copyright 1997 
by
Eddie Ciletti

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 page! 

ERROR

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 don’t pick an undersized driver like the one shown in Figure One.  You might think I’m being silly, but it’s 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.  It’s 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."  It’s sad to see cheap grab-bag tools after they’ve been used to poke holes in sheet rock.  Please don’t use those on your audio gear. 

MA SHEEN’S 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 you’ve once worshipped, keep that idea.  ISO and SAE are not compatible.  Nuts! That’s the one thing both types of machines screws have in common, although most times, you’re 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.  Don’t 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 that’s normal only for sheet metal screws.  Now you know how to keep your hardware in order.

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