All tools are forged from carbon or alloy steel and must receive proper care to ensure long life. When a tool has failed to give satisfactory service, visual inspection may give a quick answer to the cause.
Examine the cross section of the steel at the point of fracture and observe the grain structure which will very likely appear similar to one of the following three examples:
The normal structure is not disturbed but a thumbnail crack has developed from the outer surface. Fatigue develops from the prolonged use of dull tools or from undue prying or jacking while operating under full air pressure. If the proper tool for the job is being used, prying is unnecessary and harmful. This is not a manufacturing defect.
Smooth moon-like circle caused by some foreign substance being rolled into the bar. Very rare but replacement is in order.
Note smooth curved lines starting from outer edge and extending partly or totally across the surface sometimes leaving a coarse-grained area showing complete absence of fine grain (and thus absence of original hardness). This is the most common type of failure that usually occurs from 3" to 5" back from the point resulting from improper heating during resharpening. The comparatively soft area will not withstand the strain of continued service and breakage is inevitable. Replacement is not warranted.
Blade breakage following little use may develop from a hidden hardening strain. The fracture is usually semi-circular and discolored. Replacement is warranted.
This is caused by driving the point into a hard dense material for too long a period of time without penetration. This generates heat, softening the point, thus causing it to fold over. Discoloration, in a blue tone, is usually evident behind the mushroom. This is not a manufacturing defect.
Aside from the type of breakage, always check the tool to determine how much is worn back from its original length. The best way is to place it beside a new tool and note the difference in length and shape. If this is not possible, measure the length under collar and check with length shown in catalog. Tools showing considerable wear are not subject to replacement. Due to their high hardness most tools may be in use several hours before showing perceptible wear.
