Results 1 to 9 of 9

Thread: Tight tolerance

  1. #1
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default Tight tolerance

    OK, actually zero tolerance.

    Recently I've been getting familiar with the big Jones & Shipman cylindrical grinder at work making some hobbing/turning arbors to a +0 / -5 micron tolerance (obviously aiming for perfect, but we can't get there all the time ), but a few weeks ago it was time to step it up a notch because we needed a 60.000/60.030 mm go/no-go gauge ground after nitriding. Sneaking up on that last micron was one of the most nerve-wracking things I've done, but man it feels good when you get there We have a fancy CNC cylindrical grinder that will hold 1 micron all day, but perfection on a manual machine is just so much more satisfying.

    IMG_20200922_154016.jpgIMG_20200922_154041.jpgIMG_20200922_154059.jpg

  2. #2
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    One day I will get my surface grinder off the pallet and onto the solid floor, may I will get close to that sort of tolerance, good work
    always feels good when you achieve the impossible.

  3. #3
    Join Date
    Aug 2010
    Location
    Toorloo Arm, VIC
    Age
    39
    Posts
    1,270

    Default

    https://www.youtube.com/watch?v=t5MohK5FHEY

    Sorry, this always pops into my head when I start thinking about working to higher levels of precision...

  4. #4
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    71
    Posts
    5,945

    Default

    Thanks for the report. There's a real art in using manual machines, as you say "perfection on a manual machine is just so much more satisfying." Like laying down the perfect stick weld, when the slag lifts off like a scorpions tail.
    Kryn
    To grow old is mandatory, growing up is optional.

  5. #5
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by China View Post
    One day I will get my surface grinder off the pallet and onto the solid floor, may I will get close to that sort of tolerance, good work
    always feels good when you achieve the impossible.
    The only thing you need is patience; pretty sure it took me 4 adjustments and a few spring passes to take the last couple of microns for fear of pressing the fine adjust lever too far. If you have the patience to creep up on your target you can work to any tolerance you want on a grinder.

  6. #6
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Looks good Elan, how did you hold it and what wheel did you use?
    I have the same mic's, 1, 2 and 3" and only (mostly) use them for measuring when grinding, I see the sticker indicates a calibration
    date but do you use the Mitutoyo standard to check and set the mic's prior to use or do you use a gauge block or similar?

  7. #7
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    It was held on an arbor through the bore which was then held between centres. No idea what grade the wheel was, all I know is it's a brownish colour

    Our standard shop practise is to use the supplied standard bar before every use, but, because I was making a reference standard, I checked the mic I was using in the grinding room with a 60mm gauge block stack after the setting piece to be 100% sure.

  8. #8
    Join Date
    Mar 2014
    Location
    South of Adelaide
    Posts
    1,225

    Default

    Is it really 60.000mm, how much is your measurement uncertainty?

  9. #9
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Well since you can't "split the lines" on a digital mic, it would be +/- half the smallest step so +/- 0.5 um, which is probably good enough

    There was very brief talk at one point of getting one of those Mitutoyo laser mics that reads to 5 decimal places (10 NANOmetres ) but I don't think that's happening any time soon.

Similar Threads

  1. CVA tight spindle
    By morrisman in forum METALWORK GENERAL
    Replies: 44
    Last Post: 26th Apr 2016, 01:07 PM
  2. 5C Collet Square Stock Tolerance
    By electrosteam in forum METALWORK GENERAL
    Replies: 3
    Last Post: 31st Dec 2013, 07:23 PM
  3. Tight collett
    By bigphill in forum METALWORK GENERAL
    Replies: 18
    Last Post: 11th Aug 2013, 11:52 PM
  4. where can i get TRUE tolerance 8mm lathe bits
    By Nurgle in forum METALWORK GENERAL
    Replies: 12
    Last Post: 29th Mar 2009, 10:55 PM
  5. tight bushing
    By burraboy in forum METALWORK GENERAL
    Replies: 3
    Last Post: 25th Sep 2007, 09:35 PM

Posting Permissions

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