Spline and Box Joint Jig


The supplies, wood and tools listed below will provide you with everything you need to build the spline and box joint jig.

Hardware and Supplies

Item Qty Link
Hex Head Screw – 8mm x 35mm [5/16" x 1 1/2"] 2 https://amzn.to/3ZBLQ9Y
Flat Washers - 8mm [5/16"] 2 https://amzn.to/431QHED
Wingnuts - 8mm [5/16"] 2 https://amzn.to/3zrMwV4
Knurled Clamp Knob (Thumb Nut) With Threaded Insert –
8mm x 25-30mm [5/16" x 1-1 1/8"]*
4 https://amzn.to/3U9WljR
T Bolt – 8mm x 38mm [5/16" x 1 1/2"] 4 https://amzn.to/3Kr475B
Titebond III Woodworking Glue 1 https://amzn.to/431CSG0
Water Based Polyurethane 1 https://amzn.to/3UhKWyJ
8mm [5/16"] Spiral Up Router Bit, 1/2" Shank, 1" Cutter 1 https://amzn.to/3K7xN6q
12.7mm [1/2"] Dovetail Router Bit, 1/2" Shank 1 https://amzn.to/40CFl8u
16mm [5/8"] Forstner drill bit 1 https://amzn.to/3PldO6u

* Dimensions specified as "inner thread diameter" x "outer knob diameter". The part referenced here is made from brass since Amazon doesn't appear to have a plastic version with the ideal dimensions. Most of the Amazon star knobs with a 5/16" insert have quite a large outer diameter. They would work on this jig but limit the range of motion.


Item Qty Link
12mm [1/2"] MDF
600mm x 600mm [24" x 24"]
1 N/A
18mm [3/4"] MDF
500mm x 110mm [19 3/4" x 4 3/8"]
1 N/A
4.8-5mm [3/16"] Hardboard
500mm x 174mm x [19 3/4" x 6 7/8"]
1 N/A
Hardwood for 8mm [5/16"] box joint indexing pins
260mm x 8mm [10 1/4" x 5/16"]*
1 N/A

* The dimensions depend on the size of the box joints you are making. 8mm [5/16"] box joints are used as an example in the plans.


Some of the tools I used for this build. If the exact product wasn't available, I've included a link to an equivalent product.

Item Link
DEWALT 10-Inch Table Saw, 32-1/2-Inch Rip Capacity (110V USA plug style) https://amzn.to/3OCJHWF
Makita LS1219L 12-Inch Dual-Bevel Sliding Compound Miter Saw with Laser, 110V model https://amzn.to/39Mu28mF

Disclaimer: A small commission might be received for sales made through the affiliate links above.