how to add fan for extruder?

Hi everyone, I am looking to add a fan by the extruder... I have seen some great fan duct designs on thingiverse and it appears that it helps improving the quality by a lot.. only problem is, I am using RAMPS 1.3, is there anywhere I can plug the power cables into the board.. somewhere? or do I have to power it separately?

the new version of slic3r supports cooling.. so I am thinking whether the RAMPS board can control the fan too?

If you are planning to cool the hotend to shorten the melt zone and lower the temperature of the x carriage (useful/required with PLA), you are better off running the fan at all times, or wire it together with the hotend resistor.

If you want a fan to cool down the print itself (very useful for small parts, overhangs and bridges), yes you can control it with RAMPS. Where you attach it would depend on your pin setup. I don't have RAMPS myself, but if you go by this: [reprap.org] the fan should be connected to D9, which is the middle pair of the heater screw terminals.

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-Nudel
Blog with RepRap Comic

thanks nudel,

I am using it to cool the prints and i print in PLA. I've been trying to print a replacement gear for my extruder (the 11-tooth one), but toward getting to the top, it was clearly that each layers were shrinking inwards and i could see that the nozzle was dragging some parts of the plastic which was still soft, but as soon as i put my desk fan whilst it was printing, the areas got blown directly came out perfectly vertical! I i figured that a fan was what i needed. However, right now I am using my desk fan, not only it is cooling the prints which is good... but it also cools the printbed! so after about 10 mins, the print comes off the glass bed...

if I install this fan to the extruder, possibly using 40mm or 50mm fan, will it also be so windy that cools the bed?

If your extruder is able to extrude PLA without the melt zone getting too high (above the PTFE insulator) you don't need a fan on the extruder.

Instead attach a fan to the bed or the x carriage pointing down.

If your extruder is insulated, you can keep the fan on constant power or wire it to the extruder heater resistor output.

You can also connect the fan to the D9 output of the ramps board and control it with gcode.

Example:

M106 S255 //turn on fan full power
G4 P10000 //sit and do nothing for 10s
M107 //turn fan off

You can manually add this after every layer that you want to cool or you can add it to cool_start.gcode (and m107 to cool_end.gcode) to cool every layer this way. Cool has to be enabled for this to work. It may cause problems with the extruder oozing though.

Try to use slow instead and set your minimum layer time to 30s.

There is a cooling module in Skeinforge. It gives fine control over when the fan blows on the part. Give it a try. While slicer may seem easy, Skeinforge is really not hard if you understand that some of the features are not always practical to use.

Another alternative is to switch to ABS. In my oppinion, it is much easier to work with than PLA.

My working assumption has been that for ABS, since the temperature is usually in the 220°C range, heat will tend to travel faster and higher in the barrel, increasing the length of the melt zone and potentially causing issues with jamming. A long melt zone would also affect retraction. So when I've printed with ABS I set the fan set to point at the insulator above the heat barrel, and keep it on at about medium speed. Then my understanding is that when you print PLA, the barrel doesn't get as hot, so you probably don't need to worry about the melt zone getting too long. And PLA benefits from having the fan blowing directly on the print right at the nozzle, because cooling the PLA right away gives better bridging and surface details.

Since I like to mix it up —printing with PLA most of the time, but using ABS for things like extruder parts— I'd ultimately like a solution that can work well for both cases without needing to swap ducts. So I made a hinged fan duct, but it's not quite ideal. I can point it down onto PLA prints and it works fine in that position, but when I have it pointed upward for ABS printing a lot of air gets around the nozzle and onto the print. It's my understanding that ABS works best if it stays warm and cools as slowly as possible. So although the air getting onto the print is warm, ultimately I need to redesign the duct so that little or no air goes downward when the fan is pointed up.

I haven't seen any examples of a universal fan duct on Thingiverse, and the variation there is so diverse that it's hard to tell what is intended for PLA printing and what is more suitable for ABS printing.

Edited 1 time(s). Last edit at 03/02/2014 10:31PM by Thinkyhead.

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Thinkyhead
I haven't seen any examples of a universal fan duct on Thingiverse, and the variation there is so diverse that it's hard to tell what is intended for PLA printing and what is more suitable for ABS printing.

Which is why you go with a design that has two independent fans. One for blowing on the extruded work if desired, and another that blows on the hot end.

I use this 30mm fan duct by Ohmarinus on my jhead:-

[www.thingiverse.com]

It works well, but I found that temp control was more stable with fan rotation reversed.
I wired it in parallel with the heater. I do ABS more or less exclusively now.

Edited 1 time(s). Last edit at 03/03/2014 01:26PM by dave3d.