I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

--
Paul Hovnanian
-----------------------------------------------------------------------
Have gnu, will travel.

On Thu, 27 Nov 2008 11:31:01 -0800, the infamous "Paul Hovnanian P.E."
scrawled the following:

I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

Probably not too badly, given your requirements. Stone (fake or
otherwise) is ground pretty darned flat. If it's good enough for plane
iron sharpening the ScarySharp(tm) way, it's flat enough.


And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

I'd use a rubber-tipped adjustable bolt bedding on an angle iron table
with adjustable rubber feet. Support it every 6 or 8 inches and it
should remain pretty flat for you. Drill through the angle, tap, and
bed it. Piece of cake.

Alternatively, Griz has nice cheap items.

http://grizzly.com/products/searchre...urface%20plate
(Jayzuss, WTF happened to their shipping fees?!?)
They show their stands there, too.

9x12" is under $30, delivered. The same size from Lee Valley is $51.

--
Our greatest glory is not in never falling, but in getting up every time we do.
-- Confucius

"Paul Hovnanian P.E." wrote in message
...
I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

You'd need something against which to measure it -- a precision
straightedge, another big surface plate, or whatever. But those slabs can be
surprisingly flat if they were ground on a table grinder. I have a large,
3/4"-thick piece of what was known as "Italian marble" back in the '60s. It
was actually some kind of hard puddingstone. I measured it on a CMM when I
had a better class of clients g, and it was flat to just over 0.001" over
2-1/2 feet. That's my basic layout surface plate.

For smaller sizes, you can do very well with a thick piece of plate glass --
the real thing, not float glass. Plate glass is ground and you'll be amazed
how flat it can be. You might get a cutoff from a commercial glazier.


And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

I don't have any examples, but if you have uneven surfaces, think about
three feet. My small Mitutoyo toolmaker's surface plate has four rubber
feet, and they squish a little to accomodate my workbench top.

--
Ed Huntress

"Paul Hovnanian P.E." wrote:

I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

--
Paul Hovnanian
-----------------------------------------------------------------------
Have gnu, will travel.

The 18x24x4 granite surface plates from China are pretty nice and quite
inexpensive if you can avoid shipping. I picked one up at a Wholesale
Tool branch when I was in the area.

Paul Hovnanian P.E. writes:

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

Poorly. No way it could be equal to a genuine precision surface that is
flat to tenths everywhere.

Get the $25 Enco 12" x 18" shipped via UPS for free. An incredible
bargain:

http://www.use-enco.com/CGI/INSRIT?PMAKA=640-0120

Get rubber or cork pads with adhesive for the bottom. Epoxy some broad
metal or hardwood scraps to the sides for handles.

Hey Paul,

I remember a loooooonnnnngggg time ago, a shop hint in Live Steam(???)
magazine suggested a thick piece of glass would suit as a "surface
plate" for most shop uses. The way it was put was that the glass was
flat, but not flaaaaaaaatt Worked a treat for me for many years, back
in the day before "less than a dollar a pound" surface tables became
the norm.

I got a piece of float glass somewhere/somehow, about 1/2" thick and
24 X 18 or so. I made a 1X3 wood frame the ID the size of the OD of
the glass plus 1/4" all-round and with two of the sides slanted
slightly, and I tacked a "bottom" on it made out of a scrap of luan..
The frame was then 1/2 filled with damp plaster-of-paris, and then
topped up with goopy wet plaster-of-paris, and the glass set on it
while still very wet. The glass sort of "floats" on the goop, and
when it is al set up it was good. The slant sides keep the plaster of
pairs from wanting to fall out when the thing is moved later on.

Any of the counter-top stone I've seen has been fairly flat too. Not
flaaaaaatttt, but pretty darn good.

Take care.

Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXXXXXXXXXXXX

On Thu, 27 Nov 2008 11:31:01 -0800, "Paul Hovnanian P.E."
wrote:

I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

if you can find yourself at a show like Westec where ENCO and that ilk show
stuff, you can order from the catalog with free shipping and a 10%
discount - that's how I got a 2 X3 ft surface plate delivered for $50.


"Paul Hovnanian P.E." wrote in message
...
I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

--
Paul Hovnanian
-----------------------------------------------------------------------
Have gnu, will travel.


** Posted from http://www.teranews.com **

On Thu, 27 Nov 2008 15:30:00 -0600, Richard J Kinch
wrote:

Paul Hovnanian P.E. writes:

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

Poorly. No way it could be equal to a genuine precision surface that is
flat to tenths everywhere.

Get the $25 Enco 12" x 18" shipped via UPS for free. An incredible
bargain:

http://www.use-enco.com/CGI/INSRIT?PMAKA=640-0120

Get rubber or cork pads with adhesive for the bottom. Epoxy some broad
metal or hardwood scraps to the sides for handles.


Remember...surface plates are only to be supported by 3 legs

Gunner, whose 20x36 has turned into a catchall (on the custom fitted
plywood top.


"They couldn't hit an elephant at this dist..."
Maj. Gen. John Sedgewick, killed by a sniper in 1864 at the battle of Spotsylvania

Gunner Asch writes:

Remember...surface plates are only to be supported by 3 legs

Yes, that would be KC (kinematically correct).

Richard J Kinch wrote:

Get the $25 Enco 12" x 18" shipped via UPS for free. An incredible
bargain:

http://www.use-enco.com/CGI/INSRIT?PMAKA=640-0120



I've got one. Can't believe the bean counters haven't figured out how lopsided a deal it
is for them.

Wes

On Sun, 30 Nov 2008 02:59:52 -0500, the infamous Wes
scrawled the following:

Richard J Kinch wrote:

Get the $25 Enco 12" x 18" shipped via UPS for free. An incredible
bargain:

http://www.use-enco.com/CGI/INSRIT?PMAKA=640-0120

I've got one. Can't believe the bean counters haven't figured out how lopsided a deal it
is for them.

It's likely a loss leader, Wes. They take a loss on the one product
in hopes that you'll come in (or go online) and buy extra items (some
of which are highly overpriced) at the same time you're buying that
one item. I heard that at any one time, 1/3 of the items in the
grocery store are loss leaders, 1/3 are normally priced, and 1/3 are
exhorbitantly overpriced. They swap these around all the time so you
don't catch on. In the end, they get their margins.

--
In all affairs it's a healthy thing now and then to hang a
question mark on the things you have long taken for granted.
-- Bertrand Russell

Larry Jaques writes:

http://www.use-enco.com/CGI/INSRIT?PMAKA=640-0120

I've got one. Can't believe the bean counters haven't figured out how
lopsided a deal it is for them.

It's likely a loss leader ...

I expect they make money on the item if you pay the shipping.. The free
shipping is no doubt an oversight, since they have the truck symbol on the
catalog page for surface plates. But the smaller sizes ship UPS.

On Nov 27, 11:31*am, "Paul Hovnanian P.E." wrote:
I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

--
Paul Hovnanian
-----------------------------------------------------------------------
Have gnu, will travel.

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.
However, on a 12"x12" marble square, it's all over the map. +-.005"
to be optimistic, ignoring the holes.
On a sink cutout, it's better, +-.002", again there are some
significant holes in the surface..

It all depends on your requirements.

Dave J.

Mechanical Magic writes:

However, on a 12"x12" marble square, it's all over the map. +-.005"
to be optimistic, ignoring the holes.

I've tried various polished marble and granite floor tiles, and found them
all similarly crude, despite their mirror-like looks. There is no reason
to expect them to be precisely flat. A worked surface is at best a poorer
copy of the precision of the tooling used to generate that surface, and
these stone pieces are certainly not made on precision tools.

On Sun, 30 Nov 2008 18:52:01 -0800 (PST), the infamous Mechanical
Magic scrawled the following:

On Nov 27, 11:31*am, "Paul Hovnanian P.E." wrote:
I'm looking at getting some sort of surface table for doing measurements
and layout in my home hobby shop (so cost is an object and high
precision is not).

I have a piece of scrap countertop granite (black) left over from a
kitchen remodel, about 18x24 inches by 0.75 inch thick. How would this
measure up to commercially available tables?

And how would one recommend mounting this thing? At least, I've got to
think about attaching handles to the sides to make picking it up easier.
But what about a base with some feet to keep it from rocking on uneven
surfaces? Any examples out there to follow?

--
Paul Hovnanian
-----------------------------------------------------------------------
Have gnu, will travel.

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.
However, on a 12"x12" marble square, it's all over the map. +-.005"
to be optimistic, ignoring the holes.
On a sink cutout, it's better, +-.002", again there are some
significant holes in the surface..

It all depends on your requirements.

Marble is a supersoft stone. I'm surprised it's sold for anything but
wall surfaces, where it won't see any damage. The granite Paul said he
had is likely a whole lot smoother.

--
The only difference between a rut and a grave...is in their dimensions.
-- Ellen Glasglow

Mechanical Magic writes:

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.

I just ordered the 12"x18" surface plate from Enco (free shipping)
and I saw for $10 more I could get the Grade A instead of Grade B.
What's the difference?

The Grade A also has two ledges. What are these used for?

Maxwell Lol writes:

Mechanical Magic writes:

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.

I just ordered the 12"x18" surface plate from Enco (free shipping)
and I saw for $10 more I could get the Grade A instead of Grade B.
What's the difference?

Looking at the catalog page, Grade B is "toolroom grade" and Grade A
is "inspection grade". Looks like Grade A has half the tolerance of
Grade B.

The Grade A also has two ledges. What are these used for?

Dunno.

"Joe Pfeiffer" wrote in message
...
Maxwell Lol writes:

Mechanical Magic writes:

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.

I just ordered the 12"x18" surface plate from Enco (free shipping)
and I saw for $10 more I could get the Grade A instead of Grade B.
What's the difference?

Looking at the catalog page, Grade B is "toolroom grade" and Grade A
is "inspection grade". Looks like Grade A has half the tolerance of
Grade B.

The Grade A also has two ledges. What are these used for?

Dunno.

You need the ledge to clamp angle plate - or even parts - down on for hands
free inspection.
"NEED" might not be the correct term. "Want" probably is.

Go with the ledges.

JC

"John R. Carroll" writes:

You need the ledge to clamp angle plate - or even parts - down on for hands
free inspection.
"NEED" might not be the correct term. "Want" probably is.

Go with the ledges.

Done! I have a 8x12 plate, but I use it for scary-sharp/glasstone
sharpening. I'll reserve the Grade A plate for critical stuff.

On 2008-12-23, Maxwell Lol wrote:
Mechanical Magic writes:

Paul,
I have an ENCO surface plate, a small one. I mounted a DTI (.0005"/
div) on a mag base, with about a 5" reach. And I cannot report any
significant measurement when moving around the ENCO surface.

I just ordered the 12"x18" surface plate from Enco (free shipping)
and I saw for $10 more I could get the Grade A instead of Grade B.
What's the difference?

Higher precision surface. If you're going to be using it for
truly precision measurements, you'll want that -- and a matching set of
gauge blocks, and a high precision indicator of some sort.

The Grade A also has two ledges. What are these used for?

1) For lifting it to move it around,

2) For clamping measurement fixtures to, since these are stone not
cast iron, so the magnetic bases won't do you any good.

As for what the benefits of a stone vs cast iron surface plate
are, if you ding a cast iron one, you raise a circular ridge around the
point of the ding, thus lifting whatever is resting on it. If you ding
a stone one, you simply chip out a tiny amount of stone, and the
surrounding area is still the original height.

If you're just going to be using it for layout work, go for the
grade B -- that should be good enough. If serious metrology, go for
grade A or AA or ...

Oh yes -- you can also use them for spotting when scraping a
surface to flat. Probably the class-B will do for your first rounds,
and then when you get to needing more accuracy (e.g. for making your own
surface plate) you'll need a more accurate one, and if you had gotten
the class-A at the beginning, it would be worn enough by now so it would
no longer qualify anyway. :-) If you are serious about accuracy, you can
get services to come certify (and improve) your surface plate, and
certify your gauge block sets.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"DoN. Nichols" writes:

If you're just going to be using it for layout work, go for the
grade B -- that should be good enough. If serious metrology, go for
grade A or AA or ...

The Enco grade B 12x18 is $24.95
The Grade A 12x18 is $36.95.

Now I can check my 8x12 on my 12x18. :-)