Maloof Rocker - Installing the Rockers

Now that the rockers are laminated and rough fitted to the legs next is to check and see if the two rockers are balanced.  That is making sure the arc of both rockers match up.  Since the rockers are not a perfect part circle but more of a slight ellipse if the left and right legs are not in the same location on the rockers as you rock the chair will have a tendency to gradually rotate.  The process it to measure from the back of the back legs 24” down the rocker then measure how far off the floor that point is.  If both rockers match up you’re done.  In my case they were within an 1/8”, close but not close enough.  The fix is to move the leg up or down the rocker and re-measure until both sides match. 

The rockers are attached to the legs using ½” dowels similar to the ones used to attach the arms only longer.  I pulled out the square blanks I made earlier when I needed the arm dowels and headed over to the lathe.  The sequence is a little different this time because the dowels are held in place with epoxy and not regular yellow carpenters glue.  The epoxy is thicker than the yellow carpenters glue and because of that the dowels need to be little loose.  When I fitted the slats into the headrest they were fitted snug and that cause a little bit of a problem in that the excess epoxy had difficulty escaping out of the joint.  A slightly looser fit should solve that problem.  Since I am shooting for a dowel diameter of about 1/32” undersize I do not have to drive them through the die to get that exact fit.  A few thousands won’t make a difference.

Once I have the dowels in hand I can go about marking and drilling the holes in the rockers.  Marking the location of the hole in the rocker follows the same method as when I marked the location of the hole in the arm.  I start by putting my trusty dowel center finder in the hole in the front leg, set it in place on the rocker, pressed the leg down on the rocker and the center of the hole is marked.   

Because the leg is not square with the rocker I have to establish the angle that the dowel will intersect the rocker with.   That is done by sliding a snug fitting dowel into the leg putting it against the rocker and marking the angle.

Once that’s done its over to the drill press and using a clamp to hold the rocker at the correct angle drilling the mounting hole.  Notice the precision use of masking tape to set drilling depth.  Now all I have to do is cut one of the dowels to the proper length, slide it in place and I can go through the same process for the rear leg. 

This process worked well for three of the four holes.  If you remember from earlier on I had a problem when I drilled the hole in the back left leg.  For some reason the drill drifted slightly off the leg axis.  If it had just been off center that would have been easy to deal with but no such luck.  While the hole is slightly off-center the real problem is that the hole is angled about 7 degrees off square to one side.  That means for the dowel to align properly I have to match the angle of the hole in the leg when I drill the hole in the rocker.  It did take a bit of measuring and setting up a jig on the drill press but in the end it all fit together fine with the bottom of the rocker resting flat on the floor.

Now that the leg to rocker location is fixed it’s time to do the final fitting.  To do this I flip the chair over, put the rocker on with the rear dowel in place and then check the front leg to see what adjustments are needed.  With a file and 80 grit sandpaper the high spots are removed until the joint fits tight.

Using the bottom of the glue bottle as a template I laid out the rough transition curve between the secondary laminations on the rocker and the legs then used the bandsaw to rough them out.

The easy way to build the rockers would be to leave them the way they are now or rectangular.  However, I think one of the design criteria for the chair was to not have any rectangular pieces.  The rockers have a radius cut on all four corners resulting in a nearly circular rocker.  Because of the stresses introduced in the laminating of the rockers I was a little concerned with chips or even blowing out a piece of the rocker similar to the concern I had with the back of the slats.  So I went with the same method I used with the slats, “climb cutting” or cutting with the rotation of the router bit.  Only this time I clamped the rockers to the workbench and ran the router along the edge rather than using the router table and moving the pieces along the router bit.

I have to confess when doing the routing on the test chair out of habit I started the final finish pass normally and sure enough the bit caught and blew out a piece about 2” long.  Fortunately it’s on the practice piece and far enough back you would not actually rock on it.  That said I certainly paid close attention when I did the actual pieces and had no problems.

Before gluing the rockers in place I spent a little time doing some rough sanding to smooth out the transitions where the router bit cut ended.  It’s easier to clamp and swing the rockers around for sanding before they are attached to the rest of the chair.  Once that was done I could epoxy the rockers in place.

One good thing about the epoxy I am using is that I have about an hour working time although with the long working time it takes a long time to cure so I have to let it set at least overnight.  A couple of clamps provide the pressure to assure tight joints and hold each rocker in place.  Since I had a little extra epoxy I mixed in some fine cherry sanding dust and used that to fill the blowout in the practice rocker.

The next morning I pulled the clamps off, set the chair on the floor and to gave it a test run.  The chair came out really well balanced, one gentle push and it rocks for a long time.  It felt comfortable to sit in and I have to say all the work on the slats were worth it, they really support your back.

Next up – Shaping the Rocker Ends & Leg Transitions