Yarn spike kate

This is my double yarn cake holder design from Onshape re-published in convenient, pre-exported form.

It's a lightweight, somewhat portable kate for knitting directly off a pair of yarn cakes. 

Non-printed shafts required

You will need to supply two metal rods. The model is designed for 6mm diameter rods around 80-140mm long. Slightly smaller will work fine too, just fit a bit loose in the bases.

Wooden dowel shafts will probably work OK too, especially if you chuck some silicone grease or paraffin wax or something on them to help them spin better.

The onshape model can be reconfigured and re-exported if you want a version to fit a different rod by modifying the  shaft_diameter global variable then re-exporting the parts from the "printable parts" tab.

What to print

• Either the single piece base or both split base pieces
  
  The base is available here in either single-piece form or with a slide-together split for use with smaller printers.
  
  The slide-together should also allow you to pack it down further for transport, but the prototype I printed fit too tightly; I landed up having to trim it down then glue it. I've adjusted the tolerances since then but not re-printed, so no guarantees.
  

• Two spinners
  
  These are what the yarn cakes go on. So unless you intend to use this as a regular kate with bobbins, you'll want these.
  
  (You could also print just these and use them on an existing kate base if you have one with shafts that'll fit, or tweak the shaft diameter in the Onshape model and re-export to fit your kate.)
  

• Two guide inserts (optional)
  
  If you want guides, you can print the guide inserts, then stick some stiff wire in them to serve as yarn guides. Just bend a loop in the top.
  
  Drill the hole in the end of the insert to size if required for your wire, or change variable #guide_hole_d in part tab "base" (I didn't get around to making it a parameter or global yet) then re-export the guides from the "printable parts" tab.
    

• Two caps (optional)
  
  Only print caps if you want them for transporting the spinners. They're a bit spiky.  ⚠ The caps were a quick and dirty last minute addition and don't have a very satisfying fit.

Tweaks

If the spinners don't spin freely enough on the rods, you can just drill the cores out with a 6.5mm drill bit. This produces a smoother core than you'll get from 3d printed parts anyway. I often print under-sized shafts with thicker than default walls, then drill them out anyway.

Parametric model

The model is parametric, and you're free to adjust it in Onshape if you want to do things like adjust the width of shaft it takes, remove the clamp foot or the guide slots, etc. Most of these are exposed either as configuration parameters in the model, or as global variables. I used a bit of a messy mix of the two.

The most useful settings are:

• #shaft_diameter global variable - diameter of the shaft to socket into the holes in the base and slide into the spinner cores

• #spinner_shaft_tolerance global variable - how much gap there should be between the shaft and the inside edge of the spinner hollow core. Tune if required for your printer and shaft.

• #base_shaft_tolerance global variable - how much gap to allow (or "negative gap" to make it tighter) so the shaft fits firmly into the base. It might be easier to print slightly under-sized then drill the hole out if your shaft is is a convenient match for a drill bit size you have. Or you can carefully heat-form the hole with a heat gun, but it's hard to keep the shaft strictly vertical doing that.

• #spinner_diameter_xy global variable - diameter of spinner at outer edge.

• #guide_hole_d global variable - diameter of the wire to fit in the guide insert

• #max_yarn_cake_diame global variable - max diameter of yarn cakes that can be used before they collide. Controls shape and neck length of the base. Model may malfunction when it is too far from the default of 150mm, I'm not that great with onshape yet.

• include_clamp_foot , with_guides and with_bearing configuration options in the basepart tab. These are not currently configurable for the split base version.

I'm aware that the variable naming and the mix of variables and configurations is a mess. It isn't a pretty project but ... it works.

Possible future enhancements

If there's interest I might be able to make a few changes, such as:

• Minimal sized fit-check slot models for tuning the tolerances on the slots and your print settings

• Improve poor transitions in the base of the spikes

• Blank plugs for filling in the guide holes if unused. You can always re-export the model without guide holes though, it's parametric.

• A middle section so triples (or more) can be constructed

• Configuration improvements in the rather crude Onshape project - expose options more consistently, etc.