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Help with funky 45* tenon

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Forum topic by BenDupre posted 10-15-2017 11:17 PM 448 views 0 times favorited 11 replies Add to Favorites Watch
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BenDupre

527 posts in 298 days


10-15-2017 11:17 PM

Hi Lumberjocks,

I am building a corner desk. Mission style: therefore mortise and tenon.

The front apron, being a corner desk, is 45 deg. to the leg. I am trying to work out how to make this oddball tenon. Here is my test piece:

I basically sculpted this using my table saw with blade tilted, a pullsaw, and chisel. It’s less than exact and the process is not repeatable. Has anyone seen a good youtube or article on how to pull this off reliably? Seen a jig that can do it? I have a tenonning jig but darn the thing it will not tilt over to 45. It only tilts back to about 60.

Thanks for any tips!

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw


11 replies so far

View CharlesA's profile

CharlesA

3287 posts in 1607 days


#1 posted 10-15-2017 11:20 PM

You might get some ideas here: https://www.youtube.com/watch?v=FXyN1V4IgMg

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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Loren

9546 posts in 3458 days


#2 posted 10-15-2017 11:40 PM

You’ll have to take some elaborate steps if
you want to machine the whole thing.

If you can bring yourself to commit to sawing
the shoulders by hand, cutting the cheeks is
not difficult by machine. The can be cut on
the band saw, either freehand or by running
a 45 degree angled jig against the fence.

On the table saw a 45 degree block can be
clamped to the fence of a cut-off box. A
large hole bored through the block makes
it easy to clamp the work to it.

The shoulders can of course be sawn on the
table saw using 4 different setups. The
chances they will line up very well don’t
seem good to me. Any way you do it, you’ll
likely need to refine the shoulders with a
chisel.

Radial arm saws can excel at this sort of
joinery too. Still a lot of setups for just one
desk though.

View pottz's profile

pottz

2107 posts in 794 days


#3 posted 10-16-2017 01:07 AM

or you could spend a few thousand and buy a multi router!i think youll get there whatever way you choose buddy,you always do!cant wait to seethe end result.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

View Jim Jakosh's profile

Jim Jakosh

19567 posts in 2915 days


#4 posted 10-16-2017 02:07 AM

I’d do them on the milling machine, but if you don’t have one, the table saw will do a nice job. Make jig to fixture that leg at 45 degrees to the table so that the base of the jig is wide enough and longl enough to be stable passing by the blade. Clamp that piece in there and slide it across the blade in increments until you have the right width. If the base is wide enough, you can slide it by at 90 degrees to the first cut and do the whole thing without taking it out of the jig. It would be much like a sled but not riding is the miter slot.

cheers, Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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AandCstyle

2884 posts in 2067 days


#5 posted 10-16-2017 10:40 PM

Ben, another option is to use slip tenons and cut the mortises with a router. FWIW

-- Art

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TungOil

708 posts in 305 days


#6 posted 10-17-2017 02:09 AM

+1 on loose tenons. I would not recommend cutting an integral tenon at more than a 30 degree angle for strength reasons. Generally 30 degrees is the most you want to go before you compromise the strength of the tenon too much. The loose tenon eliminates the cross grain issue that would weaken a standard tenon.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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jonah

1374 posts in 3108 days


#7 posted 10-17-2017 02:52 AM

+1 for loose tenons in this application. You want to treat it like a miter spline, which you set up with the grain at an angle to the normal grain of the boards. This is basically a funky miter joint.

View BenDupre's profile

BenDupre

527 posts in 298 days


#8 posted 10-22-2017 03:15 PM

Okay so after a straight up couple weekends of puttering with this problem (and thanks to all those suggestions) I found a method that I can repeat. Thanks to Loren for the suggestion of building a 45* jig. Basically does what my cast-iron tennon jig cannot: angle to 45. So far I used my combination blade and just bumped the rip fence over 1/8 at a time. I can pull out the dado but I only have four of these to cut.


On the table saw a 45 degree block can be
clamped to the fence of a cut-off box. A
large hole bored through the block makes
it easy to clamp the work to it.

- Loren

It looks like this:

The outside shoulder is just a little fuzzy when cut this way but I can deal. I will cut the haunches with a handsaw and refine if needed with a sharp chisel.

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw

View waho6o9's profile

waho6o9

8006 posts in 2387 days


#9 posted 10-22-2017 03:20 PM

Interesting, looks like a good solution congrats!

View bondogaposis's profile

bondogaposis

4425 posts in 2161 days


#10 posted 10-22-2017 03:56 PM

This one area where hand tools excel. If you can draw the lines on the board and then cut the line. Clean up with chisels and shoulder plane. You could have the joint cut in less time than it would take create and elaborate jig on the table saw. A jig could be worth it if you have a lot of these to make, for just a few, I would use hand tools.

-- Bondo Gaposis

View BenDupre's profile

BenDupre

527 posts in 298 days


#11 posted 10-22-2017 05:11 PM


This one area where hand tools excel. If you can draw the lines on the board and then cut the line. Clean up with chisels and shoulder plane. You could have the joint cut in less time than it would take create and elaborate jig on the table saw. A jig could be worth it if you have a lot of these to make, for just a few, I would use hand tools.

- bondogaposis

I believe you are right, and I tried, however I just didn’t have the right kind of miter box to saw the shoulders accurately at 45 deg I also made a version on the bandsaw but that was not cutting square because of the blade drift.

FWIW I also could not brain out how to make a 45deg mortise into the apron (floating tenon approach) on my mortising machine because it was just too long.

-- The problem with communication is the illusion that it has occurred. – George Bernard Shaw

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