Multi Calculator Kit

[revwillie]

(08-23-2018 12:57 PM)revwillie Wrote:  Not having a laser cutter or a 3D printer, I have been making incremental improvements to the Hammond case enclosure. I bought a second one and drilled/filed out smaller openings in the front using the first case as a guide. I have magnetic shielding foil tape (steel) which I plan to apply to the new case front so that printable magnetic vinyl sheet can be used to make the overlays. The next issue to overcome is incorporating a thinner battery so that the key tops don't extend from the front of the case. When the overlay floats over all of the keys, a key press in one area can interfere with nearby keys. Also, the magnetic sheet is held away from the metal tape.
If I can get the key height right, key presses would push the vinyl sheet down into each drilled hole for its respective key.

Hammond updates: I added a few photos to the shared album:LINK

Steel foil tape is expensive and much harder to shape than I expected. It's not like aluminum foil or the aluminum foil tape used to seal up HVAC ducts. It's thicker and tougher and every edge is razor sharp. Tony's initial suggestion was to use small permanent magnets and that's a direction I might go in. The magnetic sheet material from old refrigerator magnets will cling to the steel tape surface, but not very securely. I finally have the keys fully working again after many short sessions of forming the tape followed by nursing my wounds. The pictures show my adaptation of a galaxy SIII battery for power. It fits nicely behind the pcb using a cut-down portion of an external battery charger. No charging circuitry is included, it's just a battery holder. I can use a little bit of soft packing foam behind the battery in the case when the screws are tight and this keeps the battery secure while also damping the noise of key clicks.