Doing finish work on granite plate .....

[toolznthings]

Hi All,

A easy way to get a nice finish on parts or establish a flat surface is to use a granite plate and self adhesive " Stick & Sand " papers for palm sanders used in the wood shop. The above is a Norton product, but there are many other brands.
Shown is a small 9" x 12" plate with the paper attached to the granite so I can remove mill marks on my next upcoming engine project. Inexpensive granite plates are just about everywhere these days so no need to use the one for layout work and inspection. I have the granite on rubber matting so it will not move when moving the part back and forth on the abrasive.

[RayW]

A handy hint and one which I have employed using a sheet of plate glass and double sided tape to secure the sandpaper.
By pure coincidence, I was passing a stonemasons works today and noticed a pile of offcuts of polished granite and marble on a pallet outside so made enquiries as to whether any would be available. The lady in the office said that it was already spoken for as it all goes to a local farmer who uses it for hardcore!! When I explained that I was looking for a small piece to use as a surface plate, she very kindly let me take the piece shown in the photo. It is about 14 inches by 12 and just over an inch thick, and whilst it is a bit of an irregular shape that doesn't worry me.

[Vixen]

I bought part of a 2 inch thick black granite headstone from the local monumental mason, some years ago. The front surface is polished to a mirror finish and dead flat.

When I am finished using it has a surface plate, the family can engrave my name and dates and use it for the purpose originally interned.

Waste not want not.  A surface plate as a headstone, very fitting for an engineer.

Mike

[Admiral_dk]

Waste not want not.  A surface plate as a headstone, very fitting for an engineer.]Waste not want not.  A surface plate as a headstone, very fitting for an engineer.

Amen to that - especially if he is an mechanical engineer (there is other types that never did anything mechanical - though I should be careful here, as an engineer in Danish equals a master degree in English).

Have to agree that the gravestone shop is a source I haven't thought about - so thank you to toolznthings for that tip 

[wagnmkr]

Another source for polished granite ... counter top companies ... they all have an "oops" pile in the yard and I was told to take what I wanted.

Cheers

Tom

[Mathew28]

You can find polishing pads on eBay and diamond shapping cutters and they fit on a 5" grinder but make sure it's one you can change the speed.
Mathew

[Tennessee Whiskey]

+1 to what Tom said.  Granite counter tops are all the rage these days and have become somewhat affordable.  The cutouts for sinks and the odd drop to make a piece fit is most usually going to be trashed and if one is at the right place at the right time,  a decent surface (or lapping ) plate can be had . I actually have a pretty good size stack left over from the counter redo at the store. 

Cletus

[zeeprogrammer]

I'm interested in this. There's a couple of granite companies not far from me.
Are they really polished/shaped to that kind of tolerance to use as a sanding plate?
If so...I'm heading down there.
Could use some new friends. 

[Tennessee Whiskey]

They aren't lab quality, but, they are " close enuf " for what we do

Cletus

[Tennessee Whiskey]

Here is a shot of the counter at the pool bar. You can see the reflection of the Bud Light neon



Cletus

[b.lindsey]

I don't see any Cheerwine in that fridge Cletus. Maybe it hasn't spread over to Springbucket yet

Bill

[derekwarner]

At my place of employment many years ago  we had a largish Italian marble surface plate [approx. 3m x 5m] for re-assembly measurement of largish missile launcher components...... naturally it lived at a constant 22 20 degrees C & 16 % humidity..........the surface flatness was measured in uM [microns]

The directions  were quite clear.....it was very cold to walk on   as one had to wear those synthetic sterile bootlets over cotton socks over bare feet as worn in hospital theatres..& no  on the job.......Derek 

[b.lindsey]

That would have been a monster to lift Derek. For that large a surface area, what kind of supports did it have? Without adequate support I would think it could sag more than a few microns....just curious.

Bill

[Tennessee Whiskey]

One of the YouTube guys did a field trip to Standridge Granite. Very informative. I think all of their plates were set on a three point suspension, no matter how large.

Cletus

[steam guy willy]

I all ways work to microns...............there may be a large number of decimal points involved ...but they are still microns!!!!