Adjustment Procedure for the Mod X Vibroplex
                                      By Frank Geisler.

As far as I know, nothing has ever been written on how to properly adjust a Mod X Vibroplex.  I hope you find the below adjustment procedure helpful. 


Following the above diagram numbering:

#1 Dash Side Spring Tension, turning in -- increases dash tension.
#2 Dash Lever,  dash lever pushes on leaf spring contact to produce a dash.
#3 Dash Lever Contact Spacing Adj Screw, set so that at idle the dash lever isnt touching the leaf spring contact.   About 1/64" spacing.
#4 Dot/Dash arm left stop screw
#5 Dot/Dash arm right stop screw
#6 Dot Side Spring Tension Adj Screw.
#7 Dot/Dash Contact Post (adjusts the spacing to the contact leaf spring)

A. Set  Right Stop Screw (5) so that the dot/dash arm is along the centerline of key. 
B. Set the damper wheel so it just touches the dot/dash arm.
C. Set the Dash lever contact spacing adj screw (3) so that the dash lever has about     
      1/64" clearance from the leaf spring contact.
D. Set the Left Stop screw (4) so that the leaf spring contact has a travel of about      
     1/32" or more to the dot/dash contact post.
E.  Set the Dash Side Spring Tension (1) so that the Dash Lever (2) has enough
tension to push it away from the leaf spring contact.    You will fine tune this tension later.  The more spring tension you can tolerate, the better.
F. Set the dot side spring tension adj screw (6) so that the dot/dash arm has proper
tension against the damper wheel.  You will fine tune this spring tension later --so that the key produces proper high quality dots.  The more tension you can tolerate, the better.

The adjustment procedure for the Mod X is more complicated than other keys due to the way all the adjustments interact.  The spacing between the leaf spring contact to both the dash arm and the contact post is critical to produce dots with no stutter.   On one of the Mod X keys I found  someone had replaced the leaf spring with a heavier more rigid leaf spring.    The long leaf spring spring tension is a big part of the dash side tension.  So the modified Mod X with the very stiff leaf spring was incapable of producing good code.   To reduce the leaf spring tension I cut off half of its surface area.   That key now produces quality code.  Dot stutter is when you occasionally get an unwanted half dot.  "Dot stutter is the bain of speed keys" ((( 
Send code with the key and experiment with the contact spacing that produces the best code.  There is a very narrow range of adjustments that end up producing high quality code.  Fine tuning the spring tension adjustments for best code.  
 If you dont have the adjustments set up correctly, the key can become very awkward to send with.    

While I was fine tuning a 1914 Mod X, I had to place some 3M double backed tape around the damper wheel to improve the damping.    I wasnt able to produce stutter free code without using the 3M material to help damper the dot/dash arm motion.  The below picture shows the 3m material around the damper wheel and I also equipped it with a speed control weight arm to allow better control over the dot speed.   Before placing the 3m double backed tape over the damper wheel, lock the wheel in position by tightening the lock nut at the center of the wheel.  As shown in the below picture.
The idea is for the 3M material to absorb the motion of the dot/dash arm.   I've tried many other types of materials such as cork, vinyl, sponge rubber etc.. But none of them worked as well as the 3m material placed on end.  

  
 Here is a picture of this 1914 Mod X in its original Oak wooden carrying box.  The box is dovetail contruction and has a fitted cover that slides in place.   This particular Mod X has had very little use and has been well taken care of over its life.  No sign of rust and the decal is still in good shape.

 If you have any questions about the Mod X, feel free to contact me
at w7is@aol.com . 
I own a number of Mod X keys dating from 1911 until the production ended in 1920.
When they came out with the new and improved Mod X.   I personally didnt find it much of an improvement and that might be why production was halted around 1921.  Although around the same time Vibroplex changed the design of the Original style keys to a bent lug pivot rather than the pinned pivot dash lever.   

Frank   W7IS