Tools Tuesday – Mitre Jig

Mitre Jig - in action

Introducing Tools Tuesday! Each Tuesday* I want to take some ‘action shots’ of a tool that I use and give a quick description and review of the tool.

I start with my jewellers’ mitre jig (miter jig in US English ^_^), because it’s what I’ve used more than anything else so far this week!

What is a Mitre Jig?

It’s a handy little device that allows you to fairly easily create true angles on the edges or faces of work pieces. Mine has openings corresponding to 90° and 45°, but there are newer ones out that also have a 30/60° opening.

How do I use this thing?

The knurled knobs on the top screw up and down to loosen or tighten the jig. Open the knobs until the piece you’re working on slots into the opening you need, then tighten them enough to hold the piece. The jig has a couple of grooved areas in it for holding wire or tube etc. perpendicular to the depth of the jig, or for flat pieces (sheet, or the square tube in the photo) you can butt it up against the straight tab for the same effect.

In the photos, the square tube is in the 90° slot; this is so that I can file against the jig until the end of the square tube is flush with the face of the jig, and this makes a nice, flat 90° end on the tube. I’d do this for pieces of round tube to make my tube rivets better, for pieces that need to be soldered end-on to a backplate and sit up properly and flush, etc etc.

The photos show a round tube in the grooves of the 45° slot. I would use this slot if I needed to get a 45° angle on the edge of a piece of sheet or wire etc… very useful if making boxes or right-angled corners to make sure the two edges meet correctly.

Mine doesn’t have the 60° slot, but if it did I could use that to make equilateral triangle and hexagonal frames, among other things.

I mostly use mine to true the edges of parts with a file against the jig surface. I’ve not had a lot of success sawing next to this thing (at the end of the cut when the blade comes free of the workpiece, I usually hit the jig opening at an awkward angle and break the blade) but for some people this works :)

There is a slightly recessed area at the base of the jig, so that it can be mounted and held securely in a vise.

How often do I use it?

A lot! Take the small pieces from my workbench that are in the photo… all of the square pieces are cut from the tubing and I’ve used the jig to true both ends of the pieces. Soldering backplates to make tiny boxes is then really easy as the surfaces are flat and meet perfectly. The round pieces are formed from a disc and a strip… I’ve used the jig to true both edges of the strip before I shaped them and soldered. I had marked where I wanted the exact ends to be on the strips before I sawed them and then lined those ends up with the jig and filed them to perfection so that all of my strips have consistent length.

I use my jig virtually every week, some weeks constantly and some not at all, depending on the type of work I’m doing.

What’s it worth?

I have a cheaper model, it was about $90 when I bought it but they’ve come down a little at some suppliers… the $65 one currently at Rio Grande looks just like mine. When mine is due for replacement (you do file against these; even though they’re hardened steel I’ll eventually need a new one… in a few years’ time), I’ll probably try a higher grade one. The 45° slot in mine has the faces very slightly misaligned when closed… not enough to affect the work I do but a touch annoying nonetheless.

Wrapping up – I really love this tool and I use it more than I ever thought I would when I bought it. Experienced jewellers can eyeball an angle and know it’s not right and fix it really quickly with a file, but while I’ve practiced a LOT, this is not a skill I have, so the mitre jig is one of my best friends at the bench ^_^

 

* Yes – this week my Tools Tuesday post is late; I was ill Tuesday and Wednesday is not typically a day I can work due to toddler duties. I’ll be more prepared in future! :D

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