CNC Corner Joint custom feature (update of Board Corner Joint feature)

hendrik_kueck

This is a custom feature for creating different types of CNC millable joints connecting two flat boards meeting at a 90 degree angle.
It is an update of Aaron Hoover's "Board Corner Joint" custom feature. 

Get the custom feature and read its documentation here

I was working on a custom stand for PowerBlock dumbbells I recently bought, with parts designed to be CNC milled from a plywood sheet. I was excited to find Aaron's FeatureScript and tried to use it to create the CNC compatible joints. However I found that it frequently failed if the boards where not extruded in a very specific way. This motivated me to learn FeatureScript and update and improve Aaron's script. 

The main differences from Aaron's implementation are:

• It should be significantly more robust to the boards being extruded in different ways.
• I added adjustable positioning of the overcuts (dogbones), which can be helpful for hiding them (see below).
• Added an option to fillet the overcuts (for smoother CNC toolpaths)
  
• Made finger joints symmetric (both ends are either tenon or mortise)
  
• Fixed tenon and mortise being reversed for hammer joints.
  
• Removed "fingertip tenons with key" joint type because it seemed broken to me. I didn't really touch the fingertip joint implementation otherwise. It definitely could be improved and made more consistent with the other joints in the future.
  
• I simplified and modernized some of the code and removed all dependencies.
• Added new PDF documentation

The new overcut positioning feature let's you control their placement relative to the joint's main axis using a value between 0 and 1:


I found that a value of 0 can be quite useful in practice for hiding the overcuts from the inside of the joint, or to completely hide them in the case of a joint between two boards in a T configuration.
I used this in the design of my weights stand to hide all of the overcuts. 

I hope others will find this useful. 

MichaelPascoe

Fantastic! Thanks for sharing 

hendrik_kueck

I just updated the custom feature to version 1.2.

I added the option to specify multiple tenon and mortise parts. Joints (of the specified type and using the same parameters) will be created between each pair of a tenon and mortise part. This requires each tenon part to intersect each mortise part at a 90 degree angle. Either at a corner, or in a T configuration. 

I also added a new "Edge offset / margin" parameter that lets you control the width of the tenon or mortise bits at the ends of the joint:




Finally I further improved robustness (fixed failure cases), especially for through joints and lapped and secret joint types. 

Updated documentation is here