Results 1 to 7 of 7

Thread: Precise rotation of a turntable

  1. #1

    Precise rotation of a turntable

    Hello, I have to design a turntable, that holds 3 PCBs, and stops at 120 degrees, for a piston to test the PCBs.

    My problem is, I am using a stepper motor and a photosensor to control the rotation of the turntable in 120 degrees increments, but the inertie makes it unaccurate, and I cannot think of a way to turn the table precisely 120 degrees at a time ( especially at high speeds) . Any thoughts?

    Thanks a lot!

  2. #2
    Principle Engineer
    Join Date
    May 2015
    Posts
    217
    Why do they have to be on a turn table? Or why can't they be moved in a straight line? How accurate do they have to be for measurement?

  3. #3
    Principle Engineer Cragyon's Avatar
    Join Date
    Feb 2013
    Location
    Newark, NJ
    Posts
    299
    Retractable mechanical stop at 120 deg. increments? Have you considered a programable stepper motor control electronics like Rambo board?

  4. #4
    Technical Fellow jboggs's Avatar
    Join Date
    Mar 2011
    Location
    Myrtle Beach, SC
    Posts
    908
    Back in the day engineers used mechanical indexers to drive dial indexing tables for all kinds of automated assembly processes. I used Camco indexers on several successful projects. Like these:
    https://www.destaco.com/products/mec...ttribute-stops

  5. #5

    No it cannot

    Quote Originally Posted by Hudson View Post
    Why do they have to be on a turn table? Or why can't they be moved in a straight line? How accurate do they have to be for measurement?
    First of all, thank you Hudson for your reply.

    The project is specific for a turntable, I cannot change the scope, even if it's not the best way.

    The piston(it's up to me to use an pneumatic piston, or something else that moves in a straight line) has to have pogo pins that touch some pads, testing PCBs. it has to be very exact, within the 1mm.

  6. #6
    After the table has turned 120 degrees, a sensor stops the stepper motor, and a claw that I made drops into her slot on the turntable, and keeps it fixed, fixing any small error of rotation, and then the PCB is tested, that is how I approached this and it worked.

    Thank you all for the replies, I really appreciate it Cragyon, Jboggs and Hudson.

    Have a great day fellows,
    Alex.

  7. #7
    Principle Engineer
    Join Date
    May 2015
    Posts
    217
    The indexer jboggs mentions is a good idea. Also investigate shot pins to position. The name Ferguson drive comes to mind as well.

Posting Permissions

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