Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,654   Posts: 1,481,341   Online: 1043
      
Page 2 of 2 FirstFirst 12
Results 11 to 14 of 14
  1. #11
    kmv2's Avatar
    Join Date
    Nov 2006
    Shooter
    35mm
    Posts
    3
    In answer to the question, IMO I would not use brass or any other metal screws. I would lubricate the aluminum screws to prevent oxidation (but this is extremely hard to do with aluminum, although the aluminum oxide will protect from further oxidation). In most applications you would want to aluminum to oxidize. Aluminum oxide is one of the hardest substances known to man, and is used as an abrasive for industrial applications.

  2. #12

    Join Date
    Dec 2004
    Shooter
    Multi Format
    Posts
    1,670
    In order for corrosion to occur you not only need two dissimilar metals you also need some sort of electrolyte. Unless you leave your lenses sitting in salt water when not in use you are not going to see a problem. As I said, brass and aluminum have been used extensively in the past for focusing mounts. If there were a problem then another combination would have been used.

  3. #13
    barryjyoung's Avatar
    Join Date
    Jul 2005
    Location
    Near Seattle WA, USA
    Shooter
    ULarge Format
    Posts
    411
    Images
    2
    Quote Originally Posted by Loose Gravel View Post
    Dave, I'm a little worried about the vaseline or other anti-seize compounds because they can wear off or go away in time. Is there an easy to machine stainless steel that might work.

    I remember now about aluminum wires in houses catching fire. The brass and copper connections must have eroded it.

    303 stainless steel is relatively free machining. Stay away from 304 if you are concerned about machinability. 15-5 preciptation hardening stainless is fairly easy but is tough so requires rather heavy cuts with lots of horsepower. Have you considered Monel or Invar? If you do end up going to a high nickel content alloy be warned that it machines (and taps) quite easily but will work harden if you look at it sideways so do not let the parts touch each other or drop on the floor before they are finished. Let me know if you need more information.
    Barry Young
    Young Camera Company

  4. #14

    Join Date
    Jul 2006
    Location
    Europe, France
    Shooter
    Multi Format
    Posts
    197
    Blog Entries
    1
    Images
    9

    Why not anodizing ?

    I think too that brass and aluminium will be a correct choice. We have here, on a telescope focuser, such assembly, in a rather harsh environment (basically outside, under a rolling roof, not so far from the sea coast) and there is no disabling corrosion issue.

    Why not using aluminium on aluminium, but with anodizing of the two part ? It is not difficult to do, with little care, sulfuric acid (beware !) and a lead battery charger. As far I know (I tried), two anodized aluminium parts will not "glue" any more.

    OK, this makes problems with then necessity of electrical contact, but if I understanded well your needs, you can do a little threaded hole in one of the parts to set a contact screw.

    Best regards,

    Raphael

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin