Simplified Wilson II hot end mount for Bowden extruder


#1

Hi all!

I’ve been trying to improve print quality lately and I’ve attempted to add the compact Bowden extruder to my Wilson II. There are plenty of motor mount designs, but I wanted to avoid too much incompatibility and calibration weirdness so I carved up the original Wilson II hot end mount and posted the results at http://www.thingiverse.com/thing:1471742

The main changes were removing anything related to the filament tensioner and the stepper motor mount, then adding material near the filament inlet and by the fan duct mounting lug. The main problem I’m having now is that the hot end fit is too snug and it’s difficult aligning the hot end with the filament guide tube. At present, I’m attacking the part with a file to make more space for the bushing on top of the hot end.

The design is far from optimal; it should probably have more fillets and rounding so it doesn’t catch on stray wires or have too much stress at inside corners. Importantly, the bottom of the part is not flat, causing Cura to print a few spurious ‘islands’ before laying down what should really be the main first layer. The workaround is to tell Cura to sink the part into the print bed by about 0.5 mm; this dimension isn’t critical and it ensures a solid bond to the print bed. The right answer is to fix that in Sketchup, but I can’t even detect the problem in Sketchup, let alone solve it, so I posted the bed sink workaround.

Comments and suggestions on the part are welcome; my background is in engineering but I’m an analyst, not a designer so set your expectations accordingly… :slight_smile:

Maybe the right answer going forward is to adjust the existing hot end mount design to allow a push-fit connector to be mounted on top so either direct-drive or Bowden extrusion is possible without replacing the mount. It would simplify matters and make a nice add a Bowden extruder to this kit for only $10-20 upsell option.


#2

I’m a big fan of not re-inventing the wheel, wouldn’t a simple mount like this be enough : http://www.thingiverse.com/thing:547706

You might have to design a fan mount to replace the one provided as it won’t fit the Wilson fan shroud


#3

Thanks; I didn’t know that mount existed. My goal in reinventing the wheel (er, mount) was to avoid recalibrating by replacing the mount with a like-for-like part so the hot end is (ideally) at the same position as the original. Unfortunately, I can’t trust the dimensional tolerances of whatever I print; for some reason the hot end doesn’t fit comfortably into to my modified mount. This sort of moots the point of trying to print a like-for-like replacement; the dimensions will be off no matter what I do so recalibration is unavoidable.

Inaccuracy of the printed model is a big motivation to change to a Bowden extruder. At present, I expect to print 2-3 bad parts for every usable one I get and I’d like to reduce that if I can. No idea if changing the extruder motor position will help but the thought is that reducing the mass on the x carriage should make for a smoother print. I’m not sure that will translate to a properly-dimensioned part but better surface quality is a win either way.


#4

I think you’ll have to recalibre whatever you try to print. I’ve calibrated my printer with ~30prints of the same little calibration object and got it to 0.03mm of “perfection”. Yet, when I reprinted my whole printer (made it more Taz alike) I still had to recalibrate it since all my parts wheren’t 100% perfect :slight_smile:

Btw, sorry if I sounded like a dick about “re-inventing the wheel”, wasn’t intended. I remix a lot of stuff to fit my stuff all the time!

To be quite frank, I kinda like your model, Seem a bit sturdier than the one I posted.

If you need some help with calibration let me know. I took a lot of time on this and could probably help you get close to the tolerance you’re looking for.


#5

@arclight I like the model. Just a note @AndreQ the one you listed won’t fit on the Wilson 2 Xcarriage (the four holes are spaced slightly farther apart than they were on the original Wilson X Carriage because of the change from 8mm to 10mm smooth rods).


#6

Oh! Thanks for the info. I’ll stop linking i3 parts :open_mouth: !


#7

@Andre! No worries; I appreciate the pointers to different models & tactics. I started about a month ago with zero prior experience with 3D printing; I did maybe a week of research, bought the kit, and have been “enjoying” the learning curve. So far it’s about equal parts frustration and amazement. I have yet to make my first misshapen Yoda head… :slight_smile:

As for calibration, I think I have the feed rate squared away; it seems to be dead on. I need to run a few calibration parts through to see how far off the dimensions are.


#8

Another bowden hot end mount for the wilson II as designed by TechMav can be found on [Thingiverse] (http://www.thingiverse.com/thing:1482968) too.