Schoenner drafting set

[WesPete66]

Being a draftsman, I have a fondness for the tools of that trade. I recently purchased a drafting set which is labeled "Schoenner" and "Germany" (not West Germany). I find references to Georg Schoenner having gotten patents for his hinge design on the compass & divider assy's in late 1800's, and his company in business until WW II. I'm amazed at the precision of these pieces. Even at their age they still operate smooth as can be (while the case is ragged). They make my own "modern" set, purchased in the 1980's, look like trinkets!
I would like to give these tools a proper buffing/polishing after dis-assembly, but am having trouble with the hinge assy of the dividers. The knurled knob remains centered at any position of the arms, even with the screw & knob removed. Something still holds the hinge together. Has anybody ever taken one of these apart?

 

[Reddinr]

I was given that set by my grandfather when I was a pre-teen. Except for the divider although it is rusty, I think it ended up in the attic of my family home that sold years ago and lost with the rest of the odds and ends. I still have the compass. It was a very nice set. I don't have the right tool to take the round nut off or I would give it a try. Mine is secured by a button-head nut with two tiny slots, like an interrupted slotted screw.

It looks like the u-shaped piece should just pull off. Maybe there are small flanges on it's inside surfaces?

 

[WesPete66]

It looks like the u-shaped piece should just pull off. Maybe there are small flanges on it's inside surfaces?

Yes, that is correct as it turns out. The hole through the "yoke" is flanged or swaged to the inside to lock & align the parts together. I did get it off by gently prying it apart just enough. But now the yoke is flared out, prob a poor choice! I'll not try that on the compass, just clean it best I can.

Reddinr, it's too bad that your set got lost.