Taper Cutter

This cutting jig is for creating tapered tenons out of dowels or adjusting the size of a taper you may have turned on a lathe. The specific application I had was for making Windsor chairs, where the legs have tenons that must precisely match the seat holes. The traditional way to do this is to drill and taper a block of wood, then cut out a bed for your cutter. Plane blades work well for this. This video [https://www.youtube.com/watch?v=mjFnMjlt6SE] shows that process.

You can also buy ready made tenon cutters from places like Lee Valley Tools, but I need one to match the specific reamer I had.
Also, I didn't have a block of wood that was big enough for my plane blades. So Here's the 3D model I came up with.

Since you may need a different taper angle or if you want to just borrow the blade from your Stanley #4 plane or #151 spoke shave, I've included the models (the original Fusion 360 along with exports to .step and Sketchup .skp) along with the .stl files. I made the original model parametric, so hopefully these exported correctly and you can adjust them if needed.

How I modeled it:
I followed the steps I would have used to make this out of wood. I started by taking some measurements the reamer itself, modeled that and created a solid cone shape. Next I drew a box centered on the cutter and offset it to the major diameter I wanted and subtracted the reamer volume for the box. Sketches based on the top and bottom of the box allowed me to locate two parallel lines that defined a cutting plan to form a bed for my plane blade. I offset that slightly to account for the blade's thickness. Finally I added some mounting holes for the blade and did the usual fillets and champers for easy printing.

Somewhere along the way I added threaded socket to accept a handle because it was a little hard to hold. A dowel jammed into a hole would probably have worked fine here. But I wanted to make things fancy by adding threads for a broom handle. This took me down a rabbit hole of using Fusion's Coil Tool* to make a helix that you can attach to a specific point. I'm amazed that in mid-2026, Autodesk still hasn't addressed this. The hack I came up with was to draw the somewhere near where is should be, then use the Move Body tool to place one end of the coil's major axis and the sketch point I wanted. That way when I change the box dimensions and the coil will stay centered on the cylinder I cut into it.

Here is the plane blade and reamer this is supposed to match:
https://www.amazon.com/dp/B07H49849M?ref=ppx_yo2ov_dt_b_fed_asin_title
https://www.amazon.com/dp/B0DSHRTPMW?ref=ppx_yo2ov_dt_b_fed_asin_title

Printing:
Nothing too special here. Place it on one end or the other. The larger end towards the bottom recommended, for the "bridge" in the handle's socket threads is at the top. The blade's mounting holes are meant to be self tapping so a little sag here won't hurt. No supports should be needed. Also, there's no need to get carried away on infill, 15% seemed plenty strong but I did add an extra wall loop to hopefully make the surfaces a bit more durable.

*Yes, I realize I could have used the Thread Tool to create modeled threads, but I could not find the ACME specification matching a broom handle. So I used the coil tool and got on with it. Feel free to upload the model and change it if that bothers you. According to the AI, "the standard ACME thread specification for a broom handle socket in the US is 3/4"-5 (3/4-inch major diameter with 5 threads per inch). This socket size fits standard extension poles, paint rollers, and push brooms".