Laminating an Elliptical Curved Apron

Making curved aprons, we saw strips on the tablesaw, 5/32” thick by 3” high.  We true the thickness and smooth the surface of these strips on the widebelt sander, finishing at 1/8” thick.  We bolted the form  (described in the previous post) to a 3/4” plywood backer and glued seven  of these walnut strips to it.

We unbolt the form from the backer, wash the glue, and leave it overnight.  Next morning, it was pretty in the early morning, door light.

We have found that 1/8” strips glued this way, in the curves we are likely to use, do not spring back much when unclamped.  In the photo below, the apron is against the form on the side out of the frame.  Total springback was less than 1/2”.  The apron can be pushed back true with not much more than a breath.

Making an Elliptical Laminating Form for a Table Apron

We are building a pedestal dining table.  The top is a mathematically true ellipse with a correspondingly curved apron.   The lengths of the major and minor axes of the ellipse describing the tabletop are 68” and 50.”

To build the curved apron, we needed a laminating form.  To build the form, we needed an elliptical pattern that is smaller than the tabletop by the overhang and the thickness of the apron.  Because we are laminating half the apron at a time and will be joining the halves, we needed a pattern for half the shape.

To draw an ellipse, I plot points, a method described in basic drafting texts and on several websites.  On ¼” plywood, I drew two concentric semi-circles:  one with a diameter of the length of the major axis of the top less the overhang of the top and the thickness of the apron and one with a diameter of the length of the minor axis identically reduced.  To draw large circles in the shop, I make a trammel, a stick with a hole for a pencil and holes for a nail.

From the center of the drawn circles, I drew a number of radii through the two circles.  From the points where any given radius crosses the circles, lines drawn perpendicular to the associated axis will cross on the ellipse.

I drew the ellipse by connecting the points with a smooth curve.

We cut outside this drawn line and edge-sanded down to it.  Then I cut an equidistant curve with a router and fence to make a pattern for the laminating form.

I fit scraps of plywood in random butt joints, sawed them oversize, and glued and nailed them into four layers, making sure the rough construction was larger than the pattern.

Using the pattern as a guide and flush trim bit  (bearing on top) in the router, I cut half the stack down to the pattern.  Then I flipped the stack over and routed the other half true with another flush trim bit  (bearing on bottom).  We had the form.

Designing a Custom Dining Table with an Elliptical Top

Prospective patrons wanted an elliptical tabletop on a pedestal to seat six.  It took several exchanges of drawings and comments to find the size.  A mathematically true ellipse is a very pleasing shape, but the useable space on and under is less than the length and width at first seem to provide.

The first size we investigated was 48”x60”.

48”x60” seemed too small for six chairs and diners.  We increased the dimensions as much as we could given the space in the room, and after perusing the drawings below, went with 50”x68.”

Charactermaking

Wiley Mae Weeks helped her grandfather replace the lights on the lumber trailer.

Fairing Arms to Back legs

“To fair” means to make a line or surface true to a curve–removing flat places, anomalies, and offsets.  In boat and aircraft building a well-faired surface has less resistance to water or air than a carelessly produced one.  In furnituremaking, a well-faired curve has less resistance to the hand or eye.  We often fair two intersecting parts so that one flows out of or into another.  Our rocking chair arms appear to grow from the back legs like a branch from a tree.

As a limb is integral to a trunk, the arms are deeply anchored into the legs.  In the photo to the left below, you can see the mortises in a chair’s back legs and the tenons on the arms.  On the right and below, Aaron is fitting the joints so that the arms stay in place for step one of the fairing.

At the edge sander, we fair the top surface of this intersection.

At this point in the making, the back legs and arms have previously been sculpted to their shape and contour, but we have stayed away from the intersection to be faired.  The photos below show the top of this joint not faired, being faired, and faired.

A blog post of August 8, 2011, shows Austin working the shoulders of this joint as a later step.

Modifying the Crosscut Saw

We have a Powermatic Model 66 tablesaw for ripping, and a Delta Unisaw for crosscutting.  Both take 10” blades.  There are times when we wish the crosscut could be ½” deeper.  In the photos, I am modifying the Unisaw to accept an 11” blade that we will have custom made.

A Frog on a Chair Leg

In response to a request, I replied, “Yes, we can carve a frog on a rocking chair leg.”