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