Loose Mortise and Tenon - How Loose

[tim walker]

Am making some doors for a wine cabinet and they will be rail and stile with glass inserts. I started out the old hand method (mortise chisel) but after a few expensive lessons decided to go the way of the router. Damn cherry wood is just to expensive to bust.

Anyway, have made mortises of 3/8" wide x 2" x 11/2" deep. How tight should the tenons be? Sould I be able to put them in by hand and pull them out or should I have to tamp in with a mallet. Whatf I can't get them out.

Thanks.

Tim in Houston

[Steve Clardy]

I always in-out by hand. No wobble. Need some clearance for glue.

[Rodney ORourke]

Steve is absolutely right - the mortises get significantly tighter with the glue so a firm, but not hard pressure to insert the tenon is best for a good joint.

[Mark Singer]

I make a couple of shallow groves on the tenon sides to allow the glue to escape...I cut the tenons tight and sand them to fit. Once you have a fit number them and number each side of the joint the same...now you know which fit where and you are not guess during glue up. There is always a slight difference from one to another.

[Mark Pruitt]

I'm relatively inexperienced with M&T joinery, but isn't the "preferred" method to cut the tenons first and then cut the mortises to accept the tenons? Or do I have this bass-akwards?:confused: Seems that I read this in several places years ago but can't remember where.

BTW, I'm about to become more experienced with M&T joinery, as I just ordered a Delta 14-651 Mortiser. Should be en route today!

[Steve Clardy]

Not sure about the preferred.
I cut the mortise first.

[Cliff Rohrabacher]

The term "Loose" does not refer to the fit.
It refers to the fact that the tenon is not an integral part of either piece of lumber being joined.
That is it.
The fit should be such that there is plenty of firm contact while not squeezing the glue out. It should also not be so tight that it splits wood around the mortice slot.

A nice force fit by hand is great. A force fit by hammer is not good. If you gotta hammer it in (whether you use the heel of your hand or a real hammer) it's probably too tight. If the tenon is to be inserted in slender mortises (3/8' or so) which are installed in larger heavy lumber such as 2' or thicker hard maple you might want a really snug fit but squeeze out is still a big issue.

[Kirk Poore]

...I'm relatively inexperienced with M&T joinery, but isn't the "preferred" method to cut the tenons first and then cut the mortises to accept the tenons? Or do I have this bass-akwards?:confused: ...

I cut the mortise first, sizing it with the available tool (mortising chisel or hollow chisel/bit set). Tenons are a lot easier to shave down for the right fit either on the tablesaw or with a shoulder plane.

Kirk Poore
O'Fallon IL

[Cliff Rohrabacher]

isn't the "preferred" method to cut the tenons first and then cut the mortises to accept the tenons?

I have gone entirely over to the dark side since I built a slot mortiser. I like it here on the dark side. Unless you have a 3HP slot mortiser with cast iron dovetail ways you don't know the power of the dark side. I'll say this about which you do first:

Whether you cut the slot or the tenon first is, I think, a matter of two factors. First is whether your mortising machine is ferociously precise. If you can cut the same size slot over, and over, and over, and over, and over, and over (you get the idea) with absolute precision then you can do either the mortise or the tenon first. However, If the mortiser is a little sloppy you are stuck with that as the controlling element in the equasion and you do the slots first.
The second factor is preference. I like to have the tenon stock all ready to go.

Really the difference in precision will, I suspect, lie in how heavy the equipment is built. Hobby tools won't lend themselves to much precision but will get the job done if run with care. That said, even the heaviest of slot mortisers has one inherrent failing that no amount of engineering or metal can get them around. The cutter deflects. There is only one way to control cutter deflection and that's operator control. Conversely a square chisel won't exhibit a tendency to drift off to one side as does the slot cutter because it has no "climb" or "conventional" cut mode. Ya gotta dull the chisel on one side to get it to favor one direction over another or ya gotta hit a knot or something like that.

I prefer slot mortisers though.

[John Gregory]

Not sure about the preferred.
I cut the mortise first.

I think mortise first is the right way. If you are using a mortiser with hollow chisels, the width of the mortise is determined by the hollow chisel. The same thing with a router bit. But you can adjust the tendon to fit properly with sand paper or a sharp chisel.

[Alan Tolchinsky]

I think it's a lot easier to fit the tenon to the slot since you can plane/sand the tennons to fit perfectly. Mark's suggestion of numbering the tenons so you can match the correct mortise is a great one.