Demilune Table, Part 4: Glue-up, Making the Top and Finishing Up

When we last left our intrepid joiner, the undercarriage had been dry-fit.  Next on the list was to make and apply the apron beading.  This was simple - I put some 1/4" thick material under the apron pieces and use a pair of dividers set at 1/8" to trace a guideline 1/8" away from the front of the apron.  Cut, smooth, round over and glue-up.  The apron pieces were a little long and the ends were trimmed flush with the shoulder of the apron pieces after gluing.

Two apron pieces having the bottom bead glued on

I rehearsed the overall glue-up 3 or 4 times.  It turned out to go fairly smoothly.  Because of the way I laid out, cut and fit the mortises and tenons, I thought there was a good chance that I'd get a leg that looked a little wonky.  But it was a lot of worrying for nothing.

Since few pieces were square to one another, I worked out a way to attach everything together that put very little stress on the joints.  If not done properly, you could end up having to bend things a lot to get the last joint to fit.

The two legs at left with a curved apron and the back were one assembly.
The two legs at right with their two curved aprons were another assembly.
The remaining m&t joints were close to parallel to each other.

Glued up using hide glue and in clamps

I was trying hard not to have to go out and buy more cherry to complete the top.  I had a piece of really nice-looking 7" wide, 6/4 material that I resawed, leaving a 7/8" thick piece and a scant 1/2" piece (after planing).  But I couldn't just edge-glue the thin piece to the thick piece.  I ended up "thickening" the 1/2" piece by face-gluing another board to it.

Used the frame saw to resaw the board.  First time in a long time using this saw.  It's a beast.

Note to self: cover the under-bench plane storage before resawing!

I used my trammel points to mark out the semi-circular top and marked a second semi-circle 1/8" in from the first to guide a subsequent round-over for the curved edge of the top.  In the pic below, you'll notice that the fixed point (center of circle) is 1/4" behind the rear edge of the top.  This was to compensate for the legs being 1/4" smaller in dimension that originally planned.  So the semi-circle was just shy of a half circle.

Marking the half circle

Cutting close to the line with a coping saw (the red blur)

Used a heavy set jack plane to get close to the lines, then spokeshave to finish

The 1/8" secondary layout lines guided a roundover (not yet done)

Buttons were used to attach the top to the undercarriage

And there she is

So far I've put three coats of shellac on the undercarriage and two on the top.  I'll put at least two more on the top, then wax it and put it into service.

I'm very happy with how it came out, but still it feels like the undercarriage is a little flimsy.  Attaching the top will make it more sturdy.  I'm planning to put it out into the sun for a while to quicken the pace of the darkening of the cherry.

Demilune Table, Part 3: Aprons and Legs

I finished the last post not knowing what direction I'd go with the curved apron.  After a lot of head scratching, I finally decided to stick with my original plan: a three-piece curved apron attached to the legs with m&t joints.

Two apron pieces and a practice leg - note how the two tenons are offset
regarding their lengths so they can both fit in the leg

The "real" front legs with curved front apron pieces fitted.
The aprons are sitting on the full-sized drawing to see how well the curve matches.

Getting the angles for the mortises was tricky.  Normally I chop mortises first, then fit the tenons to them.  But for this project, with very few parts being square to each other, I needed the angles of the mortises to match the angle of the tenons.  So I made the angled tenons first, the angle being a compromise between grain direction of the tenon and as low an angle to the mortising surface as  possible ( I wrote about this a little last week).

Having the rear face of these curved aprons being flat and square helped.  I referenced off that with a sliding bevel to lay out the 3/8" thick tenons.  I pared the rear cheek of those tenons flat and right to the gauge lines.  Then, setting that apron in place on the full-scale drawing, I marked the flat tenon face on the leg outline.  Finally, I used bevel gauges to find the angle of the tenon relative to the leg drawing and transferred that to the actual leg.  I wish I'd gotten pictures - I would have made it much more clear.

Middle front apron with front legs - upright

Undercarriage minus back rail

My shoulder lines are far from perfect.  However, the show face of each joint gets tight, and I'm happy with that.

Fitting the back apron was interesting.  I first cut one tenon.  Then, with the undercarriage upside down and set in place on the full-scale drawing, I butted that tenon's shoulder against the leg and marked the shoulder line for the tenon on the other end.

Rear apron with left tenon shoulder butted against the leg 

Marking the right shoulder line directly off the other rear leg

After fitting those tenons to the leg mortises, a first dry fit

You might notice that the rear apron has giant holes in it.  That apron came from a piece of (what I think is) mahogany from the scrap bin.  Even though it will never be seen (because that side will always face a wall), I later patched those holes.

Next I tried another experiment.  I mentioned last time that I want to apply a bead to the underside of the curved aprons.  I've seen tables where the bead is carried around the legs too, and I wanted to see what that would look like.  So I got the practice leg out again and made a 3/16" deep, 1/4" wide dado all around the leg.  I put a 1/8" radius on a piece of 1/4" thick, 5/16" wide  material and mitered four pieces to fit into the dadoes.

Practice leg with a bead skirt

Here's how it would look with an apron also having anapplied bead

Here's a Sketchup drawing showing what it might look like

A close-up of the corner

I think that would look great.  But in the end, I decided not to bead the leg.  The tiny piece on the side of the leg where it joins with the apron's bead had me concerned that I couldn't cut it accurately enough.  Maybe in a future project.

Lastly for this week: tapering the legs.  The front legs were tapered on the side and rear faces.  The rear legs were tapered on their inside and front faces.

Layout for tapers on front legs

Dry-fit with legs tapered.

All I have to do now is make and apply the apron beading, glue up the undercarriage, make the buttons (and mortises) for attaching the top, make the top (hope I have enough material on hand) and apply some finish.  It's getting there!

Demilune Table, Part 2: Experimentation

Warning: this one runs a bit long, but it's mostly pics ...

This project has been an exercise in experimentation.  For a couple different reasons, I didn't want to make a three inch wide bent lamination that would be about 36-38" along the curve.

First experiment: making the curved apron in pieces, shown here in pictures.  The plan is to make three separate curved apron pieces that will join to the legs with m&t joints.

The working drawing

On a poplar blank, drew a 10 7/8" radius

Some of the tools used to remove material and smooth the curve (rip saw not shown)

Cut and planed a 1/8" slice from a piece of cherry

Testing to see if it will bend to the 10 7/8" radius - it won't

Thinning the cherry down to 1/16"

Gluing it to the poplar curved piece

This worked well, albeit with a few small gaps

The bigger issue here is grain direction.  At the ends of this piece, the cherry is glued to end grain more than long grain.  I used PVA glue.  Time will tell if this holds.

Second experiment: mortise and tenon joint that will join the apron and leg.  In the picture below, I've placed the middle front apron in position on the drawing and you can see the outline of the leg.

The pencil lines on the poplar are parallel to the front face of the leg.  That's the direction
the tenon would be cut if a mortise was chopped perpendicular into the leg's side face.  This
does not utilize the long grain strength of the apron.

If the tenon was cut in line with the grain of the poplar, the mortise would have a very steep angle.  This is not necessarily a terrible thing, just a pain to lay out and execute properly.  I decided on a compromise and used an angle in between the two.

The compromise angle

I made a small template with the mortise layout and traced it onto the top of the leg.
Those lines helped me cut the angle.  The joint is being tested here in a scrap leg blank

There are issues with this.  But it's a compromise and this table probably won't be seeing any/much abuse - at least not while we own it.

Here's the next issue: there needs to be another mortise on the other side of that leg and there's not a lot of space to put it.  I've thought about staggering the two mortises.  The mortise on left would be full depth for its upper half and just 1/2" deep at bottom.  The mortise on the right would be just the opposite.

Layout of the left front leg mortises

Transferring the lines to a test piece

The test leg with mortises cut: on the right side, the top is full depth (about 1 1/8")
and bottom is about 5/8" deep.  The left side mortise is full depth at the bottom.

The middle apron piece with tenon cut

Left front leg (practice piece) with two apron pieces fitted in their mortises

A nice friction fit

This seems to have worked out OK, but there are a couple of problems with it.  First, small errors in layout or execution of the joints resulted in the apron not following the curve quite right - The combined curve of these two apron pieces is tighter (smaller radius, that is) than it should be.

The second problem is something that really bothers me: I'm not sure about the ultimate sturdiness of the table with this configuration.  Unlike a table with 90° joints holding the piece together, you can't really clamp this undercarriage together tightly without stressing some of the joints or pulling the whole thing out of its semi-round shape.

It got me thinking about alternate ways to make a single piece apron.  I woke up the other morning with a possible solution in my head.  I'd try to glue up several pieces and then shape them to the half round, like in the pictures below, then glue a 1/16" piece of cherry to it.

Bunch of pieces glued together

Then shaped to the half round (not yet smoothed in this pic)

However, it just seemed futile for strength reasons.  In the end, I might have to bite the bullet and make a half round form and glue-laminate a bunch of 1/16" slices of 3" wide wood together.  That's at least 12 slices of 1/16" x 3" x 36"!!  Not my idea of fun.  But hay, if I had just done this from the start, it would have been over a long time ago.

Back to the experiments.  The third experiment had to do with a decorative bead at the bottom of the aprons that is proud of the apron's surface.  The plan is to glue a piece to the underside of the apron.  I put a piece of 1/4" thick scrap under an apron piece and used a divider set at 1/8" to scribe an arc, referencing off the apron.  Then I cut to that line and smoothed a 1/8" radius along that edge.

The test piece with curve cut

1/8" radius along the front edge

There's the test piece sitting below the apron.  It's not the right length,
but it gives the idea and I think it will look good.

Enough for now.  Time to make some decisions about how to proceed.