By JACOB L. HAGELOW
ALTHOUGH this job is not an everyday occurrence, the man at the bench will, however, find it necessary from time to time to make a barrel cover. How often does he, after having supposedly made all necessary repairs and cleaned a watch, find upon reassembling same, that the cover on the barrel will not hold tight? True enough a barrel contractor often does the trick. In many instances though, results are obtained that are not satisfactory and the only alternative is a new cover.
Before work on this cover is started, inspect the recess in the barrel to make sure it is in good condition. Most likely you will find it rough or worn, which, of course, must be corrected first. This can be done by cementing the barrel with the recess for the cover out, on a cement chuck. Care must be exercised to get same to run true in the round end flat. Good results can be obtained for this operation by holding a pointed peg wood in the hole for the arbor and on the tee rest, and with the lathe running at a fairly good rate of speed. With a graver then it is an easy matter to recut the old recess, slightly on a taper inward to insure a snap fit. The cover then is made to fit this new recess.
In measuring for this cover as is shown in the drawing, the first dimension that is needed is the total outside thickness of the barrel or the A measurement. Now we must have the thickness of the lower boss and the barrel arbor, or B plus C respectively. A then minus B plus C will give us D, or the upper bearing. The depth of the recess is then measured for the E dimension, and this subtracted from D will give us F, or the height of the boss. To give the barrel arbor endshake, deduct about .03 millimeter from the height of the boss.
Now that these calculations have been made, we can proceed with the work. Rough out a brass disk large enough for the cover and slightly thicker than is the cover plus the boss. This is then cemented on a cement chuck and faced off flat. The stock is then cut back the F measurement, leaving the boss slightly smaller than is the diameter of the arbor.