Any tricks for measuring a chair I want to reproduce?

One idea would be to cut a piece of heavy paper close to the curve. Keep tweaking it until you have a good fit. Then you can lay the curve flat and work on the radius.

-- Steve - Impatience is Expensive

Use a contour gauge. It allows you to make an impression of an odd shape or surface and transfer it. I’m also big on prototypes and build them for every odd project. I also remember a book at the local library that had scalable plans for Stickley furniture. Remember that the arts and crafts movement was built around simple designs and many of them are freely available as plans.

-- Matt CueBall Rosendaul. I don't think I've ever had a cup of coffee that didn't have cat hair or sawdust in it.

This site has plans available for a lot of the Stickley furniture.
Maybe you can find what you’re looking for there.
If not, as someone else mentioned, it’s a popular design that’s available from numerous sources.

-- http://wddsrfinewoodworks.blogspot.com/

You could probably arrive at the final dimensions by estimating the rough stock size, then shape and sand the parts comparing them to the original as you go.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

I have made some good templates by taking a small piece of temper board and small clamps to hold it to one side and tracing it. If Slats there is space between them, take the temperd board which is only about 1/8 thick and put it on the side of the slat then use a couple of small clamps to help hold it and trace the curve out. Hope this helps….

-- What we do in life will Echo through Eternity........

This is one of those cases where woodworkers tend to complicate the simplest things. If you have the original chair to go by, cut something light and stiff with a surface you can draw on (cardboard, posterboard, thin plywood, etc.) to fit in between the back legs, hold it to the bottom of one of the curved rails, and trace it. That traced edge can be used to make your bending form, whether you make the curves by laminating or steam bending. That arc is what you need to make it and knowing the radius of the curve itself is of little or no value. For what it’s worth, I doubt that the original back rails have different radii.

You can use a similar method to story board the whole chair, get some thin sticks, hold them against the parts of the chair and mark off where one part hits another. That would give you a full size, reliable pattern for the entire chair. Build from that pattern and save the trouble of making a drawing as an in between step. The joinery should be pretty straightforward, but you might be interested in my website and books previously mentioned.

-- Bob Lang, http://readwatchdo.com/

Hear hear, Bob!

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

I took a class where we wnet to a museum, documented the ~1765 table below, and reproduced it.

We used the techniques Bob described to trace cabriole legs and curved side skirts to poster board. We created patterns from the tracings in 1/4” plywood, then used the patterns to make duplicate parts.

Remember to tape all of your tools and marking devices that can scratch.

You may have the advantage of repeated access, if necessary… Even so, digital photos are FREE! Take as many as you can, with reference items in the photo when necessary. In many cases, you may have to fine-tune a tracing to make the parts fit. It it LOOKS right, it IS right, so let the photos and your senses be the guide.

-- It's all good, if it's wood...

Do you really need to reproduce the same size of the original? Just wondering

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"

Are you talking about horizontal steam-bent slats, as on a Gus ladder-back chair like this one?

You could try making a draw-bow and use that to make bending jigs/forms for thin-strip lamination or steam bending (if steam bending, must allow for some spring-back).

Or you could cut a piece of wood to exactly the distance between the back uprights and use that as a straight-edge along with a ruler or square to measure the maximum depth of the curve and plot the curve out from that.

Or you could just trace onto a piece of cardboard (or something stiff enough for this use).

With any of those methods you’ll need to allow for tenons on either end of the horizontal slat. Which leads me to what I think is the more difficult question: how to cut the tenons and shoulders on the ends of each curved slat so they fit flush with the face of the mortised upright?

-- "Inferior tools corrode the spirit." -- Lewis Allen

Cut the tenons before the curves.

You an also use carrier boards and dual-blade tenon setups.

-- It's all good, if it's wood...

Thanks for all the advice.

Sheldon, yes it’s a ladder back. I took Bob’s advice and used cardboard to trace the curves.

In response to Bob, it’s interesting, but after tracing the slats the bottom slat on all 6 chairs is slightly deeper than the top two.

About the tenons for the back slats. I was planning on steam bending the slats and then marking a line and using a shoulder plane to cut a tenon that would be square to the inside leg face. Will that work well enough or is there something else I should consider?

I think it’s easier to cut them by hand than to jig up and cut the tenons by machine. To machine you need to approach from different directions at exactly the same angle. That kind of tedious.

The tenons will be in line, so I make a straight stick for a pattern, with the shoulders and tenons cut. Then you can put that on top of the bent rails to mark them out. I wouldn’t try to do it all with a shoulder plane. Saw around the shoulder and rough out the tenon with whatever hand saw you have, then trim to fit with the shoulder plane.

-- Bob Lang, http://readwatchdo.com/