Question about granite for flattening

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Forum topic by PeteK posted 09-06-2016 12:40 AM 1121 views 1 time favorited 18 replies Add to Favorites Watch
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35 posts in 1152 days

09-06-2016 12:40 AM

Ok, I’ll admit it. I’m cheap. So I’m trying to restore a hand plane and was wondering if I bought a 12”x12” granite tile from Home Depot, is that flat enough for using to flatten plane blades and soles? If not, then how about getting a piece of glass from a local glass guy? I don’t want to pay $50 for a piece of rock if I can accomplish the same thing for a few bucks. What say you?

18 replies so far

View Luthierman's profile


222 posts in 1599 days

#1 posted 09-06-2016 12:48 AM

That stuff isn’t that flat. While technically, it would work, there are better options. Try and see if there are sink cutouts from granite installers. That will be better for sure.Often times they are even free.

-- Jesse, West Lafayette, Indiana

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35 posts in 1152 days

#2 posted 09-06-2016 01:02 AM

So if I go with the glass option, is just any old piece of plate glass flat enough? I asked a friend who works at a glass shop. She said plate glass and float glass are the same thing. She didn’t know about the flatness though.

View Luthierman's profile


222 posts in 1599 days

#3 posted 09-06-2016 01:08 AM

If you went the glass option, it would have to be some pretty thick stuff, and that aint going to be cheap. Regular single strength stuff moves, a lot. Plus, god forbid you aren’t super careful with setting something on it. Really, even the tile would be flat enough, its not like you are running a machine shop. Tolerances don’t matter as much as guys like to think in woodworking. The tile just isn’t very big. You will quickly realize that more space is desired for flattening surfaces.

-- Jesse, West Lafayette, Indiana

View canadianchips's profile


2627 posts in 3508 days

#4 posted 09-06-2016 01:22 AM

I used the glass from an old oven door .

-- "My mission in life - make everyone smile !"

View TheFridge's profile


10859 posts in 1997 days

#5 posted 09-06-2016 01:38 AM

Not regular glass. Float or plate glass.

Personally, I have a sink cutout from a granite countertop. I got the same scratch patterns when I tested all around the piece.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View JAAune's profile


1871 posts in 2828 days

#6 posted 09-06-2016 01:44 AM

It depends upon how precise you need to be. If you’re planning on slicing 2” wide shavings at .001” thickness, you’ll need to get those soles and blades very flat. If you’ve got .002” variations in your plane setup, those .001” shavings aren’t going to happen.

I just use my jointer table for my flattening surface. Since I mostly use planes for the occasional quick job, I’m not concerned about getting that perfect setup. My shavings are a little thicker than the ideal for a proper smoothing plane.

-- See my work at and

View TarHeelz's profile


66 posts in 2592 days

#7 posted 09-06-2016 01:51 AM

If your have a Habitat for Humanity ReStore location near you, just pop in there and pick up a chunk of granite countertop. Super cheap and if you get lucky, it might be of a shape that you could turn into the top of a worktable of some sort in the shop.

-- Tar Heelz, Durham, NC USA

View nightguy's profile


213 posts in 1174 days

#8 posted 09-06-2016 02:17 AM

How about your cast iron Table Saw top if you have one.

View TheFridge's profile


10859 posts in 1997 days

#9 posted 09-06-2016 02:23 AM

People swear by their cast iron tops. Cast iron is a live material that can change shape when subject to stresses. I found that out first hand with my unisaw top. Looked a potato chip because the previous owners didn’t support the extension table or 52” fence.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Aj2's profile


2494 posts in 2309 days

#10 posted 09-06-2016 02:36 AM

Even if you found a piece of 1/4 glass that was free or flat.It will only be as flat as the surface you place it on.You will have to push down and it will bend enough to make a difference.
If you want to play you got to pay.
Where I live there is lots of machine shop coming and going.
Granite surface plates are cheap compared to what a new costs.


-- Aj

View DirtyMike's profile


637 posts in 1413 days

#11 posted 09-06-2016 03:03 AM

Fridge nailed it on the flatness of cast iron. I use a big chunk of 2 inch thick granite from a counter top. Took it to the machine shop and they said she was flat as a fritter. another plus for granite is taking pictures with it as a background..

View BurlyBob's profile


6510 posts in 2777 days

#12 posted 09-06-2016 03:09 AM

I’m on board with Jesse. I found a granite shop that will let me poke thru their scraps so they don’t have to pay the garbage dump. I’ve got 4 long narrow pieces for plane flattening and one set up with 6-7 grits for chisels and irons. I’ve got no complaints about the results I get with it.

View realcowtown_eric's profile


618 posts in 2448 days

#13 posted 09-06-2016 03:34 AM

you’d be likely money ahead to go to the local granite countertop folks and buy a 24” sink cut for less money


-- Real_cowtown_eric

View MaurerPower's profile


21 posts in 1161 days

#14 posted 09-06-2016 03:48 AM

I haven’t gotten a chance to use my granite yet, but what others are saying is true. Glass is expensive! Especially a piece big enough for a no 8. The tiles are small and the ceramic tiles that are long are not flat at all (I used a straight edge from the tool section at lowes to check). The counter tops also aren’t perfectly flat though. Some light was showing under my straight edge when I checked it over a length of 24 inches. However, the straight edge might also not be perfectly flat because it is made in China. If you want to go the counter top option call around to some local marble and granite installers, and they will have a big pile of cut offs to choose from for a very cheap price. My piece was $12 for a 6”x36~” piece.

View PeteK's profile


35 posts in 1152 days

#15 posted 09-06-2016 04:17 AM

So the concensus is granite is ok unless it’s not. Same for glass. Lol

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