UPDATE:

I've made a magnetic saw guide that's even better! It's more compact, easier to use (subjectively, for most people though :) and even more accurate! You can even cut non-45° miters with it!! Check out the video:

https://www.youtube.com/watch?v=IDGZmSuTRfE

In this Instructable, I will show you how to make a magnetic bench-top miter box, which will help you achieve perfect 90 (or even 45) degree cuts with any hand saw. This tool can be mounted on any workbench, and should be mounted on EVERY workbench!

(Watch the YouTube video: LINK FOR MOBILE VIEWERS!)

I built this magnetic hand saw guide a few months ago, yet haven't been using it as much as I'd like to. It has a few main issues, which are:

Clamping the piece that I want to cut in my homemade wooden vise is difficult with the guide on top.

Setting the correct angle is difficult, and not automatic like I'd like it to be. I need to adjust it to a 90 degree angle with a speed square, and when I tighten the clamp, it gets messed up. I rarely make a cut that isn't at 90 degrees, so that should be the default!

The teeth of the saw get stuck in the cloth towel thing sometimes.

The surface area between the magnet and the saw could be improved for better guidance.

It just doesn't fit my needs. If you're looking for a guide that's portable, can be made fairly quickly, and can cut at every possible angle, that one might be for you. For the first prototype, I wouldn't have expected more, though.

That got me thinking. I could make a guide that gets clamped with the piece of wood that I want to cut in my vise. That idea was actually pretty difficult, so I came up with a simpler, yet better idea: to not use my vise at all! In the past few months, I've been getting tired of setting up my vise every time before each use. To set up my vise, I need quite a few clamps which take time to install and remove since I sometimes need them for a different task (I don't own many clamps). I thought of making a quick release mount, but that's pretty difficult too, for several different reasons.

The guide I'm going to be making in the Instructable kills two birds with one stone ⁽ᵒᵘᶜʰ⁾ - not needing to install the vise before every cut, and improving the magnetic guide itself, drastically! Oh, and did I mention that the magnet will be hidden?

Let's get started!

Step 1: What You'll Need:

Below is a list of everything you'll need to complete this project. You should be able to find the parts in a hardware store, on eBay, or maybe outside, on the sidewalk that's near your house! If you don't see something that you think should be here, or would like to know more about a specific tool/part that I used, feel free to ask in the comments.

I made it for FREE since I already had /everything that was needed on hand.

Hardware, Materials & Consumables:

3(x) 25X2mm Neodymium magnets
Thin 4mm plywood (5 ply)
CA glue
Screws
Eye bolt & a matching hex nut
A piece of wood that has a 90 degree angle (salvaged from a chair)
Beech wood

Tools:

HOMEMADE DRILL PRESS!
Drill
Drill bit set & 12 & 25mm Spade bits
Dremel
Rotary tool carving bits
Hand saw
Hacksaw
Hammer
Caliper
Clamps

Subject/s: Woodworking, Making Your Own Tools

Approximate Time: <2 hours

Difficulty: Medium

ALWAYS USE PROPER PPE.

Step 2: Choosing the Correct Piece of Wood

This step is the same as the third step of I'ble of the first guide.

To cut at a 90 degree angle (future, that is), I need a piece of wood that has a 90 degree angle, so it can guide my saw properly. Since I don't have a miter saw or a tool that can cut accurately, I need to find one, but don't worry, it's not that hard! I searched through my collection of wood, and found a piece of beech wood that had a 90 degree angle on one side. Like most of my collection, it was made of Beech wood, and I'm pretty sure is a chair leg.

Step 3: Want to Hide the Magnets? Drill!

I drilled a 25mm hole in the endgrain of the piece of wood that I chose with a spade bit. This will allow for me to embed (hide) the magnet inside of the piece of wood, so it doesn't stick out.

Make sure to have the drill in the center.

As you might be able to see, I'm very lucky to have built my homemade drill press which can be taken apart easily, so I can use the drill separately. ⁽ᶜᵒᵐᵉ ᵒᶰ, ᶜᶫᶦᶜᵏ ᵒᶰ ᵗʰᵃᵗ ᶫᶦᶰᵏ ᵃᶫʳᵉᵃᵈʸ!⁾

Step 4: The Thin Plywood and the Magnets

Since the dimensions of the piece of wood that I used are 3.5X3.5cm*, I used a hacksaw to cut up a piece of thin plywood to that size.

I glued all three magnets (stacking a few on top of each other makes them stronger, right?) in the center of the plywood piece with CA glue, and once it had cured, I glued the plywood, magnets face in (so they're hidden), onto the piece of wood. Endgrain is normally harder to glue since it tends to absorb glue instead of leaving it on the surface, so I soaked it with a lot of glue, waited a bit, put more glue, and squeezed it tightly. Another benefit of CA glue is that it's very brittle, meaning that if I need to replace something inside, the plywood might break off if I hit it with a hammer. Hopefully!

*The piece is actually bigger, but that was the only place where I could glue on the plywood. This piece of wood was salvaged from a chair, and the evil carpenter that built the chair chamfered the edges! ;)

Step 5: Mount It Onto the Workbench!

I clamped it down to my workbench, making sure that it stuck about two centimeters out of the side. I drilled pilot holes, and screwed in some screws, which I also countersink with a bigger drill bit, so they sit below the surface.

Step 6: The Hold Down Clamp

I have to say that from a quick cut, I'm not sure a clamp is even needed!*

I cut two pieces of beech wood to 7.5cm long, yes, already using the guide! I decided one would be enough (After using it quite a bit, I think that was a correct decision), and then drilled a 12mm hole in it with a spade bit. Since I wanted the nut to fit tightly inside, I had to enlarge the hole a bit with my Dremel and some cheap carving bits. After I had finished that, I drilled an 8mm hole in the middle of that hole, and hammered the hex nut inside. I did this mostly as a (successful!) experiment, as for my homemade wooden vise, I chiseled the hole to make a perfect fit for the nut. Now, I know that there's a method that's way quicker!

I used 3 screws to secure it to the guide, and added a small piece of wood as a pad for the clamp (which later exploded from the force!).

I find that the clamp helps a lot with the shorter pieces, since I have less leverage for holding them. I think I still will use it even for the bigger pieces, so 100% of my attention goes to the saw, instead of holding it in place. What I mean is that you'll survive without a clamp!

Step 7: DONE! | More Thoughts | Video!

See it in action, on Youtube!

Some more thoughts:

I will apply varnish to the exposed pieces of wood, so they won't get ruined because of the humidity.

If you drill the hole for the nut that's used for the hold-down clamp too big, epoxy should hold it in place.

I will cut away the guide, that piece of wood is way too long. I might add two more screws too.

This could also be a nice 3D printing project. Too bad I don't own a 3D Printer!

I will be giving away free Instructables memberships to members that make their own bench-top magnetic handsaw guides. Will you be the first one?

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