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The Flat Lap
This
is part two of a series on vibratory and rotary flat laps. Click here to
check out the beginning of the series, which deals with vibratory
laps.
The rotary flat lap is a machine that
rotates an abrasive disk. The disk is usually coated with
diamonds on the top surface, and has a magnet on the bottom.
The magnet is used to attach the disk to the rotating steel wheel of
the flat lap. The magnet allows the disks to be fairly quickly
changed from once size grit to another,
eliminating the need for multiple machines (as is typical with
vibratory laps).
Since the disks tend to be diamond coated,
they are more aggressive than the silicon carbide or aluminum oxide
slurry used with the vibrating flat lap. This means that they
can get the work done more quickly, but it also means that disks are
expensive. Prices start at around $100US for a fairly small
disk, and prices of $500 and up are not unusual for larger disks.
To use the rotary flat lap (also called a
"lap wheel"), the appropriate size disk is first mounted on the
machine. Water is used as lubrication (for some stages a
slurry of water and a polishing powder is used). The portion
of the glass desiring to be ground and polished (usually the base or
an edge) is brought into contact with the spinning wheel. The
glass must be held in place until the contacting surface is ground
flat. As with most grinding/polishing activities, this process
is repeated with finer and finer grits.
A rotary flat lap costs from just below
$1000US to several thousand dollars. In addition to the lap
wheel, you must also invest in several grits and sizes of diamond
coated abrasive disks.
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Copyright 2006 Brad Walker.
All rights reserved.
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