Desk Chair Repair

FIX IT OR CHUCK IT

“Desk Chair Repair or Replace”

The other day as I sat down into my desk chair, it seemed that just as I got firmly seated, the chair made some sort of adjustment.  As I leaned back in the chair, I realized that the back slid downward about an inch, and the arms had shifted also.  So I got out of my chair and inspected the sides of the seat.  The arm was attached to the side of the seat by two bolts, with two dowel pins spaced evenly between.  The holes for the bolts and the dowel pins were all in alignment and after years of resting on the arm and leaning back, the side board of the seat had given up the ghost.  I could also feel the split as I felt the fabric that covered the seat on the side.  The chair is one of those standard; 5 rollers, blue cloth covers seat and back, and the bolts going through the arms, into the sides and the back, are the joining factor to the assembly of the chair.

My first option was to go looking for a replacement.  Probably $150.00 to $300.00 is the range for a replacement.  My next thought was what to I do with the old one.  Do I just put in the big trash container so the city will haul it away?  Then I thought that I was going to have to dismantle it anyway, so lets see if I can get it apart all the way to the problem and maybe fix the chair to use again. 

So I started with a hex wrench for the bolts going through the arms and into the seat and the back.  There were two in the back and two in the seat on both sides.  Next I turned the remaining seat up side down and found 4 bolts holding the seat bottom tightly to the metal plate on top of the pedestal.  After removing those bolts, I now hold the seat by itself.  With the use of an awl and pliers I can remove the many staples around the perimeter that secure a black cover to the bottom side.  Once it is removed, approximately the same number of staples are in the upholstering fabric attaching it to the under side of the seat.  Before I removed that upholstery, I realized there were some more staples where the rubber foam was curled under to make the front lip rounded.  They also had to be removed.  At this point I could slide my fingers between the cloth covering, with the rubber foam also, and the wood frame to be sure the two are clear of each other.  I was very careful to kind of roll the cloth back over itself as if I would turn it inside out, but just far enough to allow me to slip the wood frame gently out from the rubber foam which encased the frame.  This allowed the rubber foam to remain in the cloth which will better keep the cloth in shape and the foam contained. 

The frame came out in about 5 pieces since it was broken.  The two sides were both split into two pieces and the front lip piece fell loose just as the sides fell apart. 

Now I am down to the wood structure and the webbing.

 I like to use my camera to record the procedure as I go, then I can always check back if I have any questions during reassembly.  I used large safety pins and put one at each intersection of the seat webbing.  Then I found my permanent marker to start making my map of what goes where; marking the webbing and each piece of wood : front, middle, back, top, bottom, right, left, side, and even braces are coded.  Arrows and anything else are used to direct me as to how it goes back together.

Before I take the frame apart, I mark each piece, the relative direction, and note the ends that join together.

 

Then as I get to other parts like the corner braces, I add more markings.  I marked the front of the webbing even though it was pined.  Once the staples were all out and the webbing removed, I removed all screws holding the corner braces in place.  The glue was old and the chair had been in use for about 20 years under my 200 pounds, so most pieces came apart with just a small tap of a mallet.

Finally the two sides were ready for inspection.

The problem was just as I suspected.  The pressure of leaning back, as well as the weight placed on the arms from getting in and out of the chair, has put the stress on the points where the arms are attached.  These points happen to wind up so that the grain of the wood travels through these points and this is where the wood weakened and split.  The only solution is to re-manufacture these two pieces or throw the chair in the dump.  I chose to repair.

The first step was to make two blanks of the same dimensions as the two sides.  These sides were 4 quarter stock.  I could use a 2x4 and mill it down for the thickness, or laminate two thinner pieces.  I felt better going to Lowe’s and finding two ½ inch thick, 4 inch x 4 foot, boards of Oak.  The wood was beautiful and I felt bad about using it in this way, but I needed strength.  I took these two boards back to my shop and used polyurethane glue with about a dozen clamps to laminate two pieces to make one. 

I very carefully inspected the grain of each board so that I might find the optimal strength by trying to mate the grain in contrast to each other as much as possible.

After the glue set I ripped and cut the blanks to the dimensions of the originals, shaped the corners, and chamfered the lateral edges to match the old pieces. 

Now I must drill the holes for the dowel pins and the bolts.  Their positioning is critical to the reassembly of the chair.  First thought was to use a piece of cardboard and make a template, and then I realized I could just clamp the original with its replacement and drill through the original holes into the blank.

 The holes for the arm were positioned very low which may have added to the weakness of the structure.  To guard against this, I decided to move the holes up about 5/16”, which results in the arms and back being raised (or offset) by that amount.  This will greatly decrease the possibility of the same problem happening again.  Once clamped together, I transferred my markings from the old to the new piece.

Holes for the dowel pins were 25/64” and the holes for the “T” nuts for the bolts were 5/16”.  The depth of the dowel holes were ¾” and the bolt holes were drilled through.  Since the arms are mounted to the outside of this piece and the cross pieces of the structure are attached by dowels to the inside of this piece, I had to drill both sides.  So after I drilled the holes for the arms, I removed the clamps, and what was the outside faces of these clamped pieces is now the two faces that are against each other.  This time I matched the pieces width and length because I did not want to shift (offset) the inside assembly in the manner I did the outside assembly.

At this time it is important to use 4 dowels and dry fit each arm to its respective side board.  It will be easier to make any adjustment before the box is assembled and the cushion and staples are added.  Once that is verified, my focus turned to detail work that if not attended to now will cause major problems during assembly.  The old glue needed to be removed from all surfaces that meet as well as all dowels and dowel holes.  The slightest amount of glue remaining on a dowel may cause a gap between pieces when reassembled.  I used a 1/8” chisel for dowels and holes; my disk sander took care of all surfaces with glue residue.  Be sure to check the bottom of all holes to insure that glue is removed also.  I tapped all dowels with a mallet to insure they were seated solidly, and if they were not – I removed them with a gentle squeeze of my pliers and a very small side to side wiggle.  Next I remembered that the “T” nuts will be higher than before, so I used a ¾” Forester bit to make a recess for each nut to be flush with the surface and not prevent the end of the joining piece from making contact with the side.

I am now ready for assembly.  The front of the seat box has two pieces with the front shaped in a curve, a spacer between them, and only the larger one has dowels to mate into the side.  I arranged these 4 pieces, then glued and nailed them so I had only one front piece of the box.  I also noted that since the arms would be slightly higher then the spacer had to be milled to accommodate the bolt going beyond the “T” nut.

While that glue set, I reviewed the pieces for assembly and noted that the “T” nuts needed attention.  It must be done before the front of the box is attached to the sides.  In the original assembly the nuts were slightly damaged when pressed or hammered into the sides.

By holding the nut with a pair of channel lock pliers, I could bend and re-orientate the barbs so they were assets rather that aggravations.

Also I like to install the nut with the barbs in diagonals rather than perpendicular to the grain.  This seems to put the same tension on each barb since none are running with the grain.

I measured the length of a dowel not seated in the pieces and marked the center on the side of all dowels.  This mark will guide how far to tap the dowel into the hole.  Once the “T” nuts were in place and hammered to hold, I was ready to glue and assemble.

My Pony bar clamps are the best tool for the glue-up since the clamp has a screw clamping design and that allows me to squeeze the pieces into perfect contact.

A few pencil marks guide as to where to apply the glue on the side piece where the end of the cross members will butt.  A 1/8” dowel about 4 inches long will insure the polyurethane glue was adequately applied in the dowel holes.  A small art paint brush will best coat the joining member and dowel pins with water.

Once assembled, I rechecked the clearance for the bolts that will mount the arms on the sides and possibly extend beyond the “T” nut.

I was surprised that all dowels went into the holes, the clamps made all surfaces come in contact, and the darn thing was square by the two diagonal measures from corner to corner.

After the box had cured, I made sure that the mounting plate on the pedestal of the chair with the rollers would match the bolt holes in the bottom of the seat.   To install the corner braces, I used yellow wood glue.  The manufacturer used ¾” dry wall screws to install braces in corners.  I replaced the screws with 1 ¼” dry wall screws and I predrilled (and re-drilled) holes with a 3/32” bit as I installed the braces.

A couple of hours for that to set and I am ready to inspect the wood for sanding or hand planning.  This is necessary to prevent the wood from rubbing the rubber foam and causing it to deteriorate unnecessarily.  Ruff or sharp places will chew at the foam.

Now I am ready for the webbing.

As I took the safety pins out of the webbing, I noticed the ends of each piece showing a lack of dependability.  I used a candle and moved each end near the flame to melt the nylon and kind of weld the strands together.

Snip the excess and melt so that you now have a seam that binds.  I was very careful to insure that the pieces were kept in proper orientation and order.

I used my electric stapler to attach the ends of each piece to the front of the box.  The old staple holes were a perfect guide as to where to place each strip.

Once attached, I now had to stretch and attach the other end to the back.  For this I decided to use a couple of short pieces of wood that were burly on one side.  They were kind of like rough sewn and not planed or sanded.  These two pieces made a sandwich with each strip and my Quick Grip clamp applied the pressure.  This left a 1 inch tongue for me to position and staple.

I did not attach the last two strips to the back.  This insured I had enough room to clamp and stretch work with the strips that weave through and go from side to side.  Once all strips were attached, I used my tack hammer to insure all staples were flattened.  Next I fitted this box into the rubber foam cushion still covered with the cloth upholstering and slid my hand into places to insure that the fit was right and not binding.  The first staples are placed in the rubber foam to position and create the front lip.  As I stapled the cloth to the bottom of the box I started with one staple in the center of each side, and then front and back.  Next each corner so that the cloth is in its best position and then as I pulled gently on the cloth to snug it for a firm tension, I completed stapling one side, the other side, the back, and finally the front.  Then I tapped all staples with my hammer.  When I positioned the black slick cover that goes on the bottom of the seat, I aligned the four holes in the cloth cover with the holes in the wood for the bolts and stapled the cloth at 3 points about 1” out around each of the 4 holes.  This assures that the alignment would not move.  The perimeter of this cover staples just as I did with the seat cover.  One staple in the center of each of the four sides, then the corners, then fill in the gaps doing one side, the opposite, the back, and then the front.  Each time I positioned the cover to staple, I insured the tension was equal and smooth, and with my hammer I flattened all staples.  With the seat upside down, I now attached the pedestal.  Before attaching the arms and back, I had to locate the holes where the arms mate with the side of the seat.  Remember the holes for the arms were raised up 5/16”, so now the fabric will interfere with the dowels and the bolts.  To correct this I used a small propane torch and a 16 penny nail held in a pair of vice-grip pliers.  I found the four holes, one at a time, on each side with my awl, and then heated the nail to red hot.  By inserting the nail where the awl was and moving it around slowly and gently, the cloth melted away where the new holes are located.  The arms and back can now be mounted with no problems.

                           

My chair is now whole and sits better than ever.