Author Topic: Doing finish work on granite plate .....  (Read 7634 times)

Offline derekwarner

  • Full Member
  • ****
  • Posts: 833
  • Wollongong ...... Australia
Re: Doing finish work on granite plate .....
« Reply #15 on: April 19, 2016, 01:02:12 AM »
Bill....from memory the slab was ~~ 700mm thick...so a auto calculation suggests ~~ 28000 kg [28 tonne]...the slab was lifted and installed with the aid of a 200 tonne crane

The support mechanism was based on an American military standard [MIL Spec] with multiple hydraulic load cells firstly confirming even force loading, then during each critical measurement the slab was elevated by the same load cells with load sensing software under a surprisingly low hydraulic pressure of 2000 PSI [or ~~130 Bar]

Placing a say 250 kg component on the slab did not register as any form of angular displacement measurable by any equipment available in the Naval Dockyard facility

BTW...I have corrected the controlled temperature ...it was the standard 20 degrees C

Derek

« Last Edit: April 19, 2016, 01:06:37 AM by derekwarner_decoy »
Derek L Warner - Honorary Secretary [Retired]
Illawarra Live Steamers Co-op - Australia
www.ils.org.au

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6811
  • West Chester, PA, USA
Re: Doing finish work on granite plate .....
« Reply #16 on: April 19, 2016, 01:04:44 AM »
I all ways work to microns...............there may be a large number of decimal points involved ...but they are still microns!!!!

 :lolb: :lolb:

My dimensions have the letter E (or e) in them.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13860
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Doing finish work on granite plate .....
« Reply #17 on: April 19, 2016, 01:17:26 AM »
Thanks for the info Derek. That would have been fascinating to see. Here at the UNCC metrology lab with sophisticated nano scale instruments, the new building that houses the lab was in some ways designed around the lab...a separate isolated floor slab for example, and if memory serves they even took seismic measurements to determine the typical activity at various times of the day depending on interstate and railroad track activity even if a half mile or more away from the building itself. I think the HVAC system is capable of holding +/- .1 degree C 24/7.  Defnintely not your typical hobby set-up but you have to admire the technology involved in making those kinds of measurements. 

I would love to see pictures of the surface plate you describe....gosh...what a monster!!

Bill

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 4693
  • Boise, Idaho USA
    • Photo Bucket
Re: Doing finish work on granite plate .....
« Reply #18 on: April 19, 2016, 01:26:36 AM »
At my place of employment many years ago  :old: we had a largish Italian marble surface plate [approx. 3m x 5m] for re-assembly measurement of largish missile launcher components...... naturally it lived at a constant 22 20 degrees C & 16 % humidity..........the surface flatness was measured in uM [microns]

The directions  :Director: were quite clear.....it was very cold to walk on :ShakeHead:  as one had to wear those synthetic sterile bootlets over cotton socks over bare feet as worn in hospital theatres..& no  :wine1: on the job.......Derek

Do ya think they would have minded if you used it to lap your model steam engine parts on?  :lolb:

I'm with Brian, I have a small Granite plate that gets used mostly for lapping parts on wet or dry sand paper. I have a small one on my bench at work for the same thing.

Dave

Offline petertha

  • Full Member
  • ****
  • Posts: 782
Re: Doing finish work on granite plate .....
« Reply #19 on: April 19, 2016, 06:08:11 AM »
I have yet to buy a granite plate for measuring, but its on the acquisition list. I have 2 plates of glass 1 foot square x .25" thick which I tape 2 grades of wet/dry paper around the periphery just using masking tape (for example 320 & 600). Works great for finishing parts & my favorite lube is a spritz of WD40. That's what I use them for. But I'm curious, has anyone measured across a typical glass plate with DTI to see how much it deviates? Guessing to measure it properly you would need to lay the glass on the granite... so with granite you probably wouldn't have glass to begin with.. one of those chicken & egg things :)

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: Doing finish work on granite plate .....
« Reply #20 on: April 19, 2016, 12:30:21 PM »
If you have a cheap Chinese plate ( or tomb stone)  and can stand the space to store it....its fine

A nice Starrett Pink plate to 50 millionths......WE are going to have a conversation....just sayin....

A piece of countertop or sheet glass would be a better choice and less expensive .....

I used to do that on the table saw......kept the rust off..

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

toolznthings

  • Guest
Re: Doing finish work on granite plate .....
« Reply #21 on: April 19, 2016, 04:54:59 PM »
I guess my real point was the use of the " stick and sand " papers on whatever surface you choose. Does not need to be a granite plate.

Brian

Offline steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: Doing finish work on granite plate .....
« Reply #22 on: April 19, 2016, 06:01:46 PM »
I guess my real point was the use of the " stick and sand " papers on whatever surface you choose. Does not need to be a granite plate.

Brian

YUP.....but try not to do this on a NICE surface plate hmmm?     Please?

Sorry....I've done too much scraping to have my surface plates un-necessary accuracy ameliorated by crocus cloth and elbow grease... 8)

Table saws work great for that!!!!
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline ShopShoe

  • Full Member
  • ****
  • Posts: 462
  • Central Iowa, Central USA
Re: Doing finish work on granite plate .....
« Reply #23 on: April 20, 2016, 02:13:42 PM »
FWIW,

Tom Lipton ("Oxtoolco" on youtube) has a video showing his surface plates being reconditioned. The one he uses for sanding does show some wear. A very interesting process to watch. Find it by searching on youtube for "Surface Plate Calibration and Conditioning."

As a hobbyist, I don't get too worried, but I use my surface plates (Grizzly Specials) for layout and measuresment and testing and do sanding on other surfaces. Mostly I try to keep the granite plates (and the tools I use on them) as clean as I can.

BTW,

For ultra-precision geeks, the videos posted by Suburban Tool also get one thinking about ways to be more precise in every way.

https://www.youtube.com/user/SuburbanToolInc

Sorry if this post is too much off-topic

ShopShoe

Offline Sackett

  • Full Member
  • ****
  • Posts: 27
Re: Doing finish work on granite plate .....
« Reply #24 on: May 01, 2016, 07:11:34 PM »
Off topic,but I gotta agree with b.linsey,,,if you're running a fridge , n it aint got Cheerwine in it ,you're wasti 'lectric :cheers:

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13860
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Doing finish work on granite plate .....
« Reply #25 on: May 01, 2016, 08:50:13 PM »
I am surprised it has made it up to WV Sackett. I wasn't sure it had spread beyond the Carolinas to be honest. I am a sweet tea guy myself but Cheerwine is the only soda I will drink :) Maybe Cletus doesn't know what he's missing!!

Bill

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal