Why is Slate so Great?

Why is Slate so Great?​


...well, in DC, there's a 9' set of slate that needs to be picked up at a super Great price.

There is a table (bed and rails) real close by, right there, it's on your left, that is made out of acrylic (solid surface), it works, takes a beating.
not sure it has any more issues maintenance wise than slate, however when all is quiet one can hear the ball roll.
3 built-up panels out of scrapes @ 80lbs each.
 
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MitchAlsup said:
Surface plates held level with 3 adjustment bolts have a 1:10 aspect ratio.
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That was supposed to read 3" thick, not think.
My point is no one will be listing the slates from beneath to slide playing cards between the granite and the frame lol.
I have not seen a plate with adjustment bolts. All my plates are smaller but the bigger ones I've used were 5" or more thick.
 
JolietJames said:
That was supposed to read 3" thick, not think.
My point is no one will be listing the slates from beneath to slide playing cards between the granite and the frame lol.
I have not seen a plate with adjustment bolts. All my plates are smaller but the bigger ones I've used were 5" or more thick.
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We had a 36"×72" surface plate in a lab a long time ago.
We needed to be able to place a <chemically etched>1 micron wire probes on 2 micron wires, without the trucks rolling down the highway ¼ mile away bouncing the needles to the point we could not see them with the microscopes we were using.
 
MitchAlsup said:
We had a 36"×72" surface plate in a lab a long time ago.
We needed to be able to place a <chemically etched>1 micron wire probes on 2 micron wires, without the trucks rolling down the highway ¼ mile away bouncing the needles to the point we could not see them with the microscopes we were using.
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Metroolgy is interesting for sure.
There was/is a sports car mfg that makes a pool table for something like $100K give or take. It was posted while back.
I suppose their surface is as close to perfect as possible within the $100K price tag. Maybe even the finest pink granite.
Is there an "AAA" or maybe "AAAA" grade Grade Granite Surface?? I suppose maybe. Maybe not commonly sold. But you need a STANDARD to assign/certify other surfaces. Normally your Standard is 5X better than what you're testing.

How is that thing Certified? And that? and That?

We try for perfection. But your pocketbook always limits how perfect your equipment is.
There's also practical limits on how perfect your equipment needs to be.

I'm happy with slate.
I'm also happy with the Roundness of all my Ball Sets.
 
JolietJames said:
Most surface plates ar 3"+ think.
No way that could be an indoor table.
You would need to pour a concrete floor and build the house around it.
3pc perhaps but you would need a team to move each piece and a darn sturdy frame, plus leveling would be a nightmare.
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Plates the size of pool tables start around 12" thick...lol

Not saying it a practical choice. Just that it could be done.
 
Renegade_56 said:
That is the way houses with concrete floors are built anyway,,,,,,,, but I agree, slate is too heavy for normal granite surface plates.
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Sorry, I was implying that the table would need to be set up on the new concrete floor prior to building the house. The table could not be bright in later.
 
3kushn said:
Metroolgy is interesting for sure.
There was/is a sports car mfg that makes a pool table for something like $100K give or take. It was posted while back.
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Bugatti
3kushn said:
I suppose their surface is as close to perfect as possible within the $100K price tag. Maybe even the finest pink granite.
Is there an "AAA" or maybe "AAAA" grade Grade Granite Surface?? I suppose maybe. Maybe not commonly sold. But you need a STANDARD to assign/certify other surfaces. Normally your Standard is 5X better than what you're testing.
Click to expand...
From::

Surface Plate 2024 Complete Guide [Granite, Cast Iron, Steel]

Explore the 2024 Complete Guide to Surface Plates, including materials like granite, cast iron, and steel, for precision measurement techniques.
www.cnccookbook.com

Surface Plate Grades determine their flatness. Standard grades include:
  • AA (Most accurate): These are referred to as laboratory grade. Their flatness is (40 + diagonal (inches) of surface plate squared / 25) x 0.000,001″.
  • A: These are Inspection Grade. They’re the AA spec x 2.
  • B: These are Toolroom Grade. They’re AA x 4.
  • Workshop Grade (Least accurate): These are not really suitable for CNC applications, so I won’t quote a spec.
3kushn said:
How is that thing Certified? And that? and That?
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There are optical measurement tools that can map the surface.
3kushn said:
We try for perfection. But your pocketbook always limits how perfect your equipment is.
There's also practical limits on how perfect your equipment needs to be.
Click to expand...
I have made glass surfaces which are accurate to better than 1/10 waves:: 0.000,000,055", surface plates stop at 0.000,001 which is already 10× better than one can achieve with a surface grinder go another 20× and you are making surfaces to optical tolerances.
 
MitchAlsup said:
Bugatti

From::

Surface Plate 2024 Complete Guide [Granite, Cast Iron, Steel]

Explore the 2024 Complete Guide to Surface Plates, including materials like granite, cast iron, and steel, for precision measurement techniques.
www.cnccookbook.com

Surface Plate Grades determine their flatness. Standard grades include:
  • AA (Most accurate): These are referred to as laboratory grade. Their flatness is (40 + diagonal (inches) of surface plate squared / 25) x 0.000,001″.
  • A: These are Inspection Grade. They’re the AA spec x 2.
  • B: These are Toolroom Grade. They’re AA x 4.
  • Workshop Grade (Least accurate): These are not really suitable for CNC applications, so I won’t quote a spec.

There are optical measurement tools that can map the surface.

I have made glass surfaces which are accurate to better than 1/10 waves:: 0.000,000,055", surface plates stop at 0.000,001 which is already 10× better than one can achieve with a surface grinder go another 20× and you are making surfaces to optical tolerances.
Click to expand...
Thank you.
Found this interesting.
I'm a nerd I suppose.
 
nataddrho said:
Thermal expansion would be a problem.
Click to expand...

I was looking up the coefficient of thermal expansion (CTE!) for something completely unrelated (gage blocks for metrology) and remembered this post. I was curious what it was for steel and slate. Both are nearly the same, at 10 for slate, and 10.8-11.5 for steel. It a unit-less value. Parts per million of length, per degree C increase.

A 100" slate would grow .000010" per inch, per degree. If we raise the temp 15 deg C, from 15 deg C (59F) to 30 deg C (86F), the slate would expand in length .000010" x 100" x 15 = .015".

Steel (at its largest value in the source) would grow .0000115" x 100" x 15 = .017"

Source: https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html
 
iusedtoberich said:
I was looking up the coefficient of thermal expansion (CTE!) for something completely unrelated (gage blocks for metrology) and remembered this post. I was curious what it was for steel and slate. Both are nearly the same, at 10 for slate, and 10.8-11.5 for steel. It a unit-less value. Parts per million of length, per degree C increase.

A 100" slate would grow .000010" per inch, per degree. If we raise the temp 15 deg C, from 15 deg C (59F) to 30 deg C (86F), the slate would expand in length .000010" x 100" x 15 = .015".

Steel (at its largest value in the source) would grow .0000115" x 100" x 15 = .017"

Source: https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html
Click to expand...
Wow, I didn't expect those values to be so close. Interesting to know!

If the coefficients of restitution are also similar than I think a steel table would be playable.
 
I think the top reason is actually the existence of production infrastructure.

Who is going to fund the development and subsequent sale of a new product? Nobody, for what is on offer.
 
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