How to Set a Miter Gauge for 45 Degrees

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Setting the miter gauge on your table saw to a perfect 45-degrees can be very challenging. And, if you’re planning on making picture frames, being just a tiny bit off will be a deal breaker. But here’s great news. You’ve probably already got a tool in your shop that will give you the precision you need to set your miter gauge perfectly, allowing you to get an exact 45-degree cut.

Angles from squares

The amazing set-up tool for this operation is……a framing square. Yep, the lowly framing square. Used correctly, it’ll allow you to pivot the miter gauge to just the right spot for a perfect 45-degree angle. Thanks to the size of a framing square, you’ll get excellent accuracy.

Accurate picture framing

This video will help you get the miter gauge correctly set so you can accurately cut angles, but remember that there’s more to good looking picture frames than simply having the angles right. You also need to be consistent with the lengths of your parts. Each side needs to be exactly the same length as the opposite side. The best way to accomplish this is by using a stop block on your miter gauge.

But wait, there’s more

This is just one nugget of a tip that WoodWorkers Guild of America has for you. Make sure you’re getting the most of out your shop and your tools by checking out more great shop tips.

Discussion
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9 Responses to “How to Set a Miter Gauge for 45 Degrees”
  1. Roger Erisman

    Line up the numbers on the slot before sliding the miter gauge against it. This will save some trial and error.

    Reply
  2. Ron

    Eyeballing methods like these can get you close and if you’re lucky, dead on. How all four corners of a mitered frame come together will determine if further fine-tuning is warranted.

    Reply
  3. Larry Ruddell

    This also assumes that your framing square is square.

    Most people don’t check this very often and, when framing large items such as a house, the framing square being a little off is not usually a problem. However, for miters, it is. If you haven’t checked the squareness of your framing square recently, now would be a good time to do so.

    Reply
  4. Jay

    Setting the miter gauge to 45 degrees is not good enough. There has to be some play in the miter gauge slot or the miter gauge wouldn’t slide. That play could be up to 1 degree, so you’re going to be off for those long cuts. Even 90 degree cuts are problematic. You need some way of clamping the board to the miter gauge or it will move and rotate as you cut, giving you a very inaccurate cut. You can forget about using a miter gauge if cutting 45s on a wide board (or even 90 degrees, for that matter). Basically, the table and/or your arms are not long enough and you will not be able to either start or end with the miter gauge still in its slot. Lastly, using a miter saw, you can easily cut at 45 degrees, but that is limited to cuts of up to about 14 inches in saw travel and the longer cuts are just not accurate enough.

    To get really close on a 45 degree cut in a wide board, you will need a long combination square, and anything longer than 12 inches is expensive if it’s any good. Next, you need a wide straight edge of at least 5-6 inches. Lastly you need a router with a flush trim bit that will follow the straight edge (clamped to your work piece) as a template, making sure it is 45 degrees with the combination square. It’s best if your flush trim bit has a bearing on both the top and the bottom. Make sure that the grain is in the direction you are routing or the result will be a climb cut, potentially ruining your work piece. Using the router method, you can get really close to 45 degrees and you are not limited in the length of that cut.

    An example of where this came in handy: I was building a round game/card table, 40 inches in diameter. It had a 16×16″ chess board in the center and the 4 sides mitered into the each other and the board. Glue joint were used for all joints (other than the chess board). The sides were red oak, the board hard maple and walnut. Until using the router method for the 45 degree angles, it was trial and error with a lot of pipe clamps!

    Reply
    • Customer Service

      Hi Jay. I appreciate your feedback and it has been forwarded to the proper department. Your comments are important to us and help with the development of our online video streaming community.
      Thanks
      Jean-Woodworkers Guild of America Video Membership

      Reply
  5. Roger W. Dudra

    I like your idea! A computer program to yield low integers defining our common angles would be fun to write. 22.5, 30, 60 would be fun to know in whole numbers on a framing square.

    Reply
  6. Mark Ainsworth

    Great post. Thanks for the tip. I have a question though: If i set the pointer at 45 degrees using this technique, and then move the gauge to the 45 degrees in the opposite direction and the framing square technique indicates that I am still right on, does that mean I can trust the scale on the gauge for other angles?

    Reply
    • Customer Service

      Hi Mark. To me it means that it should be a pretty reliable indicator, but not necessarily perfect at all other points.
      Thanks
      Paul-Woodworkers Guild of America

      Reply

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