Hammond Manuals

We provide standard maintenance procedures for the manuals, including critical bussbar repair, cleaning, and lubrication.  Bussbar service may be the single most important maintenance to any Hammond organ, and will dramatically improve the sound and response of most organs.  Much like the generator, the manuals are the "second heart" of Hammond organs.  Missing frequencies are often the result of broken switch stack resistance wiring, which we can trace and repair in some circumstances.

We also provide ProKeys key "glassing", a special polishing process which renders the playing keys as smooth as glass.  For this process, the cloth polishing wheels are not mounted on a bench grinder.  This produces inferior results.  Typical bench grinders are approximately 3,600 rpm, which is far too fast for our polishing process.  Our target for key polishing was 900-1100 rpm. 

We used our Shop Smith, which is variable speed.  Polishing was accomplished with brown or white jeweler's rouge, and our buffing wheels were ~2" wide, as shown below.  We quickly learned this important point: assemble (and mark) one mandrel of four (4) cloth wheels only for use on plastic, and another for use only on metal.  This setup worked fine for waterfall and diving board type keys - no burns or problems from heat.

Another point: we did not polish keys on the key channels.  The channels were occasionally "grabbed" by the buffing wheel, and broken keys resulted.  After a few times of learning this the hard way, we always removed the keys from the key channels before polishing.

After some trial and error - meaning 'experience' - we were able to polish all (exterior) surfaces of the keys, not only the top, playing part, but also the sides and ends.

Initially, we tried this with only one (1/2") stitched cloth wheel.  When we added more wheels (to gain more width), the work became much easier, faster, and the results were far superior.

A little trick which I found to be very helpful .... after the Hammond is reassembled and at the job, I sprayed a cloth with a very small amount of liquid silicone, wiped down the manuals, then wiped again with a dry paper towel to "dry" them.  (They weren't actually "wet", anyway.)  The manuals were - for lack of better words - slick as glass.  Guitar players use something similar, called "Finger Ease", and it makes quite a difference.      

The MANUAL FOAM Problem

Sometime in the mid to late 1960s, (the exact date unknown, but probably 1963), Hammond started using FOAM to seal certain areas of the manuals against outside dust.  Riveted felt was used previously.  From a production standpoint, the foam, with its adhesive backing, required less labor, and no machinery to install, was far less expensive, and probably seemed - at that time - to be a viable alternative to the felt which the foam replaced.  Unfortunately, Hammond was wrong.

The foam used by Hammond was an early composition which may have accomplished some degree of dust sealing, but is now known to be EXTREMELY detrimental to the manual resistance wiring which it comes in contact with.  The foam and its adhesive backing definitely will deteriorate over time, and turn into a sticky substance, resembling gooey tar.  Sometimes, it just disintegrates into a sort of "gritty, adhesive sand", if that makes any sense.  I'm not sure, but I believe the chemical composition of the foam had something to do with the "gritty" feel of this substance.  Research - you'll know more than me in a few minutes.  No matter what chemicals were used to manufacture the foam, I DO know that it's got to be removed.

Typically, the decomposition would not be a problem, except for the fact that a chemical process occurs as the foam disintegrates.  The foam in each manual is actually 2 separate strips mounted on the back manual cover.  One runs the entire length of the manual and the other is a shorter piece, sealing the area where the preset wires exit the manual.  As the foam disintegrates, it expands, actually doubling or tripling in physical size, and embeds itself in the resistance wiring loom, which is plastic in the later models.  This can chemically cause the plastic to deform and melt.  Of course, it also embeds into the resistance wiring.

The wiring inside the later Hammond manuals is a very light gauge non insulated wire - by this I mean there is no cloth covering as in the earlier manuals.  It is very similar to the wire used to wind coils.  Its only insulation is a lacquer finish directly on the wire.  The chemical decomposition of the foam eats through the lacquer finish, and also eats right through these ultra fine wires.  I've noticed that this process seems far worse on Hammonds that are moved a lot.  Possibly the shock and vibration of travel accelerates the foam's action on the wiring.  You can believe it is a major problem to attempt to trace and repair these light wires when they break.  And in some cases, repair is virtually impossible.

Removing the foam residue from the manual back covers is a filthy, sloppy job - and it's pretty difficult to remove.  Wire wheels just clog up, sandblasting does nothing to it at all.  Scraping it out with gasoline and a razor blade is the best I've found for complete removal.  I can get all the foam out - but that backing tape is a real pain.  Once the foam is gone, painting - even just 2 coats of primer - is mandatory.

While not every Hammond with foam has shown evidence of this problem, it's clear that time is a factor in the deterioration process.  It will happen, sooner or later. 

Three Hammonds which I rebuilt with this manual foam problem were, unfortunately, total disasters.  It was necessary in all three cases to replace both upper and lower manuals with older manuals which had no foam.  All three organs had at least 30 broken resistance wires in each manual, and tracing both ends would have taken weeks of intense labor, which the owners were unwilling to pay for.  Understandably, it's very difficult to find a pair of manuals when you really need them, so the cost factor in all three of these Hammonds was REALLY outrageous.  

The other Hammond which suffered from this problem was very easy to fix.  Only four wires were actually broken, so locating and resoldering was quite easy, because the actual breaks were in four very obvious places - meaning we didn't have to trace anything: we just put the wires back together again with solder, and insulated them with nail polish.

2013 UPDATE: "Dust sealing" is not necessary - it's a redundant, useless "feature".  Most of my own consoles do not have any type of "dust sealing" in the manuals.  Thanks to gravity, dust does not fall upwards.

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