| Larry's profileLarry Doe's Scanner BlogPhotosBlog |  Tools  Help |
|
October 27 Stepper motor R & DAnother week-long visit to Keystone Music has yielded significant progress. I arrived in Bethlehem on Saturday, October 18, prepared to modernize the Ampico MIDI perforator with a stepper motor drive which will allow for nearly unlimited ratchet rates to be accomodated. It was found there are no gear combinations available for accurately perforating DuoArt rolls on the Taft Pierce machine and it was decided a stepper motor drive system would be the most practical solution. Of course, a DuoArt die set will have to be fabricated, which should be quite easy now that an Ampico model exists on a CNC multi axis milling machine. With slight modification, a DuoArt die set can be made. One of my objectives on this visit was to carefully examine and measure the pull-through rate of the original Aeolian perforator which had been used to punch many of the Ampico rolls during the 'Merger' period. In the photos, you will see how a dial indicator was attached to the chain-driven paper feed mechanism and precise measurements were made for both the coarse and fine ratchet wheels. The measurement was found to be 44 and 66 ratchet respectively.
Another objective was to precisely measure the drive train of the Ampico perforator in order to install a stepper motor in place of the intermittent transmission. Some research was necessary to determine the amount of gear reduction and torque required to move the paper with a high degree of precision. I made modifications to the Excel gear calculator spreadsheet and created an equation which would display the exact distance the paper would move between each punch row. I found that by using some of the existing gears with a microstepping motor controller, the step rate could be controled with a precision of 30 millionths of an inch per punch row. It was necessary to do a speed calculation to make sure the motor would be able to move the distance required within the available time window. Since this time window was unknown, I had to make a timing diagram for the perforator. This was easily accomplished by measuring the pulley diameters and figuring the nameplate RPM of the motor. A piece of masking tape was wrapped around the large pulley on the punch ram. Marks were carefully made on the tape at every point where something was happening on the perforator. (see accompanying photo) Since the RPM of the pulley and its circumference are known, the distance between the marks can be converted into milliseconds. Now, the precise time window for moving the paper is known and the existing signal from the photointerruptor can be used with a fixed delay for triggering the stepper motor. I plan on employing a Parallax Basic Stamp microcontroller for generating a train of pulses for moving the stepper motor the proper distance for each punch row. A thumbwheel switch can be used to select values from a look-up table for each of the popular pull-through rates. All of this will allow Keystone to offer accurate recuts of many popular piano roll formats. Someone once said "You don't know what you don't know." Now I think it's safe to say we really do know!
A few of the remaining titles for the upcoming catalog were punched and we met with Jason, the web page designer on Thursday. Customers wishing to place orders will be able to do so online at www.keystonemusicroll.com . The page is still under construction but should be appearing within a few days. You will be able to place your order and pay online using Google's secure payment system. At least, this is the plan as I understand it at the present time. Richard Groman will also accept orders VIA his cell phone number which I will publish here as soon as the catalog is finalized.
On Friday, October 24, after most of the work was done, we had a bit of fun. On this 83rd. anniversary of the day Dr. Clarence Hickman conceived of the ball bleed valve, we rented a truck and visited Doug Miller in Silver Springs, Maryland to pick up Richard's newly restored 1926 Lauter Humana upright foot pumper. When we arrived, we were treated to a private demonstration of Doug's two manual Wurlitzer theater organ which had been carefully transplanted from the demolished Reading, PA Lowes theater by Doug's father into the basement of the Miller residence. Doug's friend and organist, Ray Brubacher gratiously demonstrated his skills at the keyboard. With permission, I will try and publish some of the video footage of his performance on YouTube in the near future. The highlight of the day was the demonstration of Doug's newly restored 1924 Mason & Hamlin Ampico piano. Records show the piano being delivered to a 'Mr. Mason' in Boston. This is quite a unique piano since in 1929, it was reworked at the factory, receiving a new serial number. Doug has made an excellent restoration of this piano and fitted it with a 'B' drawer. I had the pleasure of hearing some of Doug's fine recordings of this piano on CDs during the return trip home. Many thanks to you, Doug, for the sample CDs and for selling me your last set of neoprene Ampico motor mounts. (The previous two sentences corrected 2/15/09)
To top off the weekend, I had the privilege of reading Richard Groman's autographed copy of Larry Givens' book, Reenacting the Artist. It was here that I discovered the coincidental occurence of the timing of our visit to Doug with Dr. Hickman's invention of the Ampico ball bleed valve.
The last day at Keystone was spent packing several boxes with about 150 original rolls to be scanned which will be offered in future catalogs. |
|
|
