Hand-Filing

Chain modification with a file guide and round file is essentially the same as with a grinder, but when modifying by hand, I file a 45° hook on each cutter instead of a 50° hook. This is because the round file leaves an edge that is hollow-ground if the hook were filed to 50°, the cutting edge would be weakened. 

When hand-filing in the shop (and especially for initial chain modification), I prefer to hold the chain in a small machinist s vise, rather than to file while the chain is on the bar. (When sharpening in the field, when the chain is on the bar, I mount the bar in a holder made especially for field work.) With a square, draw a line 90° across the jaws of the vise, then mount your chain. Position the file guide flat on top of the first cutter, touching the depth gauge, and keep the guide parallel to the line (2.  

As you modify your chain, measure the length of the top plate of the cutters to make sure that they are all exactly the same. You can use a crescent wrench or caliper for a gauge. 

It s a good idea to rotate the file in the guide slightly as you feel it start to dull. At least two files will usually be necessary to modify one chain. Never use a dull file to modify or sharpen chain—it s a waste of time. 

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Use a lathe or hand file to turn 3/e" of the length of the shaft collar to slip inside of the tube (about lVB"0D).The remaining Vs" shoulder should be left Ih" OD. (See figure one). 

Turn or hand file the front shoulder of the bushing, the outside of the en-capsulator and the threaded portion of the end wipe to allow these pieces to slip into the 1.5" ID front tube. 

In all fairness, in a survey of machine methods which are in operation, those abandoned because of dissatisfaction should be included. Ashthorpe (2) describes difficulties encountered at the Atomic Energy Research Establishment in Harwell. After two years in operation and the accumulation of 6500 Hollerith-type cards, the installation was abandoned and a multiple file of visually located index cards was established. The punched-card installation was completely dependent upon a single file of punched cards arranged in random order. It was impossible to ascertain how a document previously coded had been indexed without resorting to the punched card file. In almost all operations now used, supplementary hand files permit the rapid location of certain specific information. Ashthorpe gives an excellent description of the difficulties and frustration which may come from too complete dependence on a single punched-card file. It is a very instructive article for those embarking into the mechanical field. 

A bench grinder is handy to smooth out burs on the edges of cut tubing, but a hand file can also be used instead. 

This file has the same section as a hand file but of a thinner section. It is used for narrow slots and keyways. 

Make from 1.5 mm brass sheet, bevel edges of slot from side with pin to leave sharp edges of dimensions shown on other side. Hand file outside edges as necessary for snug, sliding fit in groove of cell holder. Blacken with dull enamel or ink. 

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