Surface Plate Questions

lpeedin

H-M Supporter - Gold Member
H-M Supporter Gold Member
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I just received a 10"x12"x2" granite surface plate from Grizzly. This might be a dumb question, but is there a preferred side to use or are both sides ground to the specifications? Also, any tips you'd like to share on maintenance, cleaning, etc?
 
One face should be lapped smooth, the other probably shows saw marks.

Gene
 
In the Grizzly catalog it states that it has a “bilateral accuracy”. So, maybe both sides are good for use as a surface plate?...Good Luck, Dave.
 
In the Grizzly catalog it states that it has a “bilateral accuracy”. So, maybe both sides are good for use as a surface plate?...Good Luck, Dave.
Dave,
I actually bought this through Amazon, but it was in a Grizzly wood box. Hadn't thought to look at Grizzly's specs - thanks,
 
Tips....clean with ammonia....use three point mounting/setting. Keep top covered when not in use.
Hi, I am new to machining in general, I would like to ask you some questions on Granite items.
What would one use a granite surface plate for? I see in a local tool catalogue that they sell "V" blocks and parallels made from granite. I thought that granite was a Brittle stone that was prone to easily breaking?

Regards Basil
 
Granite is also inherently stable, non-magnetic, has excellent vibration dampening characteristics, and will not rust.

That's just one line from a wikipedia page on surface plates. http://en.wikipedia.org/wiki/Surface_plate

It's interesting reading. Check it out.
 
Hi, I am new to machining in general, I would like to ask you some questions on Granite items.
What would one use a granite surface plate for? I see in a local tool catalogue that they sell "V" blocks and parallels made from granite. I thought that granite was a Brittle stone that was prone to easily breaking?

Regards Basil

Depending on the type of granite, and the amount of quartz or has, determines the strength. Quartz is close to being as hard as diamond. Since it has immense compression but low tensile strength, it is brittle.

Granite setup blocks (Parallels, V blocks, etc) are meant to be used for inspection only. For mill work use steel setup blocks.
 
Interestingly they follow up this line
Granite is also inherently stable, non-magnetic, has excellent vibration dampening characteristics, and will not rust.
http://en.wikipedia.org/wiki/Surface_plate
With this a bit further down
"Cast iron that has been properly cast is more dimensionally and geometrically stable over time than granite or ceramics,[citation needed] is more easily worked to a higher grade of flatness, and provides a better bearing surface to assist the creation of other master standards", and, "Cast iron unlike granite has also very uniform optical properties, and unlike glass or ceramic material very small light penetration depth which makes it a favorable material for certain optical applications"

Cheers Phil
 
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