First Time Poster – Tenon Length and Overall Table Dimensions
Hello All,
This is my first post, so thank you ahead of time for any responses. I have been an amateur woodworker for several years, but I have transitioned to a more “professional” level over the past year as I have started building projects for clients. Lately, I have been working on a few large, farmhouse dining room tables with breadboard ends. Up until now, I have attached the breadboards using dowels with elongated holes on the ends to allow for seasonal movement. While the results have been good with this method, I want to start joining them the more traditional way with a drawbored mortise and tenon. I was just about to start cutting my mortise in the breadboard, and it hit me that I did not account for the tenon length actually making the overall length of the table top shorter once the breadboards are inserted into the table top.
Am I confusing myself here, or is that something that has to be planned for in the original plans? If the table top I am building has an intended length of 71″ and the breadboards are to be 6 1/2″ wide, and therefore adding 13″ to the long boards that are 58″ long, am I correct in that the long boards actually should have been cut to 64″ if I was planning to use a 3″ long tenon on each side, which makes the table top actually 6″ shorter?
I know this is probably a very obvious question, but in all the reading I have done and all the videos I have watched on creating a mortise and tenon, I don’t think I’ve ever come across anything saying that extra length has to be added to a project to account for the length of the tenon. I guess this is what mistakes are for, but if you have any thoughts or can confirm how you go about accounting for tenon length and the overall dimensions of your project, I’d really appreciate it. Guess I’ll be using dowels at least one more time…
Thank you!
Replies
Breadboards + shoulder-to-shoulder length of the top = final tabletop length.
Anything inside where parts "overlap" has to be allowed for, in your case the lengths of the tenons on both ends of the top.
To save it you could cut back to your shoulder line and use floating tenons to attach your breadboard ends.
Yes, if your tenons are 3" and breadboards are 6 1/2" wide, you're adding 3 1/2" length to each end.
Thank you!
MJ is right; if you want to save it, use loose tenons that go into both the breadboard ends and the main top. You can glue the loose tenons into the main top, and drawbore them into the breadboard ends. If you are able to use the same set-up (i.e., a router) to make the mortises in all three pieces, alignment should be perfect. If you plan to use a hollow chisel mortiser for the ends, use a router for the main top and make the mortise the same or a bit bigger, then work down the tenon to the right size for the end after you have glued it into the main top. When you set up to draw bore, make sure to elongate the holes in the outside tenons perpendicular to the length of the tenons, to allow for the main top to change width seasonally. Another possibility that I have done is to make the edge of the breadboard end slightly "sprung", i.e., concave, so you only need to draw bore the center tenon to keep the breadboard tight over its whole length. The other tenons go into mortises that are slightly wider than their tenons, and keep the pieces aligned.
Thank you - This is very helpful!
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