Ash Chairs

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Ash chairs, companions to the Ash Table and Sideboard I recently posted.  Thanks for looking.

Designed in Fusion 360 based loosely on a Garett Hack design in Fine Woodworking many years back.  Chairs are challenging to me. This set in particular as it was the first time using my own design.  The design process seemed to take about as long as the build process.  I always start out with good intentions to log the hours.  But that quickly falls apart.

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[Rutabagared]

I’ve found chairs require a lot of mock-ups once the rubber meets the road – i.e., when dealing with the actual parts and their dimensions.  This is necessary to determine seat rail angles/lengths, back assembly rail and slat compound angles/lengths, etc.  I start with a plan view of the seat rails/legs – in particular, what angle to cant the legs inward, width of seat rear (rear rail length and angle with rear legs) and desired front seat width.  From there I determine the desired seat depth.  Then, Fusion 360, mock-up and summoning sohcahtoa, I can determine side rail lengths and their angles of attachment to the front and rear legs.  Front rails are 90º to the front legs.  “Exact” front rail length is the last dimension I determine.

I used only 8/4 stock.  I attempted to pragmatically select the straightest grain stock for the legs and rails, and cut narrower pieces (i.e., anything less than 2” wide) from the center of flat-sawn, 8/4 boards (back slats, lumbar and crest rails).

The good news is that after all this fiddly work, the Festool Domino makes short work of all the mortising.  Angles and compound angles?  - No problem!  Set the fence angle appropriately (just like you would at 90º) register on the workpiece, register the face of the domino as you would with a 90º and plunge away.  The gotchas are ensuring you use consistent reference faces/edges, ensuring selected domino lengths/mortise depths don’t pierce through show surfaces, and staggering domino lengths where they intersect in both front and rear legs.  In other words, the same gothcas as 90º joints.

I always use templates and jigs for rear legs.  Rear leg jig.

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Seat rails cut and mortised.

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[woodbutcherbower]

Lovely job. They look great.

 

[Rutabagared]

Thank you for the kind words.

 

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Mock-up time.
Seat rails:
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Back assembly mock-up in order to determine compound angles and lengths of crest and lumbar rails. I draw two lines on the inside surfaces of the rear legs; a centerline for the mortises and a line to register the front faces of the crest and lumbar rails.  I then trial cut scrap rail material until it fits snuggly between the legs registered on these lines.  By the way, the Bessey EHK series rapid action clamps are the bomb.  Ordered for this project and have since ordered many more.  They always ship quickly through HD and they have an attractive set of smaller sizes (6 and 12”).  I 've used them more than any other clamp in the shop, including for edge glue-ups instead of parallel cabinet clamps.

Lumbar rail:
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Crest rail:
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View from top (I verify the rail faces are coplanar with a straight edge).

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Mock-up for back slat lengths and a sanity check before cutting rail and rear leg mortises. 

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I cut the back assembly mortises in the rear legs by offsetting a reference surface (straight-edged piece of ¾” MDF) along a line offset from the desired location by 10mm, registering the base of the Domino against this.

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Time to lay out the back slats.  (Note to self – know the minimum stock thickness requirements of the Domino and leave the slats over-sized, cut the mortises, then plane to final thickness.).  I planed them all to final thickness only to realize they were too thin for mortising.  Redo time.

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Miscut mortises plugged.  I don’t remember what led to this.  But I usually miscut at least one set during a build.  I also usually ruin a rear leg and a front leg as well.  Note that the mating mortises (bottom edge of crest rail and top edge of lumbar rail) are cut before stock is shaped.

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Cutting curves on crest and lumbar rails.  Determine the angle of the bandsaw table by measuring the angle between the top ends of the rear legs and either reference line on the inside of the rear legs (crest/lumbar rail faces/mortise centerlines).
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I highly recommend Highland Hardware’s general purpose bandsaw blades (not the Wood Slicer, which I also recommend).  They are capable of cutting curves and leaving a finish that is comparable to the Wood Slicer).  It also prevents me from switching blades – nuff said.

Smoothing the rail curves.  I decided to try my hand and smoothing them with a new acquisition:
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As awesome as the finish was using the spokeshave and files, I still needed finish with abrasives.  My skill level is just not there.
[attachimg=1][attachimg=2]This process took quite a while, but at least I got to make a mess.

 

[rvieceli]

Beautiful work.

Ron

 

[Rutabagared]

Beautiful work.

Ron

Thanks, Ron.

 

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Taking care of the final machining and smoothing.  Grooves for seat pan.

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Rear legs.  I bought a lot of new tools for and during this build (spokeshave, two hand planes and several router  bits and files) .  One of those was a LN No. 164 (Low Angle Smooth Plane) – Lovin’ it.

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Font legs.

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Tapering the back slats (Yes. I certainly could have used  a block plane, but wanted to continue to make friends with my smoother).

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Smoothing the tops of the rear legs.  Mostly just abrasives, finishing with Mirka Mirlon Total very fine scuff pads.  I love the way ash end grain finishes.

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Glue-up.
Time for glue-up.  It has been a long and satisfying road at this point.  As long as the process took, the glue-ups went smoothly.  I went from dozens of components in the morning to four assembled chairs in the late evening.

Back assemblies.
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Corner braces.

Template
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I don’t bust this out often, but I find it's the best way to fit the bracket to the rear face of the curved front rails.

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After finishing. It’s time to build the seat pans and upholster.
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The seat pans took a stunning amount of time.  Setting all the gaps for clearance of upholstery material, creating the leg cut-outs, matching angles of the side rails, fairing the curve where it meets of front rail, etc.

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Time to upholster.  I’ve done a few dozen slip seats over the years but never worked with leather.  I ordered it online from the Leather Hide Store.  A bit stressed about using it.  But actually, found it easier than fabric.

Youtube videos are very helpful for upholstering but, like most things, upholstering takes far longer than I remember.  There is also a significant smoothy-squishy factor when applying the fabric/leather down and around the edges.  Leather requires stretching first also.

Leather hide.  The milk serves as a bovine head proxy (good name for a rock band?).

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It cuts easy with sharp scissors. Foam cut and fitted (I cut with a bandsaw).

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Upholstering requires a lot of staples.

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Underside.

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