Sharpening Glass

[John Davidson]

Well I have picked up a couple of planes, LV block and LN no4, and started my decent down the slippery slope. Wife got me a set of norton water stone for Christmas and I have been able to put a fine edge on the irons. Now I am thinking that I need a piece of glass to flatten the stones on as well as the planes that will come in the future. Are there any special requirements for this glass. Will any piece of plate glass do?

Thanks for the help
John

[Richard Gillespie]

For what it's worth, I use 1/4" plate glass. This is used on top of a 2" thick maple work bench so I'm not afraid of any deflection in the glass. There are those who maintain that you shouldn't use any glass less then 3/8" thick for that reason.

I have used Norton water stones in the past but have reverted to the scary sharp method. Therefore, I have 5 pieces 9-1/4" x 11-1/4" for the wet dry sand paper and one piece that is 6" x 37" for flattening plane soles. 4" x 36" sanding belts are used on that.

Other people have also recommended using pieces of marble left over from flooring jobs

[Wendell Wilkerson]

The only advice I would give is buy a thick piece of glass so that it doesn't flex when you put pressure on it. I bought a 3 foot long piece of 1/2 " thick float glass so that I can lap plane soles. I would have bought thicker piece but the price gets pretty high for the thick stuff. There are other options besides glass such as lapping plates or marble tiles.

Here's some lapping plates that are cheaper than the piece of glass I bought.

Hartville Tools Lapping Kit (http://www.hartvilletool.com/product.php?search_id=72383)

Japan Woodworker - Lapping Plate (http://japanwoodworker.com/product.asp?s=JapanWoodworker&pf_id=01.654&dept_id=11695)

You can buy Silicon Carbide cheap from a lapidary (fancy word for rock polishing) supply house such as this one:
Kingsley North Graded Silicon Carbide (http://www.kingsleynorth.com/gradedsc.html)
It is almost ten times cheaper to buy silicon carbide from one of these places. By the way, none of the stuff on lapping plates and silicon carbide is my idea. A fellow named Russell Seaton posted this information over on the Woodcentral bulletin board. Just want to give credit where credit is due.

Wendell

[Alan Turner]

John
I have found that a marble or granite sill, quite cheap, is the way to go, but, you need a good 3' straight edge to check it. I have a 3 footer, Starrett, which I use for set up anyway. And, I have a contact in the granite business, so pick them up free. If fact, I give one to each of my adult night school students since I cover sharpening in some detail. Good for both lapping, and for scary sharp. I put mine on my jointer, which is my flatest surface, so no deflection, of course.
I use the Shaptons, however, for sharpening. But for lapping, they are great.