How do YOU cut a 55* back angle on crown molding?

[Jack Wilson]

I am making some crown molding and the back side has 2 angles, one rests on the wall, and the other butts to the ceiling. The ceiling angle is 35*, making the wall angle 55*; The ceiling angle, at 35* is an easy cut, but what method do you all use to back cut these steeper angles beyond 45*? I ended up ripping a 10* "ramp" to run the stock over, and cranked the blade over to 45*as the face was already shaped, so only the back was flat, but there has to be a better method.







Thanks guys, and gals,
Jack

[Leo Graywacz]

35 degree angle on the tablesaw and run the molding vertical against the fence. Depending on which tilt you have for your saw will determine if you need to have the fence on the left or right of the saw. You could also tilt the blade into an axillary fence.

[Peter Quinn]

I set one angle on the saw, and run one the acute angle laying down on its back, the obtuse angle standing up on a tall fence (preferably when the blanks are still square and before molding). Well, actually that is how I did it before I got a vari-angle cutter head for the shaper. Now I just run it off a back fence and set the shaper head for 52 degrees. Oh, 38/52 is the standard angle for crown, not 35/55, but obviously you can use any two that equal 90 as you like. The reason you may want to use 38/52 is that the detents on a miter box will be for the 38/52 configuration. If you want to cut them flat with a compound angle set up, you will have to reference a chart for the odd angles. If you cut them standing up its a moot point.

I've also done it on a right tilt saw using a dado buried into a sacrificial fence, after molding, back of molding to the fence (tall auxiliary fence). The dado eats the whole triangle so no kick back. You could do the same with a left tilt by moving the fence to the left of the blade, but I hate working left handed. I did this out of necessity on some rake crown where i had to play with the spring angle to make it work, not my first choice for a small run but it works pretty well once you get it set up.

[Jack Wilson]

Thanks Leo and Peter, Peter I was copying a previous profile, which is where I got my angles from, but that was a good lesson for me, I didn't know 38-52, I DID know X+Y must = 90*. I didn't follow you on all the other stuff, but I get the verticle run before molding. I tried to avoid that because it would force an exacting set up when run thru the molder, but maybe that would have been far easier to set up that the ramp I ended up making.

[Peter Quinn]

The problem with running the vertical post molding is you have the molded face to the fence, and it may not be a flat plane, it rarely is a good bearing surface by its nature,many you don't really want to drag your molded face across a fence and risk damaging it. I understand wanting to cut the angles second. On the W&H molder they recommend cutting the back angles first for the reasons you now understand. Very difficult to rip or mold that obtuse angle later.

For the dado method (post molding) I used a right tilt saw with a tall box fence that wraps around the basic fence to give a bit more height. To this I screwed a piece of plywood. I stacked a 3/4" dado, set the bevel angle on the saw to the acute angle, set the fence very close to the blade, turn it on and raise the dado into the plywood fence. It takes a few test pieces to get just right, you might have to lower the blade and move the fence in/out a touch so the flats on e molding face are correct. But this allows you to run the molding with the back to the fence and grind off the unwanted portion rather an rip it off. On a left tilt saw the procedure works but it's done with the fence to the left of the blade, and that is uncomfortable to me.

Are you cutting your miters with a stop standing up on a chop box? If so your " spring angle" as it's called (angle between wall and molding back) is not very important. You can also cut them lying flat, and most SCMS have detent angles for miter and bevel for 38/52 crowns. My makita has a chart for off angles, but actually hitting them precisely is difficult. Easier to make a fence with stops and cut the molding standing up, well , upside down really.

What are you using to mold the crown?

[Rich Engelhardt]

I used my jointer to do the 52* side, then ripped the 38* side on the table saw.
The fence tilts well past 45*.
It worked fine for short pieces ~ 8' long and under.

[Rod Sheridan]

Tilting spindle shaper............Rod.

[Jack Wilson]

The problem with running the vertical post molding is you have the molded face to the fence, and it may not be a flat plane, it rarely is a good bearing surface by its nature,many you don't really want to drag your molded face across a fence and risk damaging it. I understand wanting to cut the angles second. On the W&H molder they recommend cutting the back angles first for the reasons you now understand. Very difficult to rip or mold that obtuse angle later.

For the dado method (post molding) I used a right tilt saw with a tall box fence that wraps around the basic fence to give a bit more height. To this I screwed a piece of plywood. I stacked a 3/4" dado, set the bevel angle on the saw to the acute angle, set the fence very close to the blade, turn it on and raise the dado into the plywood fence. It takes a few test pieces to get just right, you might have to lower the blade and move the fence in/out a touch so the flats on e molding face are correct. But this allows you to run the molding with the back to the fence and grind off the unwanted portion rather an rip it off. On a left tilt saw the procedure works but it's done with the fence to the left of the blade, and that is uncomfortable to me.

Are you cutting your miters with a stop standing up on a chop box? If so your " spring angle" as it's called (angle between wall and molding back) is not very important. You can also cut them lying flat, and most SCMS have detent angles for miter and bevel for 38/52 crowns. My makita has a chart for off angles, but actually hitting them precisely is difficult. Easier to make a fence with stops and cut the molding standing up, well , upside down really.

What are you using to mold the crown?

Using a W&H W7, I finally got it with the dado blade, makes sense, I like it. Rod, I don't have a tilting head shaper, does it tilt to 52* or more?

[Leo Graywacz]

Use a 45 degree cutter and tilt it another 7 degrees.

[Jack Wilson]

Hey Leo, great idea! So now I have 2 simple but effective ideas to tuck away.

[Leo Graywacz]

I just use the saw with an axillary fence. Just have to look out for the trapped pc.

[Rod Sheridan]

Using a W&H W7, I finally got it with the dado blade, makes sense, I like it. Rod, I don't have a tilting head shaper, does it tilt to 52* or more?

Hello Jack, no it only tilts to 45 degrees.

For 0 to 45 I use a rebate head, for 45 to 90 I use a 45 degree cutter..............Regards, Rod.