Miter Mayhem

[tkremer]

I don't know why it is, but I have the worst time making a simple miter joint. My other joints turn out nice and tight--M&T, Dovetail, Box, etc. But for some reason my miter joints are either 1/16 inch too long/short or the angle of each joint is 1/2 degree or so off.

I'm convinced the problem is my technique, not the tools. I'm using a nice cabinet saw and one of those digital tilt meters that attach to your blade with a magnet. I don't have a miter saw.

Does anyone have a foolproof method or jig for doing miter joints? I'm normally not a complete idiot and do have a little experience under my belt, but this is getting me frustrated.

[woodtinkerer]

i think i posted a question similar to this. Are you trying to make 90 degree corner by cutting the two boards each with a 45 degree cut?

[Saddlestrum]

I'm using a nice cabinet saw and one of those digital tilt meters that attach to your blade with a magnet.

...Just a thought that might help your accuracy. Remove the magnetic tilt meter before you turn on your saw and cut your joint

[Beechwood Chip]

i think i posted a question similar to this.

I just posted an answer to woodtinkerer's question that might apply to your question, too.

[PaulMarcel]

Those digital tilt meters show the degree to a tenth, but if you read the packaging, it is ±0.2º That's a lot of variance.

Big chamfer bits are the easy solution that Beechwood posted to the other thread. The tenon-jig thought I put there also works but is usually suited to larger items, like a mitered case.

[Beechwood Chip]

I'm pretty sure that the digital tilt meters show degrees from plumb (gravity), so if your table isn't dead level (as opposed to flat) you need to zero adjust for that. In any case, I'm a big fan of relative dimensioning: 45 on some measuring device is just a number, but if it fits it fits, and if it doesn't it doesn't.

[PaulMarcel]

They measure from a zeroed reference. Only one from Rockler has the additional feature of being able to measure from plumb.

[tkremer]

Oops, I looked, but didn't seethe preview Post. I must be going blind. Thanks everyone for the replies. I am trying to make a 90 degree joint From two 45 degree angles. I'd thought about a chamfer bit, but figured that was me Just over. thinking things. I'll Probably give that a try, but I also really like Paul-Marcel's tenon-jig idea. It makes a lot of Sense.

Thanks again everyone!

[tkremer]

My saw sits 0.3 degrees from level, So I always zero the tilt box first.

[harmsdph]

I had a similar issue, before i built this box for my wife:

A couple of things that helped me:

1)The setup of the blade is important but you can only consider it in the ball park (even with a digital gauge) until it is tested. Cut two pieces and make sure they form a 90 deg angle, adjust and retest until its right.

2)as you mentioned length of the sides is important, if one is longer or shorter it will push the box out of square. a sled or fence on your miter gauge with a stop block is the way to go. pieces of the same length should be cut in batches - so two setups for a box, cut one side on two pieces, set the stop to the correct length, cut the next side and then repeat for the correct length on the other two sides.

[kesac]

I'm pretty sure that the digital tilt meters show degrees from plumb (gravity), so if your table isn't dead level (as opposed to flat) you need to zero adjust for that. In any case, I'm a big fan of relative dimensioning: 45 on some measuring device is just a number, but if it fits it fits, and if it doesn't it doesn't.

You can zero those digital gauges to anything you want. Table blade, flat earth, or what ever. They are not really very accurate.

[Bombarde16]

It's actually one of the more difficult joints to cut, so don't be so hard on yourself.

All this talk of digital meters leads me to confirm something: You're tilting the blade at a bevel and cutting the box side stock flat on the table, right? I would tend towards using a miter sled such as you see about 4 minutes into this episode of WoodWorks. No fussing with tilting the blade and fussing with getting it back vertical. The pointed part of the miter is away from the fence, meaning you get a positive contact with any stop blocks you're using. Best of all, the two cuts that make up the joint are cut on opposite sides of the blade. Any inaccuracy in the setup cancels itself out. OTOH, if you cut the two parts of a miter on the same side of the blade, the inaccuracy compounds itself.

[TonyV]

It's actually one of the more difficult joints to cut, so don't be so hard on yourself.

All this talk of digital meters leads me to confirm something: You're tilting the blade at a bevel and cutting the box side stock flat on the table, right? I would tend towards using a miter sled such as you see about 4 minutes into this episode of WoodWorks. No fussing with tilting the blade and fussing with getting it back vertical. The pointed part of the miter is away from the fence, meaning you get a positive contact with any stop blocks you're using. Best of all, the two cuts that make up the joint are cut on opposite sides of the blade. Any inaccuracy in the setup cancels itself out. OTOH, if you cut the two parts of a miter on the same side of the blade, the inaccuracy compounds itself.

I agree, unless you're cutting stock that is more than 3" wide, you want to use a miter sled not not bevel the blade.

Tony

[tkremer]

I'm really learning just how inaccurate those digital gauges are. Since any time I have to tilt the blade (and I avoid that as much as I can) it's to a 45 degree angle, I might just make a really accurate setup block and use that instead of trying to rely on the gauge.

I do have a nice Incra miter gauge, so I prefer to use it for the angle. In this particular case my stock was about 3.5" wide and was forced to tilt the blade.

[kesac]

Kind of off on a tangent from the original question, but PerfectCuts.com helps me on the setup on some of those things. I also have a vernier protractor that is marked off in 5 min. of a degrees, and allows you to extrapolate a bit finer, if you use a magnifying glass. Those things are fairly cheap anymore, and considerably more accurate than those digital items.

For real exceptional accuracy, find a Machinest, and get him to give you a short class on setting up and using a Sine Bar. You can get very, very accurate with those, and some feeler gauges, and you can make one of wood or aluminum, fairly quickly.