I have just bought a quite hefty amount of what i think are very early 3107 chairs in teak.
They have a large metalcap that is stamped with "FH" in a circle and "DENMARK".
The unusual thing is that the cap is very large and also is fastened with small nails.
There are also some other things i have not seen before on 3107 chairs and that is a metal rod with black plastic endings and also small arms that you can pull out and hook up several chairs together.
I believe that the metalrod is for when you staple many chairs it provides some separation.
Also the shockmounts are a little different in that they have an opening in them in the part that faces the floor.
The ones i have seen on other early chairs have been solid.
There is no sticker with a date on any of the chairs so i suspect that there never was one.
I believe that these are 50´s production, or very early 60´s but would love to know what you guys think. 
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You are right
The chairs with a metal cap pre-date the plastic capped chairs from the 60s. Also the hardware under the seat mean they were likely set up to be used as "ganging" chairs, meaning they could be connected side-by-side next to each other as in a school, church, or other public space.
Yes
They come from a museum so most likely were in lecture hall or similar where they could put rows of chairs together.
I think the plastic cups came in the late 60´s but there was one other smaller metalcup with a central screw before this one which is also larger than the one with the screw.
Does anyone have some input on how to repair small cracks in the plywood in the laminations?
The backs are not soft and cracked all the way through, just smaller cracks in the sides where the back meets the seat (the usual place for series 7 chairs).
I was told not to use wood glue but polyethuran instead but would love to hear any opinions.
More info
Found out some more about the chairs.
They are from 1958 so the third or fourth year of production depending on who you ask.
From what i have found out there were no FH stickers with a production date until ca 1962.
These early chairs have zinkplated bases instead of chrome and the metalcap on the underside is larger and fastened with nails.
Also the wood laminations are different with only three layers (not counting the veneer) with a thick middle core of wood.
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