Author Topic: Granite surface plate..has come to me!  (Read 11359 times)

Offline FLG

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Granite surface plate..has come to me!
« on: May 17, 2013, 04:18:46 AM »
Hi all, finllay I was able to put my hand into a granite surface plate  :naughty:

The plan with this is to make precision layout and setups for tool/engine making, and also to learn hand scrap.




Now I got some cuestions:

with the ganite, I got a very poor certificate (chinese stuff), it said the max deviation is 2,879um and the grade of presition is DIN00

For a grade B surface I think is 0.0001" in flatnes, this give me a 0.0001 x 25,4 = 0,00254mm, = 2,54um, then my granite is gade C?

And Im planing to make it a stand, what considerations should I take, like some damping stuff between the granite and the stand?

Also Im using alcohol to clean it up, no problem with that?

Saludos!

Offline b.lindsey

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Re: Granite surface plate..has come to me!
« Reply #1 on: May 17, 2013, 11:37:25 AM »
Hi FLG, that looks like a nice size surface plate and weighty too i am sure. From the specifications you give, it would be almost a Grade B (toolroom grade). The least accurate would be considered a workshop grade. Even so you are close to .0001 TIR across the plate which for our type of work should be more than sufficient!!

If you look at this MSC page you will see a  commercial stand. They aren't cheap but I suspect much of the cost is due to engineering them for stability, being able to support twice the weight of the surfact plate they are sized for, and good flat construction where they support the plate. The thing i noticed is that the 4 corners stick up slightly to "capture" the plate.
https://www.mscdirect.com/product/84371574

One other thing you might consider if making a cover for your plate just to provide some cushioning against sharp corners of metal parts or other instruments when you aren't using it as a surface plate. Would also keep contaminants like oil , etc. off the granite surface.

Bill

Bill

Offline Stuart

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Re: Granite surface plate..has come to me!
« Reply #2 on: May 17, 2013, 11:46:08 AM »
FLG

look under that plate and you should see three chalk crosses , get some felt self adhesive pads about 25 mm Dia. and fix them over the thee marks

these are the marks that were used to test the plate and are the suspension points

the do as has been suggested make a cover but put four of the pads in the corners to lift the cover off the plate

give it a wipe over with a thin oil DTE light hydrolic oil and wipe it all off that will leave a nice surface to slide the gauge on

and will get the Stuart's blue off when you use that product


Stuart
My aim is for a accurate part with a good finish

Offline MuellerNick

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Re: Granite surface plate..has come to me!
« Reply #3 on: May 17, 2013, 12:01:05 PM »
Quote
with the ganite, I got a very poor certificate (chinese stuff), it said the max deviation is 2,879um and the grade of presition is DIN00


Now they even can measure to nm! A 1/1000th of a m.  :Jester:
That should be DIN876 (out of my head) grade 00. Grade 00 is for calibration. Better than inspection or toolroom.


But without knowing the size, it is hard to say what would be allowable for grade 00.


You will soon discover that it is too small.  ;)
I clean mine with light oil (like kerosene) or with a special cleaner (that smells a lot like a window cleaner).
If you start scraping, under all circumstances ignore the stupid tip to use oil based prussian blue paint. The dumbest scraping related tip of the universe.




Nick

Offline Maryak

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Re: Granite surface plate..has come to me!
« Reply #4 on: May 17, 2013, 12:04:34 PM »
FLG,

Very Nice  :NotWorthy:

I'm hoping for a nice granite surface plate with a nice inscription; but not for a lot of years yet .  :mischief:

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline 90LX_Notch

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Re: Granite surface plate..has come to me!
« Reply #5 on: May 17, 2013, 12:45:53 PM »
That's interesting.  From my experience oil on the plate always made everything harder to move.  We used alcohol or acetone.  With all the oil and grime removed, the gages would glide across the plate almost as if they were on air bearings.  We also used Starrett surface plate cleaner and couldn't tell and difference from the alcohol or acetone.  Also, by using alcohol or acetone, no residue is left behind and you're truly on your datum, not a film of oil. 

Note: Don't forget clean the bottom of the gages also.

-Bob
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Online steamer

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Re: Granite surface plate..has come to me!
« Reply #7 on: May 17, 2013, 01:36:08 PM »
Quote
with the ganite, I got a very poor certificate (chinese stuff), it said the max deviation is 2,879um and the grade of presition is DIN00


Now they even can measure to nm! A 1/1000th of a m.  :Jester:
That should be DIN876 (out of my head) grade 00. Grade 00 is for calibration. Better than inspection or toolroom.


But without knowing the size, it is hard to say what would be allowable for grade 00.


You will soon discover that it is too small.  ;)
I clean mine with light oil (like kerosene) or with a special cleaner (that smells a lot like a window cleaner).
If you start scraping, under all circumstances ignore the stupid tip to use oil based prussian blue paint. The dumbest scraping related tip of the universe.




Nick

Agree....don't like prussion blue/ High point blue at all!... I use the E S Dyjak Canode which works real well and washes off with soap and water.

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

Online steamer

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Re: Granite surface plate..has come to me!
« Reply #8 on: May 17, 2013, 01:51:08 PM »
Like Nick...I also clean my plate with a light petroleum solvent....comes in a can marked WD40..... ;D

Works well with the Dyjak stuff.

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

Offline MuellerNick

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Re: Granite surface plate..has come to me!
« Reply #9 on: May 17, 2013, 02:25:31 PM »
Quote
Agree....don't like prussion blue/ High point blue at all!


I read some misunderstanding here:
With "Prussian blue" I meant the artits's paint, the oil-based paint. You should stay away from that, as it tries and is impossible to get out of the (desired) pores of the granite. It is a good way to ruin your surface plate!


Re spotting blue:
I haven't got my hands on Canode yet. But from the pictures I have seen, it looks like being at the very low end of the quality scale. I might be wrong!


The Dykem spotting blue I know very well! I love it, it is almost the best you can get for fine scraping. Not so good for roughing. For roughing, I use a different brand ("Diamant", contains no diamonds before you ask). It has less pigments and so is easier to read with relatively thick layers.


You can use WD40, but there are way cheaper spray oils. Kerosene is quite good (but stinks), because it evaporates. I use oil for in-between cleaning, and the "window-cleaner"*) for thorough cleaning. Acetone should be OK too, but I simply don't like the smell too much.


*) It actiually is a granite surface cleaner in a pump bottle, made by Planolith. A manufacturer of surface plates here in Germany.




Nick

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Re: Granite surface plate..has come to me!
« Reply #10 on: May 17, 2013, 02:48:40 PM »
I've tried both Nick.....I just don't like  the mess with hi spot

But they still use it at Moore....though they co-mark with powder paint mixed with oil.

I've had a couple of scrapers recommend the Dyjak stuff....but to each his own.

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

Online steamer

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Re: Granite surface plate..has come to me!
« Reply #11 on: May 17, 2013, 03:04:26 PM »
But we really agree about the paint....Don't use paint! 8)

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

Offline mklotz

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Re: Granite surface plate..has come to me!
« Reply #12 on: May 17, 2013, 03:56:25 PM »
For minimum sag and distortion a beam like your surface plate should be supported at its Airy points.  These are two points located symmetrically a distance of:

L / [2 * sqrt(3)] = L * 0.289   [L = length of plate]

from the center of the plate.

Our club visited an outfit here in LA that makes precision surface plates and other granite metrology standards for industry and aerospace suppliers.  We asked what they recommended for cleaning and care.  They told us to use Orange hand cleaner, e.g.,

http://www.permatex.com/products/our-brands/fast-orange

It gently removes oil and grime and the slight residue of lanolin it leaves behind allows tools to glide easily over the surface.

Be careful though.  Some of these orange hand cleaner products contain pumice.  Select one without pumice. 
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Regards, Marv


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Online steamer

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Re: Granite surface plate..has come to me!
« Reply #13 on: May 17, 2013, 03:59:21 PM »
Hey Marv,

I might even have some of that!....I'll give it a shot.

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

Offline b.lindsey

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Re: Granite surface plate..has come to me!
« Reply #14 on: May 17, 2013, 04:08:34 PM »
And don't forget the fragrant orange bouquet wafting through the shop too  :lolb:

Bill