Do I need tenons - Woodworking Talk - Woodworkers Forum
 
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post #1 of 11 Old 06-04-2015, 01:34 PM Thread Starter
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Do I need tenons

I am building a table top that measures 38’ X 78” out of 8/4 select walnut, consisting of 6 to 7 random width boards. The top will be free floating with no end boards. Using biscuits seems useless and I don’t have access to a Lock Mortiser or any of the other large mortis machines. My question is, does 8/4 provide enough glue surface without mortise and tenon?
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post #2 of 11 Old 06-04-2015, 03:13 PM
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Table tops

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The biscuits can help align the boards during glue up.
A spline stopped 3"" from each end on each board will help align the boards during glue up and offer a better joint than the biscuits.
If you have access to a biscuit cutter or a spline cutter for your router you should use it.
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post #3 of 11 Old 06-04-2015, 03:38 PM
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8/4 provides very sufficient glue surface. Never heard of anybody using a mortise and tenon joint of a flat panel like a table top.

George
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post #4 of 11 Old 06-06-2015, 12:41 PM
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You will be fine with normal glue up. Use titebond 2 for water resistance.

You need to be more concerned with wide board cupping if not properly secured. At least alternate the boards.
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post #5 of 11 Old 06-17-2015, 05:18 PM
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How would you secure them other than alternating to prevent cupping? Spline or biscuit or are you referring to how they attach to the base?
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post #6 of 11 Old 06-17-2015, 08:24 PM
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If you glue up 8/4 wood the joint will be strong enough to dance on for a life time. I have a biscuit jointer and for the life of me I never understood how they would aid in alignment. The cut is quit a bit wider than the biscuit and this allows for alignment in either direction to get the boards aligned without getting in the way.

The best thing you can do for glue up is prep the wood by facing the lumber before planing. The glue up will go like a snap and you won't be introducing any undue pressure trying to get the pieces lined up.

Al


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post #7 of 11 Old 06-18-2015, 10:32 AM
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8/4 is plenty strong of a glue line if glued and clamped properly.

Regarding the biscuits...they can aid in alignment, and I don't understand the comment regarding them being loose. Mine cuts a groove that's perfectly sized for the biscuits....sometimes requires a bit of tapping with a mallet to have them seat fully. Is it possible you have cheap biscuits??

The tools don't make the craftsman....
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post #8 of 11 Old 06-18-2015, 11:46 AM
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The more I read the more I realize how much I don't know. A few questions here. When are splines needed in a table top glue up? If I was to make a 4/4 walnut top without a bread board would some other joinery be needed? I would think some of the support and longevity would come from the apron and base of the table... I have lots of questions, maybe someone could suggest a book/website that teaches these principles.
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post #9 of 11 Old 06-18-2015, 10:19 PM
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Quote:
Originally Posted by Jaredbc
The more I read the more I realize how much I don't know. A few questions here. When are splines needed in a table top glue up? If I was to make a 4/4 walnut top without a bread board would some other joinery be needed? I would think some of the support and longevity would come from the apron and base of the table... I have lots of questions, maybe someone could suggest a book/website that teaches these principles.
Splines and biscuits are NOT needed for edge glueing boards. They can aid in keeping the tops of the boards aligned so less sanding/planning is required, especially if your clamping technique is still being honed. Neither will prevent cupping or warping of the table top.

Breadboard ends, when properly executed, will prevent cupping/warping of the table top. However, many, many tops have been made without breadboard ends and have lasted for years without warping. Most of the problems occur in extremely humid/wet conditions.

Solid wood tops need to be carefully attached to the aprons to prevent the top from splitting or cracking, trying to glue or simply screw the top to the aprons is a sure way to ruin your top. The top has to be free to expand and contract. There are many ways to address the issue, just make sure you address it.
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post #10 of 11 Old 06-19-2015, 11:35 AM
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Do I need tenons

Porter cable biscuit cutter and biscuits are in fact top of the line products. They are sold in a sealed container. []If a biscuit needs pounding in it has already taken on moisture that it's supposed to get in the glue up process. They are compressed to aid in ease of use and to eliminate the problems with getting the glue up correct. They will in no way aid in alignment as they are much thinner than the slot which is by design.

Its been proven over and over in all woodworking tests and has been published in all major magazines that biscuits do in fact add strength to a glued joint. A table top glue up does not need anything to strengthen its joint.

If your using a wood with a great deal of movement like oak. Care needs to be taken to insure it stays flat. Sturdy fastening that allows movement is paramount. I build with cherry and have never experienced and issues with cupping and movement problems. My furniture in the north and in the south sub tropics remains as true as the day it left the shop. I also face all my lumber before planing and glue up. Inducing wood to excess clamping and pressure at glue up will most likely result in less than desirable results which may take a few days to manifest.

This is a picture of lumber that has been faced and then planed. It lays perfectly flat and was used for a large cherry table top. The glue up was a snap requiring very few clamps and nothing to hold it flat. Clamping pressure was light and this insures the glue between the wood stays there and allows the process to work as intended.

Al
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post #11 of 11 Old 06-19-2015, 05:57 PM
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Quote:
Originally Posted by Al B Thayer View Post

Inducing wood to excess clamping and pressure at glue up will most likely result in less than desirable results which may take a few days to manifest.

Al
I believe that this is a statement that cannot be over empathized. Early in my woodworking career I was one that over torqued the clamps. The computer desk that I am sitting at has a edge joint that has opened up because of that.

When you over torque too much glue is squeezed out of the joint. The clamps just need to be snug, not turned until they can no longer be turned.

George
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