Beveled cuts >45 degrees

[adauria]

I really feel stupid sometimes. The other day I was making a bird house in the garage. The roof has 3 sections - left side, right side, and center. The center piece is beveled on both sides, while the side pieces need to have matching bevels to fit again the center. The left and right sides slope downward and an angle (miter cuts in the front and back).

Suffice to say I made a few cutting errors and now need to get something together with these 3 pieces. The problem is that the left and right roof sides, I believe, need something like a 50 degree rip cut. What I mean is, if you look at the left side from the front, top facing up, you would have to bevel the blade on the BT3100 further to the right than it lets you go (by, say, 5 degrees).

So how do I get this cut right since I can only bevel from 0 to 45 degrees? I am thinking that I need to set the bevel to 40 degree (40 + 50 = 90 degrees, right), and then run the piece with the waste on the left side (fence side) of the blade, and the piece turned upside down (at least for the left side). I am on the right track? I feel like I have a mental block about this. And, believe me, I'm not that bad at math and geometry and such... just can't figure out this angle.

-Andrew

[LarryG]

No, that's not the right track. The blade is at the same angle for the keeper piece and the waste piece, no matter which way you turn either.

I know two *safe* ways to do this with a table saw. One is to build a jig that slides along the rip fence while holding the workpiece vertically. Tilt the blade to 40deg, which will leave the desired 50deg bevel on the workpiece. The other is to build a sled that sits on the table saw's top but has a bottom tilted at some known, fixed angle ... say 20deg. This angle is subtracted from the desired angle to determine the blade tilt. In your case, that would be 30deg.

Yet another possibility is to use a band saw, if you have one. The tables on many band saws will tilt five or ten degrees past 45.

[adauria]

Ah! In my head I was having this problem, and I was thinking that the cut would be the same on both sides of the blade, but could not think of another option.

I don't have a bandsaw, but perhaps a jigsaw with a straightedge might do the same thing! I need to see how far my jigsaw tilts for bevel cuts.

I guess some kind of jig is my other option, as you point out. That might work too. I did consider that, but then thought I was just being daft in not being able to figure out how to do this.

Thanks!

-Andrew

[Bruce Cohen]

It this too simple of a solution.

Set your bevel gage to the angle you need.

Mark the angle on the edge of the board.

Using a plane and the old trial and error approach, take very light passes with your plane and keep checking the bevel (angle) against your bevel gage.

It's easier than it sounds.

Bruce

[ironhat]

It this too simple of a solution.

Set your bevel gage to the angle you need.

Mark the angle on the edge of the board.

Using a plane and the old trial and error approach, take very light passes with your plane and keep checking the bevel (angle) against your bevel gage.

It's easier than it sounds.

Bruce

Hand tools! Who would have figured?!

[cabinetman]

Hand tools! Who would have figured?!

Bruce is correct for a simplistic approach. A bevel cut on the TS will leave both parts with an angle that is 90 degrees. In figuring out what angle is the keeper angle or what to set the angle of the blade, marking the edge of the board and matching the bevel angle will yield either the waste piece or the keeper piece.

As for hand tools, by all means. Using the same marking methods, an accurate bevel can be made by sighting the mark and using a shooting board to guide the plane.
.

[LarryG]

A bevel cut on the TS will leave both parts with an angle that is 90 degrees. In figuring out what angle is the keeper angle or what to set the angle of the blade, marking the edge of the board and matching the bevel angle will yield either the waste piece or the keeper piece.

"cabinetman," I suggest you reread the original post more carefully. You don't appear to understand either the question or the problem as it pertains to a table saw.

The blade can be set to only one angle at a time. When measured from the same relative origin, the bevel angle on the keeper piece and the bevel angle on the waste piece will be exactly the same; with the sole exception of a 45deg bevel cut, they will not add up to 90deg.

Draw it out on paper. The bevel angle has no bearing on which will be the keeper piece or which will be the waste. The ONLY possible difference will be in the widths of the two pieces -- but that's a function of the rip fence position, not the blade tilt.

[adauria]

That's not a bad option either, Bruce! I only have a small block plane I bought at a garage sale and cleaned up. It's not great, but it might get the job done. I might try this first on some scrap.

Not sure which way I'll go yet, but I'll keep you guys posted. Thanks for the sanity check!

-Andrew