. .

Threaded View

Previous Post Previous Post   Next Post Next Post
  1. #10
    Quote Originally Posted by birchy View Post
    OK, OK! I'll put the lump hammer down for now!

    I have got one 14T pulley to give me a 3:1 ratio (42T) on the Z axis, so might have to change that to an 18T or bigger. My thinking is that even if we had 1 or 2 degrees of rotational backlash in the pulleys, this would still not be enough to cause a problem if using ballscrews?


    Here is a simplified, why backslash in reality will not happen with these belts
    Imagine 2 pulleys on a horizontal plane with a belt mounted. When tightened the belt, all the teeth from 6 to 12 o'clock on the left and from 12 to 6 on the right will preload.

    Now imagine the belt start to move clockwise driven by the left pulley. From 9 to 12 o'clock is where the backslash will happen, but from 6 to 9 will be still preloaded. At the right pulley the same. From 12 to 3 backslash and from 3 to 6, tooth engaged.

    So at any time at least half of the engaged teeth are without backslash.

    Hence the tooth strength together with the tension plus the pulley size , if enough will not permit backslash.

    18t pulley is what i use on my machine, changed from 14, he he. For other reasons though.

    Yeah, for the Z it shouldn't be a problem.

    When i changed belts even when the pulleys were tightly fitted they gave me problems, especially the small ones connected directly to the motor shafts. They were backslashing by slipping on the shafts even if i used 3 grub screws on each. And only under heavy loads so it took me a lot of time to figure the problem. A little "super" glue eliminated this.

  2. The Following User Says Thank You to Boyan Silyavski For This Useful Post:


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Ballscrews - pulleys - timing belts
    By vre in forum Gantry/Router Machines & Building
    Replies: 0
    Last Post: 15-01-2014, 08:03 PM
  2. Advice: Timing Pulleys and Belts
    By Mad Professor in forum Belt Drive, Pulleys & Timing
    Replies: 7
    Last Post: 24-06-2012, 12:30 PM
  3. WANTED: wanted drive belt and pulleys
    By oadamo in forum Items Wanted
    Replies: 2
    Last Post: 13-05-2011, 09:00 PM
  4. Timing belt instead of rack!
    By ptjw7uk in forum Belt Drive, Pulleys & Timing
    Replies: 8
    Last Post: 18-12-2009, 12:49 PM
  5. Source for XL timing belts and pulleys
    By MikeyC38 in forum Gantry/Router Machines & Building
    Replies: 4
    Last Post: 20-08-2009, 01:21 PM

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
  •