Reply To: Hamilton 926 Tear Down

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chris mabbott
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I place two finger tips around the end of the punch tip so that it prevents any slippage that may occur, but normally there is no slip, and also because I can feel when the rivet begins to move and so reduce my tapping a little.

I use many small gentle taps rather than a few heavy blows, I just found that this way seems to work better and gradually weakens the rivet, we don’t want to damage the hole for our new staff..

You can see in this shot how little material is actually holding the staff in place, and how much material is preventing the hole from being damaged, before the rivet.

It reminds me of large motors that would seize up due to some failure, some of them react violently and actually break their mounting bolts. The bolts would shear off before the motor feet would break, due to differences in construction and shearing forces..
The staff is really no different, we have a difference in material construction, material thickness, and we have a shearing force that is vertical, instead of lateral.
When a staff is peened into place, the rivet is never perfectly flat, it should be, but isn’t. There is always one spot of the rivet that is thinner or weaker, and this yields first as you can see here, it isn’t a problem because now we can reduce our tapping to gentle blows and the staff will fall out easily at this point.

You can see in this shot that the main part of the rivet has sheared off, and a small piece is left to follow the staff, without causing damage to the hole. We still have a nice, sharp edged, well formed hole for our new staff.

chris mabbottReply To: Hamilton 926 Tear Down