Originally Posted by
merziac
"I am going to take a fine file and round the edges at the crack prone sharp edge at the spider. Stress relieving work both for me and for the crank."
This is/can be key, nothing better than finding a fatal flaw and being able to rectify it summarily out of hand, part or whatever in stock, tools, knowledge and capability to solve the dilemma without further ado = priceless.
I agree - blueprinting, modifying or just tweaking things, a engine or any mehanical part, is very satisfying and it can make a big difference.
This area of the classic Record drive side crank is known to fail. The sharp edges acts as a stress riser (this is difficult in English - not my native language), and the area is also challenging in the forging process, and as pedal power is applied cracks can develop. I have cranks that has been put thru elite and powerful cycling and nothing has happened and I have cranks that I have bought new and used myself that has failed. It is a area that has to be checked regularly.
Here I have started to smooth the sharp edge (green arrow).
Apart from stress relieving the drive side crank I also measured the spider, the five arms, for any wobble. I had to correct two of them a little to get the rings to go perfectly straight. This is a practise I have done for many years and I would not recommend doing it if not absolutely sure about what to do and how to do it. Got to have a "feeling" for the material and what force to apply. Not for the faint of heart.
Today I also checked my pedal supply. I found a pair of almost unused Record pedals of the right version for this build. Side strap loop and metal dust cap. Bearings perfect. But they have French threading.
Not a big problem as I also found this pair of SL pedals with shot cages - but with perfect bearings. As the only difference is the axle the conversion will be easy.
This is fun! Looking forward to tomorrow already.