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Starrett Granite Plate support point locations?

Luke Rickert

Hot Rolled
Joined
Oct 24, 2007
Location
OSLO
I can call them tomorrow but would like to finish up a design today. Does anyone know where Starrett puts their support pads on the bottom of their plates? It doesn't appear to be listed on the website. I really just need the distance in from the ends? (1/5th, 1/3 etc) this is a 36x48x8 (in) plate. From the pictures they appear to be rather close to the ends, I might suggest more ideally placed points further in.

thanks
Luke

G-80710 36" x 48" x 8" - Grade AA, No Ledge
 
Thanks Limy, I do know where the support points are "supposed" to be, but what I need to know is where Starrett actually puts them. After looking at pictures of their stands etc I am fairly sure that Starrett does not use the Airy Points and frankly it probably doesn't matter with an 8 inch thick slab of granite and moderate loads. If the plate is certified supported at the edges it actually would probably be a bad idea to mount it "properly".
L
 
I cannot find the page on the Starrett site today but I did when I was looking at a used plate a couple of weeks ago and I believe the support points are 20% of the length from the edge. I went out to the shop and measured my Starrett grade B plate and it is at 20%
 
thanks howieranger! 20% (so 1/5th) of the length) from the edge sounds reasonable. It seems like this is something that should be on the Starrett website somewhere.

Luke
 
Actually, how and where you support it will “matter” only under special circumstances. The plate will sag of its own weight to such a small degree as to be essentially undetectable. If you don’t believe it find the modulus of elasticity of granite and work it out.

The first being very heavy parts placed on the plate. The points specified are likely to minimize strain on the plate for average heavy setups.

The second case might be some sort of metrological research lab with all kinds of specialized equipment where light wave lengths matter.

But for nearly all of us airy points are nice but not that critical. I’ve checked this out with sensitive equipment in my shop with the help of a fellow PMer.

Denis
 
I "float" mine on dense foam pad for most uniform weight distribution.

And so easy.

The weight can be distributed evenly, but the surface will be less flat. It was made flat while the plate was rested on certain points, and unless you use those points for support, you cannot rely on the surface being flat.
 








 
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