float glass, granite for flattening planes and waterstones?

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Forum topic by Millo posted 03-14-2011 01:58 AM 13234 views 0 times favorited 18 replies Add to Favorites Watch
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543 posts in 3018 days

03-14-2011 01:58 AM

Hey all,

I got some price quotes for float glass to be cut for sharpening and flattening purposes: 3/16” 6.50 per sq. ft., 1/4” was something like $13. I was thinking of going the granite route and in the future build a little cabinet to use it as a top, essentially building a small flattening/sharpening desk/table…. was thinking of something like 12”x24” or so…. Anyhow, reading one of David Charlesworth’s books he recommends 1/2” float glass. OF COURSE, FOR THE MOMENT I SHOULD TRY TO GET SCRAPS—I will make a field trip tomorrow, and/or on Wednesday. I have NOT gotten around to researching this idea too much. STILL, I WAS WONDERING:

-What are average prices of granite and float glass per sq. ft. in your area?

-What thickness in both materials would you recommend for reliable service?


18 replies so far

View drewnahant's profile


222 posts in 3057 days

#1 posted 03-14-2011 02:05 AM

not sure about glass, but I got a piece of polished granite from a countertop shop. they sold me a double sink cutout for $5, it’s basically scrap to them. seems like the best deal to me, and though Im sure it isnt quite as flat as float glass, but it has worked great for my sharpening.

View poopiekat's profile


4349 posts in 3702 days

#2 posted 03-14-2011 02:58 AM

I use a 16” X 28” tempered glass, in an aluminum frame, from a salvaged aluminum storm door. I bought it from Habitat 4 Humanity Re-store for $5, because I needed the hinge rail for the worn-out one on my back door. So the glass was a bonus. They got dozens of ‘em here. It’s probably 1/4” thick for the heavy-duty use in a swing door.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

View bigike's profile


4050 posts in 3256 days

#3 posted 03-14-2011 04:43 AM,43513,51657
Anyone of these should help also what I did was go to a place where they do counter tops
granite of course and other stone and asked for a small piece about 2” wide by 24” long and about 1-2”thick
they gave me a piece fro free I guess it was cut offs cuz the edges weren’t finished smooth but the top was and that is most important anyway I still have it today and use it for planes and blades. GOOD LUCK!
I’m going with the grizzly site to get my next one cuz they have good prices as far as I can tell plus I want one that just looks good that’s all.

-- Ike, Big Daddies Woodshop,

View mchuray's profile


81 posts in 2966 days

#4 posted 03-14-2011 05:22 AM

Check out Grizzly. They have thick granite plates for very reasonable prices and are very thick and stable.

View ksSlim's profile


1274 posts in 2858 days

#5 posted 03-14-2011 05:35 AM

In my area, granite cut offs are $25$/sq ft. most are 24”X??X,1 1/4 thick cut to your use.
These pieces make “workable” pieces for a sharpening bench.
They are not AAA flat (<.002”) but are workable.

-- Sawdust and shavings are therapeutic

View Millo's profile


543 posts in 3018 days

#6 posted 03-14-2011 05:36 PM

Thanks for your replies.

The only issue I can think of w/ the mail-order route is that shipping can be as much or more than the granite itself, and then it is placed in danger as well—it being hard and brittle. I was thinking about his, though, because eventually when/if I build the sharpening table I’d like it to be comfortable and obviously not have too many sharp/dangerous edges and the countertop stores might be cost-prohibitive or such a small project.

bigike, that piece is a very good size.

ksSlim… that sound like a good price and pretty much something I’d like to get. So, there are grades for flatness, huh? So they usually tell you at the countertop shop about these degrees of flatness? Will they look at me funny if I bring a straightedge with me (in any case, I don’t know if the straightedge is straight/flat LOL!)?

View TheWoodNerd's profile


291 posts in 3159 days

#7 posted 03-14-2011 07:22 PM

You really don’t need lab-quality flatness or even good machinist-grade for sharpening. Some people have had perfectly fine results with polished granite tiles from their local home center.

If you have a WoodCraft in your area, they often have their granite surface plates on sale for $20. I have one, it’s fine but very heavy. If the granite tiles work for you, that’d be a lot more convenient.

-- The Wood Nerd --

View Kent Shepherd's profile

Kent Shepherd

2718 posts in 3254 days

#8 posted 03-14-2011 08:30 PM

I know a guy who works for Xerox, reparing copiers. He has given me several pieces of 1/4” glass he has removed from old machines. You can’t beat free!


View Div's profile


1653 posts in 2908 days

#9 posted 03-14-2011 10:20 PM

I’m not that fussy, normal 1/4 glass works well for me. Working 2 stones against each other is an easy way to get both flat!

-- Div @ the bottom end of Africa. "A woodworker's sharpest tool should be his mind."

View Div's profile


1653 posts in 2908 days

#10 posted 03-15-2011 06:29 AM

Hey CessnaBarry
I should mention that I use oilstones which are harder than waterstones. I have always worked stones of similar grit together; maybe I have too many stones! I use kerosene as a lubricant and flush the stones well afterwards.
Another method I’ve used was to work the stone on a flat piece of glass with automotive valve grinding compound as cutting agent. Flushing the stone well afterwards, I had no problems with grit. Maybe you didn’t wash the stones well afterwards, maybe it was because it was softer waterstones?

Don’t fly too close too the sun, don’t want your wings to melt!

-- Div @ the bottom end of Africa. "A woodworker's sharpest tool should be his mind."

View Tedstor's profile


1643 posts in 2601 days

#11 posted 03-15-2011 07:15 AM

I bought a 12×12x5/8 granite tile from a restore for $4. According to my straightedge, its flat. And its big enough to accomodate three strips of various grade sandpaper. My results have been 100% satisfactory.
I’m not sure if the thickness of the material is even an important factor. As long as its thick enough to resist the force applied to it without flexing/breaking, I’d guess its thick enough. I mean how would a chisel know if its being rubbed against a 1/2” plate vs a 2” plate? But I freely admit to being a hack, so take my thoughts with a grain of salt.

View Dan's profile


3630 posts in 2848 days

#12 posted 03-15-2011 04:10 PM

I was using a thin piece of plate glass until I dropped a tool on it and shattered it :(

Rather then getting another piece of glass I did as some others have said and got a piece of granite tile from Home Depot. The tile was 4.94 and its the perfect size. I also checked the tile and its perfectly flat and I have no complaints.

-- Dan - "Collector of Hand Planes"

View poopiekat's profile


4349 posts in 3702 days

#13 posted 03-16-2011 12:02 AM

Remember though, if you ARE using glass, it should be tempered glass. Regular window glass is not sufficient for this procedure.

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

View Millo's profile


543 posts in 3018 days

#14 posted 03-16-2011 12:02 AM

Cool, guys… thanks for your accounts and tips! I essentially wanted to lap a #7 plane on a large piece of granite or glass, although the smaller tile size works for the waterstones, so thanks for the tip!

View coloradotrout's profile


61 posts in 1971 days

#15 posted 01-21-2013 06:26 PM

I may be able to pickup a 12” x 36” x 3/8” thick piece of glass intended for shelving. Any idea how to tell if this is float glass or not? I suppose I can check with my starret straight edge. If it’s flat not sure much else matters. I have a smaller piece of 1/4”, but the larger piece will flatten hand plane soles.

showing 1 through 15 of 18 replies

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