Removing a damaged capscrew
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1. Drilling crosswise through the head of an obstinate capscrew in the barrel of the Biocut 2030 microtome. The drill diameter is approximately equal to the depth of the socket minus clearance from the end of the screw head. In this case a 2.2 mm hole is drilled in a M4 screw. Locate a center punch mark carefully. A preliminary small pilot hole helps to prevent the drill from drifting off center.
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2. The damaged M4 cap screw and an aluminum socket with 7 mm bore. A 2.2 mm hole has been drilled through screw head and socket. Also a 3.4 mm hole through the socket to fit a 3 mm hex key as lever.
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3. The four parts assembled to illustrate.
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4. With the socket pinned to the screw and a 3 mm hex key as lever, the obstinate screw is loosened.