Friday, 17 February 2012

Dining room chairs - milling, cutting joints & the seat

My Dad came over and helped me with 2 very important tasks. The first was to put the log back together so I could mark the boards to get the best layout for parts. I was particularly interested in getting the seats sorted out. There was one massive board that was wide enough to get three single board seats. By putting the log back together, we were able to get two more seats that were slip-matched.

These two, 18" wide book-matched planks were set aside for the future table.

These were perfect for the front and back legs and the arms.

The above shot made me somewhat sick. I was half prepared for lightning to strike me down for cross cutting this amazing wide board. I stood there for at least 20 minutes pacing around building the courage to do it.

I got over it pretty quickly as soon as I saw the seat blanks.

Figuring out the layout for six chairs was way more work than I anticipated. There were some defects to work around and it was a struggle to wrap my head around all the waste. Thankfully - all the stock was at least 8/4 with some being 9/4 and even a few 10/4 pieces. Dad helped me mill everything flat on the jointer and then through the thickness planer. I needed a full 2" thick for the arms - the rest of the stock needed to be 7/4. Once we had it down to 2", I re-sawed several of the boards to take a single piece of 1/8" veneer. I could not stand the thought of all that curly walnut in the cyclone. And who knows - those veneers may end up finding their way into a future sideboard.

(a few pieces of the 1/8" veneer)

Here is the pile of chair parts. The front legs are on the saw horses, the seats are on the bottom of the pile, then the back legs and the arm rests on top.

As I was milling the parts for all 6 chairs, I realized that it would make a lot of sense to work on all 6 chairs up to a certain point and then take one of them and finish it off. I decided to cut all the joints for the front and back legs and prepare all the seat parts.

The leg joints.

The front and back legs are attached to the seat using the joint that Sam Maloof invented. It struck me as an elegant and sturdy way to attach the leg if one wanted to shape the joint so it would blend together. The front leg was the easiest - it is actually a 90 degree joint - so that is where I started. I did get a trial run of these joints on the prototype, but poplar is pretty squishy compared to walnut so a full set of new jigs was required for the walnut chairs.

This joint is fairly simple and straightforward, but it is not easy. It does require an extremely high level of accuracy when cutting the initial dados - about .001" of wiggle room. Set-up is critical - everything must be 90 degrees. These joints reminded me of plane making from the standpoint that if the first cut is not done accurately - you will be fighting with it at every point thereafter. Success (or failure) is based on the previous step being perfect and any deviation or error will send you back to the beginning. It was at this point that I was grateful for my plane making experience.

Here is a shot of the completed front leg to seat joint. One other early decision was to use dowels and Dominos instead of screws and plugs to hold everything together. I used a 1/2" diameter, 2" long dowel to connect the front legs to the seat.

There is also a 1/2"D, 2" long dowel connecting the top of the front leg to the arm rest. The top of the front leg is at a 1.5 degree angle which required a jig to ensure the dowel was square to that face.

Locating all the holes was a little nerve wracking. You can see the pencil layout lines on the top of the front leg. These are the rough bandsaw cut lines - there is further refinement after these cuts and I was holding my breath that none of the dowels would break through.

The back leg joint is much more complicated. The back legs are tilted in 3 degrees (closer at the top than at at the bottom) and rotated in by 5 degrees.

(this is the only shot I have showing the 3 degree angle to the seat)

The above photo shows the back leg fit to the outside piece of the seat.

An inside view of the joint.

I used two, 1/2"D dowels to connect the back leg to the seat. I made one a little shorter for 2 reasons. I figured it would make alignment during glue-up a little easier if they were staggered, and I was also concerned about the furthest dowel breaking through the back leg during the shaping.

I cut the dowels in the seat component first. When I located the holes in the leg, I offset them by .006" - two pieces of paper. I wanted the dowels to act like a bit of a drawbore to pull the joint in tight along the edge parallel to the dowels. The above photo shows the joint going together for a test fit.

(you can see the 5 degree rotation in this shot)

The seat.

I have watched many videos of Sam Maloof shaping chair parts on the bandsaw. It is an amazing display of control and confidence. I was by no means going to attempt to use a bandsaw to that extent... but I was comfortable doing some of the shaping.

The above photo shows the contouring to the seat done on the bandsaw. I went really slowly - this was about an hour and a half to do. On the second board from the right, you can see an almost disaster - there is a dark shadow line that indicated a cut that almost went too far. What took so much of the time was figuring out how to keep track of the layout lines on the opposite edge - the one you could not see.

After the seat was glued up, it was time to shape it. A good friend of mine strongly suggested that I invest in the Festool RAS 115. It is technically a sander, but really, it is a grinder. And a marvelous grinder at that! Armed with 24 grit paper, I was able to shape the seat at an alarming rate. Not only did the paper hold up surprisingly well... the grinder itself was really easy to control. I worked through the grits from 24, to 26, to 50 and then to 80. Once I got to 80 grit, I switched to the Festool ETS 150. This sander was great to smooth out any of the ridges left from the RAS 115. I started with 50 grit, then 80 and worked my way to 220.

Below are 2 shots of the contoured seat. I took these in low light (single light source) which was the best way to be able to see the contour and not be distracted by all that pesky curly grain:)

I was pretty happy with how the contouring came out and decided to keep going. I figured I could make refinements further along if the shape was not quite right.

Shaping the front edge of the chair was a lot of fun. Spokeshaves were the perfect tool for this task. There were a few spots I could not get into easily but the Auriou rasps solved that problem in short order.

With the front edge done, I was finally going to be able to put the legs on and see how it felt. One quick problem though... the 3 degree tilt and 5 degree rotation to the back legs made it impossible to clamp them in place. I made up 2 jigs one for each leg.

The jig consists of two angled pieces of walnut - one at 3 degrees and the other at 5 degrees. These were oriented (and glued together) in such a way that they would be parallel to each other and allow for clamping and the eventual glue-up. I screwed two pieces of 1/4" plywood to the top and bottom so they would be indexed off the edge of the seat. I glued a piece of 220 grit sandpaper to the walnut - I did not want anything to rotate out.

Finally - I could take the first test ‘sit’.


Blogger David said...

Wow... You sure don't wast any time!!
Good for you, and it look real good so far!

17 February 2012 at 21:27  
Blogger Richard Wile said...

Nice build Konrad. Good to see the detailed thought process, my head hurts just reading the blog!

17 February 2012 at 21:30  
Blogger Tico Vogt said...

You are one organized mofo!

Did each of the seat boards get sawn in a straight line (except the middle, which has two) or were you contouring them at the same time?

I'd like to see how you set up to drill those end grain dowel holes.

Great work.

18 February 2012 at 08:36  
Blogger Konrad said...

Thanks David. These were taken before Christmas 2011 - I am a few months ahead of these photos.


18 February 2012 at 20:58  
Blogger Konrad said...

Thanks Richard. I am envious of the fact that you are working on the table already... I have a long way to go before I am at that stage!


18 February 2012 at 20:59  
Blogger Konrad said...

Hey Tico,

The seat boards were contoured and none of them really has a straight line (unless I am misunderstanding your question). the bandsaw was used to bulk out most of the waste. As a point of reference - there is 1" of material removed from the area where you butt is. Removing this with a grinder would take a long time - even with a good grinder. Sawing it out saved a pile of time.

I will see if I have any photos of the dowel set-up.


18 February 2012 at 21:02  
Anonymous Anonymous said...

What an artist in metal and wood !

Did you cut your 1/8" veneer with your "new to you" bandsaw?

Thank you,

20 February 2012 at 18:41  
Anonymous Anonymous said...

Thank you so much for sharing these photos and your experience throughout the process. I don't feel so strange about pondering cuts on wide boards now. I too fear that lighting may strike if material is wasted.

22 February 2012 at 08:54  
Blogger Konrad said...

Thanks Jim. Sadly - the Y30 had not arrived when I was cutting the 1/8" veneer. There will be plenty of time for veneer cutting in the near future though.


24 February 2012 at 08:55  

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