|Project by DustyMark||posted 09-27-2012 07:11 PM||1038 views||1 time favorited||6 comments|
Completed a set of six chairs and a round-ring extension table between January 1993 and September 1994. These are Thos. Moser designs. Turned parts are ash and the rest is cherry. The table is solid cherry and also has a two foot extension leaf.
The prototype chair didn’t pass the comfort test. The back of the seat blank had a straight section in it, the seat blank was not deep enough, and the seated position was too vertical. I fixed that on the second chair. Chair ergonomics is an art form.
The back bow is laminated from 9 layers of cherry, one inch thick, glued and bent around a bending form. After the glue set, I cut the bow to a one inch square cross section. I then built a horizontal boring attachment for my lathe and plunged the ends of the bow into a ¾” plug/tenon cutting bit. This left a perfect tenon to attach through the seat. The bow tenon is also pinned with a dowel. The rest of the bow is routered with a ½” roundover bit, leaving a perfectly round cross section (work smarter, not harder!)
The curved leg braces are also laminated from multiple layers of cherry and have a different form for the front and the back legs. These braces allow the legs to flex on uneven floors. I also wedged the leg tenons through the top of the seat. After nearly 20 years of daily use, none of the leg tenons have loosened.
Most of the back spindles come all the way through the bow. I used a sharp, 10’’ long by 3/8” diameter brad point bit and drilled these holes by eye through the bow. (The extra length helped to site the angle better.) Two spindles meet the bow at a very shallow angle and don’t penetrate. I cut a V-groove in an 8/4 block of hardwood, drilled a guide hole in the block with the drill press, and clamped the guide block to the bow to safely drill this difficult hole.
The spindle holes in the seat are at multiple, compound angles. The second chair turned out very comfortable. I clamped a scrap of hardwood to the top of that seat blank. I then drilled holes from the bottom of the good seat blank into the scrap. For subsequent chairs, I clamped that guide block to the top of the seat blank and drilled through the holes. That is a simple production jig that eliminates a lot of ciphering.
I rough shaped the seat blank with a chain saw disk mounted to an angle grinder and hand adze. The next stage of smoothing was completed with a carbide disk mounted on an angle grinder. I followed that with 50 grit sandpaper. There are much better discs available now than nearly 20 years ago. Funny story = I demonstrated how to shape the seat at The Woodworker’s Club of Arkansas in Little Rock. I actually worked on a blank for one of these chairs. I guessed wrong on where the chips would fly and I sprayed the first two rows of the crowd with a good blast of chips…oops!
Chairs like these are satisfying challenges. I had to build three bending forms, a horizontal boring jig for the bow tenon, a fluting jig for the leg mortises, a drilling jig for the shallow spindle holes, and a compound angle jig to drill the leg holes on the drill press. I completed the last couple in probably about 40 hours each.
-- Mark, Minnesota