By W. H. SAMELIUS
P.W.A.: - I have been instructed to carefully true compensated balance in the round and poise them. When this is done, I find on returning to work the next morning, after the shop has been cold all night, that the balance is out of round. Should I true such a balance again after assembling the watch?
Ans: - A compensating balance can only be trued and remain so at one temperature. If you true the balance at 70° F and leave it on the bench overnight to get cold where the temperature probably dropped 20 or 30 degrees you will find the balance rims have moved outward and the balance out of round. In other words, the brass rim will have contracted more than the steel rim and the cut ends of the rim will extend beyond the length of the arms. You will note that as soon as the room temperature has increased to the same temperature as when the balance was trued, it will become true again, or back to its normal form.
B.S.: - How can I make a simple cement for patching broken porcelain watch dials?
Ans: - In a clean vessel, dissolve pure white wax and mix with an equal amount of zinc white. When cold, the cement can easily be pressed into the broken places in the dial. Heat the dial slightly to make the cement flow and adhere to the surface. Cleanliness in mixing and a little heat will contribute to the production of a very white wax.
JR.L.: - I see in the late Elgin Catalog and bulletins, an announcement of a patented grooved balance staff which has been introduced. Without a doubt, this proves to be a valuable timesaver for the man at the bench.
The fact that the new staff can be driven out and not injure the balance wheel and that a new staff can be staked to the wheel, leaving the wheel perfectly flat, so no or very little truing is required and that the balance will remain in poise, is a great step forward, but how can I distinguish the new staff from an old staff when a watch comes to the shop for repairs.
Ans: - The difference between the regular model staff and the new model grooved staff is that the waist, or hub on the regular staff is tapered, where the new model staff has a straight hub.
P.D.: - I am having trouble in attaching gummed paper printed clock dials, so the dial will stick and stay flat and smooth and not peel off after a few days.
Ans: - The surface of the metal dial must first be prepared by removing the old paint with paint remover. Thoroughly clean the surface by using coarse sand paper. Wet the gummed side of the dial with a cloth and when ,Nell moistened, attach paper to metal disc laid on flat surface, then with pads and weights, hold the dial down tight until dry. You will then have no further trouble.
E.L.O'B.: - Would like to know what causes the cannon pinion to raise up off center post, no matter how tight the cannon pinion is put on?
Ans : - This question is often asked and the illustrations show the causes for cannon pinion raising.
Figure No. I - shows center post tapered at the lower end so when cannon pinion is applied, it will have a tendency to raise upward and become loose.
Figure No.2 - shows center post of equal diameter from top to bottom but with the groove slanted upward instead of downward toward the base of the arbor. A cannon pinion fitted to this center post will also cause the cannon pinion to climb up and become loose.
Figure No.3 - shows center post of equal diameter from top to bottom with the groove so shaped that when the cannon pinion is attached, it will have a tendency to work downward and remain on the post. When fitting a new cannon pinion, make sure the pinion fits freely down to the shoulder of the post. Then by inserting a brass wire in the hole of the cannon pinion, placing the cannon pinion in a V stump and with a center punch, make a small indentation or bulge that will come just below the groove of center post, as indicated by arrows.
Occasionally, we find a cannon pinion, after being placed on center post, that has a tendency to turn rather hard. This may be due to a rough hole in the pinion or rough surface on center post. In such a case, it is permissible to lubricate the center post.