Dear Swede, this was a masterclass in how to stretch 5 seconds of advice into 8 minutes and 22 seconds without irritating your audience too much. :-)

My worst mistake when cutting miters happened when someone told me to “cut this at 45 degrees”. Then I asked “What’s the temperature got to do with this”! It was the middle of summer.

Here is my secret - setup the blade angle with the saw and cheap 45 jig.  Get 2 scrap pieces of cheap wood.  Make the 45 cut on the first one and on the second one.  Take the 2 sides from the first and second one and flip one put them together then check for flatness against straight edge.   Make slight readjustment to saw as needed and repeat if necessary until you get it flat.  (you can also test for square if you prefer)

tldr, you can never get a perfect 45°. So take a bit extra off the inside to mitigate the chance of leaving a crack on the external corner

There are two ways the blade can be out of square on a table saw. Either the plane of the saw cut is not aligned with the mitre slot - OR - the saw blade does not run square against the arbour, that is it might have a wobble. It is important to check for both, especially if you have an older table saw or are using cheaper blades.

Checking both factors is similar but subtly different.

To check the first, mark a spot on the blade and check that spot both as far forward and as far back as possible.

To check the second, keep the dial indicator in the same spot fore or aft, and rotate the blade to see if there is a wobble. While the dial indicator is on the saw table we may as well check both factors.

The 44.9 trick is always good.

One other tip is that if you are cutting mitres in hardwood the piece often will shift under the pressure of the blade pushing against it (either that or the blade bows as it gets into the meat of the cut. I kind of suspect that really). I once got a very slight bulge on the mitre face in hard Maple. Only when I started clamping the pieces down firmly on my sled and used a freshly sharpened blade with a slow cut did that go away. It seems that neither hand pressure or a stop are firm enough. (I guess I am OCD when it comes to getting those mitres right :) )

Thanks for the great videos. Keep it up.

I found this interesting enough that I was at 7 min before I realized that you had tried to sell me like 6 products
already.
Not too bad at all.

The other secret is: When the blade is tilted, it pulls the workpiece sideways, tending to throw off the bevel. This is even a bigger problem with miters. My miter gauge has holes allowing me to screw in a larger back-stop. If that back-stop has a strip of high-grit sand-paper glued to it, then the added friction from the sandpaper solves the problem.

Video starts at 5:40 and the trick is to cut the miter slightly acute at 44.9 degrees.  
FFS why is this video over 8 min?

Step 1) Have a $5000 dollar table saw

There may be another dimension to adjust on your table saw. Once the blade is aligned with the miter slot, angle the blade to 45 degrees. Then cut a 45 on a a wider board, and push completely through. If there is a secondary cut off the back side of the blade, then the table needs to be tilted back to front. Check both miter slots. Insert shims on the bolts holding the table down, typically on the front side. When there is minimal saw dust raising from the back of the blade, it's in tune.

Hope that makes sense. Happy woodworking.

Yes making sure your table saw is dialed in is critical for precision joinery. You could also use a shooting board and sharp quality hand plane to ensure perfect miters after the cut.

Putting it at a bit more than 45

Fantastic, I will try all the suggestions.  I've been plagued with bad mitered joints ever since I started woodworking many, many moons ago.  I like your idea for the charging station too.

YouTube put this in my feed and I'm grateful. I just got a table saw and never thought about about any of this. Getting miters and cuts perfect has never been my strong point but I aim to fix that. Thanks

my most memorable learning curve on making miter joints was when I  didn't turn the board around to create the other side. Instead I flipped it over and regrettably had my angles that didn't match. i.e. I had 1 up and 1 down on the same piece of wood. From then on I double check before putting that second 45' cut in. I like these sets up.(yes - correct English there)

Great video, nicely narrated as well, good work bro!

For all you, who were looking for instant gratification you missed the boat. I for one, enjoy the Swede’s laid back approach to attacking a problem, with a touch of problem solving resolve that we all can learn from. Chill ya’ll.

Thanks, great advice. There is something we call in Switzerland and maybe generally "fixing something to death" This is a translation in Swiss German it sounds much better. I made a box with miters.. There were ugly as .. I was so angry I cut off the corners with another 45 and glued new wood to the corners. Which then of course looked like an accident. 12 hours later "fixing something to death" the box ended up in the stove.. I am very happy for your videos - shortening my learning cycle by copying good practice ;-)

Just so you know, you can adjust the the track saw blade in comparison to the track. There are screws on the saw for that. The back of the blade should be slightly further away from the track than the front of the blade.

I’m really enjoying your channel.  I don’t think I’ll ever make such a charging station, but that’s ok.  I like seeing the tools used, how they’re used, and different techniques.  I also like hearing different folks describe things.  Different people different explanations added together usually enhances understanding.  Like the first comment about the wrong angle.  I right away understood the error of the comment.  Frame of reference is always important.  The discussion helped bring that out.  Thank you for another great episode.  I know we are in a very global culture these days where we are becoming more unified, but if there are any unique Swedish woodworking styles, tools, or processes, I’d love to learn about them.