Thursday, February 10, 2011

Building A Mt. Lebanon Side Chair: A Web of Intrigue


While upholstery decisions are being made on the Contemporary Chairs, I have some time to complete construction on the Mt. Lebanon Side Chair.  Up to this point it has been primarily an exercise in turning spindles and making jigs -- oh, and some steam bending.  I let the back slats and back legs cook in their forms for about two weeks and released them into the wild.  As I suspected, there was significant spring back on the legs (for the record, they stayed in the steam box for 2+ hours at a constant 200 degrees F.  They just didn't seem to want to absorb any of the water.)  A bit of research tells me that hard maple is a real bear to bend, and that there is a high failure rate.

The remaining steps were to install the back slats, glue up the front and back "ladders", make the side rungs, drill the side rung mortices, and construct the chair.

Installing the Back Slats 


Although it may be difficult to see, the front of each slat lines up with the center line of the back leg, but because they are bent they, emerge at a different angle than the rungs.  This angle will vary, and you will need to eyeball it.  Kerry Pierce, in his book Authentic Shaker Furniture, outlines a method for hand-morticing these back slats that is quite workable. 



However, as I rained blows upon it,  I thought "There must be a better way."  So I made yet another jig.  This set-up allows me to suspend a router at an approximately 30 degree angle over the leg and rout for the slat . . . and I'll write about it in more detail on Sunday.  And while the 30 degree angle is fairly arbitrary, there is plenty of flexibility in the slats and the exact angle is not critical.  Once these are complete I glued up the back ladder.


Making the Side Rungs

I spent a pleasant hour at the lathe, listening to Billy Bragg and turning the six identical side rungs.  I've really become comfortable with the wrench-as-measuring-tool approach to tenons.  I just use a 3/8 parting tool and stop removing material when the 5/8" open wrench slides over the tenon.  Because the wrench is just a hair over-sized, I take one more little shaving before I remove it from the lathe.  Once the tenons are in place I shape the subtle swell-and-taper in the rung itself.


This little stack goes to be cut-off at the new Stanley Miter box, and then I get the absolute, precise OD by driving them through my dowel plate and trimming the waste with a chisel.



Drilling the Side Rung Mortices

Using the Side Rung Mortice Jig (as described in Pierce's book, Quick and Easy Jigs and Fixtures) I went about drilling the mortices.


The whole point of this contraption is to drill the holes in such a way that you create a seat that is wider in the front than it is in the back.  The geometry is simple as you drill the same angle in both the front and back ladders -- it is just that you turn the jig 180 degrees between the two to drill obtuse angles in the back and acute angles in the front.  The master angle in this case is 10 degrees (giving you angles of 80 and 100 degrees.)  And that is the angle of the wedge you cut to position the jig.

That angle, by the way, is determined by the width of the front legs.  If you were designing your own you could cut an angle that suited your eye, install the side rungs, and then cut the front rungs to create a front ladder that fit.  In this case, Pierce has already worked this out and you just work to his specs.

After drilling holes in the back ladder you turn the jig around and drill the holes on the front ladder.  The jig adjusts to accommodate the wider front.

Assembling the Chair

The moment of truth has arrived.  All the pieces are in place and it is time to see if your patience has been rewarded. 


I start by placing the rungs in the front ladder and then slowly working this unit on to the back assembly.  In this case, it goes together fairly easily.  And I know why.

According to some builders (Kerry Pierce) perfection is not your objective, and in fact he would argue that you want there to be some deliberate misalignment.  As long as it is consistent it will add tension to the chair --like a spider's web -- and make for better construction.  I liken it to the forces within a basket that give it strength and shape.  I know that I had a couple of errors in my drilling, but this really seemed to add to, not take away from, the stability of the chair.

Now on the other side, I've read a compelling argument from Peter Galbert on his excellent blog, Chair Notes, countering this error-as-strategy approach.  If you've ever seen his outstanding work, you would be hard-pressed to oppose anything he has to say about the designing or building of chairs -- so you decide for yourself.

Next, I'll apply the finish, weave the seat and have some final words about what I really think of this project.

Thanks for reading!

6 comments:

  1. Really cool - love the first photo. I have a question though. You wrote that you had significant spring back. Was this a problem? From your photos, it doesn't look so, just curious.

    ReplyDelete
  2. It wasn't really a problem, it just made the curve (shall we say) more subtle. It also makes the ritual of two hours of steaming and nearly two weeks in the forms fairly moot. Only a few Shaker chairs incorporate bends in the back legs, and now I see why!

    ReplyDelete
  3. Great post Christopher. I love seeing these things come together.

    ReplyDelete
  4. Despite the trials and tribulations, the chair has turned out very nicely indeed! Well done!

    ReplyDelete
  5. Hi Christoper,
    Great post and great blog.
    Using a wrench as a stop gauge = really clever + I wish I had thought of that!
    Cheers,
    Niels

    ReplyDelete
  6. Christopher,
    Awesome, I'm looking forward to building a Shaker chair myself, but have a question about materials. Did you use kiln dried, air dried or green hard maple, I've heard that kiln dried material does not lend itself very well to bending? Thanks for the post!

    ReplyDelete