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How tight should a joint be?

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Forum topic by Joel_B posted 12-13-2014 06:30 PM 1088 views 0 times favorited 9 replies Add to Favorites Watch
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Joel_B

322 posts in 1100 days


12-13-2014 06:30 PM

I am making joints using half laps surrounding a 2X3 DF.
The joint was too tight so I made some adjustments and now it is slightly loose.
Will the glue make up for the looseness? How loose can it be before it becomes a problem?
BTW I did these joints in three steps, First I made multiple vertical cuts on the TS.
Then removed most of the waste using a chisel and mallet, then cut to final depth on my router table.
I have done this way on other projects too except I used a miter saw and set the depth stop but the TS is much better.
Its a lot of work and time consuming so I think I should get some Dado blades.
I once asked my brother in law who is a carpenter if he had a Dado blade I could borrow and he told me they are dangerous and basically would not loan it to me which I don’t have a problem with. But if used correctly are they any more dangerous than other shop equipment?

Thanks

-- Joel, Encinitas, CA


9 replies so far

View Fred Hargis's profile (online now)

Fred Hargis

4546 posts in 2212 days


#1 posted 12-13-2014 08:25 PM

The Leigh jig folks say that .005” is about the right fit for an M&T joint, which is what you made with your 1/2 laps. But generally speaking, glue (except epoxy) is not a very good gap filler. Some folks think that the dry powder glues (the UF formula “plastic resin” glues) will fill gaps, and they are probably better than the PVA, but still not good. But just looking at that joint, I’d say you are good to go and don’t worry about it too much. As for the dado set comments, well, he’s your BIL so I’ll tone this down: the dado set is no more dangerous than any other saw blade on your table saw…they can all do serious damage when misused. But with the same cautions, they are fine for use. I’d say your BIL had a (well, never mind).

-- Our village hasn't lost it's idiot, he was elected to congress.

View Mark Kornell's profile

Mark Kornell

1168 posts in 2250 days


#2 posted 12-13-2014 10:28 PM

Joel,

A good test for tightness is a piece of paper. If you can fit one or two slips in the joint, it is OK. At three pieces, it is starting to get a little loose.

-- Mark Kornell, Kornell Wood Design

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groland

174 posts in 3131 days


#3 posted 12-13-2014 10:36 PM

When I got a tenon a little too small for the mortise, I just glued some veneer onto the tenon cheeks and re-fitted the joint. This worked well for me.

George

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Rick Dennington

5479 posts in 2913 days


#4 posted 12-13-2014 10:50 PM

Not too loose…..Not too tight…..Just right will do the trick…!!!!!!!!!!

-- My grandpa used to say: "Y'all come back when you can....come after dinner, and leave before supper.."

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AandCstyle

2799 posts in 1976 days


#5 posted 12-14-2014 12:31 AM

If the tenon falls out of the mortise, it is too loose. If you need a mallet to drive the tenon into the mortise it is too tight. If it goes together with hand pressure it is just right.

-- Art

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TheWoodenOyster

1294 posts in 1654 days


#6 posted 12-14-2014 04:16 PM

I shudder to think about some of my joints over the years. I wish I could say that all of my joints were slip fits, but the truth is that they aren’t. None of my joints have ever fallen apart. I think the guys above are correct. A hand pressure slip together fit is perfect. Hard to attain though. That is one of the reasons why tools like handplanes are priceless. No other tool sneaks up on fits like a plane does. That said, get it as close as you can and if you need to do things like add a veneer strip, there is no shame in that. I bet 99% of projects out there, even from the pros, have little “fixes” throughout. Nobody is perfect. I believe it is Saint Sam Maloof that personally said he only ever made one perfect chair. I may have made that up, but it is probably true anyway…

-- The Wood Is Your Oyster

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jmartel

7243 posts in 1869 days


#7 posted 12-14-2014 06:54 PM



If the tenon falls out of the mortise, it is too loose. If you need a mallet to drive the tenon into the mortise it is too tight. If it goes together with hand pressure it is just right.

- AandCstyle

This. And you should be able to hold the joint up in the air without one of the parts falling off.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

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skatefriday

394 posts in 1202 days


#8 posted 12-14-2014 08:25 PM


If the tenon falls out of the mortise, it is too loose. If you need a mallet to drive the tenon into the mortise it is too tight. If it goes together with hand pressure it is just right.

- AandCstyle

This. And you should be able to hold the joint up in the air without one of the parts falling off.

- jmartel

And therein lies the skill. Anyone can run a board through a saw. Getting
parts to fit like that is not easy.

View AandCstyle's profile

AandCstyle

2799 posts in 1976 days


#9 posted 12-15-2014 01:00 AM



And therein lies the skill. Anyone can run a board through a saw. Getting
parts to fit like that is not easy.
- skatefriday

That is why God created shoulder planes.

-- Art

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