Needs Pictures: 0
Results 1 to 9 of 9
Thread: Tight tolerance
-
22nd Sep 2020, 10:16 PM #1Gear expert in training
- Join Date
- Aug 2008
- Location
- Melbourne
- Age
- 34
- Posts
- 1,080
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
-
22nd Sep 2020, 10:46 PM #2China
- Join Date
- Dec 2005
- Location
- South Australia
- Posts
- 1,658
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.
-
22nd Sep 2020, 10:59 PM #3I break stuff...
- Join Date
- Aug 2010
- Location
- Toorloo Arm, VIC
- Age
- 39
- Posts
- 1,300
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...
-
22nd Sep 2020, 11:40 PM #4Most Valued Member
- Join Date
- May 2011
- Location
- Murray Bridge S Aust.
- Age
- 71
- Posts
- 5,959
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.
KrynTo grow old is mandatory, growing up is optional.
-
22nd Sep 2020, 11:44 PM #5Gear expert in training
- Join Date
- Aug 2008
- Location
- Melbourne
- Age
- 34
- Posts
- 1,080
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.
-
23rd Sep 2020, 05:07 PM #6Most Valued Member
- Join Date
- Apr 2012
- Location
- Healesville
- Posts
- 2,129
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?
-
23rd Sep 2020, 06:32 PM #7Gear expert in training
- Join Date
- Aug 2008
- Location
- Melbourne
- Age
- 34
- Posts
- 1,080
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.
-
23rd Sep 2020, 06:46 PM #8Diamond Member
- Join Date
- Mar 2014
- Location
- South of Adelaide
- Posts
- 1,227
Is it really 60.000mm, how much is your measurement uncertainty?
-
23rd Sep 2020, 07:59 PM #9Gear expert in training
- Join Date
- Aug 2008
- Location
- Melbourne
- Age
- 34
- Posts
- 1,080
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
-
CVA tight spindle
By morrisman in forum METALWORK GENERALReplies: 44Last Post: 26th Apr 2016, 01:07 PM -
5C Collet Square Stock Tolerance
By electrosteam in forum METALWORK GENERALReplies: 3Last Post: 31st Dec 2013, 07:23 PM -
Tight collett
By bigphill in forum METALWORK GENERALReplies: 18Last Post: 11th Aug 2013, 11:52 PM -
where can i get TRUE tolerance 8mm lathe bits
By Nurgle in forum METALWORK GENERALReplies: 12Last Post: 29th Mar 2009, 10:55 PM -
tight bushing
By burraboy in forum METALWORK GENERALReplies: 3Last Post: 25th Sep 2007, 09:35 PM