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How snug should tenons be made

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Forum topic by BJODay posted 10-08-2013 03:18 AM 1555 views 0 times favorited 20 replies Add to Favorites Watch
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BJODay

393 posts in 633 days


10-08-2013 03:18 AM

Topic tags/keywords: mortise tenon

I’m making a set of 3 nesting end tables. This is the first project I’m making with M&T joints. The first table fit together well on the dry fit.

On the second table, I was very careful and made the tenons snug to each corresponding mortise. I actually had to lean on them to test the fit. Well when I put it all together for a dry fit it seemed too tight. It was not square and there was no flex to make it square. I disassembled the table and sanded the tenons slightly with 100 grit paper. Then dry fit again. This time it went together easier and was square.

My questions is this, How tight do you make M&T joints?
Squeeze it with lots of force?
Use a clamp to pull it tight?
Slip in with no slop?
A little slop to allow flexing to true it up during gluing?

I have one more set of M&T joints for the largest table. Any advice will be appreciated. I’m a little concerned. I don’t want to have problems once I start slopping glue around.

Thanks
BJ


20 replies so far

View Smitty_Cabinetshop's profile

Smitty_Cabinetshop

10054 posts in 1308 days


#1 posted 10-08-2013 04:03 AM

IMHO, it’s between these two choices:

Use a clamp to pull it tight?
Slip in with no slop?

Lots of force not good ‘cause you may break / split the stock either with fitting or with glue squeeze out that has no place to go. On the other end of the spectrum, hard to quantify ‘a little slop.’ The object is to have it true with no slop, of course, so if adding gets it square, after dry fit checks, so be it. Robert Wearing suggests sawing tenons that fit straight from the saw, as corrections after the fact are tougher than doing it right the first time. He taps with block and hammer when checking fit.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive

View tefinn's profile

tefinn

1215 posts in 1127 days


#2 posted 10-08-2013 04:07 AM

I was taught that they should be a nice friction fit. If there is slop you don’t get good glue to wood bond. If too tight, you risk splitting the mortise by forcing the tenon into it.

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

View rockindavan's profile

rockindavan

284 posts in 1326 days


#3 posted 10-08-2013 04:11 AM

If you can slide it in with little force by hand, and pick up the tenon end and it stays together, you have just about a perfect fit. If you pull it back out and get a “plomp” sound, you nailed it. In reality it doesn’t always work that way but too tight of fitting joints can bite you when glue up comes around.

View Monte Pittman's profile

Monte Pittman

14597 posts in 1028 days


#4 posted 10-08-2013 07:23 AM

1+ on smitty comments

-- Mother Nature created it, I just assemble it.

View KnickKnack's profile

KnickKnack

990 posts in 2256 days


#5 posted 10-08-2013 07:34 AM

A great woodworker once told me…

”Here’s how ya know if the joint’s cut right. If ya gotta whack it with you hammer to get it closed, it’s wrong. If ya whacking it with you hat and it closes, it’s wrong. So don’t use you hammer or you hat. Get it?”

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."

View lateralus819's profile

lateralus819

1479 posts in 579 days


#6 posted 10-08-2013 10:15 AM

If its too loose, take a plane and make a shaving and glue it on the tenon. Should help.

-- Never confuse mistakes with failure. Kevin

View Loco's profile

Loco

210 posts in 439 days


#7 posted 10-08-2013 12:11 PM

Tight enough it takes 2 guys/no hammer.

-- What day is it ? No matter. Ummmm What month is it ? No moron. I paid for a 2 x 6. That means Two inches by six inches. I want the rest of my wood.

View BJODay's profile

BJODay

393 posts in 633 days


#8 posted 10-08-2013 12:48 PM

Thanks for the tips. I think most of the tenons were snug “hand tight” joints. I had three that were very tight and I think these were the culprits that gave me trouble.

Smitty: yes adjusting tenons after cutting is difficult and an easy way to screw them up.

BJ

View Roger's profile

Roger

14859 posts in 1494 days


#9 posted 10-10-2013 12:34 PM

Friction fit. (a little persuasion don’t hurt) You gotta remember, glue will be added, so, you don’t want them too tight to start. You should always, always, do a dry-fit of everything…..i.m.o.

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View suni123's profile

suni123

1 post in 379 days


#10 posted 10-10-2013 12:47 PM

Thanks for the tips. I think most of the tenons were snug “hand tight” joints. I had three that were very tight and I think these were the culprits that gave me trouble.

-- ileatherwear [url=http://www.ileatherwear.com]www.ileatherwear.com [/url]

View BJODay's profile

BJODay

393 posts in 633 days


#11 posted 10-15-2013 01:38 AM

Larealus819,

I cut one a little too narrow. I used your trick and glued on a shaving from a block plane. It worked great.

Thanks for the tip.

BJ

View Woodshingle's profile

Woodshingle

8 posts in 368 days


#12 posted 10-25-2013 11:07 PM

No one mentioned that the sides of the mortise and the tenon need to be smooth all around. If not, the joint won’t last no matter how tight it is.

View Jerry's profile

Jerry

588 posts in 338 days


#13 posted 12-06-2013 10:33 PM

Have you considered drawboring the joints?

-- I have always wished that my computer would be as easy to use as my telephone. My wish has come true. I no longer know how to use my telephone.

View BJODay's profile

BJODay

393 posts in 633 days


#14 posted 12-07-2013 05:44 PM

Jerry,

Not on this project. That is something I would like to try in the future.

BJ

View BinghamtonEd's profile

BinghamtonEd

1436 posts in 1059 days


#15 posted 12-07-2013 05:57 PM

I use the same philosophy as rockindavan. I try to make mine so I can get them together without a hammer or clamps, and they stay together if I pick it up. The clamps pull everything tight and square while the glue dries, and can close up small gaps (1/32 or so).

-- - The mightiest oak in the forest is just a little nut that held its ground.

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