Back to servicing.
Started this week with a quick refresher servicing the ETA 6498 to get back into oiling, etc after burnishing and polishing.
Then it was an introduction to the last couple of skills we need for the upcoming gear train exam. First of all we had to learn how to adjust the tightness of the cannon pinion. This is extremely important as this pinion acts as a slipping clutch, holding the minute hand during normal running and slipping around the centre wheel arbor when setting the time.
Adjusting the cannon pinion is a fairly primitive procedure for such a precise operation. Tightening involves placing the pinion between two chisel-shaped jaws and hitting the top one with a hammer to pinch the pinion. Loosening involves broaching it out from the inside. It’s tricky but possible. I proved it!
Secondly, we learned the methods used to precisely shorten the winding stem and then fix and true the crown. Strong side cutters and an India stone sort the stem out, a leather mallet takes care of the crown.
Those tasks completed successfully, we had our first mock exam on the gear train. We each received a brand new movement, case, dial, hands and crown. One of the instructors had previously bent wheels and misaligned jewels in the movement. The exam set an 8 hour time limit to disassemble the movement, correct any faults, clean, lubricate and assemble the movement and then fit dial and hands, case up and fit the crown and stem. The first time I had ever carried out the complete procedure.
I’m pleased to say, I passed with flying colours. A few things to be improved upon but that’s what mock exams are for.
A very productive week and one that I thoroughly enjoyed. I could do this for a living!