts



The photos show the assembly components and the blower fan mounted on the extruder.

The fan assembly is screwed tightly to the unused screw hole on the extruder stepper motor and can be adjusted up/down. To make sure the assembly moves only when you want it to, use a rubber washer(or similar) between the fan and the stepper motor.

There are no mods to the extruder assembly required and the stock fan does not need to be removed. A extra pair of light duty wires needs to be run back through the extruder loom to the Ramps fan connection terminals.


I think the advantages of the ducted blower fan are;

- By adjusting the copper wire angle and bend, the blower fan duct output can be focussed exactly on the area where you want the cooling (generally just on the nozzle area). I've tested a few ABS prints and the results have been very good with consistent fine layering and adhesion in the prints.

- This focussed cooling arrangement does NOT cause the heated bed temp to drop during a print. The HBP easily holds 100c even with the blower at 100%. I know that Jimwahhh ran some tests earlier which showed the benefit of fan ducting on bed temperature.

- The stock fan can still be used as before. Of course it's very easy to add a switch if you want to select which fan to use for each print (or maybe even use both!).

- The whole blower fan assembly is very light (about 30g). So the extra fan does not add much mass to the extruder assembly which might cause some more overshoot/undershoot at higher print speeds.

- The blower duct does not obstruct the nozzle very much (and can be moved out of the way), so it is still easy to clean any crap off the nozzle before printing

- It's easy to modify the blower duct length, angles etc to suit exactly what you want.

- Airflow is good (with 80mm duct) and the fan is very quiet.

- Should be possible to mount two blower fans for dual extruders.

- Only two small parts to print (best done in ABS or HIPS). If anyone wants the scad files just PM me. They are very simple to create anyway.

- The whole blower fan assembly costs less than $5.

Disadvantages

- Something else to play with!!

- Ducting needs to stay as short as possible to minimise loss of air flow.

- Can't think of any other real problems



Apols for the long post. Hopefully this will prompt some better designs.

Z

 

Now published on Thingiverse

http://www.thingiverse.com/thing:271875

 

The blower cooling fan is mainly for PLA.

I have found like many others that lots of cooling is not usually required for ABS and too much can cause the heated bed temperature to drop.

I use both the stock fan and the blower fan connected in parallel.

For both PLA and ABS I have enabled auto cooling in Slic3r. However the max fan for PLA is set to 100% but the max for ABS is 35%

This cooling fan configuration and settings works well for me.