Page 1 of 2 12 LastLast
Results 1 to 10 of 11
  1. #1
    25+ Posting Member
    Join Date
    Feb 2007
    Location
    Argentina
    Posts
    53
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Altimeter gear compound train help

    Since Mike Powellīs book is not longer available, i need a little help for making a gear compound train for a kollsman altimeter.
    I had seen a web (Scott Hendry) with a simple system (with the numbers of teeths) ,but the URL no longer exist.
    I have a photo, but i donīt understand the numbers of teeths for a 1:10:100 ratio.

    altimeter gears.jpg

    In the photo, the larger gears are 50 teeth, and the smallers are 16 teeth, but the ratio does not seem correct.
    Can anybody help me?
    Thanks in advance.

    Horacio

  2. #2
    25+ Posting Member
    Join Date
    Feb 2007
    Location
    Argentina
    Posts
    53
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    I was thinking about:
    60-30-12
    or
    80-40-16
    or
    50-25-10

    but i havenīt a clue to put gears in a 2 axis system.
    Thanks.
    Horacio.

  3. #3
    500+ This must be a daytime job 737NUT's Avatar
    Join Date
    Feb 2006
    Location
    Indianapolis, IN
    Posts
    751
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Why not buy a real altimeter off ebay and convert it. Much easier in my humble opinion as all the gearing is done. You just need to change out the drive mechanism.

  4. #4
    150+ Forum Groupie
    Join Date
    Apr 2010
    Location
    Auburn, WA
    Posts
    186
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Those gears produce a 0.1024:1 ratio. Not the exact 1:10 that you want, but probably close enough for a simulation while still using easy-to-get parts.

  5. #5
    300+ Forum Addict



    Join Date
    Feb 2007
    Location
    California, USA
    Posts
    406
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    It's 24 to 48 out to the idler shaft, then 12 to 60 back to the concentric shafts. The first gives you a 2 to 1 reduction; the second gives you a 5 to 1 reduction. The net reduction is exactly 10 to 1. A key fact is that the sum of the diameters of the first two gears is the same as the sum of the diameters of the second pair. If this were not the case the gears would not be able to mesh properly.

    I don't know how Scott was planning to use the gear set you pictured. Possibly he was not going to develop a 1:10:100 reduction train. He may have planned to simply use three separate, offset motors to individually drive three concentric output shafts.

  6. #6
    25+ Posting Member
    Join Date
    Feb 2007
    Location
    Argentina
    Posts
    53
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Thatīs the right answer... Just before your reply, i find the solution with 12 to 24, then 12 to 60.
    ALTIMETRO KOLLSMAN 1.jpg
    Many thanks Mike !!!!!!!!

  7. #7
    75+ Posting Member cscotthendry's Avatar
    Join Date
    Dec 2006
    Location
    Russell Island Australia
    Posts
    128
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Quote Originally Posted by Mike.Powell View Post
    It's 24 to 48 out to the idler shaft, then 12 to 60 back to the concentric shafts. The first gives you a 2 to 1 reduction; the second gives you a 5 to 1 reduction. The net reduction is exactly 10 to 1. A key fact is that the sum of the diameters of the first two gears is the same as the sum of the diameters of the second pair. If this were not the case the gears would not be able to mesh properly.

    I don't know how Scott was planning to use the gear set you pictured. Possibly he was not going to develop a 1:10:100 reduction train. He may have planned to simply use three separate, offset motors to individually drive three concentric output shafts.
    LOL, that's because those weren't my gears. I used the ratios Mike set out above and in his book, but I cut my own from aluminium and brass.


    P1060112.jpg

    I used an old altimeter as someone else suggested, which gives the benefit of the external knob to drive the kollesman setup mechanism.

    P1060288.jpg

    My new URL is at the end of this post, but I had to remove soome of the sim pics when I started building the Nynja. If there are pics of any sim bits that I did that anyone would like copies of, just PM me and I'll gladly send them.
    Regards: Scott Hendry
    www.scotthendry.com

  8. #8
    Our new friend needs to reach 10 posts to get to the next flight level



    Join Date
    Oct 2012
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Hello 737NUT,
    interesting post. How do you change the drive mechanism? Using stepper motors will be difficult since it requires 2 turns to find its position with an optical sensor. So that would mean using an altimeter you already have passed 200 or 2000 feet just for finding the position. Any ideas? I am having the exact the same problem.
    Many thanks
    nils

  9. #9
    500+ This must be a daytime job



    Join Date
    Jan 2007
    Location
    NEW ZEALAND
    Posts
    624
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Hi Nils,
    Welcome to the forum, take alook at What Rob did.
    http://www.cockpitbuilders.com/commu...73.0;topicseen

    Les

  10. #10
    Our new friend needs to reach 10 posts to get to the next flight level



    Join Date
    Oct 2012
    Location
    Germany
    Posts
    8
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Altimeter gear compound train help

    Thanks Les! Very interesting

    Quote Originally Posted by iwik View Post
    Hi Nils,
    Welcome to the forum, take alook at What Rob did.
    http://www.cockpitbuilders.com/commu...73.0;topicseen

    Les

Page 1 of 2 12 LastLast