Improving the Manuals

 I've been practicing and playing on my work in progress for several months now. That is long enough to start revealing design flaws.  Specifically, my choice to hang the magnets underneath the key-sticks with magnetic tape.  Every so often, one wiggles loose and I get a cipher and/or a dead note. I thought fixing these would be simple but as it happens, they are very hard to get to, even on the Great where the bottom is exposed - there is a big iron beam right in the way.    The Swell isn't so bad - I can swing it up and get in and correct them, but to get at the Great I have to remove both manuals completely.  After a few of these, I I started thinking about my options.

The choice to do it that way was driven by the existence of a part of the electric keying mechanism which I left in place because it was necessary to the proper touch of the keys.

Each key-stick has a return spring, but also pushes a lever to make the electric contacts. That lever  has its own spring. The combination of the two is required to give the correct weight to the touch.  

I removed the connection box from the Great and moved the sensor array from the bottom to upright behind the sticks.  There are very conveniently already metal bits at the end of each stick on to which I can just drop a magnet. Even more convenient - each of these things has a screw that I can raise or lower the metal bit with, which lets me adjust the speaking point of each key. How cool is that?

The touch really is too light without the second springs - no surprise there.  I made a hail mary attempt at tightening them by slipping them a on a few coils down the spring. This works, but make funny noises and feel funny and I expect the springs will fail by getting soggy over time.  What I really want to do is replace them with new springs of the correct strength to do the job of both originals

The main return spring is 0.25"  in outside diameter and about 3/4" long including end loops. The 'spring' (the weight necessary to extend the spring by 1") is 1.4 lbs.   

The secondary spring is 0.22" OD, somewhat longer, with 0.15 lb spring.

I need to buy new springs that replace the main return spring, fit into the hole drilled for them in the key-sticks, and provide sufficient spring for correct key touch - which research shows to be 3.15 oz.  I have made a key weight out of random bits to test this - if they key depresses 1/2 way under the weight, the tension is correct.   There are little leather nuts which can adjust the spring tension.

I went in search on the interwebz for extension springs 3/4" long with 0.25 OD, and about 1.75 lb spring.

I couldn't find exactly those specifications, but I came very close with correct physical dimensions, but 2 lbs of spring.  Those would make the touch a little stiffer, but should still fall within spec.

I ended up ordering 125 MXG02202-MW springs from mrspring.com (3 extra for luck).  The online ordering didn't work but everything worked out fine on the phone. Shipping was within reason  and the springs arrived promptly.  

I removed both manuals and got to work on the Great.  I unscrewed the leather nuts and removed the eye-screw + spring assembly from each.  I removed all the old springs and hung a new spring on each eye-screw. 

  I also took my opportunity to remove all the keys from the key bed and give them a good cleaning. I had cleaned as best I could before, but now I could get the grime from the sides and also vacuum under the key bed and lightly lubricate the guide pins with lanolin.   

Cleaned key-sticks had the eye-screws with new springs installed and were replaced into the key bed and leveled. I reinstalled both manuals -  I will redo the Swell later, I want a chance to test out my work on the Great for a little while first. 

Now I've tried it out - the keys are all nice and springy feeling, with tension that feels smooth all the way down.  When I removed all the old springs, I discovered that many had been replaced somewhere along the line, there were at least 2 styles with different end types and different wire weights. Having them all identical is a big improvement, I hadn't realized the differences while playing,  but I sure noticed it fixed.

This was an expensive job - $140 with tax and shipping for enough springs for 2 manuals,  but good touch is about the most important characteristic, so worth spending on.

The touch is a little stiffer, as expected, I measured it to be about 3.4 oz - right in the middle of AGO spec. The 3.15 oz touch my keys had when I got them is really the lightest allowed. This feels better to me,  I'm completely thrilled with the result.   I will have to do the Swell over very soon.