Fatten up tenons for tighter fit before glue-up?

[Bob Jones 5443]

I have some tenons with a little slop* in them, and I’d like to add a few thousandths to the cheeks to snug them up before final glue-up. Is this wise? feasible? Would paper work? How about gluing some 2 or 3 thou shavings to the cheeks? The scale is a 12 x 24 x 42 cherry cabinet with 3/8” x 1.5” x 1.25” deep tenons on 7/8” thick rails into 1.75” x 1.75” stiles/corners.

*By “slop” I mean most of the tenons would slide out if I hung them from the stiles.

[Derek Cohen]

Either glue on a piece of veneer, which may be just thick enough, or glue a thicker piece, and then pare it the final thickness.

Regards from Perth

Derek

[Jim Matthews]

If you're already within a few thousandths I expect hide glue would be sufficient already. If it doesn't "grab" it can be reversed (with more hide glue applied).

If you're after more security, consider a drawbore fixture.

https://sawmillcreek.org/showthread.php?149169-How-tight-should-a-mortise-and-tenon-joint-be

[J. Greg Jones]

I have used part b of Derek’s answer, which is to glue on a larger piece to the cheeks and pare them to the new size. It takes some additional time and work, but it does a nice job of fixing the problem.

[Bill Carey]

I have used part b of Derek’s answer, which is to glue on a larger piece to the cheeks and pare them to the new size. It takes some additional time and work, but it does a nice job of fixing the problem.

I've done the same thing with great success. As Greg says it takes a bit of time but it's worth it to get a solid fit

[Robert Engel]

2 or 3 thou is close enough for standard glue.

You can use a gap filling glue like epoxy or hide glue.

[Jim Koepke]

My vote is for adding a thick shaving or a piece of veneer. Then trim as needed.

As others have noted some glues are okay at gap filling. Beware, some glues are not.

Draw boring is a good way to hold the joint. For it to be free of wobble the tenon can't be loose to start.

This gate was put together using draw bore mortise and tenon joinery:

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It has been in use for less than two years, but no sign of sloppy floppiness. BTW, there isn't any glue holding the joint together.

jtk

[Rob Luter]

Sprinkle some fine sawdust on the wet glue covering the tenon prior to assembly. I'm talking powder fine. You'll be surprised how a little bit of dust will fill a gap. In addition, the moisture from the glue will cause both the mortise and tenon to swell a bit.

[David Eisenhauer]

I will freely admit to using plane shavings pre glued to a tenon cheek to tighten up the occasional tenon fit as required and have not had any adverse issues by doing so. I have also glued blocks to a tenon for a complete recut in the case of some serious error, but have not had to do that in a while. I don't have any veneer around to use as a thin shim, but do have plane shavings (in various thicknesses) laying around.

[david charlesworth]

I think I would prefer to glue veneer onto a tenon.

It can then be reduced very accurately with a router plane such as the 71.

Best wishes,

David

[Frederick Skelly]

Agree with others - glue on a shaving or veneer and tune to fit.

[Bob Jones 5443]

OK, the adventure continues. Thanks all for the input. The veneer sounds like it would offer the best shot at restoring precision to this little mistake. Kind of like fitting a crown onto a tooth. Plus a fine opportunity to use my 1896 Type 4 No. 71. Got it free from my brother-in-law. Aren’t tools fun?

[Robert Hazelwood]

I'd use a plane shaving or cut a thin "veneer". You can get an idea of how thick your addition needs to be by test fitting with some blue tape added. One layer of tape is about 0.005" usually.

[Jim Koepke]

I'd use a plane shaving or cut a thin "veneer". You can get an idea of how thick your addition needs to be by test fitting with some blue tape added. One layer of tape is about 0.005" usually.

A shaving could also be draped over the end of the tenon to see how that fits. One of my loose tenons was done this way at glue up and worked fine.

jtk

[Bob Jones 5443]

OK. It ain't pretty, but tenons hide from view, right? Below is a double tenon. On the top half I glued an extra-thick (~0.003" to 0.004") shaving. On the bottom, which seemed to need a bit more profile enhancement, I went the "veneer" route. I ripped a 0.025" thick strip from the clean edge of some 5/4 cherry –– the thinnest I could rip with some precision. I then glued a chip of it onto the tenon overnight. This morning I came in with my router plane and shaved it down. Now I can hold up the leg by the rail when its tenons are inserted into the mortises (on both ends of the rail).


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The veneer is a lot easier to glue on –– the shaving is an unruly curly mess to handle. Plus I can clamp it without fear that the glue will seep through the veneer the way it does through the shaving.

One down, ??? to go. I haven't checked yet just how many of these loose tenons I have, so it's time to gird my loins to the task and make sure I put a fine polish on the router plane iron.

I'll also glue on the rest of these veneer strips with their grain perpendicular to that of the rail so the router plane can shave with the veneer's grain more easily.

Looking ahead, I need to refine my tenon technique to avoid the annoyance of this rookie mistake. It's something I haven't studied enough yet. I had used a dado set to cut these tenons. I see now that that method lacks precision. At the moment I like the looks of Philip Morley's "band saw" tenon, for which he makes a shim exactly equal to the mortise thickness plus the kerf width. We'll see...

[Doug Dawson]

I have some tenons with a little slop* in them, and I’d like to add a few thousandths to the cheeks to snug them up before final glue-up. Is this wise? feasible? Would paper work? How about gluing some 2 or 3 thou shavings to the cheeks? The scale is a 12 x 24 x 42 cherry cabinet with 3/8” x 1.5” x 1.25” deep tenons on 7/8” thick rails into 1.75” x 1.75” stiles/corners.

*By “slop” I mean most of the tenons would slide out if I hung them from the stiles.

Just draw-bore them. That wouldn't even need glue for structural integrity, in many cases. It doesn't have to be a suction-tight fit. That was never a requirement, except for NASA or the Navy (padding the bill.)

[Jim Koepke]

Looking ahead, I need to refine my tenon technique to avoid the annoyance of this rookie mistake. It's something I haven't studied enough yet. I had used a dado set to cut these tenons. I see now that that method lacks precision. At the moment I like the looks of Philip Morley's "band saw" tenon, for which he makes a shim exactly equal to the mortise thickness plus the kerf width. We'll see...

The bandsaw method sounds like an easy way to go.

For hand work one way that worked for me was to make a test tenon. This was as much for a depth check as it was for fit. Then the mortises would be cut, checked and fitted against the test mortise. If the test tenon was loose in the mortise the mortise would be marked to let me know to cut the tenon a little fat. The mortises were all cut with the same Narex 1/4" mortise chisel so there wasn't really much variation to be a worry.

It might be easier to read about it:

https://sawmillcreek.org/showthread.php?262272

The articulated gate used 24 mortise and tenon joints.

jtk

[David Eisenhauer]

Using a shim to the thickness of the desired tenon thickness to create the second face of a tenon from a fence is a good way to go regardless of which machine is used if going the power-tool tenon fab route. Using scrap squares with wax paper (or similar) glued to them are useful to have for adding plane shaves or veneer shims to tenon faces with the squeeze-type clamps. I have a few of those in a coffee can for use as required. Due to the size of a typical furniture-sized tenon, I can't say that it will matter whether or not the direction of the grain run on a tenon shim will matter, but I could not make myself glue one on crosswise. Your tenons can, however, be shimmed anyway you want. I venture to say that your skill in fabbing tenons will increase with experience, but you (as most of us) may never be completely free of a loose tenon from time to time in the future. When David Charles chimes in on how to fix a loose tenon, it says something. "Hey, DC read about it somewhere, never had one himself". OK. Main thing is to enjoy the process Bob Jones number five thousand four hundred and forty three :).

[Bob Jones 5443]

Nice mind-read, David. I have been using little squares of parchment paper on these finicky little glue-ups. They're getting prettier. Here are the latest two rail-ends after truing up with the No. 71:

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Both now fit snugly! What fun. Two rails down, nine to go (unless some of the tenons already fit, which at this point would surprise me).

My No. 71 is a wonderful tool, but the Old Timer is a bit primitive because it lacks the screw height adjuster. But no matter: once the 0.025" veneer chips dried onto the tenon cheeks, I just zeroed out the No. 71 on the new chip, and then crept down to final dimension using little square shims of –– parchment paper. This allowed me to take the finest shavings, controlling the process. In the end I needed only two parchments' thicknesses to reach snugness. So that tells you how skinny the tenons were!

Next time I make tenons, I'll still aim for high precision à la the Morley shim/band saw method, but now I think I'll intentionally make them just a few thou proud so I can ease up on the final size with the No. 71. I can now clearly see it's better to start fat than too skinny.

Why are so many of my tenons skinny? I suspect it's from drying. I cut them ages ago (over a year?), and I'm sure they were not so pathetically undersized at first. They have since lived in our dry house interior for many months, recently through the dry DRY DRY California summer/autumn. (Heard about it on the news?) Could the tenons have lost dimension as they dried? Makes some intuitive sense. What do the experts here surmise? If there's any truth to this, it suggests that any M & T joint could suffer that fate after a while, even after it's been glued up. I might just give draw boring a try.

[Edward Dyas]

I have some tenons with a little slop* in them, and I’d like to add a few thousandths to the cheeks to snug them up before final glue-up. Is this wise? feasible? Would paper work? How about gluing some 2 or 3 thou shavings to the cheeks? The scale is a 12 x 24 x 42 cherry cabinet with 3/8” x 1.5” x 1.25” deep tenons on 7/8” thick rails into 1.75” x 1.75” stiles/corners.

*By “slop” I mean most of the tenons would slide out if I hung them from the stiles.If it were me I would just glue the joint with epoxy. It would be thick enough to take up the slack.

[Bob Jones 5443]

Jim, I've just taken a tour of your articulated gate story line. Very informative. You mentioned a few blowouts with the draw bore technique. Did you consider using a draw bore pin to check each M/T pair for fit with the offset bores? Maybe it's less of an issue with hardwood.

[Doug Dawson]

Jim, I've just taken a tour of your articulated gate story line. Very informative. You mentioned a few blowouts with the draw bore technique. Did you consider using a draw bore pin to check each M/T pair for fit with the offset bores? Maybe it's less of an issue with hardwood.

Don't overthink it. Play around with the dowel stock to get a feel for how it's going to react, and then go to town. You'll understand what to do.

[Jim Koepke]

Jim, I've just taken a tour of your articulated gate story line. Very informative. You mentioned a few blowouts with the draw bore technique. Did you consider using a draw bore pin to check each M/T pair for fit with the offset bores? Maybe it's less of an issue with hardwood.

My biggest error was not planning to draw bore before starting. Since the tenon was a bit short for draw boring the dowel pin was a bit close to the edge on the mortised rail.

My second error was in getting the offset correct. My first ones had too much offset, combined with how close it was to the top of the mortise caused the blowouts. Lessening the offset a little took care of the blowout.

Checking the gate panels was easier to do by clamping it together to make sure all the shoulder to rail joints closed all the way. With draw bore pins it could have take six of them to check properly.

jtk

[Bob Jones 5443]

Well, I've been through all 22 tenons now. I'd say about 8 or 9 were on the skinny side. After a couple of tries, I got the veneer-and-trim process down to a science. One or two were actually a little fat. Again, love that router plane! The others just needed the edges eased. So, the whole genesis of this thread has reached a resolution, and I'm on to the next operations.

I'll build the door after the cabinet is assembled to ensure a tight fit. The door will have six tenons of its own, so I can see if I've learned my lesson from making sloppy tenons. It will be time for me to try the band saw method discussed above, in hopes of avoiding these problems altogether. I'm looking forward to taking another skill on board.

Then after that, someone will make me aware of a better way to make tenons.