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Jensen-style Z-Chair #7: Rails

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Blog entry by Ross Leidy posted 05-20-2019 04:36 PM 312 reads 0 times favorited 9 comments Add to Favorites Watch
« Part 6: Seat frame - shaping and joinery Part 7 of Jensen-style Z-Chair series Part 8: Side structure - Getting started »

Feel free to correct my terminology, which could be wrong since I’m not chair anatomy savvy. I did research a bit, but there didn’t seem to be consistency in the terms. For this build, I’ll refer to upper/top rail as the one at the top of the back, rear rail as the one at the back of the seat, and front rail as the one at the front of the seat.

All rails are 22” long.

The front rail is 3” x 3/4”. I played around with the shape for the arc cutout, starting with a circle chord. That didn’t look anything like the chair photos – it would leave too much material and look too beefy. I switched to an oval and after a lot of tweaking, this is where I landed.

And then cut out the arc on the CNC.

The upper rail is 2-1/4” x 3/4, with the top edge rounded with an oval profile bit. It seemed from photos of the chair that the upper rail edge did not have a simple round-over. But after seeing Tango's photos, it looks like the top rail has a shallow bevel on each side so it’s thinner on the top edge, and then has a simple round-over. I’ll have to think about whether re-cut mine. Hmmmm.

The rear rail was 1-3/4” x 1”. This was intentionally thicker than the original because I wanted to make sure I built it strong enough. The 3 amigos:

Marking the rear upper/lower rails for the slat dowels. They are spaced 3” apart, leaving 2” of rail on either end.

Loaded into the mortising jig, I cut the dowel holes and the mortises in the ends of the rear and front rails.

I had been puzzling over just how to support the back of the seat frame on the lower rail, and hadn’t settled that part of the design until this point. It will mean a slight change to the seat frame, but I’ll show that in a later post. Where I landed was to attach a small shelf for the seat frame to rest on. I cut a strip of cherry with a bevel that would match the angle of the seat frame, and glued it to the rear rail.

I knew that the bottom of the rear rail had a round-over, and in the interest of not removing too much material, I used the same finger nail bit as I did for the seat frame edges.

On the front rail, I cut the bevel for the seat frame to rest on.

Finally, I dry fit the slats to the rear rails.



9 comments so far

View Tango's profile

Tango

98 posts in 3939 days


#1 posted 05-20-2019 09:40 PM

Hi!

The top rail is rounded with a fixed radius and is not a bullet profile. Maybe the picture angle was not the best and appears to be thinner. I will take my time and produce a CAD master template for this chair. It will take me some extra time but I think is worth.
Also, the top and bottom rails are about 7/8 thick stock. I will confirm this for you as soon as I have a chance to stop by my daughter’s house.

Regards!

View Tango's profile

Tango

98 posts in 3939 days


#2 posted 05-21-2019 12:21 AM

Sorry Ross.I was wrong! The top rail is indeed “bullet” shaped. More like a smooth parabolic curve…
See the measurements on my restoration blog.

View Tango's profile

Tango

98 posts in 3939 days


#3 posted 05-21-2019 02:35 AM

The blue curve is pretty close to the top rail shape.

View Ross Leidy's profile

Ross Leidy

49 posts in 2328 days


#4 posted 05-21-2019 01:47 PM

Of course, cosh. :) Are you a math guy?

I won’t be able to replicate that exactly, but I think I can take a little more off that the top of the rail with the bit I have.

View Tango's profile

Tango

98 posts in 3939 days


#5 posted 05-21-2019 02:59 PM



Of course, cosh. :) Are you a math guy?

I won t be able to replicate that exactly, but I think I can take a little more off that the top of the rail with the bit I have.

- Ross Leidy

Hahaha I’m an architect but no mathematician. Just familiar with geometry.

I assume that a lot of the shaping in this chairs were made by hand (sanding, filing, scraping). To replicate a profile like this will require working with spokeshaves or heavy sanding.
By the way, the overall weight of the chair is on the light side and looks fragile but once assembled is quite sturdy.

View mafe's profile

mafe

12040 posts in 3475 days


#6 posted 05-22-2019 09:28 AM

Again really interesting to follow along, thank you for all the time spend documenting.
You are doing a wonderful job here, don’t let the smallest of details kill you, what you do is your version, not an exact copy, so try to feel your details, this is the more important.
Tango, wonderful to read your dedication. ;-) And yes it was normal to do finish with spokeshaves and cardscrapers back then. You can see that on old photos from the Danish furniture maker shops.
Look forward to follow.
Best thoughts,
Mads

-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View mafe's profile

mafe

12040 posts in 3475 days


#7 posted 05-22-2019 09:31 AM

Ha ha, I sounded like the teacher, sorry…
I used to teach at the school for constructing architects in Copenhagen, so bad habits.
(I am educated constructing architect and after that building architect, here in Denmark, the wood working is a hobby that grew on me, after I had to take an early retirement due to a neck operation, so I’m a wood rookie). :-D
Best thoughts,
Mads

-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View Ross Leidy's profile

Ross Leidy

49 posts in 2328 days


#8 posted 05-22-2019 01:51 PM

Mads – I’m happy to hear your perspective. Who’s going to disregard comments from a Danish architect?

Tango – I’m surrounded by architects! This is awesome!

View mafe's profile

mafe

12040 posts in 3475 days


#9 posted 05-22-2019 01:57 PM

Ha ha ha, be careful what you wish for!
Smiles,
Mads

-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

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