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MMD > Archives > December 1996 > 1996.12.05 > 15Prev  Next

Re: Perforator Advance Distances
By Bob Taylor

After I made my inquiry last night about the Ampico step advance distance of the original factory perforator, I realized I made a very big goof. I was thinking in terms of inches when I did my calculations and posted my question erroneously. Where I asked, "I still wonder if the Ampico scheme isn't really 360 steps per inch," I obviously meant 360 steps per foot. I apologize to all for my lack of common sense in proof reading my post.

Editor Robbie stated:

> It seems to me that the hole size has no effect on the perforator
> advance distance. Could you explain what you mean, Bob?

Robbie, you are right. The punch size was only important to me for the manner in which I was trying to calculate the perforator step distance. I was using the length of each sustained note as a base. The Ampico uses slots preceding chain bridging. These slots are seven "steps" long. Measuring the length of the slot, and subtracting the diameter of the punch, and then dividing the resultant number by six, will yield the step rate. Of course the problem is that the sample is too small. But even this fast system to calculate step rate shows a rate very near 360 per FOOT.

Since last night, I decided to calculate the Ampico step a different way. The longest perforations on Ampico rolls are in the soft pedal (3T) track. Many rolls have perforations in this location exceeding one foot. On several rolls, I counted the perforations in this track for exactly one foot. There are exactly 60 chained holes per foot. The 3T track is produced by making two perforations, followed by 4 blanks, and then two perforations---and so on. In other words, there are six step per sequence. Sixty sequences yield exactly one foot of paper. The result -- exactly 360 steps per foot.

I don't think measuring the test roll 6-inch segment is a valid basis for establishing the step rate for the Ampico perforator. I am puzzled why it would be different from production copies. The 360 rate seems more logical. It occurs on many production rolls and is easily calculated, today.

What are your comments?

Bob Taylor

[ Bob, you precisely measured the advance on your _roll_, but
[ still unknown is how much the paper has expanded or shrunk.
[ Wayne hopes to determine the _intended_ steps-per-foot from
[ analysis of the 1922 test roll and its accompaning text.
[ Wayne also notes that the stability of the Ampico perforators
[ is unknown; we have no proof that they used a ratchet-and-pawl
[ drive on all the perforators, and Mr. Stoddard may have installed
[ an infinitely-variable advance mechanism.
[ Robbie

(Message sent Fri 6 Dec 1996, 01:23:52 GMT, from time zone GMT-0600.)

Key Words in Subject:  Advance, Distances, Perforator

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