Mortise & Tenon question............need some advise

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Blog entry by Al posted 04-16-2009 03:34 AM 1737 reads 0 times favorited 6 comments Add to Favorites Watch

As I embarked on my new addiction of woodworking, I spent the winter months orginizing my small workshop and built some jigs for future use. From plans, I built a pretty cool tenonning jig from PlansNow and put it to the test this past weekend with good results. However, when reviewing the plans, the mortise dimensions are a bit longer than the tenons. Is that a technical reason to help with the fit or am I doing somthing wrong? Since the tenons are already cut, I sure would like to use them “as is” if possible. The mortises (spelling ?) have not been started. However, logic tells me that the mortise and tenon should be a perfect fit. Thanks again for your support. Al

-- Al Meriden, Connecticut

6 comments so far

View ART LACKEY's profile


113 posts in 3581 days

#1 posted 04-16-2009 03:45 AM

Hi AL, you are the first LJ that i’ve seen from ct. I am in the northwest corner working wood.

-- Old turners don't die, they just turn to dust!

View garysharp's profile


119 posts in 3682 days

#2 posted 04-16-2009 03:47 AM

Al, like DaveR I like the size to finish up about the same size. I start with the tenon a little over size and use a shoulder or rabbet plane to cut the tenon down to a nice fit.

-- Garysharp "When sharpening woodworking tools, good enough,...isn't" “Your life’s complete only when your knowledge passes on”.

View Moron's profile


5032 posts in 4096 days

#3 posted 04-16-2009 04:16 AM

I always cut my mortises first and then cut my tenons to fit

rarely the other way around

I spend my whole winter orgainzing snow…..........and today was the first day, that the night before, was above freezing in 2009

-- "Good artists borrow, great artists steal”…..Picasso

View fidelfs's profile


14 posts in 4269 days

#4 posted 04-16-2009 06:57 AM

When you say mortise dimension longer, do you mean the length of the mortise is larger than the tenon?
The tenon deep and mortise deep may be the same, you can changer the end of the tenon to allow the glue or you make the mortise a little deeper to allow for the glue or they can be the same.
The thickness of the tenon and mortise are the critical measurements. The tenon must fit snug within the mortise.
the tenon length is not as important. If you see the Domino from Festool has 3 settings, the first one is to have a snug fit for aligment and the other 2 are larger to help with the final assembly.

Hope this helps.

View Pete_Jud's profile


424 posts in 3955 days

#5 posted 04-16-2009 07:12 AM

I always cut the mortise first then cut the tenon to fit the mortise. It always takes me a coupe of trys to get it right with some scrap.

-- Life is to short to own an ugly boat.

View patron's profile


13640 posts in 3543 days

#6 posted 04-16-2009 04:48 PM

hi al :

myself i always make the tenons shorter 1/8 ” . the mortice allways has garbage in the bottom and rather than clean it out perfectly and flat , i scrape it out and slightly bevel end of tenon to not srape the glue as it seats ,thus distribiting glue evenly . glue or any liquid does not compress ( hydraulics ) ,so the 1/8 ” is a reservoir for the exess glue unless you are making through joints nothing is visible .

stay safe


-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

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