Nakago-ana Cutouts ?

[Kanenaga]

Rather than hijack another discussion, I borrowed this partial photo from another thread just for illustration. And please dismiss me if this has been discussed before.

 

It's about the double cutouts around the nakago-ana in this tsuba, which create a "figure 8" shaped cavity. I see this from time to time, most often on Owari-sukashi tsuba but occasionally also on other iron sukashi tsuba, always on one side only. It's not clear to me that these chiselings alter the dimensions of the nakago opening itself. Does anyone know what these are for?

 

[lonely panet]

these CUT OUTS  are in fact areas of the tsuba that have been punched in to fit the blade.  over repeated mountings occuring the more the depressions grow might be called tagane in akasaka tsuba maybe.

 

if there was a soft metal insert they would be called sekigane and they would be modified to fit the blade rather then the body of the tsuba

[Dan tsuba]

I agree with Kanenaga when he stated-

"It's not clear to me that these chiselings alter the dimensions of the nakago opening itself."

The only thing that alters the dimensions of the nakago-ana is the added sekigane (my opinion).

Now, I don't know what that means.  But it is interesting. 

[FlorianB]

I think I can see the point. You’re wondering about where the material has gone.

 

If You punch down the areas in question the metal is expanding to the inner space naturally. This rude hammering isn’t sufficient alone to get a correct adjustment to a tang.

So after the hammering the inner sides of the nakago-ana are filed down again to get on the one hand the favoured fitting and and on the other hand smooth inner walls of the nakago-ana. 

 

At least by this filing process a part of the metal is lost indeed. 

[FlorianB]

One rare example where You can see the punched down iron (from E. Kremers book)

 

[Spartancrest]

To confuse the matter, even when the tagane-ato have been punched and spread the metal into the nakago-ana in order to fit a particular blade, it is also possible that the metal could be filed back in order to fit a THICKER blade. This will result in heavy tagane-ato marks but little to no metal spread into the hole. Fitting a tsuba to a new blade therefore works both ways.

[Spartancrest]

late reply - this shows some "extreme" tagane-ato https://www.slam.org/collection/objects/8666/    The tang of the blade would be very thin unless it represented fullers?