Monthly Archives: March 2014

So I’m cruising along on my little Byrdcliffe-inspired cabinet and I run headlong into the door, specifically the mortise and tenon joints on the door frame.  The carcase of the cabinet is all glued up, nice and square with nice night joints.

Cabinet carcase glued up

But the mortises for the door frame are giving me fits.  I’ve made  a handful of mortise and tenon joints – a small enough number that I can probably count them on my fingers – over the past two years.  Generally I’ve used a router or drill to clear the waste and squared things up with a chisel.  On a few I’ve chopped them directly, which felt pretty good.  There is a joint on the Blacker House sconces that makes a L-bracket to hold the sconce body, I chopped a pair of mortises for that joint that came out pretty nice.

Dual through mortise and tenon on the Blacker sconces

I know from experience that if the mortises on this door are just right the door won’t be right either.  The mortises need to fit the tenons nice and snugly so there is a reliable glue surface, and they need to be exactly true or the door don’t lay flat on the bench.  Ask me how I know that, go ahead…

So yesterday I ended up chopping bunches of mortises for practice.  It wasn’t much fun, kind of frustrating because I don’t seem to be progressing past a point.

My initial problem was glowing out the end, but I can avoid that by making the stiles over-long and then trimming them to length after the door is assembled.

End blowout, this is from the chisel bevel digging in

More end blowout, this is the more typical problem just from the pressure splitting out the wood

I tried pre-drilling the mortise, but on this particular mortise that just gave me a sloppy, wallowed-out slot.  The drill bit wanders a little, and truthfully it didn’t really seem any faster to me.

So I practiced chopping mortises with both a regular 1/4″ chisel and an English-style mortise chisel.  I think there is something wrong with the geometry of the mortise chisel as it tends to stick in the mortise.  I’ll have to check it with some calipers, but I think it’s wider behind the cutting edge.  It’s a lot harder to keep it aligned too, the shaft isn’t as true and my LN chisel.  I suspect that is a factor in my difficulty in getting the mortises truly plumb.

Here is what I’ve found so far.  Having the workpiece (and mortise) oriented so it is straight in front of me make it loads easier to keep the chisel plumb and have the mortise end up mostly straight.  But none of my mortises so far have been straight enough.  I have a piece of scrap that I test fit in each, and it’s never quite right.  Generally it leans away from the rabbeted shoulder slightly, which isn’t going to work.  I can pare the mortise to get it to stand straight, but then it’s too loose.

The other thing I’ve found is that it’s relatively easy to get a 3/4″ deep mortise, but getting to a full inch across the whole mortise take a lot more work.  I don’t know if that’s technique or what.  I’ve been using the “Central V” approach, I’ll have to experiment with other approaches.  In fact, as I write this I’m remembering a blog post by Chris Schwartz that talked about his struggles with mortising, and I’m already feeling better.  In his article, he mentions another site that has a number of great articles on hand mortising, I’m going to read all of those articles today, and do some more practicing tonight.

Practice hasn’t yet made perfect, it’s only made scraps and frustration

The plans for this cabinet from Chris Schwarz’ original article had a fairly simple door.  The rails and stiles had a 1/4″ wide by 1/2″ deep groove down the middle of the inside faces.  The rails had a corresponding 1/4″ thick by 1/2″ long stub tenon.  That would be fairly easy to produce on the table saw, but I don’t think it would work well for my variation of the cabinet.

Here are the problems.

First, I’m not making a frame-and-panel door.  I’m doing a door with a stained glass insert, so I need a stopped rabbet that opens to the back to insert the glass into.  Second, the glass will be heavier than the carved panel and need a little more support, so I’d like a little stronger joinery.  It’s a lot of work to make the stained glass panel, I don’t want it to get damaged.

So my updated design uses mortise and tenon joinery.  To pull off the stopped rabbet the shoulders are staggered.  This is a fairly standard approach, I just needed to figure out the dimensions to make it work with my stock thickness and width.

I started with a CAD mockup of the door.  The overall dimensions are approximate, but the thickness and width of  of the stock are spot on.  The design for the glass is stretched to fit, I’ll have to lay that out more carefully before I cut any glass to make it.

CAD Mockup of the Door

In the exploded views you can see how the outside shoulders of the tenons are set back further — by the width of the rabbet.  I have the mortises at 1″ deep, which seems plenty strong.  But I’m not sure how to make the mortises, I don’t have a lot of experience making mortises.

Part of my consternation is that I’ve been saving my pennies (literally) for a big hollow chisel mortiser that I could use to make doors and gates — and I’m still a few pennies short of a mortiser (there is a joke in there somewhere).  I could do it with a router and a template, but the rabbet causes problems in designing the fixture which then has to sit on top of it.  By time I have the thickness of the jig (accounting for the guide bushing) plus the depth of the rabbet I don’t have enough bit length left to make a deep enough mortise.

Since routing won’t work, I could drill a series of holes, and then clean that up with a chisel.  I tried that and wasn’t happy with the results.  The drill bit wanders (even using a drill press and a fence).  It doesn’t really seem like it’s any savings over just chopping with a chisel in the first place.

I did several practice mortises with a chisel.  I can get a reasonable mortise — in fact, a pretty nice mortise, as the rabbet helps keep things on track.  But I made the mistake of cutting the stiles to the correct length instead of leaving “ears” on them.  On every attempt at chopping a mortise I split the end out.  Not good.

So I have to make more stiles now, and this time leave them long.

Exploded View

Dimensions for the mortises, rabbets and tenons