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Mk7 replacement with cooling fan

by hansj66, published

Mk7 replacement with cooling fan by hansj66 Oct 15, 2012


The design files for this thing have been removed as a protest against Stratasys after their decision to file a patent infringement lawsuit against Microboards Technology. Their decision is extremely destructive and also underlines that the patent system is obsolete as it no longer serves any purpose for the betterment of society. Its main role is as a blunt weapon used by incumbents to hamper innovation. I see absolutely no reason to continue indirectly supporting Stratasys by providing free content to Thingiverse.

After printing with ABS for a year, I decided to give PLA a try. The extruder nozzle clogged on almost every print, so I decided to attempt to add some additional cooling.


Remove the thin support material on part 2 and mount a ball bearing with an inner diameter of 4mm. You may have to cut the screw that holds the bearing in place to avoid making contact with the stepper motor or heat sink.
Spring dimension is probably not critical. The spring I used is 8 mm in diameter and 35 mm long.

The fan is a standard PC power supply fan.



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I love it! I've been tinkering with something similar after seeing the replicator 2's extruder at maker faire, and NYCC.

Thanks, but there are no guarantees :) I made it through a 6,5 hour print without any clogging yesterday, so I it looks promising so far.

What temp did you find worked best for you? I've finally got around to printing the fan hood and finding a fan that works, but I find I get a lot of jams.

I experimented with temperatures in the 190 degree ballpark (HBP at 50). The higher the extrusion temperature, the harder it will be to prevent heat propagating back up into the extruder. With the fan active, I managed to print a 15 x 20 x 18 cm big Xenobird (http://www.thingiverse.com/thing:15047)http://www.thingiverse.com/thi... without any problems, but I still always had to pull out the filament, cut it and then reinserted it before each print to avoid it clogging. In my case, clogging will always happen if I start a new print with PLA that has melted and then been reheated in the nozzle.

You can see the result here: http://www.timeexpander.com/wordpress/archives/5678http://www.timeexpander.com/wo.... It is printed in clear PLA and finished in latex paint.

I got this problem too recently...
Always clog then failed...
And cooling fan seems not save me :(