Archive for February, 2012

Chair Repair Part 2

February 25, 2012

The most visible damage to the chair was actually the easiest to fix.  The broken off seat clamped up nicely.  I got a nice line of glue squeeze out with very little clamp pressure.  This  tells me there is good wood to wood contact in the joint (the excess glue is wiped off before it dries).

The tenon going into the broken off arm rail was epoxied back into place . . .

. . . and reinforced with a dowel inserted from underneath where it will not be seen unless the chair is turned over.  I try not to depend on epoxy alone.

I don’t like to depend on glue alone either, so I cut out dovetailed “butterflies” to reinforce the glue joint in the seat.  The butterflies will be inlaid across the joint on the underside of the seat.

The butterfly is traced with a knife and the material between the knife lines evacuated in order to receive the butterfly.  In the picture below I am drilling out most of the waste; the rest of the material will be removed with a chisel.

Chisel work.

The butterfly is glued and hammered into place and trimmed flush a with a block plane.   The blue rag is taped into place around the seat leg to prevent damage if I bump into it with the block plane.

You can see the outline of the butterfly below.  If you have room to get a trim router in to remove the waste, it is much faster then the drill.  Here I’m about to use a Colt with an upcut spiral bit to remove the waste between my knife lines.

I free hand route up almost up to the lines . . .

. . . and place a chisel directly in the knife line to finish removing the material.  Both butterflies you see below span the glue joint and penetrate into the seat about 5/8’s of an inch.


Chair Repair Part 1

February 25, 2012

Repair work can rewarding and a nice change from building furniture.  The following is how I repaired a client’s chair that had been broken during a move.

Some of the damage to the chair is apparent from the picture below.

The first step is to test all the joints and find out which ones are loose.  I marked the loose joints with blue painters tape.

Loose rungs are best fixed by removing the entire rung.  This allows you to scrape the old glue off .  If you are lucky the old glue is hide glue.  If the chair is old and remnants of the glue dissolve with water, chance are you dealing with hide glue.  This chair was not built with hide glue, which means new glue will not stick to the old dried glue.  The old dried glue must be scraped off of the tenon to expose fresh wood so the new glue has something to adhere to.  Of course, this scraping process removes some material so it loosens the joint.  In my case most of the joints in the leg stretchers were  loose enough that a blind wedge was required to fill the gaps.

To make a blind wedge cut a kerf in the end of the tenon  . . .

and insert a wedge.  The depth of the tenon’s mortise must be considered when making the wedge.  The wedge must be long enough and angled enough to spread the tenon into the mortise, but not so long that the tenon spreads too much (or the wedge bottoms out in the kerf before it fully seats).

Although you can’t see them (hence the name “blind wedges”), there are wedges in both ends of the rung between the clamps.  Clamp pressure forces the wedges into the kerf.  The clamp on the top of the leg is holding the leg for alignment purposes only.

The top of the leg is glued and doweled in place.  I don’t trust glue alone so a Miller dowel was inserted (the end of the dowel was trimmed after I took the picture below).

A chunk off the end of the broken arm rail was barely hanging on, I completely removed the chunk with hand pressure.

I glued the chunk back in place and pinned it with dowels for reinforcement (I forgot take pictures when drilled and inserted the dowels).  I like to make my own dowels using a Lie-Nielsen dowel plate.

After the chunk was glued back in place a inlay strip was needed to fill the gap left by some missing splinters.  The inlay strip will also help hold the chunk in place.  I placed a strip of cherry over the gap and traced it with a knife.

I evacuated material inside my knife lines using a chisel to create a square recess for the inlay strip.

Here is the strip after it was glued in place.

I trimmed the excess with a chisel.