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Rear Fan Mount for Gregs X-Carriage

by karmavore, published

Rear Fan Mount for Gregs X-Carriage by karmavore Feb 16, 2013

Description

UPDATE! I'm pleased to see the positive attention this little part has gotten. I've added a version that has the belt clamps (for GT2 belts) built in, which has a couple small benefits. You can modify the scad to make something similar for your belts. Or I can help you out if you leave a note. (6/8/2013)

I'm using Greg Frost's excellent X-Carriage on my Prusa Mendel reprap. I was a bit frustrated, though, that I couldn't find any designs here to mount a fan behind the x-carriage. So I made this, and I've had much success with it. For me, at least, this allows the fan to be closer to the print head than if it were mounted on the sides, and it saves a non-trivial amount of x-axis print space.

If you futz with this design, and I hope you do, please let me know what you come up with. I leave as exercise for the reader the creation of built-in belt clamps, fan ducts, fan brackets, and the like.

Recent Comments

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People like to choose their own connectors; there are several options out there. See the instructions page for what I use.
Perhaps I'm missing something but I see two versions of the part that connects to the carriage but no parts for connecting a fan to those.
I'm seeing both posts on my end, and the awesome info in them both, It's handy to know all this. Thanks for the info!

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Instructions

  1. Make sure that you're using Greg Frost's x-carriage, or one of it's derivatives where the centers of mounting holes for the belt clamps are about 43mm apart. (Or, print and use a new x-carriage from the part from which this is derived. Or, use the scad file here to create a whole new x-carriage and use that one.)
  2. The piece that connects the fan to this mount is not provided here. Select one, and print it out. This part uses a 15mm wide mounting block, which appears to be some sort of de facto standard. You'll have to choose a fan bracket that matches this mount and the size of the fan you have. I'm using a 40mm fan and "40mm Fan Bracket for Jonas Kuehling's RepRap X-carriage", thing #37872.
  3. Attach the fan and bracket to the mount using an M3 screw of suitable length. I'm using a 25mm with no nut. I squeeze a M3 washer between the mount and bracket to keep things nice and tight. Some sanding of the bracket was necessary to make the fit.
  4. Unfortunately, you're going to have to disassemble your x-carriage somewhat to get this bracket on. Remove the your belt clamps, and place this mount between the clamp/belt combo and the x-carriage. Hold the whole thing together with 25mm M3 screws, washers, and nuts. You know the drill. (There should be no need to drill.) I don't use those clever x-belt tensioners, and this part might make their use difficult. Please comment if you have experience to contribute on this point.
Perhaps I'm missing something but I see two versions of the part that connects to the carriage but no parts for connecting a fan to those.
People like to choose their own connectors; there are several options out there. See the instructions page for what I use.
This is probably a really silly, noob question...but what is the purpose of the fan? I have seen many of these around, but I have yet to see what the fan is for. Thanks in advance!
Looks like my first post got deleted for too much innuendo. <rolls eyes="">

Two very dry, bland reason explanations:

1) It cools the higher part of the hotend. If your plastic melts too high up, it can jam the whole operation. If the heat gets high enough, and your extruder is made of PLA, that melts, too.

2) It cools the plastic. This is important for layers with little area that therefore print quickly. See the "ears" on this, for example:http://www.thingiverse.com/thing:18218. If you don't use a fan, you print melted plastic on top of melted plastic, and the "ears" appear gloopy. The fan has also significantly improved my bridge quality.

But too much fan is bad, too, as it increases the likelihood of part warping. This is particularly true for ABS prints.</rolls>
Owl statue
by cushwa
I'm seeing both posts on my end, and the awesome info in them both, It's handy to know all this. Thanks for the info!
Everybody starts as a n00b at everything, by definition. No worries. The fan serves two primary purposes, AFAIK:

1) It actively cools the shaft on the hotend. This keeps heat from advancing far enough up the barrel, where the melted plastic would cause jams or even melt your extruder body.

2) It actively cools the plastic itself. This is particularly important if you're dealing with layers with little area that therefore print quickly. If you don't actively cool the plastic at the tips of the "ears" on this owl, thingiverse.com/thing:18218, say, you're printing melted plastic on top of melted plastic. You wind up with something, technically speaking, gloopier than it needs to be. The fan has also made my bridges much better.

Some people use separate fans for the two tasks, or a single fan directed at one of them. I mostly am trying to do (2), but I don't care if I get a little (1) out of it.

But you have to be careful, too, because too much blowing sucks. It will increase the likelihood of part warping considerably. I print with ABS, so my fan is rarely on. That said, print quality really suffers without it.
Owl statue
by cushwa
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