|Oozy, webbed nylon printing|
At first my prints were unbelievably oozy - the nylon just flowed from the nozzle and leaked all over the print. I also had problems getting it to adhere to standard blue tape. Apparently both of these are pretty common.
|Damaged bed surface after print removal|
The oozing problem was far more insidious. Initially, I tried to use retraction, but it had no effect (actually it made things worse by causing the print head to sit still momentarily, melting the plastic beneath it and letting it flow). I then happened upon a great idea; get rid of retraction entirely. Get the print head moving so quickly that not much plastic has time to flow while it's moving. In combination with the 'avoid crossing perimeters' flag in slic3r (which forces the printer to complete each part separately, getting rid of that spiderweb of inter-part trails), and the switch to a 0.2mm nozzle produced magnificent results:
|InMoov index finger - the surface is still a bit rough, but the sanded joints are slippery-smooth and its many times stronger than the ABS versions I've managed to make (which suffer from cracking and shattering near the weak, stress-bearing pivot points).|
Nylon loves to absorb water, water that boils and bubbles out of the extruder during printing; it's often recommended to dry it out in an oven at low heat before printing, but I haven't found that to be necessary. There's a small trail of steam from the print nozzle, but there appear to be no adverse effects, though this may not be true if you live in a high-humidity area.
I could comfortably hammer the printed lego parts without damage; a massive improvement over ABS. Despite some reports that gluing/bonding 618 is ineffective, I found that superglue worked perfectly on sanded nylon parts (see the index-finger above).
Apparently, natural nylon is very easy to colour with fabric dyes too; this allows each printed part to be coloured separately, removing the need for multiple rolls in different pre-dyed colours (though I have yet to test this).
All in all I'm quite impressed; nylon 618 is a fiddly material for printing, but the results are certainly worth it for any part that needs significant mechanical strength.