I am making an tall stand that I plan to join the aprons to the legs with floating tenons. The aprons will be about 6 inches wide and made of quater sawn douglas fir. Does the grain orientation of the stock for the floating tenons make a difference?
Traditionaly I think such a wide tenon would be made up of two smaller tenons with a sub tenon. With the floating tenons would I just cut two smaller mortises and forget about the sub tenon?
I want to use the floating tenons for two reasons. One, I never have tried them before and two, the ends of the aprons are not square, they have a slight taper so the legs flare out. With the floating tenons, I don’t have to cut anything except the apron ends at an angle.
Adam
Replies
The direction of the grain should be in line with the grain in the aprons.
If the floating tenon grain were aligned with the legs, vertically, it would be cross-grain in the tenon, and would not be very strong.
________________________
Charlie Plesums Austin, Texas
http://www.plesums.com/wood
Hi Charlie,I should have been more clear when I asked about the grain. I meant does the tenon stock need to be quater sawn if the apron is or can I use flat sawn stock? Thanks,
Adam
I would just use flat sawn. Long grain along the tenon for strength. Then we are looking for face grain or edge grain (anything but end grain) to give a strong glue joint with the wall of the mortise. Since good glue joints are stronger than the original wood (fracture normally occurs away from the joint), the floating tenon becomes the "same" as a regular tenon, but with one saw cut instead of nine.
Note that the top and bottom of the tenon in the leg mortise will be an end-grain joint, which has minimal strength. Therefore, this is a good area to include any "play" if you need to make a fine adjustment, and the place to leave the small gap for the air and excess glue to escape.
The one time I used a sliding dovetail in this position, the tail was so close to the edge of the leg that I could see the wood trying to split there. Once it was all glued, it was fine, but it turned me off of sliding dovetails in this role. If I did it again, at minimum I would make the dovetail narrower (less angle), but if the dovetail is really narrow, I am back to a tenon.________________________Charlie Plesums Austin, Texashttp://www.plesums.com/wood
Mute,
I've used loose tenon joinery on quite a few pieces. It certainly simplifies the dimensions of the joined components. Joining a curved crown rail to the posts on a bed was a piece of cake using this method.
As Charlie said, the grain must be the same direction as the apron for strength.
Another method I've started using to join aprons to legs is a sliding dovetail. Haven't tried it on tapered legs and aprons, but it should work OK. I leave the aprons longer than I'll need until I determine the exact dimension of the cut on the end of the apron.
Regards,
Bill Arnold - Custom Woodcrafting
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One thing I just LOVE about sliding dovetails is I can sneak up on a perfect fit and still be on center..
"One thing I just LOVE about sliding dovetails is I can sneak up on a perfect fit and still be on center..."
Will,
That's a good point, too. After you know the depth (length) of the dovetail, then you can cut the aprons to final length. With all other adjustment being the width of the dovetail on the apron, all it takes is a little tweak to get it perfect. I have an Incra LS system on my table router, so I can tweak the width of the tail by a couple of thousands until it slides just right.
Another thing about sliding dovetails is they are self-squaring. I've prepped for a glue-up by having clamps at the ready, but really haven't needed them because the sliding dovetail was perfectly snug (without being TOO tight). When I checked for square and tight, all joints were dead-on. Of course, being somewhat anal, I still put clamps on the piece!
Using sliding dovetails in this application is a matter of experience. For some, it's more comfortable to continue with M&T, which is fine. I like to be able to demonstrate a joint that can't possibly pull apart and that's what I get with the sliding dovetail.
Regards,
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Bill,
I am very interested in using sliding dovetails in more of my woodworking projects.Could you explain the process you use for cutting these?
Matthew,
The only way I've used sliding DTs to any extent is attaching table aprons to the legs. I use my router table for all operations. Assuming 3" aprons, I cut a DT from the top of the leg down about 2 1/2", positioned as shown in the attached graphic. Next, I take a scrap of apron stock (or other scrap the same thickness) and take small cuts on both sides until the apron slides easily into the leg. The apron needs to be milled on both sides with every adjustment so the DT stays centered. The DT should slide in with hand pressure only and not so loose it falls out. The final step is cutting off the bottom 1/2" of the DT on the apron so it will slide all the way into the leg.
Regards,
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Bill,
Thanks for the explanation and the picture. Sometimes I woeey that this method is complicated. But the idea of "sneaking up" on the correct cut sounds right.
"... the idea of "sneaking up" on the correct cut sounds right."
And you only have to sneak up on it with your sample piece. After that, all the others will fall in place.
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Bill got it..I LOVE sliding dovetails.. (However if a good fit DO NOT glue up a 4 foot wide one and expect it to get to the bottom of it! Then ya need to make a tapered one!
Will,
Sounds like you speak from experience! Wood swells when wet, huh?
Too bad smearing a little glue on certain other things won't have the same effect!
:-)
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I'm intrigued...what size DT bit for say 3/4 stock for the apron? What about router power? thanks
I use a 1/2", 14deg bit. Most of the pieces were done using a 2.25HP router which worked fine. I now have a 3HP router in my table, so some operations seem a little easier.
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Will,Do you think a 24-hour epoxy would be OK for these joints?
The epoxy would grease the joint during fitting...Thanks,Ted
The epoxy would grease the joint during fitting...Geeeee OLD here.. Not sure I understand???.. Yes.. the foam comes out..The glue works OK by me but open time is only about 15 minutes so you MUST plan your glue-up clamping..Maybe I just get Lucky!..To be honest.. I do my laminations for the bows in stages.. Like in Half En' half.. First glue up is now the 'form' for the other half..Not sure if proper but a bow never came apart.. Well, some really strong folks can break them if 'dry shooting' (which is NOT allowed for a bow)!EDIT:: Do you think a 24-hour epoxy .. The longer the open time the better I would 'think"? Gives you time to get it all right!Edited 10/22/2005 3:42 pm by WillGeorge
Edited 10/22/2005 3:43 pm by WillGeorge
Adam,
Over a 10% change in moisture content, a flatsawn 5 inch wide tenon will want to expand 1/16th of an inch more than the mortise of the quarter sawn apron. This will create some stress but probably not enough to crack the apron, but why chance it? I'd orient the grain of both pieces the same way.
Also, oriented this way there will be less stress on the glue joint in the leg mortise since there will be less change in the wide dimension of a quarter sawn tenon. The mortise in the leg, because its long dimension goes lengthwise with the grain, won't change in dimension at all with moisture content changes, so the less movement in the tenon the better.
Again this is academic, probably any combination of grain would work, but the nice thing about building your own furniture is you can be fussy and try to get everything just right.
John W.
Was wondering if you could make your floating tenons out of ply, then you would not have the movement issue?Troy
Edited 10/12/2005 5:25 pm ET by Troy
The apron, being solid wood, would still expand and contract so having the tenon expand and contract in the same way, by matching up the orientation of the grain, is actually an advantage. Gluing a wide plywood tenon into the apron would possibly cause small cracks to appear in the apron face during dry weather.
John W.
Thanks everyone for the tips.I think I will need to use two separate tenons, for my five inch width. With only one tenon, I think I would remove so much material that it will compromise the strength of the leg.Adam
Edited 10/12/2005 9:09 pm ET by Muteability
Look at those Beadlock jigs. Those work great.
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