Granite surface plate

[aldel]

A few days ago, whilst wondering around the local Wickes DIY store, I came across some highly polished granite floor tiles. In various colours, pink, black and white and about 1cm. thick.
Mmmm I wonder how flat they are? I took two and firmly placed them together polished face to face. The only way to part them was by sliding.
Now I thought that means they must be pretty darned flat, perhaps I could use one as a cheapo surface plate.
Parted from £3.75, I now owned one nice white granite tile.
That evening I mentioned this to a neighbour who works in an engineering works and he offered to get it checked for me.
Its been confirmed today that although no precise test measurements have been given that it is indeed more that good enough for my requirements.
(checking the flatness of plane soles)
I accept that it not up to the standard of a proper certified surface plate
but good enough for me. If it get chipped, scratched or dropped then I will just get another one.

Its worth a try. Now a search for some engineers blue.........

Cheers Aldel

 

[Philly]

Alan,
I have used one for a while with wet and dry paper for my sharpening. They certainly are pretty flat-I "mapped" mine out with a straight edge and feeler gauges and have marked the flattest part out for use.
nice and cheap!
cheers
Philly

 

[Steve Maskery]

Aldel that sounds excellent. What size are the tiles please?
Cheers
Steve

 

[aldel]

Aldel that sounds excellent. What size are the tiles please?
Cheers
Steve

They are 12" square x 1cm thick. I tested my try squares against this tile and found the outer edge on one was bowed.
I have since returned to the store armed with my 12" engineers square and got permission to test some granite tiles. In an opened pack of 5 white granite ones I found 3 to be flat on both sides and 2 to have some just discernable dips on the polished sides when held up to the light. The ground but unpolished sides appeared to be dead flat. I tested a box of 5 black granite tiles and they all appeared to be spot on. The black ones are thicker and finer grained but about £7.50 each. I was lucky with the first one purchased. I chose white because I thought it would provide a better colour contrast.

All credit to Wickes, the staff were very happy to allow me to test them.
So if you plan to buy one take your best straight edge with you!

cheers Aldel

 

[Steve Maskery]

They are 12" square x 1cm thick.

Sort of Mid-Atlantic granite then, eh, Aldel?

 

[Keith Smith]

Another option is 10mm float glass, when I went to the local glazers they gave me some off cuts for free, and it's as flat as a lake of molten tin.

Keith

 

[DaveL]

I will second the glass. I have been using a double glazing sealed unit from a door for lapping planes on. 8)
I also have a mirror, this is nice and flat, they need to be or the image is just like at the fun fair. :shock:

 

[gidon]

Aldel
Thanks for the tip - I may have a little look down my local B&Q.
I too use glass, but some some 1/4" offcut (not float) I got for a glazier. Works fine and is as flat as I can measure. And I used to use a shaving mirror which worked fine too.
As I think DC mentions (in what seems the umpteenth article on his ruler trick ) in this month's PW, what's underneath is as important - ie a flat bench.
Cheers
Gidon

 

[Vormulac]

Pardon my ignorance chaps, but what is 'float' glass, as opposed to the clear, brittle stuff that comes from the glaziers?

V. :?

 

[DaveL]

but what is 'float' glass,

Its produced by 'floating' the glass on a

lake of molten tin

as it cools back to its stiff form. This gives a very flat and smooth finnish. 8)

 

[Alf]

The archives know all, the archives tell all...

Cheers, Alf

Expecting the Search facility to put an ad in the Lonely Hearts column if it keeps being left out like this