In my not-so-spacious garage workshop, every tool has to earn its place. Not too long ago, I designed a table saw sled that’s been a huge game changer for me, simplifying countless of projects. And then I got an idea, and I thought: What’s the next jig for the workshop? Could I reuse the sled? That’s when I got the idea of the table saw spline jig addon. I approached this build in the same way I did for the table saw miter sled.
The spline jig is not an entirely separate tool, but rather an extension that easily integrates with the crosscut sled I crafted. The best part is, that you can easily attach it when necessary and remove it when you’re done. This is a huge bonus for those of us where space is at a premium.
Now, for those wondering what a spline jig is – it is the best way to add strength to miter joints and add those beautiful splines in picture frames and wooden boxes. No more eyeballing or manual measurements; this table saw jig makes sure all your cuts are precise and consistent. You simply place the workpiece in the jig, set the stoppers and you’re ready to go.
In this guide, I’ll walk you through the step-by-step process of building this simple spline jig for table saw. Trust me, at some point in your woodworking journey, you’ll face mitered corners. Believe me, it is a valuable addition to any workshop. If you’ve ever thought about making those fancy picture frames or box splines, then this is the tool for the job.
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DIY Table Saw Spline Jig Video
If you want to see how it is done, watch the video below for a step-by-step guide on how to make a table saw spline jig.
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Table of Contents
- The Material you will need
- General Questions
- What is a Table Saw Spline Jig and What is it Used For?
- Different Types of Spline Jigs for a Table Saw
- How to Make a Spline Jig for Table Saw
- Step 1: Build the Cradle
- Step 2: Build the Jig Base
- Step 3: Make the Fence Attachment
- Step 4: Cut the Kerf
- How to Cut Splines on a Table Saw
- Conclusion
- FAQ
*Safety is your responsibility. Make sure you know what you’re doing and take all necessary safety precautions while working with power tools. Safety comes first! Always be cautious and careful when using any power tool.
Materials you will need to build a Miter Spline Jig
Spline Jig Addon
2x Plywood Boards (Base) – 100mm x 320mm x 12mm (3.94″ x 12.60″ x 0.47″)
2x Plywood Boards (Cradle) – 115mm x 300mm x 9mm (4.53″ x 11.81″ x 0.35″)
1x Plywood Board (Attachment) – 115mm x 300mm x 9mm (4.53″ x 11.81″ x 0.35″)
Plywood Reinforcements
– 4x 50mm x 50mm x 12mm (1.97″ x 1.97″ x 0.47″)
– 4x 25mm x 25mm x 12mm (0.98″ x 0.98″ x 0.47″)
Plywood 12mm – https://amzn.to/3TPULp2
Other:
Wood Glue – https://amzn.to/48ltKhJ
Table Saw Blade – https://amzn.to/48maocv
M6 Bolts, Washers, T-Nuts, Wood Screws – https://amzn.to/41PodgQ
DIY Tools:
DIY T-track Bolts
Tools:
Table Saw – https://amzn.to/47mWiGf
Trim Router – https://amzn.to/3HbQcOg
MicroJig GRR-Ripper – https://amzn.to/3vjQSP7 (Grr-Ripper Review)
Cordless Hand Drill – https://amzn.to/3HqLEnH
Corded Hand Drill / Drill Press Stand – https://amzn.to/3NSA3Bo
T-track Clamps – https://amzn.to/3tEKaCW
One Hand Clamps – https://amzn.to/48jGxkZ
Spring Clamps – https://amzn.to/41Nuh9D
Machinist Square / Speed Square
Japanese Ryoba Saw – https://amzn.to/48if4Qz
Check all the Tools I Use
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What is a Table Saw Spline Jig and What is it Used For?
A table saw spline jig is an accessory, a jig, specifically tailored for table saws, designed to assist woodworkers in creating splines – those thin decorative inserts or reinforcements for mitered corners. Splines are primarily used to strengthen and beautify mitered joints, and corners in frames, boxes, and other woodworking projects. The jig ensures the workpieces are stably anchored in the accessory while the sled glides across the saw and cuts through the material.
Benefits of a spline jig:
- Strength and Beauty: The spline jig allows for the addition of splines that not only reinforce joint corners but also elevate the aesthetics of any project.
- Safety: The jig ensures safer operations and reduces any unexpected wood movements, by keeping the wood secure during the cutting process.
- Versatility: Perfect for various projects, from picture frames, and boxes, to small cabinets. The size of the spline jig does not limit you to thin wood pieces only but can accommodate larger workpieces as well.
Different Types of Spline Jigs for a Table Saw
There are a couple of common methods to cut splines on a table saw. One approach uses a jig that moves along the table saw’s fence, while another uses the miter slots, working like a sled. Let’s take a look at these two:
1. Fence-Based Spline Jig
This jig attaches to the table saw fence and glides over it. To set the cut position, just adjust the fence closer or further from the saw blade. Insert your frame into the jig, lock it, and you’re good to go.
- Works for both small and large picture frames.
- Quick and straightforward setup using the top of the fence.
- Compact design.
- Best for frames; not ideal for boxes or cabinets.
2. Miter Slot Spline Jig
Think of this as a sled that moves using the table saw’s miter slots. It’s a bit bigger, kind of like a cradle, perfect for larger pieces. You can adjust the cutting position by setting stoppers on the jig.
- Suitable for frames, boxes, and even small cabinets.
- User-friendly setup.
- Might not work well for very large frames.
- Takes up more space.
Let's Start Building!
Building a miter slot spline cutting jig involves making the base (which is installed on the sled’s front fence), and a V-shaped cradle to accommodate the workpieces. This design is an add-on for a table saw crosscut sled. All the parts can be cut on a table saw, with a few minor adjustments using a router or a jigsaw.
The jig is made of plywood (9 and 12mm) and can be attached to the sled’s fence either with t-slot bolts or t-slot clamps. It can accommodate wood pieces up to 80cm in length (possibly more). Although the overall dimensions of the workpiece are what truly matter.
Spline Jig Properties:
• Material: Baltic Birch plywood
• Total Dimensions: 340mm x 230mm x 95mm (13.39″ x 9.06″ x 3.74″)
• Attachment: T-Track using T-track bolts or T-track clamps
How to Make a Spline Jig for Table Saw
Step 1: Build the Cradle
Start by cutting two plywood boards to these dimensions: 115mm x 300mm x 9mm. I used a table saw sled and a push block to get these cuts. Once cut, join the boards at a right angle using clamps and glue.
TIP: While you could angle the board edges at 45 degrees for joining, it’s not essential for this jig. Your table saw blade is tall enough for the task. This adjustment is more relevant if you’re making a jig for a router since router bits aren’t as long as saw blades.
Step 2: Build the Jig Base
Begin by sizing two plywood boards to 100mm x 320mm x 12mm. Next, with the help of a miter sled, cut eight rectangular support pieces: four of them should be 50x50mm, and the other four should be 25x25mm. Using the miter sled ensures that you achieve perfectly angled isosceles 45-degree triangles.
TIP: Stick some painter’s tape on the wood before cutting the supports. It’ll give you cleaner cuts.
Attach the support pieces to the base using glue. Place the larger supports on the outer edges and the smaller ones towards the inside. Use a square to ensure the supports stand at a right angle to the base. Remember to avoid the center of the boards, since that’s where you’ll be cutting the kerf later on.
After securing the support pieces to the bases, attach the cradle on top. Set the cradle upright on your workbench and fit the base pieces around it.
TIP: Use clamps to keep one base piece steady, then position the cradle alongside it.
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Step 3: Make the Fence Attachment
Cut the attachment board to the specified measurements (115mm x 300mm x 9mm). Next, route out 2 slots for the larger supports. These slots will allow the supports to slide in, creating an overlap between the attachment board and the jig’s base. This overlap provides enough surface for both glue and screws.
Drill two 8mm holes in the attaching piece, aligning with the t-track on the table saw sled fence. Apply glue on the overlapping area, align the jig with the fence, and fix it to the attachment piece. Let the glue set. Once dry, reinforce the boards with screws making sure the heads sit flat against the board.
Step 4: Cut the Kerf
Mount the spline jig on the table saw sled using either bolts or t-track clamps. Lift the saw blade to about 2 cm high, then turn on the table saw. Carefully make the cut. For neater and more accurate cuts, consider using painter’s tape.
How to Cut Splines on a Table Saw
Using a spline jig on a table saw is the most effective way to cut splines. This tool allows you to create splines in picture frames, boxes, cabinets, and other wooden items. Here’s a simple step-by-step guide to cutting splines in a wooden box, though the process is similar for other wooden pieces. Use a flat tooth blade for the cuts. The wooden strips will align perfectly leaving no spaces at the ends.
- Position the jig on the table saw and slide the box into the jig.
- Set the side stoppers to mark the spline’s exact location and clamp them securely.
- Adjust the blade height to ensure the cut doesn’t go completely through the joint. The depth will vary based on the corner’s thickness.
- Power up the saw and push the jig through the blade.
- Flip the box and repeat for all four corners.
- Adjust the stopper to add more splines.
To finish your box, first apply glue to the splines and slide in thin wooden strips. It’s a good idea to choose strips slightly narrower than the splines because they can expand with the glue. Wait until the glue dries, trim any sticking-out parts with a saw, and smooth out the box corners using a sander. To make the spline visually pop-up, consider using wooden strips that have a different color than the box itself.
TIP: You can also make some creative splines by tilting the saw blade to 45 degrees.
Conclusion
I’ve really come to appreciate the value of a spline jig in my projects. It provides strength and style, unmatched accuracy, and consistent repeatability. It’s amazing how such a simple jig can offer so much precision. This is one of the essential table saw jigs you want to have in your workshop. Give it a shot, it is well worth it!
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45 Degree Spline Cutting Jig
Woodworking Jigs I used to build it:
These are the tools and jigs I have used to make the spline jig addon. Not all of them are necessary though.
Frequently Asked Questions
Do I need a spline jig?
Using a spline jig ensures stronger and more attractive joints, especially in decorative boxes and picture frames.
Can I use a spline jig on any table saw?
Yes, most spline jigs are made to work with many table saws. Just make sure your saw has miter slots or a fence, and you’ll be good to go.
How does a spline jig enhance joint strength?
It adds extra material (the spline) into a slot in the joint, increasing its durability and strength.
Can I make my own spline jig or should I buy one?
Both options work. Homemade spline jigs can be designed to perfectly fit your needs, while store-bought ones offer convenience and professional design.
