# How tall mortise/tenon can be.



## 716 (Nov 22, 2015)

In a glued application how wide the apron board can be before the wood expansion becomes a problem. Let's say for hard maple material.


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## jeth (Aug 18, 2010)

Hello.. probably about 3 inches or so would be the limit before you would want to allow for movement, dividing the tenons and only partially gluing, as you get wider (think breadboard ends as an example) using pegs through slotted holes in tenons to secure etc.

They look like sliding dovetails(??) not straight tenons, if you're worried you could just glue the top end or not glue at all in that case as the mechanical joint of the tail will stop them sliding out. Probably be best to glue at least an end so the legs can't slide off!


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## a1Jim (Aug 9, 2008)

Jeth said exactly what I would recommend.


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## wormil (Nov 19, 2011)

I made a table with a 4.5" apron, been ten years and no issues. Mahogany, which is pretty stable.


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## 716 (Nov 22, 2015)

Thank you all. that was very helpful!


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## bonesbr549 (Jan 1, 2010)

I would add that its material dependent as well. If the apron material is QS then movement will be greatly reduced and some species are more volitile than others. Tight grained woods would be the best. IMO. I've done aprons 6" no issues, however I follow a rule, and any cross grain situation exists I allow for some movement period.


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## pintodeluxe (Sep 12, 2010)

A 6" wide piece of bigleaf maple will change dimensions by approximately 1/32" (depending on how it was cut) as moisture content changes from 6% to 10%. I usually use wide rails on side panels for bookcases and and the like. In those instance I may or may not split the tendon. That depends more on leg thickness than expansion / contraction. You can glue only the center of the tendon if you wish, but I think for board width < 6" in an air conditioned house, wood movement is negligible.

I haven't had the occasion to make aprons wider than 4-5", and have never had a problem. I use quartersawn stock though, which is usually more stable.

Clever tool for calculating mood movement…
http://www.woodbin.com/calcs/shrinkulator/


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## hotbyte (Apr 3, 2010)

Here's an interesting article on sizing tenons…

http://www.popularwoodworking.com/techniques/joinery/tenons-rule-so-here-are-the-rules-on-tenons


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## wormil (Nov 19, 2011)

Results of the anvil test mentioned in the article linked above.

http://www.popularwoodworking.com/techniques/the_anvil_test


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## hotbyte (Apr 3, 2010)

> Results of the anvil test mentioned in the article linked above.
> 
> http://www.popularwoodworking.com/techniques/the_anvil_test
> 
> - Rick M.


They really need videos of the anvil drops and splinters flying


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## BinghamtonEd (Nov 30, 2011)

I've done a 4" wide drawbored tenon in cherry on my daughter's bed going on 2 years now and no signs of any issues.


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## wormil (Nov 19, 2011)

> They really need videos of the anvil drops and splinters flying
> 
> - hotbyte


Matthias! Get in here!!


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