NavList:

   

Reply

Brad, as someone who has also made a Bygrave cardboard copy, I think you
are making problems where they do not exist. Sure, it would be better if
the scales were on stiff tubes, but even if they are printed on a couple of
rolled up transparencies and slid, one inside the other, I don't think
squashing, bending or poking the thing would (within reason) make any
significant difference. Both scales will be distorted in the same way and
so - and this is the important thing - will not move against each other
significantly.

Too, I don't see any real need to lock the scale tubes while moving the
cursor about. It is a fact that 99.999% of all slide rules ever made rely
on friction to stop the scales moving against each other while the cursor
is being manipulated. If necessary, it is easy enough to use one hand to
clamp the scales together while moving the cursor with the other. With
typical German thoroughness, Dennert & Pape decided to put a lock ring onto
the MHR1, so the scale tubes could not move against each other as the
cursor tube was being manipulated. Perhaps they made the scale tubes so
well that there was not enough friction to do the job. That was certainly
not a complaint you could make about the Bygrave I tried! The fact that
Dennert & Pape put a lock ring on the MHR1 does not mean that all Bygraves
were thereby redundant. And I don't think a lack of friction is going to be
a problem in the Lapook version of it.

While I have got my hands on the megaphone, I would like to say a big
thanks to Gary for all the work he has done in coming up with a cheap,
practical, usable version of the Bygrave/MHR1 that anyone can get up and
running with a minimum of effort - and have a lot of fun too. As a
navigational computer, the Lapook/Bygrave ticks all the boxes. It is cheap,
easy to use, has good accuracy and needs no batteries. It is waterproof (to
any depth), shock proof, nuclear bomb EMP proof and - the ultimate accolade
- may even be child proof!

Geoffrey Kolbe

Brad [7439] wrote:
>
>
>Hi Gary
>
>Just to be clear, I was not questioning the accuracy of the Flat Bygrave,
>WHEN FLAT.  Just as you have indicated, when flat, the device yields
>perfectly acceptable results.  Since the scales are a realization of the
>equations, unquestionably, they should work when used as directed.
>
>If, however, one scale was distorted by an out-of-flat condition, then we
>would see errors proportional to the error in flatness. One scale flat,
>with the other distorted will yield problems. That was my assertion and
>remains so.  Sharp as you are, you should see that as well.
>
>My comments also indicated wrapping the scales around cylinders, which
>eliminates the distortion of one scale to another.  That solves the
>out-of-flat condition by making the surfaces stiff.  The follow-on
>problem, how to lock one cylinder to another securely, forces a mechanical
>solution.  Bygrave himself didn't solve that properly.  There are a few
>mechanical arrangements I can think of to do that, all involving multiple
>moving parts.  This would force your simple Flat Bygrave solution to a
>more complicated cylindrical Bygrave solution, and keep the device out of
>the hands of many who would try.
>
>Again: Nothing wrong with the Flat Bygrave when used properly.  You should
>be rightly proud of it.  Gosh knows I would be!
>
>Best Regards
>Brad


--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply