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

Maloof Rocker - Making the Rockers & Sanding

The rockers are not cut from a solid piece but for strength are made from thin strips that are laminated together against a form.  Each rocker has 9 layers of cherry and one layer of katalox.

The rockers represent the last major pieces that have to be built.  So to start I pulled out the last piece of cherry reserved for the rockers and checked it for flat and square which, good news, it only had a minor bit of cup.  A few passes through the thickness sander took care of that.

The katalox however was in no way straight or flat.  It had a nice combination of cup, a gentle bend along the long edge with a dog-leg near the end along with a few waves thrown in plus just a tad amount of twist.  In that one board there was just about every kind of contortion you could imagine.  Fortunately I only need 2 strips 1¾” wide, just over an eighth of an inch thick and about 54” long plus a couple more 8” long.  To clean up this mess I started with a long straight edge to give me my rough long dimension of the 54”.   With a straight pencil line to start I used the bandsaw to make my first cut.  Next, I used the power hand plane clean up the bandsawn edge to give me a true straight edge.  That left me with some cup, the twist and waves.  The thickness sander took care of the cup and waves.  The twist is not great and when I laminate it up because the finished piece is thin and flexible it will get flattened.  However, because of the twist I had to cut the strips with the bandsaw rather than the table saw.  To give me a little buffer I cut them a little thick and will finish up with thickness sander.

There are a couple of ways to cut the multiple strips of cherry needed.  One is to set the rip fence at the desired width and cut away.  This works good most of the time but as the pieces needed get thinner your fingers get closer and closer to the blade.  I have a push block that will allow me to cut pieces as thin as ¼” with no problem.  However, these pieces are just .17” wide which rules out using the push block I have.  I could make a special push block but am a little leery of having a piece this thin between the blade and the rip fence with such a big fairly heavy piece on what is normally the waste side.  The cherry blank is 9” wide, almost 2” thick, 55” long and weighs about 25 pounds. 

The other way takes a little more time but works well.  Its advantage is that the thin layer is on the outside or what would normally be the waste side of the blade.  This means that it cannot get trapped between the blade and the fence.  The disadvantage is the after every cut you have to reset the fence and it can be difficult to get pieces of a consistent thickness.  The solution to getting a consistent thickness is a simple jig that sets in the miter slot.  A screw on the end is run in or out to set the piece thickness.  

To use, the rip fence is adjusted so that the main board just touches the screw head then the jig is removed and the cut is made.   The process is repeated over and over until you get the needed number of strips.  In my case that is 18 plus a couple of extras or 20. 

The pieces are rough cut at .17” but the final dimension is just over 1/8”.  The extra is 45 thousandths of an inch is so I can run the cut pieces through the thickness sander to remove the inevitable saw marks and make sure the surfaces are parallel.

I keep the layers in the same order as they are cut.  This assures that when the strips are laminated back together in the rocker form the grain will be consistent across the finished piece.  In order to be able to put them back in their original order I number and mark the end of each board and group in sets.  Red for one and green for the other.  These are the stacks with the katalox inserted where it goes.

When I glue up the 10 pieces in the form it is controlled chaos.  Because of the limited working time I have with the glue.  I only have about 10 minutes from the time I start spreading the glue to when I need to have the 21 clamps tightened down.  This means everything needs to be laid out and ready to go before I start applying the glue.  

The glue goes on first, I have about 6 square feet to cover and it needs to be applied with no missing or thin spots.  Next is to stack the layers up, quickly wipe excess glue off the joints and set the stack in the form.  Starting in the middle I work toward one end keeping the layers flush and aligned then do the other half.  Once everything is tightened down I wipe the glue squeeze-out off and let it sit overnight.  Then next morning I will pull off all the clamps, inspect the form for damage and go through the process for the other rocker.  Using one form for both rockers assures that they will be identical.

Once out of the form I mostly flatten one face on the rocker with the power hand plane checking with a square to make sure the adjacent faces are square with each other.  I will use this face as a reference for adding a secondary lamination.

Under each of the four chair legs where they are attached to the rocker is a secondary stack of 7 laminations made up of 3 cherry layers, 1 katalox and then 3 more cherry.  This will provide the material for the transition from the leg to the rocker.  To locate I set the chair on the rocker roughly where it goes and mark a line about three inches either side of the leg.

The laminations are then cut, glued in place on each of the rockers and allowed to cure overnight.  I probably could machine them after about four hours in the clamps but since they are bent and under some stress I wanted to give them overnight to cure.

Once this secondary set of laminations has cured I have two choices in milling them to the correct width, either the planer or the thickness sander.  I chose the thickness sander because there are lots of grain directions and curves going on here and I am just a little paranoid about the planer ripping a big chip out of the rocker or leaving me a big snipe on the end.  Neither is a concern with the thickness sander – it just takes little longer to get there.

After getting the rockers to the right width I set the chair on them and checked to see if the legs sat tight on the rockers.  No real surprise here, they didn’t fit tight.  To get a tight joint I took a compass set just slightly wider than the gap and used that to scribe a line around the leg. 

Grinding to that line with the disk sander will not provide a final tight fit but gives me a working setup for continuing.  The joint will need to be fine-tuned once the dowels are fitted in place that tie the chair to the rockers.

I mentioned in the last post that I would be doing the 99% final sanding and I have been working on that, at least from the seat up.  It was not quite as bad as I thought it was going to be.  Although I swear I have completely sanded away any and all of my fingerprints.  I had taken everything to 80 grit so the next step was 120.  This took me about 3 hours to go over all the chair’s surfaces.  The next step is 150 followed by 220 where I quit until all the woodworking is done.  Just before finishing I will hand sand with 320. 

One problem that showed up early on when I cut the seat to shape was a knot on the seat’s left side.  As the project progressed final shaping did not remove the defect although on closer inspection it is not a knot but more like a bark inclusion. 

As it will still be there when I am done I have to do something with it.  Right now I have cleaned out the loose material and have come up with three options.  First, completely remove the defect and fit in a cherry patch.  Second, fill the hole with black epoxy and third fill the hole with a mix of turquoise granules set in a clear epoxy.

Next up – Installing the Rockers

Maloof Rocker - Final Headrest Shaping

The headrest as installed is a fairly heavy blocky chunk of cherry.  There are a few steps and a lot of material to be removed to transform it to the lighter more graceful piece I need to end up with.  

The bottom of the headrest has an arc that carries on into the leg and that is where I started the integration of the headrest by drawing in the guidelines. 

Headrest and Leg Before any Shaping

With those in place I used the pneumatic grinder and carbide burr to rough in the arc.  Using sanding drums and some hand sanding I ended up with a seamless transition between the headrest and the leg.

Bottom of  Headrest and Leg Transition Done

With that connection done I moved on to the front of the headrest and the leg joint.  All this requires is for the leg to be ground down flush with the headrest. 

Front of Headrest and Leg Prior to Shaping

This is done fairly simply using the angle grinder with the 50 grit sanding disk installed.

Front of Headrest and Legs Shaped

The back of the headrest is not quite so simple.  First is to draw in the guidelines for the reveal that will be ground into the leg.  As shown here the headrest starts out nearly ¾” thicker than the leg and  has to be ground down to the bottom of the reveal via a smooth taper.

Back of Headrest and Leg Before Shaping  (Note top of headrest is at bottom of photo)

Because there is a fair amount of material to remove here I started with the coarse carbide disk then switched to the 50 grit sanding disk.  Once I had established the rough outline I used a round rasp to refine the reveal following that with hand sanding.  With one leg done I duplicated it on the other leg. 

Initial Shaping to Form Leg Reveal

At this point nearly all the headrest is still 1¾” thick, a long, long way from where it needs to be.  The next phase of sculpting falls into two flows. 

First, is to smooth out the initial taper I had done to form the reveal working toward the center of the backrest leaving it the thickest at the center.  Second is to reduce the top of the headrest down to about approximately a ¼” thick.

The starting point for all this is where I left the rounding over of the bottom of the headrest done before installing the slats.  From that existing arc it’s a smooth curve ending up at the ¼” thick top edge.  To help me out I added a handful of reference lines.  Because this sculpting has even more material to remove than the initial taper the coarse carbide disk is an obvious choice to start with.  As with the other sculpting the progression once the major material removal is done is to use 50 grit disk sander, rasps, the pad sander, and lastly hand sanding.  After using the rasp to smooth out the curves I needed to check for high and low spots.  To do this I used a piece of chalk to coat the back.

Headrest with Bulk of Rough Shaping Done

I then lightly filed the surface which left chalk only in the low spots giving me a clear indication of where I still needed to so some work.

Chalked Headrest Showing High and Low Spots

Headrest and Right Leg Sculpting Nearly Done

With the majority of the back shaped and smoothed I could work on the very top corner of the reveal and its transition.  Using the 50 grit grinder, sanding drums, rasps, and hand sanding I created a smooth transition between all the surfaces. Once that transition is done I can finish running the radius I had routed a long time ago on the outside edge of the leg on up to the top.

The last bit of shaping involves softening the inside bottom arc of the headrest/leg.  With the sculpting of the back done and sanding completed to 120 grit here is what the headrest looks like.  A far cry from the big square block it started from.  Nothing like taking $8 worth of 8/4 cherry and turning it into sawdust. 

Headrest to Leg Sculpting Done Except for Sanding

Final process is sanding.  Since the basic woodworking on the chair from the seat up is done I can now go back and sand up to a 99% finished surface.  I need to remove any machine, rasp, file, sanding drum, scratches, humps, bumps or other irregularities starting with 80 grit and ending with 220 grit.   Because of all the curves the vast majority of the sanding is done by hand.  However, rather than do all that sanding at once and completely remove all the skin from my fingers I am going to intersperse it with the work on the rockers.

Next up – Making the Rockers & Sanding

Maloof Rocker - Headrest Shaping Part 1, Slat & Headrest Installation

There is a small amount of shaping work that has to be done to the headrest and some final sanding before it and the slats are installed.  Most of the shaping to the headrest tying it into the legs is done after it is in place. 

I start by drawing some guide lines for the rounding over of the bottom of the headrest. 

 

Headrest Blank with Slat Holes

Since the round over has a progressively smaller radius similar to a quarter ellipse and tapers at each end it is not practical to cut it with a router.   I started with the pneumatic grinder and burr and got a rough shape.

Headrest Initial Shaping in Progress

From there rasps and sanding give me a finish shape.  I sanded where the slats go and the roundover to 320 grit since it is a lot easier to finish sanding there without the slats in place. 

Headrest Ready to Install

The same logic applies to the slats.  I had already sanded them to 150 and now worked my way through the grits to end up at 320.  Lots of hand sanding and my fingers were really complaining by the time I finished.  While using the 320 grit sandpaper I also broke the hard edges just slightly.  The idea is to still have a hard edge but not one that's sharp enough to cut you.

 

Slats Sanded and Ready to Install

To give me the long time I needed to install the slats I used a slow set epoxy.  It has a working time of nearly an hour and a curing time of between 24 and 36 hours.  In order to minimize the mess I applied blue painters tape to the rear of the seat and the bottom of the headrest then cut out the holes for the slats.

Seat and Headrest Taped for Slat Install

I used a razor knife to cut the holes in the blue tape.  However, my razor knife had too square an edge for me to get in and make a clean cut in a half inch hole so I ended up regrinding the blade tip to a greater taper.

The glue-up process is not bad.  I load the holes in both the seat and the headrest with the epoxy then install the slats in the seat first.

 

Slats Installed in Seat

Slats and Headrest Installed

After they are in place I line up the 7 slats with their respective holes in the headrest, not quite like herding cats but close.  From there assembly sequence is, drive the headrest in place, clean up the epoxy that oozes out, apply Tightbond glue for the headrest to leg joint and clamp in place.  Lastly, I need to twist the slats so the flat face you will be leaning against follows the slight arc of your back and the holes drilled in the seat.   Since the epoxy has a long open time I had to come back after an hour or so to check for any additional ooze out.

Because the headrest piece in the headrest to leg joint is an end grain glue joint it is not strong enough  as is for regular use.   The solution is to add some #10 X 2½” screws, 6 of them in fact.  While the epoxy was curing I cut a small piece off the katalox and made six ½” plugs.

 

Cutting Plugs for Headrest

The next morning after the epoxy cured I removed the clamps and the blue tape.  After that I installed the screws through the rear legs into the headrest.  The process is the same as the other plugged holes: drill ½” holes for the plugs, drill clearance and pilot holes for the screw, install screws and glue plugs in place.

Headrest Plugs Installed

Next up – Final Headrest Shaping