1 May
2003
1 May
'03
5:54 p.m.
--- Philip Pemberton <philpem(a)dsl.pipex.com> wrote:
If someone wants to send me one or two plotters with
bad drive gears,
I'd be willing to have a go at repairing them. My technique involves
repairing the damage with Araldite (epoxy adhesive - sets rock hard)
and then putting a small (#10) staple in across the damaged section.
I have a number of NOS plotter engines with nearly all (pre) cracked
gears. I will be happy to loan you one, but I think you will find that
your technique is not suitable for such a small gear. The diameter of
the staple wire is about the same as the thickness of the plastic
between the bottom of the groove and the bore. There are two gears
per engine - X and Y. Same size. Same problem. One on the left,
one on the right.
I have used similar techniques (with success) fixing Atari joystick
actuators (I used to get the joysticks for free from overenthusiastic
friends with 2600s)
You would have to get the plastic to mate up rather closely where
the crack is - the "problem" is not that the shaft slips in the broken
gear; it's that the gap causes the gear not to mesh with the driven
gear and the gear train binds, preventing X or Y motion.
I'd be tempted to take a few 10ths of a mm off the
inside of the hole
for the shaft that the gear fits onto. If they're cracking, the shaft is
probably too big for the hole. Enlarging the hole very slightly should
reduce the pressure a bit and hopefully make the gear last a few more
years that it would have done if it were not modified.
The shaft diameter is 1/20" (1.27mm). If you enlarge the bore by
7%-14% (one or two tenths of a mm) off the inside of the gear, it will
freewheel and fly off the shaft then get lost in the carpet.
I have some closeup pictures I can e-mail to someone (no ftp access from
the machine they are on) :-( The relative sizes of the gears are
visible, as are the cracks.
-ethan
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