Bulb Finger Joints are useful and attractive co-planer joints for connecting different sheet materials which are very easy to produce with machines such as CNC routers, Water Jets & Lasers. A great benefit of these joints is the strength along the plane of the joint without having to glue/ weld.

This Instructable shows the simple geometry behind this joint and explains how to draft this & how you can adapt its form to allow for greater  control of the technique and hence the overall design.

I'm  explaining this in terms of drafting it with programs that can export to the manufacturing tools capable of fabricating these components, though the form can be achieved with a basic compass set.

Thank You TechShop Detroit for helping me with this design :) www.techshop.ws

Step 1: Basic Geometry Overview

The bulbs are created by a vector slalom between regular circles that are tangent to each other.

Specifically,  at the diagonal tangent of eachother  about a stright line (spine) being slalomed.

This means that if you draft a circle and draw a perfect X through its center to the circumference, the intersection of this line with the circumference should  meet along the 'spine' of the connection, joining with the same point of other circles.

This way the circles are stringed together  by these diagonal tangents alternating along this spine.  Once the chain is complete all you need to do is delete the shorter segments of each circle or create a new layer and trace  as you want using this as a framework.

Spineally! An understandable method to make these fantastic finger joints. Thank you Idanen.

About This Instructable




More by ldaenen:Chaordic Vector Patterns Bulb Finger Art! (Manipulate CNC slot scheme for asthetic, spatial & structural considerations) Projection tracing technique for large walls in confined spaces. 
Add instructable to: