I started this project two years ago when I acquired the manuals from a parted-out Hammond B2 organ. My goal is to build a MIDI controller unit to be used with the Native Instruments B4 program. The basic plan is to use one key contact per key to trigger a MIDI encoder circuit board. I have found several sources of MIDI encoder circuit boards. More about this later. Topics: The Parts I Need
A Tale of Blotches and Keycombs
Assembling the Manuals
A 73-key Hammond?
Wiring And Keyswitches
Building the Cabinet
Resources and Links
Here's a list of the parts I've collected so far: The manuals from the B2. These were REALLY dirty, and the keys were badly stained. Greyish blotches too A complete set of drawbars from a BV/CV type Hammond. Ratchet type Complete sets of keys from 2 Hammond M2/M3 spinnet organs Compete sets of keycombs from 2 Hammond M2/M3 organs A switch tablet panel from a B2. This is the panel that goes across over the back of the upper manual, underneath the drawbars. In a B2, this panel has the Vibrato/Chorus tablets, the rotary knob that selects the type of Vibrato or Chorus, and the start and run switches Wood to build a cabinet to house all of this--I chose oak for three reasons: I like what it looks like It's hard and durable Of the hardwoods I like, its the least expensive It's easy to get in useful sizes and shapes
When I started to dismantle the two manuals, I discovered two things: That the white keys were all stained with the "Grey Blotchies"--it wasn't pretty! That the keycombs were badly worn. The little squares of felt on each keycomb "tooth" were worn to the point that the keys were clacking against each other rather badly I already had replacement keys, so the first step was to obtain replacement keycombs, after doing some research on the HamTech message board, and discovering that new keycombs are not available. Period. End of story. But used ones are, mostly extracted from parted-out Hammond spinnet organ models M2 and M3. When I posted a question on the HamTech message board about repairing or re-felting keycombs I got a lot of excellent advice about renewing the keycombs, plus offers from three people who had M2 or M3 keycombs to sell. I bought full sets of M-series keycombs from two of these guys. What I got in both cases were keycombs in nearly new condition. Once the replacement keycombs arrived and the weather cooled off to the point where I could work in the garage, I began the process of dismantling the B2 manuals and cleaning up 50 years of dust, dirt, and rust that had accumulated under and around the keys. Once that was done, I began to reassemble the manuals with the "new" keycombs and the unstained keys. The first picture is of the lower manual part way through the installation of keycombs and keys. As I said before, the original keys on these manuals were badly stained, with unpleasant-looking greyish blotches all over them. Apparently Hammond used a different plastic formulation in the late 40's and early 50's, because only the M2, B2 and C2 organs exhibit this greyish blotchiness upon significant exposure to sunlight (so I have been told).
The next picture is another shot of the lower manual during the installation of the replacement keycombs and keys:
Next is a close-up of a few of the white keys and the keycombs. The job of the keycombs is to guide the up and down travel of the keys. Each finger of the keycomb has a small square of heavy felt that limits how far the key can move side-to-side, yet allows the key to move freely up and down.
The keys I am using in this project were actually acquired to re-key my Hammond Model A, which has the older style keys with rather sharp side edges. I have a total of about 200 of these keys, in very good shape--with NO GREY BLOTCHES! What I don't have is white sharp/flat keys to replace the sharp/flat preset keys on these two manuals. The solution I came up with is to use all black keys in the preset panels of both manuals, as shown in the next picture (I think the look is rather nice--don't you?):
This next picture shows the lower manual with all of the new keys installed:
Next I set up the two manuals together on my work table so I could take some measurements for the cabinet design. This next picture shows what it looks like so far:
I took another close-up of the two manuals together to show what they look like in more detail. I really like the resulting picture. My intention was to show the sheet-metal screws that I had used to mount the metal fall boards, which were originally mounted in a manner that required dismantling the keyboard assembly to remove the fall board. These sheet-metal screws make it easy to remove these boards just by taking out the screws--you don't even have to pull the keyboard out of the organ cabinet to do it!
I know it's hard to tell the difference, but this picture is of the UPPER manual, with the new keys and keycombs installed, as well as the sheet metal screws for the fall-board:
After setting up the keyboards as shown in the picture above, and thinking about the MIDI controller I am using now (a Roland A70--a VERY nice keyboard), I decided to experiment with building a 73-key version of the Hammond keyboard. So I removed the black preset keys from the two manuals, disabled the latching mechanism, and installed standard keys in place of the black ones. The result is shown below:
Here's another shot, showing the two manuals and the drawbar assembly:
The next step in the process involves removing all of the keyboard wiring that connects the output of the Hammond's Tonewheel Generator to the key switches. The next picture shows what this wiring looks like during the removal:
Finally, a view of the keyswitch assembly after all of the wires have been removed:
In the above picture the keyboard assembly is upside down, shown from the rear. The several hundred resistance wires that connect the TWG to the keyswitches have been removed, along with the looms that the wires were strung on to keep them organized. The goal here was to eliminate as much weight as possible, and to reduce the height of the lower manual in order to reduce the size of the overall keyboard assembly. Taking out the wires and looms allows me to reduce the overall height by about an inch.
「该帖子被 正Q 在 2008-10-17 17:29:45 编辑过」 |