Parametric Herringbone Gear Set for Greg's Accessible Wades
Description
*** UPDATED 25/12/2011 ***
uploaded my latest script which I've worked on a lot. It's generating some nice gears now.
Also updated the STL, ratio is 45:11, nut trap should fit perfectly straight off the bed now.
Instructions
This is a detailed part (due to the tooth profiles) so use your smallest nozzle.
Print in PLA, it will last a lot longer due to being harder than ABS.
Set 0 extra shells (skeinforge)/ 1 perimeter (slic3r) because you can get hollow teeth with extra shells/perimeters.
Use 80-90% infill. I've already removed lots of plastic, what's left is what's needed. If your infill is too low, the most likely failure is the nut trap in the small gear will break.
You'll need really good cooling to do the base of the small gear properly. When the large gear is finished, crank your fan up to max, perhaps convince your slicer to slow it down a little too.
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(1) Downloaded the herringbone-gears_new_fixed.stl.
(2) Sliced in Slic3r 0.9.9 - Approx. 2 mins on a Windows box. (Quad core i7).
(3) Printed perfectly. Thanks!
Andrew (3dhacker.com)
Gear2's setscrew's captive nut has a bug: It's always created right on the edge of the gear's shaft.
//setscrew captive nut
translate([(gear2_shaft_outer_d)/2, 0, gear_h+gear_shaft_h-gear2_captive_nut_r-gear2_setscrew_offset])
Uses the diameter where gear 1 uses the radius; changing this paragraph to
//setscrew captive nut
translate([(gear2_shaft_outer_d)/4, 0, gear_h+gear_shaft_h-gear2_captive_nut_r-gear2_setscrew_offset])
generates the nut trap in the right spot.
Fantastic, and thank you. But... I made the parts thinner to fit behind the belt in my Prusa setup and although the small gear looks great in OpenSCAD, whenever I put it through Slic3r 0.9.5 the "herring" is only at the top and bottom 2mm, the middle 4mm is just straight tooth (that's about 11 layers at my current .37 layer height... anybody have any ideas why that might be?
Hey,
These gears look really nice but I just cant get them to slice ... using Slic3r 0.9.2 I get a bunch of spurious lines firing off from the big cog to what looks like infinity.
Any ideas?
I tried opening in SCAD and playing but A. it then rendered the small gear wrong and B. I paniced and decided
i really need to learn SCAD ...
The Small gear is Broken, doesnt appear properly in openscad or Slic3r. I appears to have messed up facets.
Slicer v0.8.4
OpenScad 2011.12.30
cloud.netfabb.com is your friend. The gear script frequently makes gears that are less than stellar in terms of mesh.
If openscad won't export, adjust the number of teeth by 0.001 or so, eg gear1_teeth=11.001. this sometimes gives it enough wiggle room to make a better mesh.
also, try an openscad version that's less than 9 months old ;)
I
&
lt;3 the herringbone or 'Citro
ën' gears. (from the the inspiration behind the Citroën logo) Especially the math behind designing the perfect gearset. :-)
I've been using this gearset on my two Prusa's for 4 months. Just one issue this far. No matter how nice and strong I print them, I seem to wear them down quite fast. Every
400 hours I need to replace them. -Being every 3 weeks with my obsessive printing. The solution right now is to keep a spare set laying about at all times.
-I have two suggestions for improvement, if I may.
First off, a slightly larger tooth module to increase lifespan. Simply more tooth-materia
l to wear down before failure.
Second I looked up the formulas for designing helical gears in my machine-element book, and it seem that the tooth geometry is slightly simplified. A boring tooth-study is sure to improve lifespan further.
The latter however is a daunting task as the feature size of
the teeth no-matter module is so small that an ideal tooth-shape will never be possible to produce on a reprap due to print quality limitations.
Please don't look at my comment as a criticism. O:-) These gears truly rocks my reprap. No backlash, great for precise filament retraction before rapid m
ovement. :-D
you must be printing them in ABS for them to wear that fast, try PLA - it's significantly harder and should last a very long time.
If you want larger teeth, then put fewer teeth on each gear!
As for tooth profiles, I've used others' work for those, and I'm sure they're simplified. These gears take long enough to render and slice as it is! If you want to post an updated involute gears script with better tooth profiles, or for
greatest win parametric resolution on the tooth, that would be great!
I made a video of this print http://www.youtube.com/watch?v...
&
amp;feature=g-upl
&
amp;context=G2d8cba4AUAAAAAAAAAA
Killer herringbone gear Hunter. Thanks for this quality piece of hyper functional art. RichRap gave a big recommendation to this set. I would slap this set on my RepRapPro Huxley today, but I have her running so smoothly right now, I dare not fix something that's not broken... this time ;) This proud set will be the extruder set for my Huxley's offspring.
Slic3r Settings I used:
; generated by Slic3r 0.7.1 on 2012-04-14 at 17:41:33
; layer_height = .25
; perimeters = 1
; solid_layers = 4
; fill_density = .90
; nozzle_diameter = 0.5
; filament_diameter = 1.70
; extrusion_multiplier = 1.0
; perimeter_speed = 50
; infill_speed = 40
; travel_speed = 130
; extrusion_width_rat
io = 1.45
; scale = 1
; single wall width = 0.36mm
191C Hot End (216C For First Layer), 75C Bed
I allowed Slic3r's cooling function to drop speed to 5mm/s if layer time ever dropped under 20 seconds. I also had two fans at 90 degree angles blowing on the bed. 8-)
Beautiful looking gear. Looking forward to printing this based on RichRap's recommendation. The small gear is failing to slice in Slic3r. The combo STL is working though. Any thoughts?
Great stuff, thanks! You might want to check the small gear stl is valid. First attempt, I printed both and the small gear was a little distorted (poss too fast/hot). So only needing the small gear, downloaded it and slic3r complained big time. And nothing showed up in the Pronterface gcode preview window. I didn't bother trying a netfabbing repair, just split the two gear stl with Meshlab.
The central part doesn't seem to slice properly using Skeinforge - there is no infill. Works in Slic3r though.
Skeinforge will not even print the infill for the central part of Greg's normal large gear. Frustrating.
Did anyone find out why Skeinforge won't slice the central part of the large gear correctly? I am getting reports of dangling edges during the slicing process. Any ideas?
Well, after much trial and tribulation (thanks triffid, appreciate it!), I have completed my one-off 47t herringbone gear Hack-a Day logo skull mashup.
I'm not completely happy with it, and will likely polish and reprint with .35 tip and finer layer height to hopefully clean up th eskull faces.
See my "I Made One!"
At 51:11 gear ratio, the large gear may foul on your belt clamps, and if you turn the carriage around the other way, the motor may rub the belt.
Suggest using a lower gear ratio, so the big gear is a bit smaller!
Will post updated scad soon, is not hard to change yourself!
Excellent work triffid_hunter.
Where do we find:
include
&
lt;MCAD/involute_gears.scad
&
gt;
include
&
lt;MCAD/teardrop.scad
&
gt;
License
More from triffid_hunter
Excellent design! Gears mesh really well.