42 Safety Turning Knob Crack

[siamackz]

In the process of restoring a Waterman 42. On dismantling the pen I noticed that the turning knob that operates the nib extension and retraction mechanism has a crack inside. See pics below:

 

I am wondering:

1. Do I need to fix this, or will it be fine once it is put back and held together by the bottom of the barrel anyway?

2. If I need to fix it, then what should I use? Can super glue work instead of loctite? Its so much easier to find, and cheap enough so that it doesnt hurt when the entire bottle dries up in a few days of opening it!

 

Thanks,

Sia

[artart]

For now the crack does not extend to the whole length of the knob, but, once the central shaft is put back and secured to the knob with the wedging pin, there will be hoop stress on the knob and with time the crack will eventually extend to the whole knob.

I think it's advisable to fix it, but it will work as it is for a while

[siamackz]

For now the crack does not extend to the whole length of the knob, but, once the central shaft is put back and secured to the knob with the wedging pin, there will be hoop stress on the knob and with time the crack will eventually extend to the whole knob.

I think it's advisable to fix it, but it will work as it is for a while

Will an adhesive actually keep it from cracking under such stress though?

[fountainbel]

Glueing will withstand the radial tension of the rod and the lengthwise pin in the filling knob in my opinion

The best approach is turning the part which sits in the barrel 1.2- 2mm off on its outside diameter and install a friction fitted hard rubber ring over the reduced diameter.

Francis

[siamackz]

Glueing will withstand the radial tension of the rod and the lengthwise pin in the filling knob in my opinion

The best approach is turning the part which sits in the barrel 1.2- 2mm off on its outside diameter and install a friction fitted hard rubber ring over the reduced diameter.

Francis

This makes sense, thank you Francis! I really need to get a lathe and start making repair parts already. Post this summer, for sure! Once I submit my Ph.D dissertation paper and get some of my life back !