Answer: The correct way to arrive at the proper diameter for a pinion is by mathematics, however, you asked for an easy method and one that is practical so the following formula will prove helpful and satisfactory for all practical purposes.
The full diameter for a 14 leaf pinion should equal the distance of 6 teeth from point to point on the driving wheel. For a 12 leaf pinion, the diameter for pinion should equal the distance from tip to tip of 5 teeth. For a 10 leaf pinion, the diameter should be 4 full teeth. For an 8 leaf pinion, the width of 4 teeth measured at their points deducting 1 space. For a 6 leaf pinion, the distance of three teeth measured from the point. If these measurements are carefully followed, the pinion will be usable.
RHY: What kind of grease is used to keep moisture away from crown and stems in waterproof cases?
Answer: Riggs Gun Grease is used to pack in the pendant and around the stem. It also acts as penetrating oil when the steel parts are badly rusted.
JC: Recently I purchased a package of diamond dust, expecting to use it for resurfacing and polishing pitted cap stones. I find the powder too coarse. Is there anything anything I can do to take out the coarse powder?
Answer: Procure five small glass vials of about 1 ounce 'capacity, mark vials from 1 to 5. Fill dial No.1 with clock oil and thoroughly stir diamond powder into clock oil. After ten minutes pour off the oil into bottle No.2, allowing that to stand 45 minutes, repeat and pour off into bottle No.3, allowing it to stand 24 hours. Repeat and pour oil into Bottle No. 4 allowing it to settle for 24 hours and finally pour remaining oil into bottle No.5 and allow to settle until clear. You will now have 5 grades of diamond powder. No. 3 and No.4 for fast cutting and No.5 for polishing.
ECB: Please explain the use of different watch brushes, at what stages are they used, purpose of each brush and cleaning, of bridges and cases?
Answer: As a rule the watchmaker is equipped with three grades of watch brushes, fine, medium and coarse. The fine brush may be used for brushing sawdust or other fine lint from train wheels or plates of the watch that has passed thru the sawdust method of drying. The fine brush may also be used for dusting the dial without danger of damaging the hands. The medium brush may be used for brightening the watch plates that may be spotted or slightly tarnished, especially after the cleaning solution has failed.
By charging the brush very lightly with rouge, a vigorous brushing will brighten the plates. The balance wheel can also be greatly improved by using the brush charged with rouge. A stiff brush can be used for brushing and brightening cases or bands. This brush should also be charged with rouge. A stiff brush is also used for brushing clock plates, wheels and pinions, using naphtha for solvent.
It is suggested if you are using new brushes that the bristles be run across some rather coarse sand paper so as to take the sharp corners off the end of the bristle, or the brush may be run across the sharp edge of broken piece of glass, which will serve the same purpose.
PD: How can I true a solid balance wheel in the flat. I seem to have more trouble with solid balances than the cut balances.
Answer: When trueing a solid balance in the flat, the first move is to check the level of both arms. If they are not of the same level, bend the arm up or down until you get desired results. Check the rim between the arms. If they are not of equal height, carefully twist the arm until the rims are level. When twisting the arms, care must be taken that you do not bend the arms up or down throwing that section of the balance out of flat. With a little practice, you will soon accomplish and conquer what may seem like hard jobs, when in reality it is very easy compared to the split balance.
MEC: You ask if the only way to bring the dial position and pendant position to correspond in a wrist watch is by shaping the ends of the pivots.
Answer: There is a limit to how much time you can alter the rates by altering the balance pivots and in many of the small watches the balance pivots are quite large, consequently showing a fast rate in the pendant position over the dial position. By flattening the ends of the balance pivots, you will increase the dial position, however, there are times when the balance pivots are so large that you cannot control or bring the two rates close together, unless small pivots are used which would then give you a slower rate in the pendant position which would compare favorably to the dial positions. Many of the factories deliver their watches with a tolerance of a minute to 1 1/2 minutes plus or minus in 24 hours.