|TOOLS: How to use 'em
Before diving into any repair job, please make sure your tools have
been blessed by the Electron Goddess. More than a few machines
make it to my shop with missing screws, loose screws and screws in all
the wrong places. Sound like a Country Song? Welcome to the TOOLS
The most common do-it-yourself error is using the wrong tool for the
job. The screws encountered on tape machines may look small, but
donít pick an undersized driver like the one shown in Figure One.
You might think Iím being silly, but itís not worth risking damage to the
screw or the driver. This is especially true of screws that have
been over tightened. Figure Two shows a driver with the proper
fit, which should be snug, like a puzzle.
Figure One: The Wrong Tool
Figure Two: The Correct Tool
The first rule of Phillips screw extraction it to press down on the
screw (with the driver) before turning. If you let the driver slip
out of the screw head once, the damaged screw may be near-impossible to
extract without surgery. On the left of Figure Three are two
standard Phillips drivers and on the right are two Posi-drivers.
Their shapes are unique, Posidrive types being common in British-made gear.
Figure Three: Variations on the Phillips Theme
The yellow arrow points out the tip damage. This is as much a
fault of the driver (the metal its too soft) as it is abuse. Spend
a little extra money on better tools. Itís worth it. A sticker
on the side of a cash register at Dale Electronics says, "Good things are
not cheap. Cheap things are not good." Itís sad to see cheap
grab-bag tools after theyíve been used to poke holes in sheet rock.
Please donít use those on your audio gear.
MA SHEENíS CREW
Figure Four: A Nice Set of Threads!
|Notice the fine threads of Figure Four. (You were expecting
maybe a suit?) Three are classified as machine screws because their
fine threads come in handy when trying to make precision adjustments.
ISO sizes are metric-based while SAE types are referenced to the American
system of measurement. For example, a 10-24 screw has 24 threads
to the inch.
||DOT's THE TRUTH
Modern metric screws have a "dot" stamped on their heads. The
screws in Figure Five to the left, are "mated" with a "screw
checker," which is a handy gauge for sorting unknown sizes. The worst
case of cross-pollination is when an "American Standard" screw ends up
in a foreign product. If this sounds like a toilet bowl youíve once
worshipped, keep that idea. ISO and SAE are not compatible.
Thatís the one thing both types of machines screws have in common, although
most times, youíre likely to see a chassis tapped to accept a machine screw.
This is why, if a screw resists turning, you should reverse direction and
try again. Donít force the issue, in fact, avoid using power tools
because they can quickly get you into a jam. Screw material is soft;
using force will break the heads right off.
The odd screw in Figure Four is designed to mate with raw metal.
No nuts required. There may even be a little resistance to re-threading,
at first, but thatís normal only for sheet metal screws. Now you
know how to keep your hardware in order.
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