Saturday, March 16, 2013

Polysix - Trimming the New Keybed

As I introduced in this post, I'm replacing the keybed in my Korg Polysix with a new keybed that'll have both aftertouch and velocity sensitivity.  The new keybed is a Fatar unit that I bought from Keyparts UK.  It plays as smooth as's really nice.  When the new keybed showed up on my door, I immediately unpacked it and stuck it into my Polysix to see if it fit.  It fits great...except for one critical detail...the Polysix's circuit boards are arranged so that they extend underneath the stock keybed.  As you can see below, the new keybed has more feet, and some of those feet want to stand right on top of the circuit boards.  Noooo!

The New Keybed Has Feet That Want to Stand on the Polysix PCBs
So, what is one to do?  Well, why just cut off the offending feet!

Looking at the build-quality of the keybed, it is built really strong.  It is quite stiff.  So, if some of the feet in the middle were to suddenly go missing, there's no concern (in my mind) that the keybed would sag.  No, it's too stiff for that.  And, the feet are simply plastic tubes, not metal.  It's almost as if the feet were designed to be easy to cut.

I wasn't quite sure what would be the best method of cutting the feet.  Would I just use a razor and my utility knife (aka box cutter)?  Would I use my hacksaw?  Dremel with cutting wheel?  After chatting with a very handy guy at work (who is asked to hack things to pieces all the time), he suggested that I use a small hand-held cutting tool that he had (see pic below).  It's got replaceable "blades", most of which are actually small fine-toothed saws.  That little saw looked perfect for the job.

Small Hand-Held Saw for Cutting the Plastic Feet
The hardest part of figuring out how to use the saw was figuring out how to hold the keybed so that it didn't slide all over the place.  Being a manually-operated saw, you do have to be a bit vigorous with your movements...movements that end up pushing and pulling the keybed all over the place.  So, as you see below, I leaned it against my leg and end the far end down at the floor between my feet.  Then, saw saw saw  on the keybed and, poof!, off pops the unwanted keybed foot.  Magic!

Sawing Off a Foot from My New Fatar Keybed
I ended up cutting off four of the middle feet from the backside of the keybed.  the Polysix PCBs don't reach all the way to the front, so no cuts of the front feet were necessary.  With the four middle rear feet removed, I was able to place the keybed in my Polysix without its feet standing on the the PCBs.

New Fatar Keybed Inside my Korg Polysix
You might think that I'm now done and could move forward with wiring the keybed to my new Arduino-based key assigner.  Unfortunately, that's not the case.  Now that I'm able to get the keybed into the Polysix without those pesky extra feet, I can now see that the keybed sits 3/8" too low compared to the stock keybed.  This is because the feet of the keybed (the ones that I didn't cut) are shorter than the feet on the Polysix's stock keybed.  This shortness is not just a problem of looking a bit funny.  No.  The shortness means that the entire back of the keybed is now resting on the Polysix's circuit boards.  That's not god.

Luckily, the shortness problem is easily solved by putting 3/8"-thick pieces of plastic under the keybed's remaining feet.  The plastic pieces boost the height of the keybed, which gets it up off the PCB.  Easy.  Pictures of that part of my installation will be the subject of a future post.

Thanks for visiting!

Edit: My next step...Cool Connectors for the Keybed Cabling
Edit: And after that...Boosting the Keybed

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