Evolution of the Extendadot --- Dot Speed Control
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The Extendadot came about after many years of frustration trying to slow down the dots on speed keys. The idea was to distribute the weight along the dot arm equally. To balance the dot arm so that it can produce higher quality dots. And to also provide a way to extend part of the weight beyond the end of the key. Extending the weight further behind the key allows lighter weights to be used. If you load up the dot arm with heavy weights in an attempt to slow down the dots, the key can become clunky and awkward to send with.
The Extendadot has a nylon vertical upright at the end to provide a fast and easy way to change the end weight. The nylon upright will accept any standard Vibropolex round weight and even a Lightning rectangular weight can be threaded onto the 8-32 nylon threads if desired.
Its evolved into three basic designs.
1. The Original with the round dot arm
2. The Lightning with the flat dot arm.
3. New Sliding Weight Rod for round dot arms.
While trying to come up with an easy way to slow down the dots on the McElroy/TAC keys, I decided on a Sliding Weight Rod. The McElroy/TAC keys have a dot arm larger in diameter than the other vintage keys.
It can be made to fit any speed key from the Vibroplex, Les Logan, Johnson, McElroy. I have even made different versions for the Vibroplex Mod X.
The first Extendadots were made of brass and it limited the high speed dots to something less than 30wpm. The light aluminum version will generally allow higher speed dots in the 40wpm range. But it varies--depending on how stiff the keys main spring is. The older keys made before WW2 were generally fairly fast. While the keys made after WW2 are normally easier to slow down. The main spring stiffness varied from year to year. So due to the variation in the stiffness of the main springs, its just the luck of the draw on how fast your key will make dots. The general rule of the thumb is if you desire to send speeds above 30wpm with the Extendadot attached to your key, then it needs to be made out of light weight aluminum. The Lightning speed control body is made of aluminum while its sliding weight tube is made of brass. Pictured from left to right, Lightning, Original brass, Original aluminum. I'll post pictures of the new Sliding Weight Rod soon.
Contact me via email for additional info: extendadot@gmail.com
For speed key tests and more information on how to improve the keying of your speed key, go to this link.
http://speedkeytests.blogspot.com/
The new Lightning style speed control pictured above takes the place of your rectangular weight on the flat dot arm of your Lightning key. It provides for a sliding weight tube so that the dot speed can be controlled independently from the position of the body on the dot arm. This new design works very well to control the dot speed on the Lightning style keys.
Dot Stutter and How to Manage it
Dot stutter occures when your key produces an extra half dot at times.
Some keys suffer from dot stutter more than others. On keys that have little or no dot stutter, you will find that the dot arm dosnt flop around on the damper wheel. As the reason for dot stutter is the movement of dot arm as its being dampened. When your dot arm flops around on the damper, it just stands to reason it could add an additional half dot at times. & If you load up your dot arm with more weights in order to slow it down, you will notice dot stutter gets worse as the heavier dot arm causes the damper to move around more.
The best way to prevent Dot Stutter is to lock the damper in position and place 3M double backed tape around the damper wheel. A side effect of using the 3M tape is the key will then become almost silent as the 3m material absorbs all the dot arm motion. Another side effect of the 3m material is you be able to use a narrower dot contact spacing for sending higher speed code.
There are a number of ways to help prevent dot stutter:
A. Using a wider dot contact spacing
B. Increase the dot side coil return tension
C. Unscrew the right side stop screw further to allow the dot arm to contact the damper wheel more securely.
D. Place 3M double backed tape (on edge) around the damper wheel.
Using the 3m double backed tape fix provides the best defense against dot stutter.
1. Use a wider dot contact spacing. The wider the dot contact spacing, the less a problem you will have with dot stutter.
2. Sometimes increasing the dot coil return tension will help -- but not on all keys. Each key can have different keying characteristics due to the wide variation in main spring stiffness.
3. Another thing that can help is to allow the dot arm to hit the damper more securely. You can accomplish this by backing off the right side stop screw until the dot rod just touches the damper, then back off the stop screw another quarter turn. So that the dot rod hits the damper wheel more securely and dosnt allow it to flop around as much. Using 3m double backed tape around the damper wheel helps even more -- as in the next step.
4. You can find ways to dampen the dot arm more effectively. Such as placing 3m double backed tape around the damper wheel. As long as the dot arm contacts the 3m tape instead of the metal damper wheel, the 3m tape will almost instantly dampen the movement of the dot arm. I've found quite a few speed keys that could never be adjusted for decent code without using the 3M double backed tape fix. So today I use the 3M damping material on all the speed keys.
The type of 3m double backed tape is the Scotch 3M #314 used as mounting tape to hold items to walls. But any type of the 3m double backed tape would probably work just as well.
1. First,the articulated damper arm needs to be locked in position using a rubber band, string, dental floss etc.. On this key I used dental floss. The thin dental floss can slip under the damper post and become almost invisible. As shown in the below picture.
2. After you lock the damper arm in position with dental floss, lock the damper wheel by tightening its center screw. Then place some 3m double backed tape onto the damper wheel so that the tape is slightly larger diameter than the metal wheel. The side that contacts the dot arm can be cut flat so that more surface area contacts the dot arm.
With the 3M double backed tape in place, all the damping will take place on the surface of the 3m tape. The 3m double backed tape will almost instantly dampen the dot arm. Thus preventing dot stutter. It will also reduce the amount of noise the key makes. A worthwhile advantage to using the 3M material on the damper wheel, is you can then unscrew the right stop screw further in order to allow the dot arm to contact the 3m material more securely. Which helps to prevent dot stutter by not allowing the dot arm any chance to flop around on the 3m material.
Once the 3M material is placed around the damper wheel, you will then be able to use a much narrower spacing for the dot contact. And that will allow using the key with a lighter touch. And a lighter touch allows for producing higher quality high speed code. So the 3M tape fix has a lot advantages. You can easily remove the 3m tape later if desired. And a person could even paint the white 3m material with silver paint to match the nickel plated piece parts. 
Below on a 1927 key, I used dental floss without slipping it under the damper post. You can see its best to slip the end under the post. As it allows the dental floss to be less visible. 
Extendadot on 1926 Vibroplex Custom Ivory Key
Set up this way, the key produces such great code its every bit as good as machine generated.
This custom 1926 Vibroplex Original with Ivory finger pieces was produced using a flat main spring that is much longer than normal. I'm not sure if that was such a good idea, but its how they decided to build this custom key.
I equipped it with an aluminum Extendadot due to the keys light touch.
In the slow speed position, the Extendadot extends the end weight a considerable distance beyond the end of the key. The pendulum motion of the longer dot arm produces higher quality low speed dots and at the high speed position it distributes the weight more evenly across the dot arm. Which produces higher quality high speed dots.
Its a much better way to slow the dots down compared to using extra weights on the dot arm. If you simply pack the dot arm with weights to slow it down, it just makes the key clunky and awkward to send with.
Lightning (Champion) Speed Control
You can change the speed 3 different ways.
1. Change the slip on end weight
2. Slide the weight tube back and forth
3. Slide the entire assembly back and forth on the flat dot arm.
The below picture shows it in the slowest speed position.
The below pictures shows the weight tube retracted to the meduim speed range.
The below picture shows the assembly retracted to the highest speed position.
There are two slip on end weights for vertical upright at the end. They are a perfect slip fit and dont require a set screw to hold them in place.
1917 Vibroplex with Aluminum Extendadot
I suspect that Vibroplex used a number of piece parts off many other keys in their attempt to put one key in good working condition. This key is a real kick in the pants to use on the ham bands :-)
Morsekeys Bug 02 Brass #10
After I ordered a Brass Bug02 from George (VK2DLF) .... It took well over a year to
receive the key from www.morsekeys.com .
This is one is Ser #10 in a brushed brass finish. Its a very unique speed key---
unlike any to date. Most speed keys have at least some play in the pivots.
The pivots on his key have no discernable play in any direction. Very well done.
The hardware on the key is made of stainless steel. It comes with a small &
large weight plus an extension for the end in order to place the weight beyond
the end of the key. The stainless adjust screws are large diameter & rather coarse
threads. So adjusting small increments requires some fiddling. The weights should have
a nylon insert on the adj screw so that they can grip the dot arm better.
Its easy for the weights adjustment screw to loosen up after a time.
But not a big deal to place a piece of nylon under the screw head.
This key favors the slow speed end and I mean slow speed.
Its the best sending LOW speed key I've ever used. Going down way below
10wpm and working very very well. With very crisp --- well defined dots.
And well balanced dashes to go with it. The flat main spring is held in place with
4 screws. So its easy to change the flat main spring. George sent me a few
different main springs so that I can increase the top speed of the key. As I
sometimes like to send over 35wpm. The key has two dampers to prevent
dot stutter. The dampers are made of matted fiber -- one at the keys rear and one
up towards the front. The finger pieces sit very low to the desk due he used
thin (self adhesive) vinyl feet 3/4" diameter --- but only 1/16" thick.
There are 4 feet, one on each corner.
So the key is not self leveling like the Vibroplex --- with its 3 feet.
But there is no wobble -- as the key sits level on the desk. And is very stable.
I sure wish I had a key of this quality back in 1957 when I was trying to
learn how to send with a speed key :-) This key makes code at the lower
speeds just like magic !!! A quality piece of work. Thanks George.
I made a simple temporary speed control for the Bug02 as shown below. It allows for a fast way to change the weights without having to slide them off the dot arm. It adjusts to any angle. 
The Great Les Logan Deluxe 501 "T" handle bug with Aluminum Extendadot
I've owned a number of the Les Logan "T" handle speed keys. The Les Logan 501 Deluxe "T" handle key pictured above was the only speed key ever produced that had an easy to replace dot and dash contact post. The large coin silver contact on the post simply unscrews and can be replaced in just a few seconds. If you ever have a chance to pick up a Les Logan Deluxe Chrome model 501, you wont be sorry. Les Logan didnt place serial numbers on any of his keys although on a few keys he used a manufacturer code -- if you can figure out what it means. So there is no way to tell when a certain key was manufactured. He sold the Speed X brand to EJ Johnson around 1947. Johnson used up the supply of the "T" handle bases he inherited from Les Logan. When those were gone, Johnson changed the design. And that was the end of the "T" handle bugs. The only situation you might run into is the adjuster knobs can seize up in the pot metal casting for the "T" handle. The knurled knobs can get scored up as you try the free them. You can run an 8-32 tap through the holes and use anti-seize compound on them. Which should keep it from seizing up for many years. Towards the end of production of the Speed X brand Speed Keys in 1972, Johnson let the quality control slide quite a bit. Some of those small based Johnson keys towards the end of production were of marginal quality. Pictured above is the aluminum Extendadot speed control on this great model 501. The handle made it easier to carry the key around from different operating positions. This particular Deluxe 501 shows no signs it was ever used. It still has the two screws that were used to secure it to the bottom of the shipping box. This Deluxe was dropped off at a Goodwill store. So there is no way to find out where its been since 1947. The other Deluxe 501 key I came across was new in the box and never used. It was left at a church rummage sale of all places. Another mystery as why it was never used. Both of them are very fine keys and make great code.
Below is the picture of a new in the box Deluxe 501. They shipped it screwed down to a heavy cardboard product.
At one time I enjoyed using the T handle Les Logans so much I placed 3 model 500 black crinkle bases at the operating positition. Each one was adjusted for a different speed and I used them in quite a few CW contests.
I made articulated finger pieces so the keys were easier to key.
Vibroplex Mod X Speed Control and Adjustment Procedure
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 Eye 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 it 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. 
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
