Looking to buy/ for info on optical comparator overlays
Close
Login to Your Account
Results 1 to 7 of 7
  1. #1
    Join Date
    Jan 2012
    Location
    st louis
    Posts
    271
    Post Thanks / Like
    Likes (Given)
    37
    Likes (Received)
    32

    Default Looking to buy/ for info on optical comparator overlays

    Hi

    Im looking for a good source of new or used overlays for a 12" comparator I have.
    I could use a thread pitch, radius or angle or ?
    If you have some used ones for sale let me know or know where I could get some without spending $100 each for them.

    Thanks
    Matt

  2. #2
    Join Date
    Jan 2007
    Location
    wales.uk
    Posts
    1,199
    Post Thanks / Like
    Likes (Given)
    137
    Likes (Received)
    187

    Default

    The ones I had were just laser printed OHP sheet, clear plastic stuff,
    There were thicker acrylic scribed and inked plates at x10 scale, they were just done my hand on a drawing board, fairly easy though rotering pens are annoying when they dry out!
    I’ve made them on a photocopier using OHP film and a copy of machinery’s too
    Mark

  3. #3
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    3,751
    Post Thanks / Like
    Likes (Given)
    4088
    Likes (Received)
    12754

    Default

    Quote Originally Posted by boslab View Post
    The ones I had were just laser printed OHP sheet, clear plastic stuff,
    There were thicker acrylic scribed and inked plates at x10 scale, they were just done my hand on a drawing board, fairly easy though rotering pens are annoying when they dry out!
    I’ve made them on a photocopier using OHP film and a copy of machinery’s too
    Mark
    I've often done similar for special features on items. Easily drawn on an old drawing table on transparent material.

    A thread profile should be very easy to draw.

    http://flexiblemeasuring.com/images/...basic/1.09.pdf

  4. Likes matthewlee liked this post
  5. #4
    Join Date
    Oct 2012
    Location
    NE Ohio USA
    Posts
    651
    Post Thanks / Like
    Likes (Given)
    129
    Likes (Received)
    249

    Default

    Hi Matt,

    Just a thought:
    Years ago we printed our own overlays from CAD on an HP inkjet printer. We used overhead projector stock (like cellophane designed to be used in printers) . I think you can still get it at Staples or Office Max etc. Anyway we were surprised at the quality and accuracy of the printed overlays. If I recall the HP printer was not an expensive model. Hope this helps.

    Oh and it gives you the flexibility to print nominal, upper, lower limit profiles for your parts on the same sheet.

    Best Regards,
    Bob

  6. Likes matthewlee liked this post
  7. #5
    Join Date
    May 2001
    Location
    Massachusetts
    Posts
    1,159
    Post Thanks / Like
    Likes (Given)
    30
    Likes (Received)
    149

    Default

    These guys supply at least some of the optical comparator manufacturers:

    Optical Comparator Charts - Visual Inspection Products - Optical Comparator Charts

  8. #6
    Join Date
    Oct 2010
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    5,311
    Post Thanks / Like
    Likes (Given)
    4795
    Likes (Received)
    1952

    Default

    While I support the idea of printing your own overlays, if you are actually using them to check parts, it is imperative to double-check the overlay as-printed. It is extremely common for printers and copiers to slightly distort, by scaling in the paper-travel axis. I have seen a badly setup copier expand the travel axis by 5%, which is gross.

    In addition to X-Y axis calibration, you want to make sure that the overall CAD/print/copy process came out to the correct real-world scale. So I would put three extra points on the overlay, one pair widely separated on X, the other on Y, and both a known model distance. Then when you get your print or copy, verify the actual distance between the points.

  9. #7
    Join Date
    Feb 2011
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    2,494
    Post Thanks / Like
    Likes (Given)
    1997
    Likes (Received)
    1102

    Default

    I've picked a couple used glass screens up from Ebay for our J&L comparator. The screen that came with it had all the data rubbed off, so I kept it for a backing and bought a couple basic Mylar screens from J&L. They're not the cheapest, but good OEM quality. Also have a ream of the printable projector film that we can print anything else onto.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •