[GreenKeys] BRPE models

Sun Jan 21 03:56:56 EST 2024

Well, I'm the new kid here but I think that we're missing a point regarding
handling tapes of different widths.  AFAICS there are only two positions for
the "guiding edge" (the rear tape edge) WRT the punch block.  Either the
tape is aligned to use the zero-level (7/8" and 1" tape) or aligned to omit
the zero-level (11/16" tape) hole punch.  Ref:
https://www.navy-radio.com/tty/brpe/hole-config.jpg

Teletype implemented mechanisms such that either the Tape Guide Bracket (PN
142942) is permanently affixed at the proper position WRT the bunch block or
it has a two-position click-detent mechanism in the case of use with the
"universal" punch block.  In either case the Tape Guide Bracket alone is
insufficient to ensure that the tape remains positioned against the guide --
it only constrains one edge of the tape which might wander away from it or
even skew as it reaches the punch pins, resulting in mispositioning or a
jam.  While one might count on drag from the tape roll and various rollers,
turns, and fricative surfaces there would be no positive positioning control
ensuring that the tape remains precisely aligned as it enters the punch
mechanism.

The "universal" punch block (on my BRPE21) includes a swing-down guide
positioned for the front-edge of a 11/16" tape (and is machined with an
internal guide for the front-edge of a 1" tape); simultaneous with the
swing-down of the 11/15" front-edge guide there is a rear guide that is
brought forward to position the rear tape-edge to align properly for the
one-level hole punch.  It's a both-or-neither action that is independent of
the two-position detent for the far/rear edge of the separate Tape Guide
Bracket, which must itself be correctly positioned.

The "regular" punch block apparently has a permanently affixed front-edge
guide (Tape Bias "Spring" PN 142897), although it is slotted for two screws
and therefore might be sufficiently adjustable in an 8-level configuration
to correctly guide a 7/8" tape.  See the diagram on the bottom half of Page
10 in "215B_BRPE_Technical_Manual_May1971.pdf ".  So a (e.g.) BRPE11 "6 - ,
7- , or 8- level, 7/8" or 1" width fully perforated paper tape output" might
front-edge guide a 7/8" tape properly if there is sufficient adjustment in
positioning the Tape Biasing Spring, but AFAICS that would be either a
two-screw field adjustment or an as-shipped configuration not intended to be
later adjusted to position a 1" tape.  As Doug said, "fiddly", but he
implies that there is sufficient "play" there to bring the front-edge "tape
biasing" guide to a correct 7/8" position.

Doug also noted that by the use of shims on the Tape Guide Bracket "they
make it possible to convert an 8-level machine to just about any width of
tape".  While that's possible, AFAICS that's not how Teletype did it, nor an
ideal approach as the Tape Guide Bracket only provides general tape
alignment while the punch block and attached mechanisms provide precise tape
positioning just prior to the row of punch pins.  I suspect that trying to
punch a 5-level tape based on merely shimming the Tape Guide Bracket but
using a "fixed" 8-level punch block will result in a tape that will
intermittently bind a mechanical 5-level reader as the tape may wander a bit
side-to-side as it passes under the punch pins.  An optical reader would
probably be insensitive to that amount wander for the data holes but perhaps
that amount of wander in the feedhole could prove problematic.  I expect
that getting the initial tape feed "just so" to ensure correct alignment of
the initially punched feed holes will help keep the tape feeding "true";
that would be a "fiddly" operation requiring a bit of care and "good"
tensioning of the tape along the feed-path prior to the Tape Guide Bracket
both when setting up the tape initially and then throughout the punch
operation.

In my BRPE21 there's no possibility of adjustment to properly constrain the
front edge of a 7/8" tape.  One is entirely dependent on drag from the tape
roll and various rollers, turns, and fricative surfaces to ensure that the
tape "holds true" against the Tape Guide Bracket and remains that way as it
proceeds through the punch block as the front edge guide in the punch block
mechanism is designed for a 1" tape.  From the Teletype design engineer
perspective it clearly was the case that they were more concerned about
excellent handling of 11/16" tape than the touchy handling of 7/8" tape;
couldn't have it both ways.  Their choice of priority assignment makes sense
to me.

-----Original Message-----
From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net>
On Behalf Of Jones, Douglas W via GreenKeys
Sent: Saturday, January 20, 2024 10:41 PM
To: w9ddd at tapr.org; greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] BRPE models

From: John, W9DDD [w9ddd at tapr.org] -- Saturday, January 20, 2024 12:07 PM

> Is this the bit that switches between 11/16 and 1" tapr.

The bit in the illustration you posted is the one that makes conversion easy
with click stops and detents.  The other approach to conversion involves a
little fiddly guide that screws to the punch block with a pair of 0-80
screws and can be positioned to guide different tape widths by pulling the
screws, moving the guide and then screwing them back in.  Oval slots in the
guide and extra screw holes make it adjustable over a wide range, but it's
not an adjustment you want to do casually.

The other way to adjust the rear edge of the tape involves spacers you use
to shim the tape guide forward.  Again, a bit ugly but between the guide
screwed to the punch block and the spacers, they make it possible to convert
an 8-level machine to just about any width of tape.

And the switches to turn off some of the magnets?  I'd have expected the
software driving the punch to take care of that in computer-driven
applications.
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