Wonderful Idea..... I retired from San Diego in 95.... Sadly I saw the 32nd Street Naval Station Wood Hobby Shop closed in about 92 and turned into big offices for the Moral Welfare Recreation Staff.... Big Bummer in MY book.... They needed more room for the BLOATED TOP STAFF and AXED the Wood Shop.... Norfolk, VA Naval Station had a GREAT Wood Shop in the 80's...
OK.. NOISE... Being a Resourceful guy like yourself.... I think I would start with the CUT MOTOR.... Penn State Industries sells THIS....
http://www.pennstateind.com/store/TCLVSKIT.html Don't even know the RPM of the Current Cut Motor.. This maxes out at 4400 RPM.
Hopefully the Firmware Lord will chime in on this off the wall idea.... I would rig THIS motor above the machine in line with the X Axis and have the business end of the motor with an appropriate shaft coupling to attach to the flex shaft. The Flex would just drape down in the center of the X Axis far enough aft to allow the flex to easily move left and right in Y and up and down in Z. I am "Guessing" that this motor will be much quieter than the current cut motor.....
The "Trick" is to fool the Computer... I believe that even with the Cut Motor Magnet moved to the Shaft Connection Area, that the Computer will give you a CCM or Check Cut Motor "IF" the Cut Motor SPEED Monitored is not what the Computer is expecting.... This is where the Firmware Lord could point us in the correct direction.... Because I also believe that the X Termination Board and the Q1 Circuit on that board along with the Optical Isolator Chips has some limited speed control over the Cut Motor Speed... Hence we do see a speed variation in some cut operations... IF the Cut Motor were replaced with a RELAY and that RELAY turned on the Variable Speed Quieter Cut Motor.... It "Might Work".... IF we got a CCM in the past, I believe that the Cut Motor just went into a "Programmed Speed" based on a value placed by the Firmware Lord and Company. This usually made the Cut Motor run at a high speed with NO Cut Motor Feedback via the Magnet... I believe if the machine was cutting some Text and detected the Motor bogging down that it "Might" speed up the RPM.... OR that effect could just be my over active imagination or just a pre programmed speed based on the Text Scheduled to carve....
SO with ALL that.... It just might work... The Variable Speed would be useful as before you changed to this system you would buy a portable reflection Tachometer and measure the Shaft Speed for various operations and you could use the Variable Speed to be sure you had enough RPM's to properly cut the project....
Another option..... A Poor Option... AIR DRIVE Motor... But based on my experience with a Air Operated DRILL.... Very Noisey....
Another option.... A FLUID PUMP.... for a Cut Motor.... A Hydraulic MOTOR....
With a future move to the other side of the POND.... THIS research could be very useful....
Another more expensive option.... Convert a Spindle Motor.... The Exact name is slipping me at the moment... but a Variable Speed Drive Motor that a Shop Bot and the Big Boys use.... But a smaller version... The PLUS for them is LESS NOISE....
I have mentioned this idea in the past and the mention of replacing the Cut Motor for a RELAY got a Thumbs DOWN from LHR.... I think it is the speed issue... A Solid State Relay would be an option.... Stay away from the Mercury Wet Relays as tipping the unit can cause the Relay to activate.... Scientific Atlanta a Antenna Positioner Company made a controller to move antennas in a Test Range setup. I worked for this company in San Diego called Microwave Specialty Company. The day I was hired the Boss said he had a project for me... Change out the smaller Antenna Positioner on the Roof of the building with a heavier unit that also had Tachometer Feedback. I had to make all the connection Boxes and wire a 3rd Axis that was being added... I did it as seen by this picture below... The New Controller had Mercury Relays and a warning sign on the front... One day a Engineer went to move the control box with the power on.... Tilting the control unit caused the relays to activate making his antenna as seen on the TV Camera MOVE.... He was not happy.... Then HE saw the Sticker... So stay away from Mercury Power Relays.....
Picture: The new heavier Scientific Atlanta Positioner I wired for the Roof of the Building. This building sat along RT 78 near I 15 in San Marcos, CA. And for years working still at the NAVY, I would drive by this place always looking to see what NEW Antenna was on the Roof... Being a Navy Radar and Computer Tech... One day 2 years before Retirement I walked in on a Saturday Morning and was Hired on the SPOT... Worked 2 years as the Calibration Tech nights and weekends...
GOOD LUCK !!!!
AL