Circular Knitting Machine (CSM)

This OpenSCAD file describes my version of a circular knitting machine. This is an original design, but some details and ideas were obtained from various sources . User RoundandRound (https://www.thingiverse.com/RoundandRound) very gracefully produced an assembly guide which can be found in the files section.

Design criteria:

• Bi-directional (for heel and toe knitting);
• Minimal moving parts;
• Low friction;
• Minimal contact of yarn with printed parts (no snagging);
• Minimal sanding;
• Low cost: budget under 50 Euro

The machine is driven by side-by-side pullies with a 2GT timing belt to reduce friction. Also the machine runs on three ball-bearings, using 4.5mm steel BB's as balls.
There are 2 push-up cams, leaving the needles normally in the up position. They can be pushed down to do maintenance; eg. to pick up dropped stitches. This eliminates having to use mechanical "flippers" to push the needles up. (Usually the needles are pushed up (to clear the needle latches) just before the stitch is made. Here the needles are also pushed up right after the stitch is made. This makes no difference for the knitting, it just looks differently)
All cams have a groove to glue in a soft metal wire (1mm) as a bearing surface for the needles. I use common annealed galvanized steel wire. This eliminates steel on plastic contact, which reduces friction and wear. Also this eliminates the need for sanding of the cams (see picture).
The machine uses cut-down KR830-KR850 needles. These were the cheapest I could find.

UPDATE: I took pity on people who cannot find metric fasteners and are unclear on how to use OpenSCAD. I included UNC versions of the three parts that use nuts. These should now accept #4 UNC nuts. I have not tested this personally. Print the smallest part first and see if it fits. If you have trouble, let me know and I'll adapt the design.

In response to user wishes I included several modifications. Please ignore these if you don't know what they are all about. These files are indicated with the user name.
The file "main_base_elena71.stl" is a base which facilitates mounting jeepingJohnny cylinders. However, your mileage may vary as I found those needle slots to be too wide, which resulted in jams. guide_top_elena71.stl is a modified yarn guide.
Another modification is in the mod_T5 file. This is still experimental and provides parts for a T5x10 belt. Please use the included test file to check if your belt matches. (updated on 12-18-23)

A large version is also available: thing:6325127

Also included is a customizable version in CSMv4.zip which is also better optimized and thus a lot faster. It can produce versions with cylinders from 60 - 300 mm diameter. The parts it produces (cylinder = 120mm) are largely compatible with the original version, but don't count on it. Attachment points are increased from 3 to 6. This is mainly for the larger versions, but can be used as backup in case of damage for smaller machines. With thanks to Konchog and SavageRodent for all the helpful hints. (updated 12-21-23 with several base options as well as timing belt sizes and profiles.)

The colors in the pictures indicate:
yellow -- 3D printed parts
blue -- piano wire parts
green -- standard hardware (bolts, nuts etc)
red -- other parts with minimal fabrication required (shafts, pins etc)
magenta -- BB's