Moog MG-1 cabinet restoration

My customer, Dave, located me in an internet search for synthesizer repair.  Dave is a component level trouble shooting technician himself having worked primarily on computers and entertainment electronics for 30 years or so.  He was not seeking my technical expertise but rather my woodworking skills, so this project merges two of my strongest subjects: vintage synthesizers and woodworking.

Dave is the proud owner of a Radio Shack MG-1 that he is restoring and customizing. The MG-1 was made for Radio Shack by Moog Music back in the 80's.  The case for the MG-1 (Moog Rogue also used the same case design) is a little different than most instrument cases in that the front panel and bottom plate are held together structurally by the molded plastic end panels.  These panels have slots in which the edges of the metal panels are inserted and attached with a bead of hot melt glue.  The unit Dave is restoring has the left end panel missing and he requested wooden end panels be fabricated to create a custom look for his Radio Shack synthesizer.

There is at least one company already specializing in making wooden synthesizer cabinet parts.  Synthwood has an extensive offering of custom parts and services but they do not list end panels for the MG-1 as an available product.  These Moog panels differ primarily from others in that they have a structural function and they are not simply cosmetic. The sheet metal parts connect directly to, and are supported by, the end panels.  Additionally, the panel includes a filler block which encloses a space between the ends of the keyboard assembly and the end panels.  This makes these parts significantly more complex to fabricate than a cosmetic panel that attaches to an existing chassis with a couple of screws.

Router jigs to accomplish the precise machining required were designed and constructed (see article on "Jigs").  Routing for each end panel is done in two operations - one operation for the front of the panel to receive the bottom plate, and another operation for the back and top to receive the front panel assembly.  The left and right panels are a mirror image requiring separate jigs, so: four steps requires four jig designs.  Then the filler blocks are fabricated and attached to the panel with glue and screws. Finally the bottom edge of the panel is scored 1/16" deep and half way across the thickness of the board to allow the bottom plate to recess flush with the outside bottom edge of the panel.

I've been looking for a reason to design and construct a router jig of some sort.  That skill set will be handy for upcoming plans I have for myself, so I agreed to give it a shot.  Building and fine tuning the jigs was certainly a learning experience.  The experience was enhanced by the fact that the sheet metal parts I had to work with appeared to be bent and torqued from original specs. 

Now that I have the jigs I can make these parts fairly efficiently, though it is a time consuming process.  When someone asks I think I'm going to say "$70 and I'll make a pair for you out of wood on hand (see Cherish Earth Project) or send the wood of your choice and the price is the same.  The Dimensions should be at least 5 1/2" X 28" (or 2 ea. X 14") and 3/4" thick finished or 4/4 rough.

Pictured here is a piece of black walnut salvaged from a dunnage pile somewhere In Tualatin, OR, that I selected to make the first finished prototypes from.  I wanted to see the sapwood edge left parallel to the sloped front leaving the bottom to be cut across the grain.  Another approach is to have the grain parallel to the bottom edge so the cross grain cut edge is visible from the top.  This cross grain cut produces some fascinating grain patterns and is a common technique sometimes used in making gun stocks. 

The hot melt glue connection used by Moog in this cabinet design has some significant characteristics.  It does an excellent job filling voids and is easy to apply contributing to an inexpensive manufacturing process.  On the down side, hot melt glue does not have particularly great adhesion to the plastic and metal surfaces being connected in this application. It remains somewhat pliable, especially in warmer temperatures.  I suspect that, if left in the direct sunlight for any length of time (never a good idea for any electronic device) the case warms enough to contribute significantly to the pliability of the glue connection.  Eventually these connections tend to come apart.  In the case of Dave's MG-1 the condition resulted in a lost end panel  Not a good design for an instrument destined to become a collection piece!

My suggestion to Dave is that he assemble his MG-1 using epoxy instead of hot melt glue.  Loctite makes a 5 minute epoxy kit that comes with a small scale auto mix nozzle that looks to be about the right size for flowing a bead into the routed out slot.  I bought some of this for about $5 at Home Depot, but I see that Amazon has it on line for $1.99!

Maybe we can get Dave to comment after the restoration is complete.  He is replacing pots, sliders, caps, etc. and I'm expecting a call when he is ready to calibrate the VCO and VCF.