Please help with beveled miter angles!

[®smpr_fi_mac®]

Please help me.  I've never cut beveled miters before.  I spent two hours yesterday setting up my cuts.   One end on my Uni and the other end on my 66.  I thought I had it perfect.  Then I went to assemble...and it didn't work. 

I'm using crown molding, which apparently adds some complexity.  I don't have a SCMS, and my RAS doesn't have the depth of cut to make it work. 

My setup on the 66 was the blade tilted to the left 45* with the fence set at 45*.  Then the Uni was just the opposite for the other end of the piece, blade rolled to the right at 45* and fence to the opposite 45*. 

Can you guys help?

[K. L. McReynolds]

Try coped inside joints. No angles and easier to file the fit perfect.

Outside corner joints are a bit(understatement) harder. But, using scraps, you can play with settings.

[KC]

Try coped inside joints. No angles and easier to file the fit perfect.

Outside corner joints are a bit(understatement) harder. But, using scraps, you can play with settings.

Nothing to contribute here, but you can count me as a fairly competent wood butcher that is simply unable to cope molding.  I've tried and tried and tried some more.   Every couple years I try again.  Watched 50 YouTube videos of guys that make me feel like a miserable failure because I can't do it.  


That said, with the help of Kreg crown cutting jig, I've gotten pretty good at doing in on the miter saw.

[®smpr_fi_mac®]

I don't think that's a good option here. I'm trying to set up a production run to build boxes with the molding. The top of the box is larger than the base.

[brianwelch]

I have only ever used my miter saw for crown moldings, but the key is to do the cutting with the crown upside down. Bottom of the saw table is analagous to the ceiling for reference. Compound miters introduce a complexity I have not yet had to attempt.

[srv52761]

Try this.
If your crown is 45°/45° (equal extension on both ceiling and wall.. I know, you are not putting it on wall, but pretend)
Set your blade bevel to  30°
Set your miter gauge to 35.3°

If your crown is 52/38 
Set your blade to 33.9
Set your miter gauge to   31.6

Back side goes flat on the table saw, profile up

Test on scrap.

Best is to cut and glue off wall, then apply and cope the adjoining inside corner, but then you are not using a wall.

[®smpr_fi_mac®]

I think I have it figured out...if my blade is tall enough. I'll set up a stop block on my sled to position the lower edge of the molding and set the fence to 45*. Then place the molding between that lower block and the fence. 

If my blade has enough height then this should act like a miter saw does. 

We'll see. 

Once I have a successful method, I'll post up pics of the end product so you guys can see what I'm trying to do!

[MstrCarpenter]

Google is your friend. "compound angles for 90 degree angle chart". There are also calculators and apps. I use a 15" Hitachi so I don't have to deal with them but if your T.S. has the depth of cut, a miter sled with a tall fence will work just as well, if not better, because it is self-correcting to 90*. I like to put two layers of masking tape on the table (sled), hold my crown at the proper angle and score the tape, then remove the excess leaving the remaining as a stop for my spring angle.

[Bill Holt]

Although I have never done it, I'm pretty sure srv52761 is pointing you in the right direction.

[Ray Newman]

All I can say about this project is I wish you luck!

Tried to do what you are doing and just like me setting up a router table and a locked miter router bit, it just never seemed to work out! Both are the spawn of the devil's woodshop!