Monday, August 5, 2013

Restoring a Reed Organ Part 11: the Octave Coupler

The Octave Coupler:
The octave coupler is an interesting mechanical device that allows you to play two notes, an octave apart, while playing only the lower of the two keys.  The device is engaged when the "octave coupler" stop knob is pulled, engaging a linkage that is attached to a rod underneath the coupler system which slightly elevates the coupler bed so that an angle rod (the coupler rod) can activate the corresponding key an octave higher.  

It is a great place for collecting dust and bits of debris, including this missing stop face!  Clearly, too much dirt and debris will affect the way the coupler mechanism works.  After retrieving that Melodia stop face and vacuuming the coupler, we dismantled the entire mechanism to get an idea how it works and what needed to be done to return it to its original functionality.

The mechanism has a couple of strips of wood to hold it in place, as well as felt in several places that keep the couplers from hitting each other and making noise.

We removed the wood braces and the couplers revealing the felt bed.  Clearly this one has been redone.  You can see the original red felt in between the pegs that that keep the couplers in their proper working positions.  The previous restorer has taken the easy route and placed green felt below the pegs, rather than work around the pegs and punch holes in the felt.

The underside of one of the braces shows the remains of more original moth-eaten red felt.

You can see that I taped down all the coupler rods in order from bass to treble as I wasn't sure if they were all exactly the same or not.  I did not want to get all 45 of them out of order and have the mechanism improperly calibrated.  I thought this was the best solution until I got around to cleaning the coupler rods.
This is the underside of the coupler bed.  It has a two little brackets (one is seen on the right hand side) by which it is affixed to the top of the reed cells.  The two vertical cross beams are what the activating rod pushes upward to move the coupler bed into position when activated.  You can see all the old felts removed and resting on the coupler rods.

One by one I cleaned the coupler rods with 0000 steel wool.  They were quite dirty and had some corrosion where they came into contact with the old felt over the years.  After cleaning, I placed a little piece tape on the end of each, with a number of the rod (1 through 45) and placed them in a coffee tin until I was ready to re-assemble the whole mechanism. It was a long and tedious job, but book how nice and shiny they are now!

The next order of business was to cut new felt for the coupler bed and braces. When I tried to punch holes in the felt, I just couldn't get a nice clean hole punched.  It was then that I realized why the previous restorer had taken the easy way.  I'm told the organ had functioned quite nicely for several years until it had essentially been abandoned, so I decided to follow the previous restorer and simply place the felt strips alongside the pegs, rather than try to punch holes in them.  I think it worked out just fine, and when I reassembled the whole mechanism, it appeared to work very smoothly.

Here are the coupler rods going back on...

 And here is the fully restored mechanism with braces in place.  All in all, I think it worked out very nicely. 

The sub-bass is activated by a similar coupler system, except with only 13 notes.  It is slightly more complicated as each coupler is held in place by a small individual wood brace with a felt bushing.  I have not gotten to that yet, but am thinking of bringing that one home with me (as it is a nice, small mechanism) so that I can work on it in my spare moments.

1 comment:

Ian Thompson said...

Thanks for that nice clear account.
I bet the action is now so light that you can hardly feel the extra weight when the coupler is ON.
Incidentally, it looks like an early-1870s Mason & Hamlin all-downward coupler: rationally designed and very nicely made. I wish that were true of all OCs!
Ian T, England