Rotary Press Coils/Coil Waste?

I've been doing a little research on rotary press coils and have a couple questions for any experts out there. Not much to find in the US Specialized or Max Johl's book.

1. Plate layout for rotary press coils were mostly 170 subject. Why 170? If the coils were sold in groups of 100, 500, 1000, wouldn't it make sense to have plates of 100 so there would be no waste for a given run.

2. Probably related to question 1. also but when coil waste was then re-purposed by adding perforations (think US 578, 579, and 595), they were issued as 70, 100, or 170 sheets. It seems that the waste was always from 170 subject increments (or a 170 split into 70 and 100 - perhaps for better storage in PO drawers?) Again, why the 170 multiple for the waste?

Thanks!

Good question - good answer!!

Ken

Thanks for that link Rodgcam ... nice exhibit! Where did you find that?

I'm still a bit perplexed by the 170 subject plate size though ... I saw reference to that size but no reason for such an odd number. Doesn't fit evenly into the # stamps/roll. Why not just create a 200 subject (10x20) then there's no waste (?)

The regular rotary press plates for this series is 400 subject plates that are then split into 4 panes of 100. When it comes to making coils, they used a 170 subject plate (10x17). Here's the layouts ... first is for regular, second is for coils:

For U.S. coil stamps a small Stickney rotary press was used. U.S. patent # 1,115,127 of 1914
For U.S. sheet and booklet stamps a large Stickney rotary press was used. U.S. patent # 1,378,386 of 1921
These presses used two paired recess engraved bent printing plates.
For coils, the plates were joined together on the side with ten stamp subjects across.

(17 x 10 = 170) for horizontal coils with vertical perforations
(10 x 15 = 150) for vertical coils with horizontal perforations

The Stickney web fed bar perforator that perforated these web fed
Stickney rotary press stamps were made to perforate at the most
10 stamp subjects across at the time.

The Stickney coiler used to cut and separate coils into rolls had
some waste at the beginning and end of the coil rolls so that a
little more than needed was cut off to compensate.

Check the following: https://www.rfrajola.com/PDR2017/Sh...Shoults2.pdf