ETX TECHNICAL TIPS Last updated: 23 November 2003

Possible cure for rocking motion at front of ETX125 new model OTA

Sent:	Sunday, November 23, 2003 13:53:01
From:	wes.trimble@sympatico.ca (Cecily & Bud [Wes Sr.])
I was trying to figure out what would help eliminate the slight rocking
motion at the front end of the OTA  on the new model 125. Here is the
method I used to completely eliminate the motion with the dec locked on
mine. Im not saying it will work on all, and anyone trying this does so
at their own risk. I do not accept any damage incurred by using these
instructions.

List of Materials:           
2-McMaster-Carr part #6077K16 Polished aluminum knurled-rim knob without
handle, 3 diameter Solid hub.
2- 1 long brass socket head cap screws 10-24 thread. 
1- Red permanent type Lock Tight- Could use blue also.

In a drill press. Lock the knob upside down so the small end is up. [Pad
the polished surface that is in contact with the drill press vise.

There is a small dimple in the exact center of the small diameter boss
that is facing up. Drill completely thru the knob with a drill that will
accept tapping threads for the 1 10-24 cap screw above.

Turn the knob over, relock in drill press vise, and counter bore the
hole thru the knob with a 1/.4 drill to a depth of 1.

Using a 10-24 tap locked in the drill press chuck,[[[DO NOT TURN ON THE
DRILL PRESS}}}, to make sure your tapped hole is  square to the hole,
put slight pressure in the spindle control, and with the other hand turn
the chuck while maintaining a slight downward pressure on the
handle.{{{PLEASE PULL THE PLUG ON THE DRILL PRESS BEFORE STARTING THE
TAPPING PROCEDURE}}}.

After the hole is tapped and the threads are cleaned, start threading
the brass socket head cap screw into the knob with an allen key. Before
all the threads disappear into the counter sunk hole, apply  2 drops of
Locktyte to the upper threads and continue  to screw it in until it
bottoms in the hole. NOTE: as the head starts to enter the counter bored
hole it will get snug because both the hole and the cap of the screw are
both .

When finished the 10-24 brass screw will be protruding about . Let the
locktyte set up and do the same with the other knob. When both are
ready, remove the locking discs one at a time and replace with the new
knobs. NOTE: these knobs will lock down the dec circles and dec clutch
with very light tightening with two or three fingers.  DO NOT
OVERTIGHTEN<, REMEMBER THE THREADS ARE BRASS.

When snugged up, all the movement at the end of the tube had all but
disappeared, so I can only assume that the rocking motion was caused by
insufficient clamping pressure. REMEMBER, PROCEED AT YOUR OWN RISK.

Wes [Bud] Trimble
Toronto
Canada

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