Parametric Herringbone Gear Set for Stepper Extruders

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Published on February 20, 2011

Description

This is an OpenSCAD script for the generation of a stepper motor gear set, to your exacting specifications.

I'm sure there's other scripts like this out there, so here's what makes mine cooler than theirs:

* I made it!
* It's ANIMATED! Yes, OpenSCAD has an animation option, and this set will take advantage of it. It seems like Thingiverse may not render a GIF though, so here's a link to a copy: scribblej.com/wadesgears.gif (obviously, that's animated through 1 gear length so it's only 5 frames).
* I made it!
* The perfect companion to: Parametric Tensioner: thingiverse.com/thing:6492
* I made that, too!
* Goes great with: Stepper Motor Mount thingiverse.com/thing:6549
* I made it!


... that's about all I got, really. Based loosely on TheRuttmeister's excellent herringbone gear set here: thingiverse.com/thing:5795

THANKS to the entire crowd on IRC Freenode in #reprap, #makerbot, and #makergearv2.

SPECIAL THANKS to GregFrost for his involute gears script and some special handholding while I was writing this.

Instructions

There's an option at the top of the script that determines whether you are generating the model to view it, or to print gear1, or to print gear2. Start by measuring your hardware and adjusting the numbers in the script to match. Then generate the model for viewing, checking that everything looks sane. For fun, you can turn on the animate option and watch it spin!

Once you have things the way you want them, switch to generating each gear separately and render them to .STL for printing. Simple!

AFTER RUNNING THE SCRIPT, IT WILL SHARE SOME VITAL FIGURES WITH YOU:

* It will tell you the radius and diameter of each gear; make sure you didn't generate something too big to print! The Large gear .STL I uploaded here is really nearing the limits of my ToM build platform, so ... be careful!
* It will tell you the minimum and maximum drive shaft bolt length it will accomodate. This is the length of the bolt IN THIS PART, so make sure you add it to the bolt length of your tensioner and the space between them, if any. If you are using my script to create your tensioner ( thingiverse.com/thing:6492 ), that will also report bolt lengths for your convenience.
* It will tell you how far apart the axels of the gears must be (which is hopefully the same amount YOU told IT), for designing your motor mount (I'll be adding this as an option to the above Thing when I have time).


ABOUT THE .STL FILES:

I'm printing these now so I'll be taking photos when they're done. These should be appropriately sized for using a makerbot stepper motor 60mm away from the drive shaft. The drive gear is designed to accept an M8 bolt, to be used in conjunction with the 608-style tensioner STL in the parametric Wade's tensioner Thing.


Hope you find this helpful! As always, feedback is appreciated.


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Hey, I just had one question I wasn't clear on. Did you make this?

;)

Where did you get the MCAD library? I picked up a copy from https://github.com/elmom but I think something's wrong because the small gear isn't rendering with any teeth (see pic, rendered with CGAL, didn't generate any warnings)

hi, I'm trying to reproduce thing:10538 without all the mesh errors, do you know what parameters I need to supply for it to fit Greg's accessible wade?

I'm putting out a public call for help here... for my own reasons I'd like to modify this script so it can output a third gear, inverted and properly sized to fit around a planetary arrangement of the first two gears.

There's /no way/ I'll figure this one out on my own, so if anyone has the time, knowledge, and pity to do it...

I'm green with envy about the quality of that print in the photo.

Thanks - it's basically a stock ToM when it comes down to it. The material is Transparent Blue PLA from Makergear.com.

When I get the time, I'm absolutely updating this to make something like Chylld's sprung gears an option: http://www.thingiverse.com/thi...

I should take another tip from TheRuttmeister and have the small gear shaft grow to a larger size; that would give much more fit for the nut without having to change the gearing ratio... it will be done -- eventually. :) I'm on a mad path to a particular goal here.

The numbers in the .scad file are a bit off; the pictures you see here show that a bit. I need to increase the shaft sizes on both, and the captive nut size just a tad. A drill and a dremel made these prints perfectly useable though. Or almost; I'm a little worried about the room around that captive nut. We'll see.