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Forum topic by UncannyValleyWoods posted 09-25-2013 07:54 PM 1957 views 5 times favorited 32 replies Add to Favorites Watch
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UncannyValleyWoods

335 posts in 529 days


09-25-2013 07:54 PM

My engineering skills are fairly insufficient. I tend to find that my gut instinct in constructing new devices tends to be totally contrary to the inter-workings of reality.

So, please feel free to help me think this out.

A few weeks ago I received some amazing help planning out some compound joints. Here is a sketch I was provided.

I would like to build a jig to cut multiples quickly and efficiently.

My gut says, build a small sled, lay out the necessary angles and attach rest blocks along the angles. I would then only need to lay the wood across the blocks and run the sled down the table saw. It seems fairly simple in my mind, but when I attempt to execute it, it appears to be the work of a cross eyed slug. I can’t seem to figure out how to properly lay it out properly. Math is a serious issue with me. I typically have my wife help me with this sort of thing, but I’m not having much luck on this one.

I know that the angles I need are all 30 and 60 degrees. The depths vary, but that’s not as big a deal as the placement of the joints themselves. If you look at this picture, you can see that there are two cuts, one on top of the other, wherein the placement is offset slightly. I’d like to achieve this by perhaps dropping in stop pegs at the correct distances.

Hopefully my request for help will give someone another great puzzle to solve. lol. Thanks in advance for any advice.

-- http://www.etsy.com/shop/UncannyValleyWoods


32 replies so far

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hobby1

283 posts in 963 days


#1 posted 09-25-2013 08:35 PM

deleted
misunderstood the question.

View Lee Barker's profile

Lee Barker

2169 posts in 1516 days


#2 posted 09-25-2013 08:37 PM

Looks to me like Trial and Error are your two best friends.

Lay out a (scrap) stick with the desired cuts on both sides and set a stop and treat one as a given and then go to the opposite angle and invoke the spirits of T and E.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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hobby1

283 posts in 963 days


#3 posted 09-25-2013 08:42 PM

are the red and yellow pieces the same thickness ?
are they flush only at the top,
or flush at the top and bottom ?

View Loren's profile

Loren

7621 posts in 2313 days


#4 posted 09-25-2013 08:58 PM

Got a radial arm saw?

If so, figure it out using a dado blade, then make tapered mitering
fixtures and set the arm at 90 degrees.

There’s an old article in FWW on precision joinery for shoji screens
using lap joints production cut on a radial arm saw.

-- http://lawoodworking.com

View bigblockyeti's profile

bigblockyeti

1601 posts in 386 days


#5 posted 09-25-2013 09:18 PM

Loren beat me to my solution, the only other thing I would add is having a removable strip under the for deepest cut and not for the half depth cut.

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UncannyValleyWoods

335 posts in 529 days


#6 posted 09-25-2013 09:19 PM

Nope, unfortunately I do not have a radial arm saw. I’ve cut these joints on a table saw, before. It’s tricky, but they came out nicely. I’m simply looking for a quick way to make repeat cuts.

Hobby1, yes each piece is flush when put together.

-- http://www.etsy.com/shop/UncannyValleyWoods

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hobby1

283 posts in 963 days


#7 posted 09-25-2013 09:21 PM

deleted
Misunderstood the process in which it was done, from the picture.

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UncannyValleyWoods

335 posts in 529 days


#8 posted 09-25-2013 09:22 PM

Yes. They are the same thickness.

This is what they look like put together.

-- http://www.etsy.com/shop/UncannyValleyWoods

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hobby1

283 posts in 963 days


#9 posted 09-25-2013 09:37 PM

Thankyou,

I see where I’m making my mistake, I’m thinking in terms of the red and yellow pieces half lapped to same depth with eachother, like a traditional halflap, but there not, the red piece is dadoed further then the yellow, and the yellow having it dadoes raises the red on the blue cut to give that extra height, on the blue piece which is the depth of the dadoe on the bottom of the yellow piece, and so forth…

It bugged me until I looked at the drawings again.

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UncannyValleyWoods

335 posts in 529 days


#10 posted 09-25-2013 09:53 PM

You’re totally right hobby. It’s a very intense joint. You can see why I would want a simpler way to set up the cuts. As it is, I set up two table saw sliding miters and just reset the blade depth between cuts. It’s the a right way of doing it, but it’s not very efficient. I need to make ten of these stools and would like a quicker way to work through the dados.

-- http://www.etsy.com/shop/UncannyValleyWoods

View Dan Krager's profile

Dan Krager

1573 posts in 899 days


#11 posted 09-26-2013 12:28 AM

It’s apparent that the red and blue pieces are mirror images holding the same cuts. The yellow, if split by a “horizontal” plane in the middle, is mirrored top and bottom. That one is simple. Dado blade, stop on fence, flip it over.
The red and blue are more trying because each cut from red and blue require a stop on the other side of the blade at the same distance. That has to be done twice for the two depths of cut along with changing the angle. A good digital angle gauge helps a lot. You can also mark it on a sled.

I would think, once you get a sample working, that a jig setup could be trivial by marking on the fence where you put the stops for the sample. ? Furniture makers used to drive nails into a piece of plywood as stops for odd shaped pieces, three per piece marking the “true faces” or accurate measuring points. Several pieces could be done on one sled if laid out well and the piece outlined and marked well.
Easier said than done
?
DanK

-- Dan Krager, Olney IL http://www.kragerwoodworking.weebly.com

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REO

614 posts in 739 days


#12 posted 09-27-2013 01:42 AM

|I am going to watch this one. wont have time to play with it till the weekend.

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MrRon

2846 posts in 1909 days


#13 posted 09-27-2013 11:21 PM

Uncannyvalleywoods;
In your second photo showing the 3 members extending beyond the center point; is that the way you want it? Or do you want to stop at the center? The joint will be different depending on which way you want. I’ve laid it out using Autocad, but I can’t continue with a jig unless I know which way. I assumed you are using 3/4” square stock.

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HuckD

205 posts in 379 days


#14 posted 09-28-2013 01:31 PM

I hope you share pictures of the completed stools.

-- Time is what keeps everything from happening all at once.

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Grandpa

3156 posts in 1341 days


#15 posted 09-28-2013 07:28 PM

Can’t you use a sled with some inserts to make the adjustments in depths and angles. This would make repetitive cuts easier…..I think.

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