A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Manufacture new Bygraves?
From: Brad Morris
Date: 2009 Jul 7, 09:16 -0400
From: Brad Morris
Date: 2009 Jul 7, 09:16 -0400
This is the method used by the Germans. They wrapped the scale around aluminium tubes. -----Original Message----- From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Gary LaPook Sent: Friday, July 03, 2009 4:02 PM To: NavList@fer3.com Subject: [NavList 8928] Re: Manufacture new Bygraves? I have had great success with printing the scales of the flat Bygrave and wrapping them around a tube and sealing them in place with clear adhesive plastic sheets. Here are some pictures of one example: http://www.fer3.com/arc/m2.aspx?i=106329&y=200809 Links to the scales: http://www.fer3.com/arc/img/107473.lapook2.pdf http://www.fer3.com/arc/img/107473.lapook1.pdf http://www.fer3.com/arc/img/108719.revised%20form%206-18-09.pdf http://www.fer3.com/arc/img/107419.bygrave-manual.pdf I picture of one made by Geoffrey Kolb: http://www.pisces-press.com/graphics/Bygrave.jpg Try it. gl Hanno Ix wrote: > Hello: > > I agree. Bygraves could be build. > > However, there are some cumbersome questions, the most obvious being, > How to generate a drum-shaped scales with the required accuracy and > resolution. Remember, we will have to maintain sub-millimeter acc/res > over many turns, with "many" meaning perhaps 20 to 50. This should be > possible, but is still not easy. > > If someone could generate the mechanical construction and quality > assurance methods for this challenge we could talk about manufacturing > more seriously. Her are my ideas: > > Personally, I am thinking of an ink-jet head printing on a turning > drum where the printing is synchronised with a digital encoder on the > drum' s axis. The process control could be handled by one of the > relatively simple contollers on the market. > > Another approach would be to replace the ink-jet printing with an > engraving system. > With the first I personally have experience, with the second none > whatsoever. > > However, more problems lurk. What are the limits for excentricity of > the drums when in use? How about friction? How to stabilize the thing > when under the influence of temparature changes, humidity, sun's UV, > spray salt water, etc, etc. > > So, you can see that the conceptual simplicity of the Byraves is > offset by many practical obstacles. > > Compare this, for instance, with the Ageton method (H.O. 211)! Only 12 > pages of a table, a sheet of paper and a pencil is virtually all you > need to get a generally higher res/acc than with a practical Bygrave. > > Yes, you will also need the skill and concentration to exercise the HO > 211 calculations under virtually any condition at sea - particularly > when you are a submarine commander at war. Well, I guess, in this case > a Bygrave, well designed under a government contract, does make sense! > > > > > > > --- On *Fri, 7/3/09, Greg Rudzinski /
/* wrote: > > > From: Greg Rudzinski > Subject: [NavList 8924] Re: Manufacture new Bygraves? > To: "NavList" > Date: Friday, July 3, 2009, 9:40 AM > > > There must be a combination of PVC tubing that fits on itself snugly. > If the white PVC were engraved with black and red scale markings as a > regular plastic slide rule is then I think you would have something. > > On Jul 3, 12:18 am, > wrote: > > A few years ago, when I and a couple of friends wanted each to > own a gear hobbing machine, we cooperated. One made the casting > patterns and saw them through the local foundry, another did the > heavy machining and I did the small parts like feedscrews and > their nuts. It occurs to me that several handy people could > combine their skills to produce replica Bygraves slide rules. > There will surely be someone who knows where to access tubing in > which each size nests snuggly in the next largest size, someone > else will know how to produce hard-wearing replica scales, another > may be prepared to turn the bobbins at each end and I would > volunteer to do small bits of metalwork. The results do not have > to make profits, though a little would be nice. Since there seem > to be very few surviving Bygraves calculators, one could at least > have the satisfaction of owning a replica. The starting point of > course would have to be accurate, dimensioned drawings of an > original, preferably following the metric system, so the > manufacturing consortium would not have to be confined to the USA. > > > > Any offers/takers? > > > > > "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you." --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To unsubscribe, email NavListemail@example.com -~----------~----~----~----~------~----~------~--~---