How do you prevent mortise "blow-out" near ends of workpiece?

[Jon Toebbe]

In an interesting example of the classic chicken and egg problem, I've decided to build a sturdy bench for the lathe I've inherited from my grandfather. I'd like to turn tools handles for, oh say refurbished mortise chisels, and am building the bench using drawbored M&T joinery.

Unfortunately, each of my "mortises" at the tops of the legs have turned into the female half of a pretty ragged looking bridle joint as soon as I try levering out waste near the ends. :mad: Apart from leaving the legs long and cutting them to length later (that ship has sailed), is there any clever trick for preventing the tops of my leg mortises from blowing out?

Oh, and as an aside that's probably obvious to more the more experienced among us, Marples bevel-edge chisels are not the right tool for this job. :rolleyes:

Thanks,
Jon

[Mike K Wenzloff]

Hi Jon,

Use a brace and drill out the end...or even drill out the entire mortise.

The trivet below I recently made I did that way. Not much room at the end, and I had just enough of the board I used to cut the pieces to length. So I also had little option.

http://wenzloffandsons.com/temp/ot/trivet_0005.jpg

Take care, Mike

[Steve Wargo]

Mike has some good points. The other option is to take to possibility of the blow out completely out of the equation. Use a haunched mortise and tenon. This will give you much more meat at the end of the mortise.

[Jon Toebbe]

Use a brace and drill out the end...or even drill out the entire mortise.

Now that is a very sensible solution to the problem... why didn't I think of that? :o I'm not a huge fan of the "drill and pare" method of cutting mortises, largely because I don't have a drill press or a steady enough hand to free-hand several overlapping holes. One clean hole -- I could probably swing that with sufficient care.


The other option is to take to possibility of the blow out completely out of the equation. Use a haunched mortise and tenon.

Yeah, for my first two leg mortises that decision was made for me... :rolleyes: I'm building the legs out of 4x4 douglas fir, sawed/planed down to 3x3. Therefore, one face has flatsawn grain and is a bit sturdier. The other, however is quartersawn grain and splits at the top of the leg is you look at it funny.

In any event, thanks for the quick replies. I think I'll try Mike's idea on the joints still to be cut, and Steve's on the blowouts I've already got.

[Larry Rose]

Try leaving the stile long and saw to size after assembly. This takes the stress onthe stile out of the equation.

[David Weaver]

This might not go that well in the neander forum, but the easiest thing to do is put them on a multi router and just pare out the corners.

Not a method that the luddites would approve of, but the results are very good. If you don't like drilling the whole thing, just drill the ends so you have a reference point on the other side of the piece of wood - then you can pre-cut a little from the other side so that any tearout would be in the wall of the mortise (i.e., you wouldn't really get any). Using a backer board would just be easier, though.

[Mike K Wenzloff]

This might not go that well in the neander forum, but the easiest thing to do is put them on a multi router and just pare out the corners.

Not a method that the luddites would approve of, but the results are very good. If you don't like drilling the whole thing, just drill the ends so you have a reference point on the other side of the piece of wood - then you can pre-cut a little from the other side so that any tearout would be in the wall of the mortise (i.e., you wouldn't really get any). Using a backer board would just be easier, though.
Nah. It goes over about as well as suggesting in the general woodworking forum to use a mortise chisel as a solution...Had the question been asked up there, I may well have said to run out and spend a few grand on a multi-router. Or to spend less for a WoodRat. Or build one's own horizontal router/mortiser.

But really, the easiest thing is to use what one has or wants to use. Not a concept power tool junkies would approve of. But the personal benefits are excellent.

Take care, Mike

[David Weaver]

I would be drilling them out if I didn't know someone who had a multi-router. I'm not spending $2650 myself either - for the joy of being able to cut weird miters with a router, and cut mortises, tenons, and finger joints very easily.

At my skill level, chopping them out entirely by hand isn't an option yet if I don't want to have to apologize for the workpieces, but I'm working on it!

[Mike K Wenzloff]

No worries, David.

I know a shop locally that has 4 multi-routers and is buying another. They work great.

Thing about chopping mortises is simply doing them. And using good mortise chisels. Tenons do need to fit the mortises, but that's it. They don't need to be perfect looking.

One of the barriers to getting better--or even doing--hand work for many people is bringing the seeming perfection of using powertools to it. I don't mean that as an excuse for sloppiness or poor work, but rather to say there are parts of the work which do not need to achieve that level or apparent perfection in order to build something soundly.

Take care, Mike

[Jon Toebbe]

At my skill level, chopping them out entirely by hand isn't an option yet if I don't want to have to apologize for the workpieces, but I'm working on it!
I'm as n00b as they come, and I don't have a proper mortise chisel yet, but I can tell you that despite my little problems with the ends blowing out

it's not as hard as it looks
it's fun to pound a lever (though don't get too carried away with a bevel-edge chisel, DAMHIKT)
tenon shoulder conceal all :)

I figure that since it's shop furniture made from cheap construction lumber, I can afford to make a few stupid blunders in the process of figuring it out. That's especially true since I can come up the stairs grumbling profanity, post something here on Sawmill Creek and have suggestions, tips, and useful ideas in literally minutes. So give 'er a go! They can't come out any worse looking than mine! :)

[Wiley Horne]

Apart from leaving the legs long and cutting them to length later (that ship has sailed), is there any clever trick for preventing the tops of my leg mortises from blowing out?
Jon

Hi Jon,

The classic solution is the one Larry gave--leave what are called 'horns' beyond the mortise, an inch or so overcut, and trim them later after the joint is assembled.

From where you are now, the drilling suggestion has already been made. Another thing you can do is provide lateral support just outside where you'll be chopping. For example, catch the board to be mortised between dogs (or in a long clamp), and place a short block between the mortise end and its dog, to support the short grain.

Wiley

[Jerry Palmer]

Mike W. said:

One of the barriers to getting better--or even doing--hand work for many people is bringing the seeming perfection of using powertools to it. I don't mean that as an excuse for sloppiness or poor work, but rather to say there are parts of the work which do not need to achieve that level or apparent perfection in order to build something soundly.

Not adding anything here except that I felt that merited repeating. :)

[Clinton Findlay]

Drill one hole and then use a coping saw to cut the mortice.... clean up with a rasp if you feel keen. An alternate way.

Edited: spelling!

[josh bjork]

If the ship has sailed, why not use all brindle joints? Pin them if you must, and be happy. They seem more appropriate for the very top joint on a leg anyway.