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Preparing a granite surface plate

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blue_luke

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#1
Hello all! :)
In the next few weeks I will buy a few more tools for my hobby machining shop and I intend to buy a granite surface plate.

I have been gathering informations about this subject and it seems that for my purpose I shall be happy with a 12"X18"X3" grade 'B' (tool room)
I intend to build a welded square tubing base for it and use a three point leveling system to set it perfectly level.

Funny enough I can't find much information about how to treat the surface initially when it's new, and then at routine maintenance intervals. Maybe since these are very simple devices there is simply not much to say about them? But without being maladively perfectionnist, I like to know and understand these basic things!
So the questions are:
- is there an initial treatment to be given to a new stone?
- Are there some products I should never touch the stone with?
- Other considerations I am ignorant of?

Thanks, Luc
 

Moderatemixed

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#2
I have a Starrett 24 x 36 x 4 plate. I watched youtube videos regarding "Bessel and Sperry points" which helps sort out your mounting. There are formulas online which I found helpfull. Too, I watched "Suburban Tool" and they suggest using "ammonia" to clean the plate. I went to Canadian Tire and got a $3 jug and it works amazingly, just make sure you ventilate the shop when you use it. I keep my plate covered when I am not using it with a vinyl Starrett cover. I am just a basement shop so I have not had the plate resurfaced or re-calibrated yet, but for you that won't be an issue. Good luck.


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woodchucker

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#3
well, I have never treated my plate. I clean it with simple green. Don't sand or file on it. Don't hammer on it.
Clean it, cover it with some tempered hardboard when not in use. It will protect it from the crap that normally winds up finding it's way to that surface.
 

Ulma Doctor

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#4
Hi blue_luke,
a thorough cleaning is recommended for a new stone.
granite dust can create all kinds of scratches on the plate and instruments
i use straight dollar store ammonia, after seeing a great video by Don at Suburban Tool Co
Tom Lipton at Oxtool uses Starrett brand surface plate cleaner
i have heard of people treating their surface plates with lanolin, it is an acceptable practice and recommended by some
 

eeler1

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#5
Hey Mike, does that apply to newly-reconditioned stones as well? Mine just got re-done, should it get a good clean with ammonia?
 

blue_luke

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#6
Hmmmmm....
That is exactly what I was suspecting. A new plate was probably fairly well cleaned after manufacturing but there must be still some dust, particles and whatnot on it.
So this has to go somehow. I did not know about using amonia on granite.

Also while on the subject, a 'B toolroom grade" plate is surfaced to 0,0002" which is is about twenty times better than my abbility at machining right now! I will buy one from a machine tool distributor, I 'need' the comfort of buying something certified, but just out of curiosity, how flat are the granite found at countertop or toombstone fabricator ?
Also, again out of curiosity, I had some belgian, french and austrian colleagues at one point or another in my career and contrary to us north-american as where we refer to a 'surface plate, or a 'granite', they refered to a 'marble plate' or simply a 'marble'
Is it just because granite is more common in America, and marble more comon in Europe, or this is just a semantic quirp?

Luc
 

Eddyde

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#7
In my opinion marble would make a poor surface plate, It is soft and porous. So my guess it's a case of translation.



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Bob Korves

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#8
Granite is stable and long wearing against abrasion. Ammonia is a great choice for a cleaner. Some surface plate cleaners contain lanolin, which makes the rock look nice, but builds up a film that compromises the accuracy, which is the sole purpose of the plate. Your measuring tools should be be accurate to an order of magnitude higher than the work you want to calibrate with them. For some work a yard stick is close enough...
 

toploader

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#9
While watching some Vintage Machinery videos on YouTube. Richard King advised the guys in the class to use windex. I have Starrett surface plate and it seems to work well.
 
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Ulma Doctor

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#10
Hey Mike, does that apply to newly-reconditioned stones as well? Mine just got re-done, should it get a good clean with ammonia?
Yes,
I got quite a bit of diamond dust to come off onto the white rags when i cleaned mine after calibration

Ammonia will not compromise granite.

you can spend more money if it makes you feel warm and fuzzy, but there is no magic in other cleaners , rather only preference
 

Ulma Doctor

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#11
Hmmmmm....
That is exactly what I was suspecting. A new plate was probably fairly well cleaned after manufacturing but there must be still some dust, particles and whatnot on it.
So this has to go somehow. I did not know about using amonia on granite.

Also while on the subject, a 'B toolroom grade" plate is surfaced to 0,0002" which is is about twenty times better than my abbility at machining right now! I will buy one from a machine tool distributor, I 'need' the comfort of buying something certified, but just out of curiosity, how flat are the granite found at countertop or toombstone fabricator ?
Also, again out of curiosity, I had some belgian, french and austrian colleagues at one point or another in my career and contrary to us north-american as where we refer to a 'surface plate, or a 'granite', they refered to a 'marble plate' or simply a 'marble'
Is it just because granite is more common in America, and marble more comon in Europe, or this is just a semantic quirp?

Luc
I can’t say for tombstone, but i have checked countertop granite- it failed when blued up on my A plate
It’s better than the garage floor but not precision by any stretch .
 

blue_luke

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#12
My dad was an artisan bookbinder and I remember as a kid he had this big piece of granite from a friend who made tombstone, monument bases, and that sort of things, hence the question! :)
That stone was used as a surface where one operation required that the book spine be hammered to give it the roundness.
Just hamering on a bench, no matter how sturdy it was built, did not produce the required results.
 

Moderatemixed

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#13
I tried the "piece of countertop" option first and found it to be within .003. It was
small however and when I got a piece that was 14" x 14" the error was "bad" to say the least. I paid $250 for a Starrett 24 x 36 x 4 on Kijiji (Craigs List for Canadians). If you are a bit patient you can get a "name brand" for a decent price. That said, a buddy has a 12 x 18 "Chinese" plate and it is as accurate as my Starrett. (.0005 over 18 inches). I think marble was used because of a lack of granite overseas (rampant speculation). Good luck..... let us know what you end up with.


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Bob Korves

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#14
While watching some Vintage Machinery videos on YouTube. Richard King advised the guys in the class to use windex. I have Starrett surface plate and it seems to work well.
I have used Windex (well, actually generic cheap Windex substitutes) and it is a great and cheap cleaner for surface plates and for scraping cleanup. The downside is that some of it causes iron and steel to rust pretty badly and quickly. BTW, the water soluble Canode spotting inks will also cause corrosion if you leave them on your parts or tools.
 

Bob Korves

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#15
That said, a buddy has a 12 x 18 "Chinese" plate and it is as accurate as my Starrett. (.0005 over 18 inches).
.0005 is not accurate enough for a 12x18" surface plate. On a 18x24 the entire surface should be within .00015 for a grade A plate of that size. Names like Starrett mean nothing on a used surface plate, and there is no reasonable substitute for having your plate professionally inspected and calibrated so you know what you actually have. Anything else is guessing and hoping. Shiny does not mean flat. Small dings do not compromise the flatness.
 

Moderatemixed

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#16
Bob..... I missed a zero. But thank you for correcting me as you seem to do so for everyone, I feel honoured.


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middle.road

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#18
Back to Old Carl here. (The Tool & Die Maker that I first worked with and should have paid better attention to...)
Back to work after the two week summer shutdown, he was removing the cover from the surface plate in the shop
and asked if there was any coffee left in the pot. (I had brought in a Bunn-O-Matic when I first started there.)
'Sure' says I, and he asked me to fetch it. He then proceeded to use the coffee, black, no cream, to clean the surface plate.
 

Ulma Doctor

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#19
i agree, simple green will not compromise granine either,
but simple green can leave residue that doesn't flash off

fretting over, protecting and cleaning a piece of flat rock would be considered heresy by any other profession or pastime
 
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Bob Korves

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#20
Bob..... I missed a zero. But thank you for correcting me as you seem to do so for everyone, I feel honoured.


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You are quite welcome, and I hope you and others will return the favor whenever I or anyone else spreads information that may be incorrect. We are all learning here, and incorrect information does not help anyone. I really want to be part of the solution and not part of the problem, so please let me know when I am mistaken or out of line.
 

gradient

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#22
Hmmm, I think people who practice the sport of curling also fret about how clean and flat their rocks are, not only machinists :)
 

Dabbler

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#23
As a curler, you are tight! we fret about how the different rocks slide!

I use ammonia wipes in a pop up container. That way I have a clean cloth every time, and they are lint free.
 

petertha

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#25
What is it about ammonia (either as a concentrate or ingredient within Windex or whatever) that makes it good for granite to begin with?
 

kev74

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#26
What is it about ammonia (either as a concentrate or ingredient within Windex or whatever) that makes it good for granite to begin with?
Just a guess, but ammonia is an effective solvent that is relatively safe and non reactive with granite and steel tools. It also leaves no residue behind.
 

Bob Korves

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#27
Ammonia is an effective and inexpensive cleaner that cuts oil and grease and does not leave a residue. It does not harm granite.
 

woodchucker

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#28
Just a guess, but ammonia is an effective solvent that is relatively safe and non reactive with granite and steel tools. It also leaves no residue behind.
But ammonia is a caustic, so how is that safe with tools.
 

Bob Korves

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#29
I have never had a problem when using it on my surface plate with tools that I really care about. I do let it evaporate completely before using the surface plate. I don't think I would like to leave my tools submerged in ammonia, so I don't. I actually have had more trouble with generic WIndex type products than with ammonia.
 

kev74

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#30
But ammonia is a caustic, so how is that safe with tools.
The only metal I can recall seeing ammonia react with is copper. Its supposed to harm the iron oxide in steel bluing, but I never left it on blued steel long enough to see the damage.
 
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