by Yun-Han Lin
Joints are the basic elements in woodworking. They are easy to use and come in low prices. Before we get started, here is a brief introduction of the joint jigs that we see often!
Joint jigs that Makers often use:
1. Trimming machine or circular saw
These are the two most common types of jigs. The structure is easy and I learned from my trial that there is a piece of wood to position the drilling hole. The wood piece got rubbed against by other wood pieces that I was working on, so it could be worn out and deformed, causing the box joints to become loose.
2. The ultimate box joint jig
It has been discussed before in another article- Lethe Bed for Circular Saw. This box joint was designed by John Heisz, an experienced carpenter/youtuber that has been making woodwork for years. He can handle wood pieces that come in all kinds of sizes and lengths and he works fast and clean. Also, he can adjust the width of the joint with ease.
3. Router jig
This type of jig usually comes in medal ones that are ready-made. The cost is high, but they are durable. The problem was that the joint and the drilling hole need to be compatible to the jig, which did not give much room for adjustment.
Easiest box joint ever by Novice Workshop
Click the video to see the working process.
Pros and cons of jig made using laser cutting
The width and thickness of this jig can be easily modified using computer software for any needs. Also, instead of manual production, laser cutting is fast and has high precision. The overall cost is low, because we used medium density fiberboard (MDF) mostly, which can be replaced whenever we want.
Why parameterize the specs?
One problem with this jig is that there is little room for adjustment. Different specs would fit specifically into certain jigs. For this reason, it would be easier that the design drawing can be modified, so there needs to be a graphics software to do the math.
Specs setting using Fusion 360
After you activate the software, click “Modify” and choose “Change Parameter” to customize parameters for your project during drawing.
For our project, we set parameters that include “wood_thick,” “side_clearance,” “wood_length,” “joint_num_est,” “joint_num_act,” and “joint_width.”
Let’s start with the easy ones: “wood_thick” and “wood_length,” which need to be adjusted first. They will directly decide the number of finger joints and their width. “Side_clearance” determines the size of the outer frame. The larger the value, the larger the upper surface.
The next is the critical parameter- “joint_num_est”, which is decided based on the ones previously mentioned. For this one, we enter: “(wood_length / (wood_thick * 2/3) ).” The standard width of a box joint is two-thirds of the thickness of the wood. With this width divided by the length of the wood, we can have the total number of finger joints!
Is that all?
The screenshot below is the draft after I changed the length of the wood from 194 millimeters to 400. From this, we learn that we definitely need to click into each drop-down menu to handle the settings in detail.