mortise and tenon and glue

[Jack01]

I am cutting mortise and tenon for the workbench.
Do I make the mortise exact size of tenon to make a snug fit or slightly larger to accommodate glue?

[Admiral]

Cut the mortise, then the tenon a bit proud, and trim the tenon to fit snugly such that you don't have to force it, but such that it does not fall out. That's been my practice.

[Gary G™]

I like them to whoosh air out during the dry fit.

[Handplanesandmore]

Snug fit as others have said. Do not leave any room on the walls for the purpose of accommodating glue as you want the strongest joint. The tenon is usually cut slightly shorter than the mortise is deep, allowing any excess glue to escape into, if needed.

Simon

[jteneyck]

The only exception to what was recommended above is if you use epoxy.  Epoxy doesn't like to be starved so I make the tenons just a little looser than when using yellow glue.  Not sloppy, but so they go together with only low force and no whacking.  If you forced me to put a number on it, I'd guess that the tenon is 0.005" narrower than the mortise with epoxy, half of that when using yellow glue.  

John

[rwe2156]

If you make it too tight, you won't get it together because of hydraulic pressure.

So you have to have some room for the glue to distribute.

Chamfer the edges of the tenon helps a lot.

[retrdwoodwkr]

The wood will swell slightly with many glues.  Don't linger with a tight joint.

[Steve Altman]

I am cutting mortise and tenon for the workbench.
Do I make the mortise exact size of tenon to make a snug fit or slightly larger to accommodate glue?

Not with your hat, not with your hammer...

[mound]

I am cutting mortise and tenon for the workbench.
Do I make the mortise exact size of tenon to make a snug fit or slightly larger to accommodate glue?

Nice and flush, friction/piston fit almost.

It was mentioned that "too tight" and you won't able to get it together with glue. You can get around this by pre-compressing the tenons (hit the faces with a hammer on an anvil, etc), then apply glue and put the joint together.. The tenon will expand back out and be super tight.

[fredhargis]

I'm just throwing this out: according to Leigh (in their FMT manual) the best clearance is about .005" (they didn't get into epoxy versus PVA, but I'd bet they refer to PVA joints). That said, I wouldn't get the feeler gauge out to check every joint.