If you build boxes, frames, or small casework with mitered corners, a spline jig is one of those shop projects that pays for itself almost immediately. It adds strength, improves repeatability, and gives you a clean way to add decorative contrast at the corners. I gathered 10 free DIY spline jig plans and tutorials from a wide mix of trusted woodworking sources, with each entry linking to the original build page so you can choose the version that best fits your saw, your workflow, and the kind of projects you like to make.

How to Make a Miter Spline Jig and 3 Ways to Cut More Interesting Splines

Overview: This is one of the most complete free resources in the group because it covers both the jig build and the full spline process afterward. The tutorial walks through building a fence-riding jig, preparing spline stock correctly, and then using the setup for standard splines, angled splines, and even dovetail-key variations. It is especially useful for woodworkers who want one project that teaches both the jig and the design possibilities that come with it.

Why it is great: It goes beyond a basic jig build and shows how to turn splines into a real design detail.

Link to original plans: https://kmtools.com/blogs/news/miter-splines

Spline Jig Strengthens Miter Joints

Overview: WOOD Magazine’s plan is a classic, drawing-driven cradle jig sized for cutting spline slots accurately on frames and small boxes. The instructions focus on a simple MDF build with a beveled rear cradle and a front cradle aligned at 90 degrees, which makes the design easy to study and reproduce in a home shop. If you like shop fixtures that are compact, simple, and visual rather than overly complicated, this is a strong pick.

Why it is great: The illustrated format makes it especially easy to understand at a glance and build from shop scraps.

Link to original plans: https://www.woodmagazine.com/woodworking-plans/jigs/spline-jig–miter-joint

Simple Spline Jig

Overview: DIY Montreal’s version is refreshingly approachable and practical. The build starts with a snug box that rides on the table saw fence, then adds a larger face and two 45-degree supports sized for frames and small boxes. The steps are clearly written, the materials are realistic for a scrap-plywood project, and the tutorial keeps the whole build grounded in what most hobby woodworkers already have on hand.

Why it is great: It is beginner-friendly, compact, and genuinely realistic for a fast weekend jig build.

Link to original plans: https://www.diymontreal.com/simple-spline-jig/

Video: Making a Spline Jig

Overview: This Rockler tutorial is ideal for woodworkers who prefer to see a jig in action before building one themselves. Michael Alm demonstrates a simple plywood spline jig and shows how to use it on an actual mitered box, which makes the build sequence and the cutting setup much easier to understand. It is a helpful resource for visual learners and a nice reminder that an effective spline jig does not need to be elaborate.

Why it is great: The video format makes the build and the actual use of the jig feel immediately accessible.

Link to original plans: https://www.rockler.com/learn/video-making-spline-jig

Box Spline Jig

Overview: Billy Newton’s jig is aimed squarely at woodworkers who want especially clean splines on boxes and trays. The tutorial walks through building a base with runners, adding angled wings, and then tuning the setup for accuracy. It also adds two smart shop notes that are easy to overlook: using stable sheet goods for the jig itself and using a flat-tooth blade and sacrificial surfaces to improve the quality of the spline cuts.

Why it is great: It combines a solid jig build with genuinely useful technique tips that improve the final results.

Link to original plans: https://www.newtonmakes.com/blog/box-spline-jig

Make a Table Saw Mitre Spline Jig

Overview: Rob Brown’s jig is a great choice for makers who want a more shop-ready, purpose-built fixture instead of a quick one-off sled. The article explains how the jig works with the rip fence, why the fence attachment matters, and how to use it for consistent, attractive slots in mitred workpieces. It also includes helpful practical thinking about fitting the jig to your own fence setup rather than assuming every saw is identical.

Why it is great: It feels like a durable long-term shop fixture, not just a temporary solution for one project.

Link to original plans: https://canadianwoodworking.com/project/make-a-table-saw-mitre-spline-jig/

Routed Miter Joint

Overview: This Fine Woodworking shop tip takes a different path from most table-saw-centered spline jigs by using a router-guided setup for larger miters. The jig is made from a 2×4 ripped at 45 degrees, extended with an added face, and fitted with a guide spline for the router base. That makes it particularly interesting for large furniture-scale workpieces that are awkward or unsafe to manage with a conventional table saw spline jig.

Why it is great: It expands the spline-jig idea beyond small boxes and opens the door to larger casework and panels.

Link to original plans: https://www.finewoodworking.com/2005/10/25/routed-miter-joint

How to Make a Spline Jig for Table Saw (Step by Step)

Overview: AllFlavor Workshop shows a spline jig add-on designed to work with a table saw sled, which is a clever option for small shops that want versatility without storing another large fixture. The post walks through the base, the angled supports, and the use of side stops to place spline cuts accurately. It also highlights the practical appeal of a removable jig that can be added when needed and set aside when the sled goes back to regular work.

Why it is great: It is a smart space-saving approach for woodworkers who already rely on a crosscut sled.

Link to original plans: https://allflavorworkshop.com/spline-jig-for-table-saw/

Splined Miter Joint

Overview: Woodcraft’s guide is packed with value because it does not stop at one jig style. It includes a twin-faced table saw jig for frames, a simple router-table sled for smaller work, and an angled jig for case miters, along with practical advice about blade choice, bit setup, and spline-making. For woodworkers still deciding which style of spline jig belongs in their shop, this resource gives a useful look at several proven options in one place.

Why it is great: It gives you multiple jig directions at once, making it ideal for comparing approaches before you build.

Link to original plans: https://www.woodcraft.com/blogs/shop-knowledge-guides/splined-miters

Splined Miter Table Saw Jig

Overview: Jay Bates lays out a straightforward spline jig built largely from a single sheet of plywood, with a cradle-style form that supports mitred work securely during the cut. The post walks through the sequence of cuts, assembly of the angled faces, and options for running the jig with runners or a miter gauge. It has that very practical, get-it-done feel that makes shop jigs easier to commit to building.

Why it is great: The build is simple, efficient, and easy to imagine recreating from common shop materials.

Link to original plans: https://jayscustomcreations.com/2014/05/splined-miter-table-saw-jig/

A good spline jig does two things at once: it strengthens a weak-but-beautiful joint, and it makes decorative joinery feel much more repeatable. Some of these plans lean toward quick fence-riding jigs for frames and boxes, while others are better suited to sled setups, router work, or more permanent shop fixtures. That range is exactly what makes this list useful. Whether you want the fastest possible build or a more refined jig you will keep for years, there is a solid free option here to match the way you work.

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