Re-using a chain pin/rivet

[silva]

The level of detail makes that a very interesting post.
Basically it could be seen as the "price" of wanting a narrower chain in order to get more gears.
From a mechanical viewpoint, a weakness due to less material withstanding a same force.
A countersunk connection implies less material than a protruding one.
Abit the same story as the 15t version of a brake disc bolt on rear cog for fixed gear, due to common hexagon bolt heads voiding space that the chains links need to engage, countersunk bolt heads and corresponding drilled holes in the cog are used, which also lowers the force required for a rip off.
Still I wonder what actually happens in the case of peen not breaking off - the case of < 9 speed, when a pin is pushed out (chainbreaker). Basically it's pushing a thing through a hole that is too small for the thing. Somethings gotta give (by deforming). But what? Pin, plate, or both? And is that deform temporary (elasticity) or permanent? The production-peening is certainly permanent, but the applied force could be the reason.
Steel is hardened. Hardening comes at the "price" of a reduced elasticity in the hardened part (surface). Does the hardening degree (depth-"case depth") of pins differ from that from plates? I gave a hammer blow on the pin end that I pushed forth and back. I didn't notice something visual in both before and after (pushing pin forth and back and hammer blow). But the difference may have been below visual recognition.

 

[Yellow Saddle]

The level of detail makes that a very interesting post.

Thank you.

Basically it could be seen as the "price" of wanting a narrower chain in order to get more gears.
From a mechanical viewpoint, a weakness due to less material withstanding a same force.
A countersunk connection implies less material than a protruding one.

No, it implies more, in this case.

Abit the same story as the 15t version of a brake disc bolt on rear cog for fixed gear, due to common hexagon bolt heads voiding space that the chains links need to engage, countersunk bolt heads and corresponding drilled holes in the cog are used, which also lowers the force required for a rip off.

I'm lost, but it doesn't matter.

Still I wonder what actually happens in the case of peen not breaking off - the case of < 9 speed, when a pin is pushed out (chainbreaker). Basically it's pushing a thing through a hole that is too small for the thing. Somethings gotta give (by deforming). But what? Pin, plate, or both? And is that deform temporary (elasticity) or permanent? The production-peening is certainly permanent, but the applied force could be the reason.

Both the pin and plate deform elastically. Steel is amazing and people find it hard to visualise it deforming in such a way.

Steel is hardened. Hardening comes at the "price" of a reduced elasticity in the hardened part (surface). Does the hardening degree (depth-"case depth") of pins differ from that from plates? I gave a hammer blow on the pin end that I pushed forth and back. I didn't notice something visual in both before and after (pushing pin forth and back and hammer blow). But the difference may have been below visual recognition.

Hardening doesn't come at the price of reduced elasticity.
Hardening simply moves the yield point upwards. In other words, it still remains soft and elastic, but doesn't deform until a higher force comes to play.

 

[silva]

Thank you.

1) No, it implies more, in this case.

2) I'm lost, but it doesn't matter.

Both the pin and plate deform elastically. Steel is amazing and people find it hard to visualise it deforming in such a way.

3) Hardening doesn't come at the price of reduced elasticity.
Hardening simply moves the yield point upwards. In other words, it still remains soft and elastic, but doesn't deform until a higher force comes to play.

1) Countersinking removes material. It's a conical in the 3D, a triangle in the 2D, link plates material is halved relative to a riveted (protruding) pin.
2) To make clear, and for what it matters then: http://www.velosolo.co.uk/shopdisc.html "15t Disc Cog".
3) Elastic but doesn't deform until higher force, doesn't that equal a loss of elasticity? It's like blocking a deformation until breakage.

Addition to 1) some confusion (protruding versus riveting), what precisely did you mean with "riveted"? I was talking about a peened pin end being a protruding pin end that received a blow that deformed two sides (the lines) to beyond the cross section of the pin, thus preventing the pin from going through the hole (from that side).
This could be called "riveting" too, but with a countersunk hole in the plate, the pins end is deformed in a same conical (with some roundings) shape as the holes countersunk.
The material/strength (and wear) comparison is thus between that conical shape versus the combined parts of the peened end that prevent the pin from going through the hole.
I think it's gonna need a 3D spherical calculation to find out that.
Also, it is possible that formation of the rounded-conical shape causes local weakening due to bigger deformation than the one of the peening.
For what it's worth, it's the whole that counts, and that is not so easy to determine. Maybe there is some study out there on this particular subject.