mid-century dining chair – replace curved plywood seat

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bettyrubble
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mid-century dining chair – replace curved plywood seat

Postby bettyrubble » Fri Jan 19, 2018 8:45 am

Seeking help from the community.

I have a dumpster find: six dining chairs + table with leaves. I adore it.

All six of the chair seats were recovered sometime in the 80s. Three chairs have busted seat bottoms.

Yesterday, I stripped the upholstery from one of the broken chairs. I discovered that the seat bottom had been a curved piece of plywood. The plywood had completely de-laminated into shreds.

I have photos with important details, but I cannot load them. In case it is helpful, this vendor is selling a set of chairs identical to mine:
http://www.midcenturymodernfinds.com/se ... mark-1960s

Based on the depth of the recess, I infer that the original curved plywood seat base was only about 1/8” thick. This is confirmed by a few bits of plywood that still cling attached to the frame. The plywood was attached with glue and staples. The staples show that the plywood was indeed very thin!

How do I replace these curved seat bases?

I have toyed with the idea of using a sheet of Formica or other high pressure laminate to build up a seat bed, one layer at a time, using contact cement between the layers, perhaps going as thick as three layers.

I am a resourceful DIY-er, with a lot of great tools, but precision work is not my strength, and I worry about trying to steam-bend plywood to the proper arc.

Thank you in advance for help and feedback.

AsonnyA
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Re: mid-century dining chair – replace curved plywood seat

Postby AsonnyA » Fri Jan 19, 2018 9:20 am

Photos aren't shown, didn't load. You might try downloading the pics on a free site, like Flickr, Picasa, Photobucket, then post the link.

I doubt the seat support was curved initially, intentionally. It probably bent over time, because of weakness of the thin ply, or the delamination resulted in its bending, as you describe. You can likely install 1/2" ply (ridgid) and pad it well. Many dining chairs have a 1/2" ridgid support base, this way.

Padding typically includes 2" (sometimes 3", depending on the seat frame design) foam, a layer of cotton, then the fabric. When I upholster dining seats, I also install a layer of fiberfill over the cotton. The fiberfill allows the fabric to lay and flow over the surface, as it's being stretched/snugged, much easier and smoother, than if applied over cotton. Sometimes, I even install a thin layer of muslin type fabric (a liner, per se) over the fiberfill.... makes for even smoother application of the fabric. Forming and cutting (around corners and other contours) of the muslin, allows for your "learning" how best to apply the main fabric, i.e., allows you to make and learn from any cutting mistakes and fitting mistakes on the liner, rather than making those kinds of mistakes on your fabric.

Some dining seats have coil or K-arc springs, rather than solid bases. These seats are similarly padded, as the ridgid seat supports.

As to attaching whatever ply support: Staple, nail or screw the ply on all 4 corners (and/or between the corners, as well), to help prevent any racking of the framing, especially if these older or otherwise damaged chair frames are a little unstable. As to any leg or bracing looseness, do any woodwork repairs before installing any ply, paddings and fabric.... and even refinishing, if applicable.

Another option, rather than installing a ply seat support, is to install jute webbing, as the seat support. If you elect this option, stretch each webbing strip as tight as you can, across the spans. There's a special tool for stretching jute webbing, but otherwise, try to tighten the webbing as tight as you can, if you don't have the tool. Weave the strands of webbing, across the span, if you elect this option.

I'd like to see the pics, despite my surmising your scenario(s).

Sonny

bettyrubble
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Re: mid-century dining chair – replace curved plywood seat

Postby bettyrubble » Fri Jan 19, 2018 10:16 am

Thank you, AsonnyA, for your feedback.

I have a Shutterfly account now where you can see photos of my first chair:

https://bettyrubble01730.shutterfly.com/

Please let me know if you have any difficulty viewing it.

In case it is helpful, there is an SF Bay Area dealer selling two chairs that are the same as mine--assuming the mark on my chair is authentic:

http://www.midcenturymodernfinds.com/se ... mark-1960s

Based on the dealer's asking price for two chairs, I am guessing that my complete set may have monetary value. More importantly, I adore mine. For both reasons, I'd like to replace the curved seat bottoms. I also think that a flat piece of ply would not sit down properly in the recess, unless I routed it flat. I'd have to do that on six chairs: daunting. Easy to mess up the frames.

Your webbing suggestion is intriguing; I need to cogitate on it.

I have two walnut chairs, American made, that I pulled from a curb in Cambridge, MA. They were covered in four layers of latex paint. I completely rebuilt the seat bottoms of those chairs with 1/2" birch ply, rounding the edges with a router, but they were flat, a snap. I am more intimidated by putting a curve into anything.

Thanks in advance.

AsonnyA
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Re: mid-century dining chair – replace curved plywood seat

Postby AsonnyA » Fri Jan 19, 2018 2:11 pm

Okay, so the seat bases are curved. Simply use 1/8" ply... it will bend to that contour without your having to do any pre-bending of the ply. Securely, firmly, attach the center of the edges of the ply to the center of each the seat frame member, i.e., start in the middle of each edge, and work your way to the corners. If need be, attach an additional 1/8" ply.... this would further add support to the support.

If you use jute webbing, I would still recommend you stretch the webbing tightly across the span. If you hand-tighten it, it will slightly sag, when in use, so the curvature will be accomplished. Make sure you attach the jute webbing's ends securely to the seat frame. Don't know if you are familiar with jute webbing.... here are 2 pics:
1) Enlarge the pic by clicking onto it. Hopefully, you can see how it's attached at the ends.
https://www.flickr.com/photos/43836144@ ... ed-public/

2) The over lapping weave. You might want to align each strand right next to one another, rather than spaced.
https://www.flickr.com/photos/43836144@ ... ed-public/

Jute webbing is available at most fabric stores.

It looks like the padding on your chairs is thin. Probably 2 layers of cotton is sufficient.... or 1 layer of 1" foam and topped with a layer of cotton OR foam topped with 1 of cotton plus 1 of polyester (fiberfill batting). Your original padding should be about the best suggestion for any replacement padding, if need be.

Sonny

bettyrubble
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Re: mid-century dining chair – replace curved plywood seat

Postby bettyrubble » Fri Jan 19, 2018 3:01 pm

Thank you so much, Sonny.

I'll make a cardboard template of the seat bottom, and then I will try to pop in the 1/8" plywood. I will count on your experience that it will flex successfully. I will also take your advice to put in a second layer. If the seat bottom is a bit higher off of the frame, I don't think it will be a big deal.

Thanks for the detailed advice about the reupholstery part of the project. Whoever did these chairs last time put in a layer of cotton on the base, a thick layer (about 1") of dense foam, and then another layer of cotton. The foam is bevelled so that the edges taper, kind of like a knife edge, and the cotton is feathered out, both layers. The whole job appears (to me, at least) like a pro did it. Of course, I'm saving it so I have a template.

If I have trouble with the seat bottom, I'll go with the webbing. It will be worthwhile to order the proper tension tools when I get to that point.

I will report back on my results with pics once I've done one of the chairs. Thanks again!

AsonnyA
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Re: mid-century dining chair – replace curved plywood seat

Postby AsonnyA » Fri Jan 19, 2018 3:51 pm

You can easily make a webbing stretcher tool. Cut off the heads of six or seven 6D Common 2" long nails. Sharpen the tips of the nails, pin-point sharp, there abouts. Get a scrap board (good hardwood, like oak, hickory, ash, etc) 4" wide X 3/4" thick X 6"-8" long. Drill pilot holes 1" deep and about 1/2", or so, apart into one end of the board, such that the nails are held firmly in the holes (you don't want the pilot holes too big, that the nails sit loosely), then insert the blunt end of the nails into the holes.

You want about 1/2" of nail sticking out from the end of the board.

Punch the sharp nails into the webbing (you probably have to press the webbing, on each nail site, for the webbing to be poked through) and use a lever action to tension the webbing. Attach one end of the webbing, really well, then tighten the webbing using the stretcher.... secure the webbing while in tensioned position.

Sonny

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Re: mid-century dining chair – replace curved plywood seat

Postby AsonnyA » Fri Jan 19, 2018 4:09 pm

[quote="bettyrubble"]

> I'll make a cardboard template of the seat bottom, and then I will try to pop in the 1/8" plywood.

Fold some newsprint in half. Mark the front and back centers of the chair frame. Align (tape in position, if need be) the folded edge of the newsprint with the frame's center marks. Draw one half of the template and cut. The unfolded newsprint should be a mirror image of both halves of the chair frame.

Should you ever decide to tackle the upholstering of a contoured or curved head board, or the like, use this folding technique to produce a mirror image of the contoured profile. It's hard to draw the whole profile and both sides match. The folding technique makes for more perfect matches of contours, especially intricate contours.

Use your center fold/crease to align centers-on-centers of your ply panel, before cutting the profile (or centers-on-centers of your head board panel, etc., before cutting the profile).

Though chair seat profiles aren't hard to create all in "one drawing", practicing the folding technique might be a good learning experience for future use for other more complicated projects.

Sonny

bettyrubble
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Re: mid-century dining chair – replace curved plywood seat

Postby bettyrubble » Fri Jan 19, 2018 5:33 pm

Great idea with the half-template/folded newsprint! Will do!

Also, thank you for the instructions for making the stretching tool. I'm pretty sure I'm going to wind up making one--just so I have it.

Just because.

Some women compulsively acquire shoes; for me, it's tools.


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