# Granite Surface Plate



## LJP (Mar 27, 2014)

I bought a Starrett pink granite surface plate 24" x 24" x 4" thick, CL, $75, nice condition. I have yet to set it up.
I am running out of floor space and don't really want to set it up on its own stand, I know it will become a place to pile crap.
My bench, in the middle of the floor has a 3" thick solid maple top. I was thinking of making a heavy duty "drawer" for the granite plate. It will be protected and out of the way until it is needed.

So until NASA calls me to do some custom work for them, I was wondering, how much can a piece of stone twist that is 24" x 24" x 4" thick?
All opinions welcome!
Thanks, Larry


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## chips&more (Mar 27, 2014)

Larry, surface plates of that size usually come with three feet on its bottom side.  Don’t think that plate gonna twist on you. I like to have my surface plate referenced to gravity. You never know how handy that is until you use level for set-up! So, being in a draw makes that option a tough call…Good luck.


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## Smudgemo (Mar 27, 2014)

I agree with C&M - three feet and leveled to gravity will probably work better.  

Seems like you'd need some serious hardware to make yours slide out like a drawer, and in addition to possibly breaking past the stops and landing on your feet, would it tip the bench?  I like the idea, but have my doubts that you'd like it.  

Mine is 2'x3', and it's not light.  Not at all.  I also don't have a ton of space, so I made a plywood cover lined with felt to protect it while not in use.  Yeah, crap piles up, but I don't use it a ton and I can lift the whole mess off of it quickly when needed.  Maybe you could make the stand into a cabinet for more storage instead? 

-Ryan


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## LJP (Mar 27, 2014)

Ryan and Chips, you both make good points about leveled to gravity. I hadn't considered useing it as a level surface, but now of course I see that is a basic part of how to effectively use it. Glad I asked.
The hardware to make it slide as a drawer, shouldn't be a problem, as a custom cabinetmaker I have made some pretty heavy things, slide and swing.
Thanks for the input!
Larry


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## arvidj (Mar 27, 2014)

I am on a similar path ... though a small plate than defined by the OP ... and am curios about the 'level to gravity' concept. Given that my house snaps and pops during the significant tempurature changes this winter I have to assume the basement floor is also shifting to some degree. I this leads me to believe that I should 'level to gravity' every time I want to use it as a level reference.

If that is a reasonable assumption then a robust drawer and attaching a small 'level to gravity before each use as a level reference' sign would seem to address the issue.

I am also assuming that 'level to gravity' is not necessary if I am simply using the plate as a 'flat surface' reference.

Awaiting assumption validation or corrective education,
Arvid


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## DMS (Mar 27, 2014)

I did exactly what you are suggesting and am very pleased with it. I don't use my plate as a level surface, only as a flat one. And I don't use it very often. When I need it, I just pull the drawer out, and it's clean and ready to use 

Mine came without feet, so I added some large rubber ones (3 of them) 2 on 1 edge, 1 in the middle on the other. This 3 point contact is important, as it prevents rocking/twisting. There are also general rules about the spacing of the feet.. but I forgot what those are


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## JimDawson (Mar 27, 2014)

I have my surface plate hiding under my tool box on my mobile bench.  I built a box around it to keep it clean, and so I wouldn't have to kill the kids when when they try to use it for an anvil.  I just move the tool box sideways, and lift off the cover.  It is a little inconvenient to get to sometimes, but it is well protected and I don't need it that often.


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## Walltoddj (Mar 27, 2014)

I have a 18"x24"x3" green granite and if I recall it was 180lbs when it was sent to me. I have mine on the top of my Proto roll around till I can find a better place to set it up. I have a 24" Starrett height gage and a 12" digital Fowler in the roll around to keep them safe.

Todd


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## toag (Mar 27, 2014)

Clean flat surfaces are magnets for trash in my place.  ive kept stuff off my plate (18x24). I was thinking the same thing, or even a folding table like contraption... dunno, still thinking about it


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## chips&more (Mar 27, 2014)

DMS said:


> I did exactly what you are suggesting and am very pleased with it. I don't use my plate as a level surface, only as a flat one. And I don't use it very often. When I need it, I just pull the drawer out, and it's clean and ready to use
> 
> Mine came without feet, so I added some large rubber ones (3 of them) 2 on 1 edge, 1 in the middle on the other. This 3 point contact is important, as it prevents rocking/twisting. There are also general rules about the spacing of the feet.. but I forgot what those are




Yes, and I believe the general rule is “two support points separated by 5/9 of the objects length”. So, with the SP in question, apply the math in two dimensions.


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## LJP (Mar 28, 2014)

Thanks for the input, All. I am going with the drawer idea. Not enough valuable floor space. I ordered full extention slides rated at 200 lbs. Starret web site says that SP weighs 210 lbs. I will post pictures when its done.
Larry


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## DMS (Mar 28, 2014)

I would just add that you should make sure that there is enough weight attached to that drawer so that it doesn't topple. Mine is in a cart that has more or less all of my tooling, so it is very stable, but 200lbs sticking out 18 inches is a lot of force; just be safe. You may want to consider some collapsable legs on the front to support it in use as well.


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## Roger (Mar 30, 2014)

Like a number of hobbyists I'm jammed up for space. I built a sturdy frame out 2/4's and 3/4" plywood sized to hold the granite at my desired height. Then I made a protective box of 1/2" ply that fits closely on top. This servers as an excellent surface to spread my plans, notes & calculator, close but not collecting the nasty by products of machining. The area underneath is used for raw material storage. 
Roger M.


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## astjp2 (Mar 30, 2014)

I made room for my 36x48x8 surface plate, its a grade b but I was able to level it to within .0005 per foot.  Considering my floor is only 3" thick, it will probably move with the seasons.  Having a level surface is nice, flat is even better.  I did make my stand to fit the plate, it was 400 for the plate and a day to build the stand.  Tim


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## kevinpg (Apr 14, 2014)

I was in Woodcraft this weekend and they had a sale on their wood river surface plate for 27 dollars. I picked it up on a whim. 

It is 9x12x2 and shows an accuracy of 0.001 mm/m or 0.0001".  the inspection report inside the box states The ACCURACY (yes, all caps) to be 2.4 um, 00 Level.  

I am thinking it will be sufficient for my little Sherline and unimats.

Funny thing, the sales guy was pushing me to get the larger one for 80 bucks so I could adhere 2 pieces of sandpaper to it.  He was surprised I wanted to use it as a reference surface for more accurate measurement.

I figure for 27 bucks, it is hard to go wrong.


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## astjp2 (Apr 15, 2014)

Thats a steal!


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## Chuck Forman (Apr 29, 2014)

Complete Novice here.  Acquired cheap a 14" X32" cast iron surface plate from estate of a machinist.  Weighs about 90 lbs.  Casting underside has very heavy ribs and "feet".  Plate surface sits 2.5" above bench top.  Very neat looking machined pattern of fine arching lines out from a point that's not in the center of the plate.  No numbers or other markings. 

Should I make the time and space to level and firmly support this on my cement shop floor or will this sort of heavy iron plate be stable/flat (not level, obviously) with temp change, etc sitting on wood bench? 

Maybe this Iron piece is more decorative than functional and I should simply watch for good deal on a granite surface rather than invest scarce time, energy and floor space in a solid stand.  Any Input much appreciated.


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## astjp2 (Apr 30, 2014)

Your questions depend on what  you want to do with it, that will help you determine how you set it up.  Tim


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## Marco Bernardini (Apr 30, 2014)

LJP said:


> My bench, in the middle of the floor has a 3" thick solid maple top. I was thinking of making a heavy duty "drawer" for the granite plate. It will be protected and out of the way until it is needed.



Larry, what about a "sliding top" covering the plate?
In this way the plate will have an almost static location in the middle of the bench, where to be set by gravity, it will be protected and you don't even have to remove the junk from the top to use it.
Add a padlock to the top and you'll be sure nobody will use it as an anvil, too!


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## LJP (May 1, 2014)

Marco, the sliding bench top idea is a good idea. I think what it really comes down to is which is more important. I have been using a bench for 40 years, only recently bought a surface plate. My solution will be to make a heavy duty drawer for the plate.
Thanks, Larry


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## kevinpg (May 22, 2014)

http://oklahomacity.craigslist.org/tls/4469199334.html

this looks like a deal. if I had time, i would get it. of course, it needs checking but looks promising.

there is a pic in the ad.

A 24" x 36" x 4" granite Starrett surface block. Includes a heavy 1/4" thick angle iron support table on rollers and adjustable feet. It has threaded inserts. Also has a hole bored thru it that was used for passing electrical cords thru it. Bring your trailer when you come to see it. The strips on the top surface are adhesive residue. They are not imperfections in the granite surface.

Would consider delivery for an additional fee.


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## Marco Bernardini (May 22, 2014)

kevinpg said:


> http://oklahomacity.craigslist.org/tls/4469199334.html
> 
> this looks like a deal.



The price is not far from what we pay here for flooring granite.
The holes are pretty odd: generally a Starrett block is not a thing people use in the same way of an MDF scrap, so look at it carefully, specially for cracks.


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## kevinpg (May 22, 2014)

Marco Bernardini said:


> The price is not far from what we pay here for flooring granite.
> The holes are pretty odd: generally a Starrett block is not a thing people use in the same way of an MDF scrap, so look at it carefully, specially for cracks.



that is exactly my thought. why would you drill a through hole for electric cables? An attorney once told me you can lose your ming trying to understand the motives and actions of others. 

so, if I get the chance, it would be worth looking over.


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## astjp2 (May 23, 2014)

It was probably for a small CTLM or to mount a piece of equipment on that needed a flat surface to measure from.  Tim


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## Lurk (Jul 31, 2014)

*Re: New Granite Surface Plate*

Newbie Question:- I have just set up my black granite surface plate.... or will when I find a mate to help lift it onto the new stand I made up. Its only small at 24x18x4"  -big enough for my neads. I was wondering if there is anything I should coat / clean it with / wipe over before I do anything else with it. Does it need a sealer ? 

It still has some grinding dust on the lower face which I thought to clean of with water. But before I do that I thought I would ask.

Thanks for the replies...
Lurk.


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## JimDawson (Jul 31, 2014)

I use a glass cleaner like Windex.  Seems to work fine.  Do not use a sealer.


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## Lurk (Jul 31, 2014)

JimDawson said:


> I use a glass cleaner like Windex.  Seems to work fine.  Do not use a sealer.



Thanks Jim. I have some in the kitchen, just have to sneak it out to the workshop !


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