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    Re: Bygraves
    From: Hanno Ix
    Date: 2009 Jul 18, 11:36 -0700
    Hello:

    One of the difficulties I presently face in making test samples of Bygraves is the creation of accurate and well readable scales. The topic sounds perhaps trivial but well designed scales contributes much to the quality of the end product.

    In non-linear scales, how do you choose the graduations, and what is the rule to change them when the labels become "too close" ?  Where do you put the numbers - on top or next to the corresponding mark? Also, there should be means to shift and stretch them for certain amounts so as to adapt them to the drums, paper thickness, etc. Are there any programs or algorithms specifically for rulers and scales?

    I know some of you have made scales. Please let me know how you did it before I get lost in re-inventing this wheel.

    Regards




    --- On Thu, 7/16/09, engineer{at}clear.net.nz <engineer{at}clear.net.nz> wrote:

    From: engineer{at}clear.net.nz <engineer{at}clear.net.nz>
    Subject: [NavList 9119] Re: Bygraves
    To: NavList@fer3.com
    Date: Thursday, July 16, 2009, 7:59 PM


    Frncis has made a great start. I think it is possible to get something looking even more like the original.

    Ronald van Riet gives the dimensions of the tubes in millimetres, but I think the original outside diameters would have been imperial sizes:
    2 1/2 in; 2 5/16 in; and 2 1/8 in. Nowadays, the only stock imperial sizes that are near are 2 1/2 and 2 1/4 in.  There is a wide range of tube wall thicknesses, so it will be possible to get to the required dimensions by turning and/or boring.

    The hexagonal top and the fluted base will be easy to make if a suitable material can be sourced.

    I suggest we make a start with the simplest item, the Bygrave, and graduate to the more complex German instrument. I can obtain suitable aluminium tubing for only the two larger diameters - and only in 5 metre lengths. If someone out there can send me 10 inch lengths of tubing with the right inside and outside diameters to reach the required diameters, I would be happy to make a start and pass the results on to the "scale fitters". This could prove the concept as well as setting up a cooperative to supply those who don't own the necessary machine tools.

    Bill Morris
    Pukenui
    New Zealand







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