Joining wedges or 'pie slices' - Woodworking Talk - Woodworkers Forum
 
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post #1 of 11 Old 01-25-2012, 11:03 AM Thread Starter
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Joining wedges or 'pie slices'

I'm endeavoring to cut and join 12 wedges into a circle about 18" in diameter. Here's a CAD rendering:



The wedges will be cut from a board I create by edge joining strips of alder, jatoba and walnut in varying widths. I'll plane the whole board to 0.75" thick and then cut the wedges.

For something like this I want the joints to be as perfect as possible with no visible gaps to ruin the look of the finished piece.

My question is more to do with getting a perfect edge on the sides of each wedge. I've never tried to join wedges into a circle before and I'm a little intimidated. I did a practice run using my sliding compound 10" miter saw and a pine 1x10x8. The resulting wedges have two problems:

1. Angle is off by a fraction of a degree, but that error compounds 12 times so there's a large gap between two wedges when the other edges are pressed tightly together. I think I can get around this by joining two sets of 6 wedges resulting in two half-circles, then running the flat side of each half-circle on my jointer to create two perfectly flat surfaces for joining into the final circle.

2. The sawed edges are rough enough that a lot of sanding would be required to get a near-perfect edge. I find it very difficult to sand evenly which is the only recourse on the test wedges. Should I try a different blade? Currently I'm using a 60T carbide tipped blade that came with the saw. Or should I make a jig for my table saw and also use a different blade?

I'm not looking for a solution that involves zero sanding, I hope I didn't leave that impression, but rather not relying on excessive sanding to get a flat edge. I'm hoping there's a trick to get very close and then sand to touch it up.

Thanks for your help!

Last edited by imhotep531; 01-25-2012 at 11:10 AM.
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post #2 of 11 Old 01-25-2012, 11:22 AM
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A TS jig set up properly should yield segments that require no sanding.

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OH, wait a minute ............Yep!.............That's what he said!

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post #3 of 11 Old 01-25-2012, 05:38 PM
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1. Yes, that would work. Just remember that if the pieces are too far off, you may have to take off a lot which could result in a slightly odd looking finished product. Hopefully, they're pretty close.

2. I have a DeWalt 10" compound miter saw. I replaced the blade with a blade identical to the one that came with it. I wasn't very happy with how it cut. I then replaced that blade with a "Diablo" blade from Stein's. That one is a million times better than the DeWalt blade I got. A bit more expensive too. You could try getting a better blade. I'm happy with my Diablo blade.
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post #4 of 11 Old 01-25-2012, 06:12 PM
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If it's 12 sided (pie shapes), it's a dodecagon, and the angles will be 15 degrees.

You could make a template from 'oak tag board' (heavy construction paper), and cut your angles. Make 12. if they fit well, use one to make one from 3/4" wood. Lay your template on the wood and draw an outline about 1/8" larger than your template. Cut on the oversized line. Hot glue the oversized one to the sized one and rout with a trim bit. Do 11 more.

Or, make a template and a wedge for the TS fence to cut the angle on the wood.

Or, set stops for your miter saw and cut them to size.

When you go to dry fit, you can fit 2 or 3 at a time. When you run into having a gap, the differential can be addressed on 2 or 3, so all of it isn't attributed to one joint.

You can accurately sand the edges by setting up an "L" with plywood, and sit it on some sandpaper (full sheet). The backside of the "L" will keep your piece guided perpendicular to the sandpaper.






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post #5 of 11 Old 01-26-2012, 08:49 AM Thread Starter
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Quote:
Originally Posted by Itchytoe View Post
2. I have a DeWalt 10" compound miter saw. I replaced the blade with a blade identical to the one that came with it. I wasn't very happy with how it cut. I then replaced that blade with a "Diablo" blade from Stein's. That one is a million times better than the DeWalt blade I got. A bit more expensive too. You could try getting a better blade. I'm happy with my Diablo blade.
I have wondered if those Diablo blades are worth the extra cost. Sounds like they are. I have one other blade I'd like to try first and then I'll look at a Diablo if I'm still not satisfied. Thanks for the testimonial.
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post #6 of 11 Old 01-26-2012, 08:53 AM Thread Starter
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Quote:
Originally Posted by cabinetman View Post
If it's 12 sided (pie shapes), it's a dodecagon, and the angles will be 15 degrees.
I was talking about the angle near the center of the wedge which is 30 (360/12 = 30). The other two are angles on each wedge are 75 each. But yeah, I did set my miter saw to 15 for the cuts.

Quote:
You could make a template from 'oak tag board' (heavy construction paper), and cut your angles. Make 12. if they fit well, use one to make one from 3/4" wood. Lay your template on the wood and draw an outline about 1/8" larger than your template. Cut on the oversized line. Hot glue the oversized one to the sized one and rout with a trim bit. Do 11 more.
That's a great idea. I may try this if my crosscut-sled / jig combo don't satisfy me. Thanks for the creative idea.

Quote:
You can accurately sand the edges by setting up an "L" with plywood, and sit it on some sandpaper (full sheet). The backside of the "L" will keep your piece guided perpendicular to the sandpaper.
Thanks for the tip!








.[/QUOTE]
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post #7 of 11 Old 01-26-2012, 09:38 AM
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Quote:
Originally Posted by imhotep531 View Post
I'm endeavoring to cut and join 12 wedges into a circle about 18" in diameter. Here's a CAD rendering:



The wedges will be cut from a board I create by edge joining strips of alder, jatoba and walnut in varying widths. I'll plane the whole board to 0.75" thick and then cut the wedges.

For something like this I want the joints to be as perfect as possible with no visible gaps to ruin the look of the finished piece.

My question is more to do with getting a perfect edge on the sides of each wedge. I've never tried to join wedges into a circle before and I'm a little intimidated. I did a practice run using my sliding compound 10" miter saw and a pine 1x10x8. The resulting wedges have two problems:

1. Angle is off by a fraction of a degree, but that error compounds 12 times so there's a large gap between two wedges when the other edges are pressed tightly together. I think I can get around this by joining two sets of 6 wedges resulting in two half-circles, then running the flat side of each half-circle on my jointer to create two perfectly flat surfaces for joining into the final circle.

2. The sawed edges are rough enough that a lot of sanding would be required to get a near-perfect edge. I find it very difficult to sand evenly which is the only recourse on the test wedges. Should I try a different blade? Currently I'm using a 60T carbide tipped blade that came with the saw. Or should I make a jig for my table saw and also use a different blade?

I'm not looking for a solution that involves zero sanding, I hope I didn't leave that impression, but rather not relying on excessive sanding to get a flat edge. I'm hoping there's a trick to get very close and then sand to touch it up.

Thanks for your help!
It is just like segment bowl turning . Just glue up 1/2 of the circle . You will have 2 halves now sand only the end's of the 1/2's so that they fit perfect. Sound's like a new blade would be better than the one you have now. It should cut with out any mark's on the cut . I have 80 teeth i belive on mine and the cut is glass smooth. If you get a good blade than you will very little sanding. good luck Don't cut the wood and let it set over nite it will change
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post #8 of 11 Old 01-26-2012, 11:45 AM
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Just so you know, gluing up solid wood in pie shaped pieces will likely expand and contract with changes in humidity. The joints will open up in time, maybe sooner than later. The tips will be rather fragile just cutting them. Work that has this appearance is typically done with veneer, not solid wood. You may get lucky but I wouldn't bet on it.
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post #9 of 11 Old 01-27-2012, 11:02 AM Thread Starter
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Just so you know, gluing up solid wood in pie shaped pieces will likely expand and contract with changes in humidity. The joints will open up in time, maybe sooner than later. The tips will be rather fragile just cutting them. Work that has this appearance is typically done with veneer, not solid wood. You may get lucky but I wouldn't bet on it.
So would a better approach be to cut a circle from solid wood or plywood, and then make my pie slices 1/8" thick and glue them individually to the top of the circle? I'm not opposed to this, whatever works.
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post #10 of 11 Old 01-27-2012, 01:31 PM
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Quote:
Originally Posted by imhotep531 View Post
So would a better approach be to cut a circle from solid wood or plywood, and then make my pie slices 1/8" thick and glue them individually to the top of the circle? I'm not opposed to this, whatever works.
The saw cut is the problum the reason the cut's are not perfet circle. Get them so that they go togother like i mention glue 1/2 of the circle and than the other than sand if needed and glue the two 1/2 circles togother. That is what turners do. You would be very lucky to get all 12 pieces to go togother perfect the saw blade has to be perfect with no wobble at all . Of course you can't see it but just a hair movement and that add's up. do the 1/2 circle thing.
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post #11 of 11 Old 01-27-2012, 02:32 PM Thread Starter
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Originally Posted by del schisler View Post
The saw cut is the problum the reason the cut's are not perfet circle. Get them so that they go togother like i mention glue 1/2 of the circle and than the other than sand if needed and glue the two 1/2 circles togother. That is what turners do. You would be very lucky to get all 12 pieces to go togother perfect the saw blade has to be perfect with no wobble at all . Of course you can't see it but just a hair movement and that add's up. do the 1/2 circle thing.
Yes thanks I'm planning on doing that. It crossed my mind early on so I mentioned it in the OP. I was referring to hammer's caution about joining solid wood slices and the gaps that may form later due to humidity changes. I'd really like to avoid that.
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