frame mitering

[Dan_Shade]

ack, what a pain it is to mitre picture frames.  I spent all afternoon saturday making a miter jig up and it's not quite "right".  I spent 3 hours sunday trying to "tweak" it, and it's still not quite "right".

I see fancy trimmers, and fancy hand crank disc sanders.  Have any of you guys come up with a good trick to make perfect miter joints. 

I'm aiming for museum quality.

[beenthere]

I made a plywood board that drops in my radial arm saw table clamp. It has two aluminum angle irons pinned at 90°. That has been a great way for me to get perfect miters. Don't have to change the radial arm saw from its normal position, and each 45° is done without resetting anything.
There are commercial jigs that will do the same thing, I believe.

[Furby]

Same thing works on a table saw.
Key is to get your jig correct to begin with.

[Dan_Shade]

any tricks on getting it right? 

it's a frustrating experience, have to make 4 cuts on each tweak, making sure they are the same length each time.

Here's a pic of a frame I slapped together real fast from some white oak:



not sanded or anything, I just mitered it, and glued it up.

[low_48]

You'll find that the quality and sharpness of your blade is almost as important as the jig. If the blade is dull,  it will cause the wood to wander or pull the wood as you cut. I always prefer a fixture that slides on the table saw. You can take some time to get it close to 45 degrees from the blade, but making the included cut dead on 90 degrees is the most important. If you cut one piece on side a of the fixture and the second piece on side b, they will add up to the 90 degree cut. Always use a stop to keep exact lengths on the common parts. Some sandpaper on the fences will help hold the wood dead tight. Here's a good link to building the jig.
http://www.woodmagazine.com/woodworking-plans/tablesaw/tablesaw-miter-jig/

[Dan_Shade]

I made a sliding jig, but mine has the angles opposite of that one.  i'm planning on adding sand paper

it could be my blade, I don't know.  It's pretty darn close to being right, just not "perfect".

[flip]

If you've ever watched Woodworks on Diy, David Marks has a pretty nice miter jig for his table saw.  Looks like it is made out of plate aluminum for the base and has some nice hold downs.  I think if you go to DIY .com or Davids web site he said a machinist buddy built it for him. $$$$$$ : 

A good blade goes along way to good joints ;)