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Staves with Compound Miters

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Forum topic by ChunkyC posted 12-28-2011 01:51 AM 5329 views 1 time favorited 22 replies Add to Favorites Watch
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ChunkyC

856 posts in 2722 days


12-28-2011 01:51 AM

I need a little help. I have a project in my head, an 8 sided waste basket that’s wider at the top then the bottom. How in the world do I cut the staves?

The staves need to be 4-3/8” at the top and 3-1/2” at the bottom with a 22.5° miter. It’s not a lot of tapper but the bottom should set just about 1” in from the top rim, if that makes any sense at all.

I started in the shop today by doing some test cuts in a blank of MDF that measured was 4-1/2×11-1/2. I setup my tapering jig and cut the first side. Then it dawned on me that the saw blade would need to tilt 22.5° back the other way to make the cut on the opposite side.

I’ve seen turners do this but they use the miter gauge and make a series of cross cut, flip the board and make another cross cut. Wash, rinse and repeat until they get enough pieces. The problem is that I don’t like the idea of ripping individual staves one at a time using the miter gauge.

The only thing that I can come with is to move the fence to the other side of the blade (left side) and then use the tapering jig on the opposite side of the fence. Now I suppose this would work except for the fact that my tapering jig is made to only work on one side of the fence. So what to do?

Thanks.

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135


22 replies so far

View AaronK's profile

AaronK

1441 posts in 2932 days


#1 posted 12-28-2011 01:57 AM

could build a custom tapering jig set to this specific angle. that will allow you to cut exactly the same angle on both sides of the fence/blade.

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Loren

8315 posts in 3115 days


#2 posted 12-28-2011 02:00 AM

I haven’t done this in awhile but as memory serves you make a jig
with a step for 1/2 the taper and a second step for the full taper.
Cut one side, then flip the board and make the other using the
full step.

In your project step one would be a 7/16” offset from a parallel
rip. Step 2 would be 7/8” offset.

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ChunkyC

856 posts in 2722 days


#3 posted 12-28-2011 02:36 AM

I’m thinking out loud, always a bad thing when that happens.

I could cut the tapers at 90° and then use my jointer plane with a fence set to 67.5°… Sounds like a sweaty day in the shop though.

Aaron: I like that idea.

Loren: Sorry but I don’t follow.

c

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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AaronK

1441 posts in 2932 days


#4 posted 12-28-2011 03:46 AM

loren’s idea is a good one – if you have a jig already, his will not require you to make a new one since it all takes place on one side of the fence. if I understand correctly, for the second cut you flip the workpiece around, so that what was the last end to hit the blade will now be the first… the cut will be on the other side though. does that help?

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casual1carpenter

354 posts in 1943 days


#5 posted 12-28-2011 03:55 AM

“I’m thinking out loud, always a bad thing when that happens.”
Second that thought for myself also.

Anyway,..........

A taper jig is for pieces in my mind. You are cutting sheet goods.
Now suppose you rip MDF 11-1/2” wide by what ever length.
Set your 22.5° bevel.
Use a 90° sled or miter gauge in conjunction with a taper jig cutting one compound miter.
Spin the taper jig 180° and flip the MDF over cutting the other compound miter?

The taper jig against sled or miter gauge

Guess I would need a piece of wood at saw to see this myself, might be a brain burp.

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ChunkyC

856 posts in 2722 days


#6 posted 12-28-2011 04:28 AM

The problem with using a tapper jig is you can’t flip the piece. When you do, the taper ends up going the other way. In other words, the taper jigs need to be flipped too for this work. I know it’s hard to “see” but because you’re referencing off of the fence, which is parallel to the blade, the old flip and go trick doesn’t work.

I went back down to the shop and had a think on this. Here is what I came up with:

I made a one time use crosscut sled. My last cross cut sled warped on me. Never one to toss anything out that might be used someday, I used one of the halves to construct a sled. The nice thing about it is you don’t have to be accurate with it at all. Just screw the rear fence on in old place. Works pretty slick with an MDF blank.

My hands still need to be awful close to the blade but at least now, the piece is completely supported and doesn’t have slide on the table top. Makes it a lot easier to handle. I have a couple of toggle clamps that may find their way on top of the sled before it’s all said and done.

I cut a piece of scrap walnut just on one side. You can see it stuck between the sled and the fence. Now I can move the miter gauge back to zero while I cut the oak blanks and have a reference to get back to the angle.

Thanks for all of your help!

c

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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Jim Finn

2417 posts in 2389 days


#7 posted 12-28-2011 05:58 PM

I use a shop made sliding taper jig that clamps the wood against an adjustable fence. I use it to make stars, Vases and items like you are talking about.

-- "You may have your PHD but I have my GED and my DD 214"

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ChunkyC

856 posts in 2722 days


#8 posted 12-28-2011 11:35 PM

The problem with using a tapper jig is you can’t flip the piece.

...

the taper jigs need to be flipped too for this work.

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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ChunkyC

856 posts in 2722 days


#9 posted 12-29-2011 12:59 AM

Thanks for everyone’s input. Here is a pic of a dry assembly halve:

I only cut one stave wrong, the first one of course.

The assembly is upside down. It was a little more stable with the larger diameter on the bottom. I see that the saw blade was a little more than 22.5°. I’ll just sand the edges flat once I get it glued up.

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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Jim Finn

2417 posts in 2389 days


#10 posted 12-29-2011 03:00 AM

It is difficult to get the angles to come out perfect. What I did with the waste basket in the photo was, I set the sliding taper jig to 5 degrees and the blade angled at 18 degrees. I made 2 extra staves and when dry assembling the whole basket I added or subtracted a stave from the target amount (10) to make them fit together the best. Then I lay them all down flat with the outside up and masking tape across the staves to hold them together. I then flip the assembly over and put glue in between the staves and roll it up to shape, masking tape to shape, use rubber bands or strap clamps to pull it together and let dry. I put a groove near the bottom of each stave to receive the flat round bottom. I installed the bottom as I rolled up the sides. Kinda’ tricky bot makes a nice job and keeps the basket round.

-- "You may have your PHD but I have my GED and my DD 214"

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ChunkyC

856 posts in 2722 days


#11 posted 12-29-2011 04:07 AM

What I’ll do is glue the two halves together as sub assembles. Then all you have to do is glue a couple sheets of sandpaper on the workbench and sand the bevels until their flat. Do this with both halves and you’re good to go. I’ll start with a plane to get them close and then the sandpaper. Works great and you don’t have to do a lot of test cuts to get a blade that’s exactly 22.5°.

WudnHevn: Glad you found sizes. I have it AutoCAD if that helps. It’s not drawn with solids, 3D wireframe. It can’t be rendered in it’s current form but it was a lot faster to draw it this way.

c

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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Jim Finn

2417 posts in 2389 days


#12 posted 12-29-2011 04:28 AM

......”Point is that the angle changes with the amount of taper…...” ////// Yes this is the issue. In my experience 5 degrees is the max taper that does not require you to take this into consideration. Here is a photo of a taper jig similar to the one I made.

-- "You may have your PHD but I have my GED and my DD 214"

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ChunkyC

856 posts in 2722 days


#13 posted 12-29-2011 04:35 AM

My angle is 4.48° :)

I knew that the angle changes with tapper. I wish I would have remembered. I’m a dummy.

-- Chunk's Workshop pictures: http://spadfest.rcspads.com/thumbnails.php?album=135

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casual1carpenter

354 posts in 1943 days


#14 posted 12-29-2011 04:52 AM

WudnHevn, Jim Finn, Guys how does the angle of an octagon change?

Octagon
From Wikipedia: A regular octagon is a closed figure with sides of the same length and internal angles of the same size. It has eight lines of reflective symmetry and rotational symmetry of order 8. The internal angle at each vertex of a regular octagon is 135° and the sum of all the internal angles is 1080° (as for any octagon).

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AaronK

1441 posts in 2932 days


#15 posted 12-29-2011 05:03 AM

yeah that angle will vary between 0 (or 90) and 22.5. probably with something like the cosine of the angle you want the final thing to have.

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