Elliptical Gear with no center pivot

by cohlwiler, published

Elliptical Gear with no center pivot by cohlwiler Oct 20, 2015

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80550Views 20502Downloads Found in Math Art
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A slight remix of PerryT's wonderful Elliptical Gear set. I liked playing around with the gears connected at the off-center pivots, and thought it would look cool to remove the center ring entirely.

You can find the original thing here, along with other types of connecting arms: http://www.thingiverse.com/thing:37659

I've made a new oval gear with a spiral design in the middle. Check it out here: http://www.thingiverse.com/thing:1125461

Print Settings

Rafts: No

Supports: No

Resolution: 0.2 or 0.3 mm


Make sure the holes are smooth and pop in the pins gently.

Be aware that the left and right sides of the gear have different teeth positions with respect to the hole. Thus, you may need to rotate one of the gears 180 degrees to get the right alignment. If this doesn't make sense, look at the photos below.

Correct Alignment

Incorrect Alignment (right gear was rotated 180 degrees)

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fantastic worcs great

Great great design!
However you cause me a problem here..
Every friend/family that playing with it want me to print them one too...

Printed with:
Geeetech i3c
25% infill

For all the guys with the problems..

  1. reduce the printing speed
  2. try to print a bit hotter

This little toy is great! My friend loves gears, so I printed one for him, but I might have to print one for myself too! As another commenter pointed out, push in the arms when they come off the printer. Had no trouble with the tabs breaking. Great design!

Cool little model, we actually did a Time-Lapse of it being printed you can see it here https://youtu.be/vjopfTVGwYw

Nice work. I printed it with my PP3DP UP Mini! and it worked flawlessly.

Here I posted a video of the gear in action:


This comment has been deleted.

I have tried with both HIPS and PLA and the flanges break easily on both.

Wow! Worked great the first time! Used glow in the dark material, so mesmerizing in the dark! Thank you Mr. Cohlwiler!!!

I printed with Robox, PLA, and it worked great at full size. When I scaled it down to 50%, the tabs on the arms broke repeatedly; The gears, however, came out great.

Great design, which tool did you use?

Feb 9, 2016 - Modified Feb 12, 2016

Looks great but the flanges keep breaking. Onto my third attempt now. First two at .3mm height, 20% infill. Next at .2mm, 40% infill. If that still does not work I will try ScottW1's suggestion to use horizontal size compensation.

After five tries I just could not make any that would not break. Yours looks really nice though. I am going to have to give up on it though, for now : (

Printed on Lulzbot Mini in Esun PETG. Everything fit perfectly, but I did use "horizontal size compensation -0.05mm" in Simplifi3d. Nice design!

Gonna need to print this tonight, might be the FIRST print on my homemade printer's new bed.

Mine printed fine in PLA at 210, and had no issues with the flanges breaking. The gears were too close though (partly because the bottom layer smeared out a little). I used 123D Design to stretch the arms by 1mm and that worked better; I was concerned that scaling it would make the flanges too big, but I guess the "smart scale" option was smart. I used a 0.3mm layer height and 20% infill.

Worked perfectly. Made one from PLA on my Lulzbot Taz5 using Simplify3D slicer software. (Love the printer and the software.)
Marvelous widget.

A few tips:
Make the gears first, then make the arms and pop them into the gears as soon as they come off of the heated bed.
The plastic will be still pliable when warm. Warm up the arms with hot water if you still can't pop in the arms.
Lay the gears flat on a hard surface, (like a desk) and push the arms firmly into the hole with the heel of your hand.
Set your printer for ~40% infill. Perhaps give it 5% extra on the extrusion to make sure that the layers bond well.
I used a 0.5mm nozzle and set my printer for a 0.2 layer height.

Jan 14, 2016 - Modified Jan 14, 2016

I too tried to print this also in PLA with a Flash Forge Dreamer clone using .2 layer height. Looked perfect, yet the teeth are just too brittle, all 4 joints broke one or two teeth off when trying to insert them into the gears.

Any tips from those who got this to work?

I'm sorry to hear that you're having problems with the teeth breaking off. Not sure if you've seen this, but I posted some ideas as a comment on this make: http://www.thingiverse.com/make:182887. I'll be sure to post an update if I find a good solution to this issue!

Elliptical Gear with no center pivot
by mwomack

I love this thing, but I can't seem to make one that doesn't break during assembly. I have used PLA and HIPS, and every time I broke the flanges as they "snapped" into the holes. I have tried filing/sanding the holes to make it easier for the flanges to fit and slide, and it got better. I only broke one of the flanges for each hole. Is there a trick to this thing? Does it only really work with ABS?

All of mine were printed in PLA. I'm sorry to hear that you're having trouble with the flanges. If you have any more info about your printer and settings, or close-up pictures of the pieces, I might be able to help.

Sorry for the delay. I made another go at printing some new arms, but still ended up breaking the flanges. I posted some pictures here: http://www.thingiverse.com/make:182887

Elliptical Gear with no center pivot
by mwomack

Having the same issue with PLA. Have tried temperatures between 190-205, I started having stringing issues at 210.

Pretty cool design. Good for showing off the basics of a 3-d printer.

Could you provide the file for the arms?

Nov 1, 2015 - Modified Nov 9, 2015
cohlwiler - in reply to Chtapodi

Sure thing! They're in the downloads section now. All credit for the arm design goes to PerryT, and you can find other compatible arms here: http://www.thingiverse.com/thing:37659

Elliptical Gear Set with connecting links.
by PerryT