Repair Broken Arms on an Heirloom Chinese Chippendale Corner Chair

This heirloom chair was purchased over 50 years at an antique shop. During that time the end of the arm were broken off when someone used the arm to pulled themselves up from the chair. A repair was tried by gluing the arm back on, but due to a design and material flaw the repair did not last and the other arm broke also.

Material used in the repair:

Wood filler

Epoxy Resin and Hardener

Walnut Sawdust

Stain, Dark Walnut, Mahogany, and Hickory.

Finish (boiled linseed oil 40%, spar varnish 40%, and mineral spirits 20%)

Wooden Dowel Rod

Quick Setting Epoxy

Filler Epoxy (JB Weld)

Wood Glue

Masking Tape

Tools:

Clamps

Portable Drill Guide (customized)

Drill Bits

Level

Shims (popsicle sticks)

Sand Paper

When the chair arrived there was the chair and arm ends. The right arm had been repaired before and showed wood deterioration . Because of the poor condition of the right arm an additional support is needed so that the repair will support everyday use. In addition to glue and epoxy it was decided to reinforce the joint with a wooden dowel. The next challenge was to drill the dowel holes so the arm and broken piece would align as before the damage.

Problem: How to drill matching holes in the arm and the broken piece. A portable drill press can drill matching holes but it it has to register off of a flat, parallel, and perpendicular surface. These arms are hand carved with compound radii, the bottom of the arm is flat, but the arm support from the seat is located right where the break occurred.

A new registration fence was fabricated from a piece of clear plastic off a old computer tower. An aluminum plate was machined to create a plate at a right angle to the base plate. Then the clear plastic fence was attached to the right angle plate. A long drill bit was placed in the chuck and then a line was scribed from the base to the end of the fence. With these two adjustments (distance from the center of the drill bit and travel of the drill bit) matching holes can be drilled.

The broken piece was aligned to the arm and then a piece of masking tape was placed approximately in the center of the arm continuing to the broken piece. The tape was cut at the break. Now that a line is established the portable drill press was setup on the arm. The fence is setup to the center of the arm up and down and the scribe line on the fence is adjusted to align with the left side of the tape where it meeting the wooden arm. The fence is clamped in place. A level is placed on the fence and it is shimmed with popsicle sticks till level. The hole is drilled in the arm. Then the portable drill press is clamped in the bench vise. The broken piece is clamped to the portable drill press, with the fence aligned to the edge of the tape, the popsicle sticks were transferred (remember to transpose right to left) Then drill the hole. The left arm had a good alignment and fit. The right arm did not align, The hole in the broken piece was enlarged a 1/64 inch at a time until the align was obtained. Then the end of the dowel was was glued with 5 minute epoxy and inserted into broken piece, aligned, and left to cure. The piece was removes and a filler type epoxy (JB Weld) was placed around the dowel to fill in the oversized hole.

Wood glue is applied to the arm, the piece and clamped into alignment. The left arm was a good fit. The right arm had damage from the previous repair and parts were missing.

Epoxy was used to fill the large voids. Walnut sawdust (did not have mahogany) was added to the clear epoxy to color it to match the existing finish. Masking tape was placed to form a container to hold the epoxy in place. After the large area was filled with epoxy and cured, wood filler was used to fill the smaller voids. The filler was sanded to match the contours.

The repair was stained with walnut, mahogany, and hickory stains to match the existing finish. A oil varnish finish was applied to the repaired area. With the large repair area of the right arm it was not possible to hide the repair, so a similar area was created on the left arm making it look like the repair was part of the chair design.