Breadboard end tounge to thickness ratio?


Hello everyone,
I have done breadboard ends on 3/4" thick material before and I have always used a 1/4" tongue, 1:1:1. I have never made a breadboard end on anything thicker before.
The big 'ash table I am working on is about 3' wide 6' long, 1-3/4" thick. I was wondering what ratio I should use?
Here is what I was thinking,
A 6" wide breadboard end, 1" tongue thickness, 3" deep.
That would leave 3/8" of breadboard top and bottom and 3" of solid material behind it.
How does that sound?
Thanks,
David.
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Sounds reasonable to me, with 1 change. Leave about 4" in the center of the table end with only a 3/4" tongue. This will help to keep the 3/8 thick breadboard edge from warping as seasons change.
Art

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Rule of thumb for a tenon is 1/2 to 1/3 the thickness of the board, so 5/8 to 7/8 thick tenon. If it is too thick, the bread board doesn't have enough meat to hold well, although as heavy as you are making it, I would think that it would be ok. robo hippy
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.

Like one strong breadboard bordering on overkill.
Pete
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always
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material
My gut would say that closer to the 1:1:1 ratio would be optimal.
I think is was FWW that did an article on this a while back. They had a bot more complicated tennon arangement. The tennon was only 3/4" deep all the ay across but had 2-1/2 deep by 2" wide (roughly) segments spaced about a foot apart.
Ascii rendering: .--H-----H-----H-----H-----H--.
The breadboad was pinned through the "toungues", A tight pin in the center and sloted holes for the pins on the sides.
-Steve
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Dave,
I built a 4' wide, 7' long farm table top last year with breadboard ends - big and heavy. I don't have the url for the article anymore but the advice was something along these lines:
1. Consider that the breadboard end is long grain and the tongue support is cross-grain. 2. When someone (and they will) decides to sit on the edge of your table (the breadboard ends) you need the thickness on the breadboard so don't go less than 1/3rd. 3. As for depth - what is the max depth of your mortiser? 4. With a breadboard end 6" wide you will get noticeable wood movement so be sure to allow a bit extra depth in the mortise on the breadboard. 5. Width of table will also change (up to about ~3/16" total I'm estimating) so be sure to allow extra room on the sides of the mortises for the tongue to move. 6. Make the center tongue width about 8" and this gets pinned (from underneath) with a slight draw (1/32") to draw the breadboard tight to the table edge. 7. The other 8" tongues get a slotted hole so the dowel can move as the tabletop expands and contracts.
Here's a suggested width for the tongue widths and gaps between the tongues on the tabletop:
2"gap -- 8"tng -- 2"gap -- 8"tng - 2"gap -- 8"tng -- 2"gap = 36"
The breadboard mortises (8" wide ) must be slightly wider to allow for wood movement.
| | | | | Tabletop End | ----| |----| |----| |---- |________| |________| |________|
^^^Breadboard fits on this end ^^^^
Bob S.

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Dave, With a top that thick, why bother with breadboard ends. Unless its part of the style/design, I doubt that doing breadboard ends will do nothing but cause problems you don't need with that heavy of material. I may be wrong but I'd just finish the ends and let the heft of the top speak for it self.
Dave
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Dave,
I haven't read the article but in the Feb issue of FWW there is an article that may have more info for you.
http://www.taunton.com/finewoodworking/pages/fw_currentissue.asp
Bob S.

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