Greene & Greene Gamble House Side Chair #27: Back Splat Splines

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Blog entry by TungOil posted 12-22-2018 02:55 PM 1228 reads 0 times favorited 4 comments Add to Favorites Watch
« Part 26: Shaping and Sanding Part 27 of Greene & Greene Gamble House Side Chair series Part 28: Chair Assembly »

With all of the hand shaping and sanding of the chair parts out of the way, the next step is to fabricate the ebony splines and cut the recessed grooves in the back splats to accept the splines.

I start by making a jig to cut the ebony splines. The jig holds a length of ebony securely, allowing me to shape the rounded face of the spline on the router table. I round over the face on several pieces of ebony, then slice off the spline stock to the correct thickness on the bandsaw and repeat until I have enough stock for all of the chairs.

To route the slots in the back splats for the ebony splines, I make a small slot routing jig. The jig is a simple flat plate with a square opening that uses a router guide bushing to produce the slot in the back splat. To vary the length of the routed slots, I fabricate some small spacers to reduce the size of the opening. The jig clamps in place on the back splat using two toggle clamps on the bottom. The slot jig has center lines marked to align each slot accurately on the back splat.

After marking the center line for each slot on the back splat, I carefully align the slot jig and clamp in place. Using a plunge router, I route the slots. The length of the slots varies from top to bottom. The bottom two slots are widest, while the top two slots are each 1/4” shorter than the slot below.

After routing the slots, I square the ends using a square punch and clean up the waste using chisels.

I cut the ebony splines slightly oversized, then use a small jig clamped to the belt sander to square the ends and adjust the spline length to fit the finished slot. The jig is clamped square to the sanding belt and has both a flat face for adjusting the spline length and an angled face to put a slight chamfer on the back of the spline to allow easier insertion into the slot.

For the lower splines especially, it is critical to have a perfect fit- too long and the spline will spread the back splat and possibly split the part, too short and there will be a visible gap. Since each spline is slightly different, I number the back of each spline as well as the mating slot for later reference.

On the original chairs, the splines are pinned with as many as 10 silver rods each. To approximate that look I use 5/64” nickel silver rods- the type used to affix knife scales. Two per ebony spline seemed like a good compromise to get the look without an extraordinary amount of effort.

After the spline has been fit to the slot, I bore the holes for the silver pins. A standard twist drill has a tendency to wander off center when trying to drill the rounded face of the spline, so I use a 5/64” end mill mounted in the drill press to be sure the holes stay centered in the spline.

I cut off two short pieces of the nickel silver rod and glue into the spline with CA glue.

I then finish sand the spline, rounding and blending the pillow shape through 400 grit which shapes both the ebony spline and cleans up the silver rods flush with the ebony. The bottom spline below has not been finish sanded yet, the top is completed.

The finished splines fit snuggly into the slot.

The ebony splines are ready to insert, but I set them aside for now since they will be installed after the chair is assembled.

Here the splines are in position but not set into the slots.

Next steps: chair assembly.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

4 comments so far

View a1Jim's profile


118258 posts in 4821 days

#1 posted 12-22-2018 03:32 PM

Looks like a great project and a lot of cool techniques. I look forward to seeing your progress.


View sras's profile


6346 posts in 4373 days

#2 posted 12-22-2018 04:05 PM

I am enjoying every post of this project!

-- Steve - Impatience is Expensive

View EarlS's profile


4754 posts in 3591 days

#3 posted 12-22-2018 05:15 PM

Just when I think there can’t be any more detail work….. Those are going to look incredible with the silver pins in the ebony. Wow!!! All of these details reiterates why there aren’t many original G&G pieces. Sheer perfection.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View edapp's profile


347 posts in 2673 days

#4 posted 12-26-2018 01:15 PM

I am loving these updates. Learning a lot about patience by following along here… I need to slow down in the shop a bit…

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