• The math didn't check out

    Zoé • 12/11/2018 at 21:50 • 0 comments

    I made a mistake somewhere and my big gear is a few teeth short:

    Now I'm printing a piece which fits there.

  • Motor mount design complete

    Zoé • 12/10/2018 at 19:25 • 0 comments

    So far I printed 2 of 6 big gear segments, and by tomorrow the missing ones will be finished. The motor mount and the small gear look good. For sideways support I'm using 608ZZ bearings and a small base. A 45-mm long screw holds the gear in place.

    I'm thinking about painting the table surface but I'm not sure if it's worth the effort.

    What is left to do:
     - add an index magnet and a hall sensor (design a mount)
     - start working on the firmware and wire the motor up
     - source lumber for the shelves, work on the shelf design

  • Big gear design fixed

    Zoé • 12/09/2018 at 15:29 • 0 comments

    Thanks to Daniel Watson @is0explore@twitter.com I fixed the big gear geometry. https://twitter.com/is0explore/status/1071764065645748225

    Turns out the Gear library I am using creates weird geometry if the bore of a gear is too close to its diameter. As a workaround, I create a gear with a small bore and then cut out the inner part. It's being printed now!


  • Big gear designed

    Zoé • 12/06/2018 at 23:21 • 0 comments

    I designed the big gear but ran into a (probably) Slic3r weirdness:

    I checked the STL in Blender and it looks alright. I tried to reduce resolution but it didn't go away... Any idea? I'm running Slic3r Prusa Edition Version: 1.41.1 on x86_64-linux

  • Bearing design complete

    Zoé • 12/06/2018 at 18:48 • 0 comments

    I bought a used 600 mm diameter table for 10 € and transported it back home on the train... Ü

    I designed retainer rings for the bearing balls in OpenSCAD and printed them out of PLA. I'm sure it'll be up for the job strength-wise; the component doesn't carry any significant weight, only keep the balls in place. See the diagram:

    The .scad file is uploaded in case anyone else wants to build it. As always, it is fully parametric.


    Since it's too big to be printed in one piece, I cut it up into identical sections and added alignment pins. I also created an alignment tool to get them in place.

  • I got balls of steel!

    Zoé • 12/06/2018 at 17:08 • 0 comments

    Instead of trying to make an axle and make sure it's centered, I figured I just create my own bearing by putting balls between two wooden surfaces and supporting it at 3 points around the circumference to restrict its movement on the XY plane to a circular one.

    So I was looking for bearing balls to make this big bearing, and I figured that it is not economical to order 200 pieces of 15mm balls through Aliexpress because balls are heavy. Probably steel isn't much cheaper in China either. So I found a company in this very same city Wien which sells all kings of spherical things, and they sell "polishing quality" steel balls for 8 € per kilo. I estimated that I need about one kilo of 15 mm balls in order to get a single line of balls around the 600 mm diameter table.

    When I was in the shop, it turned out that they charge you 10 € extra for any orders below 50 €. So instead of getting 2 kilo of steel balls, I bought 6 kilo - I didn't wanted to pay this handling fee. I bought 5.56mm, 12.7mm and 15mm diameter steel balls, 2 kilo each, so I now have about 3000 pieces, give or take a few hundred.