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View Yacman23's profile

Granite for flattening

by Yacman23
posted 09-17-2016 01:16 AM


27 replies so far

View Ross's profile

Ross

142 posts in 2512 days


#1 posted 09-17-2016 01:30 AM

Works for me. I have been using a piece of remnant granite counter top to flatten chisel backs and plane irons for years. I have used cement blocks to flatten plane soles

-- "Man Plans and God Laughs"

View cooltimbers's profile

cooltimbers

10 posts in 3872 days


#2 posted 09-17-2016 01:31 AM

I assume you mean as a substrate to attach sandpaper to? If it is flat, then I guess so.

View BurlyBob's profile

BurlyBob

6640 posts in 2805 days


#3 posted 09-17-2016 01:40 AM

Definitely!. Like Ross I’ve been doing it for several years. I’ve got one sizable piece set up with 6-7 pieces of wet/dry paper from 220 to 2500 grit. I’ve also got 3 longer 4”+ slabs maybe 28” long with double lengths for flattening plane soles. I’m very satisfied with the results.

View TheFridge's profile

TheFridge

10859 posts in 2026 days


#4 posted 09-17-2016 02:43 AM

I have a large sink cutout. I get the same scratch patterns no matter where I put the paper. I’m happy.

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

View Bill White's profile

Bill White

5228 posts in 4500 days


#5 posted 09-17-2016 02:56 PM

Sink cut-out here as well. 3 cm thickness and flat. Free. What’s not to like?
Bill

-- [email protected]

View Woodknack's profile

Woodknack

12927 posts in 2920 days


#6 posted 09-18-2016 03:52 PM

I have several granite pieces and none are truly flat.

-- Rick M, http://thewoodknack.blogspot.com/

View HokieKen's profile

HokieKen

11397 posts in 1678 days


#7 posted 09-19-2016 12:17 PM

I have a granite surface plate that is dead flat and I have two 12” granite tiles that are pretty close to flat. Close enough for dressing chisel backs and planes. But, I had to buy 24 tiles and sort through them to find 2 that were flat enough to suit me. I just returned the rest to Lowes. Granite is an excellent substrate and is very stable but isn’t usually truly flat unless it was intentionally ground to be that way. Most of it is slightly dished. I’d say check it and if it’s flat enough, then use it.

-- Kenny, SW VA, Go Hokies!!!

View HickWillis's profile

HickWillis

115 posts in 1199 days


#8 posted 09-19-2016 01:54 PM

For the folks who have sink cutouts or whatever it may be…are they from when you bought granite for your kitchen, bathroom etc? Did the granite company charge you anything to keep the cut out?

-- -Will

View Aj2's profile

Aj2

2532 posts in 2338 days


#9 posted 09-19-2016 02:04 PM

I have not seen any granite scraps big enough to work with flat enough for me.
They are not very thick and will flex.
I paid 185 for my 30long 24w 4thick.Its not super precision but I use it a lot for a reference surface.And small assembly table.

Aj

-- Aj

View Bill White's profile

Bill White

5228 posts in 4500 days


#10 posted 09-19-2016 02:11 PM

Sink cuts are waste. The granite fab shop here throws the broken splashes and cuts in the dumpster. They do not charge me for the remnants.
Bill

-- [email protected]

View BurlyBob's profile

BurlyBob

6640 posts in 2805 days


#11 posted 09-19-2016 03:16 PM

Ditto what Bill said. the outfit I found was glad to have me haul off some. They have to pay to dump the scraps.

View HickWillis's profile

HickWillis

115 posts in 1199 days


#12 posted 09-19-2016 03:29 PM

Good stuff, thanks fellas. I have a granite shop near me, I’ll stop in and see if they have any scraps.

-- -Will

View JayT's profile

JayT

6311 posts in 2751 days


#13 posted 09-19-2016 04:08 PM



Ditto what Bill said. the outfit I found was glad to have me haul off some. They have to pay to dump the scraps.

- BurlyBob

Same here. Stopped at a countertop shop and asked if I could buy a small piece of cut off. The guy laughed, pointed me at the waste pile and told me to take as much as I wanted so they didn’t have to pay to dump it.

A couple things I learned at a Woodworking Show session with Rollie Johnson. Try to find the darkest granite you can, darker means denser and more stable—that’s why reference plates are made from black granite. Second, try to see if you can find some that has been surface ground flat, but not yet polished. It will be the flattest at that point, as the polishing process can introduce some small imperfections.

Regardless, a decently flat piece of granite will get your planes flat enough to use.

-- https://www.jtplaneworks.com - In theory, there is no difference between theory and practice. In practice, there is.

View Kelly's profile

Kelly

2468 posts in 3484 days


#14 posted 09-19-2016 04:30 PM

I use a Makita and a Milwaukee variable speed grinders to work granite. I dribble a bit of water on the bits, pads and stones to GREATLY extend their life (I use a 3/8 hose off an adapter, with a valve, mounted to a garden hose). I run the grinders at near the lowest settings.

The pads, stones and router bits are available all over the Net. I have pads ranging from 50 to 6,000 grit. The stones are large and just spin on, but only run about ten bucks. They are about forty or fifty grit and will remove a lot. Perhaps too quick for these purposes, since I’ve used them to round over edges.

If you had a piece of scrap that was close, you may only need the 100 or two hundred to start. Finer grits would only be necessary to bring a polish. In fact, if you were within a few thousand’s, you could touch the face with 800 or 1000 and check it.

I suspect most tiles and slabs are going to be fine for most of us.

View tshiker's profile

tshiker

62 posts in 1849 days


#15 posted 09-22-2016 11:03 PM

If for some reason you can’t find or don’t want scraps there is this option, http://www.grizzly.com/products/18-x-18-x-3-Granite-Surface-Plate-No-Ledge/G9653

View splatman's profile

splatman

586 posts in 1939 days


#16 posted 09-23-2016 05:21 AM

Would it work to rub 2 sink cutouts face-to-face with some water and abrasive to grind them totally flat?

View Cooler's profile

Cooler

299 posts in 1383 days


#17 posted 09-23-2016 01:32 PM

Granite is ground, and depending upon who did the grinding it may be flat or it might not be.

Glass, on the other hand, is floated and will be flat. I’ve used glass to “machine” a small engine cylinder head when replacing a gasket.

You can get double strength glass almost anywhere.

Burnish the edges of the cutout granite and put on some feet and you have a cutting station.

-- This post is a hand-crafted natural product. Slight variations in spelling and grammar should not be viewed as flaws or defects, but rather as an integral characteristic of the creative process.

View splintergroup's profile

splintergroup

3002 posts in 1762 days


#18 posted 09-23-2016 02:07 PM

The cheap import granite surface plates are perfect for that. I think I got my 9”x12”x3” for under $20 and free shipping a number of years ago.

View Cooler's profile

Cooler

299 posts in 1383 days


#19 posted 09-23-2016 02:39 PM



The cheap import granite surface plates are perfect for that. I think I got my 9”x12”x3” for under $20 and free shipping a number of years ago.

- splintergroup

Grade B surface plates (cheaper than Grade A) are generally guaranteed flat within 0.0001” (one tenth of a thousandth).

In our QC office we have a 3’ x 4’ x five or six inches thick. It rests on a robust steel stand. I have no idea what it weighs, but heavy for certain.

-- This post is a hand-crafted natural product. Slight variations in spelling and grammar should not be viewed as flaws or defects, but rather as an integral characteristic of the creative process.

View smance's profile

smance

5 posts in 1593 days


#20 posted 10-01-2016 10:00 PM

If you don’t want to pay ~$80 in freight, I grabbed mine off amazon. They have a few different sizes.

View SignWave's profile

SignWave

472 posts in 3575 days


#21 posted 10-02-2016 06:49 PM



Would it work to rub 2 sink cutouts face-to-face with some water and abrasive to grind them totally flat?

- splatman


You can do this, but it would take 3 pieces to get totally flat. If you only have two, an imperfection in one will be transferred to the second. If you use three and rotate which pair you’re using, the imperfections cannot get transferred.

-- Barry, http://BarrysWorkshop.com/

View Cooler's profile

Cooler

299 posts in 1383 days


#22 posted 10-02-2016 08:33 PM

Would it work to rub 2 sink cutouts face-to-face with some water and abrasive to grind them totally flat?

- splatman

You can do this, but it would take 3 pieces to get totally flat. If you only have two, an imperfection in one will be transferred to the second. If you use three and rotate which pair you re using, the imperfections cannot get transferred.

- SignWave

I’ve tried to smooth the edge of a granite tile. Marble will yield to sanding discs; granite will fight tooth and nail.

For ten dollars he can get a piece of double strength glass.

-- This post is a hand-crafted natural product. Slight variations in spelling and grammar should not be viewed as flaws or defects, but rather as an integral characteristic of the creative process.

View clin's profile

clin

1070 posts in 1536 days


#23 posted 10-03-2016 04:09 AM

I bought a Grizzly Grade B (0.0001”) surface plate from Amazon. It’s smallish at 9” x 12” and was about $30. I wanted something I could move easily. At that price, not worth my time to scrounge up counter top scrap and hope it’s flat.

-- Clin

View Yacman23's profile

Yacman23

4 posts in 1157 days


#24 posted 10-08-2016 03:35 AM

Sooo sorry to leave you guys hanging! I’m new to the forum and dont know what I’m doing. Thanks for all of the great tips. Very helpful!

View Tim's profile

Tim

3859 posts in 2501 days


#25 posted 10-08-2016 04:53 PM


Would it work to rub 2 sink cutouts face-to-face with some water and abrasive to grind them totally flat?

- splatman

You can do this, but it would take 3 pieces to get totally flat. If you only have two, an imperfection in one will be transferred to the second. If you use three and rotate which pair you re using, the imperfections cannot get transferred.

- SignWave

You could use both sides of one piece to get the 3 needed surfaces. But I can’t even imagine how much time it would take to lap by hand three granite surfaces together to get them flat. This is one of those things that unless the process sounds fun to you, it would take way more time than it would be worth. I was curious once how this was done though and found some detailed procedures online for the order of the surfaces to lap against each other and when to rotate one of the surfaces.

View Bill White's profile

Bill White

5228 posts in 4500 days


#26 posted 10-08-2016 05:34 PM

I guess that I must weigh in on the absurdity of having a woodworking tool flattened to within .0005”.
Wonder what our old fellows did? They got the item sharp, and used it. Chisel, plane, etc.
I do use a granite sink cut out. It works well. Did I check it to be sure that it was micron flat? NO!
I’ll give ya sharp all day long with my surfaces and stones.
Bill

-- [email protected]

View Skatergirl46's profile

Skatergirl46

17 posts in 1137 days


#27 posted 10-08-2016 06:47 PM

Cool idea! I have a granite slab that I use for leather working/tooling. That should work great. It’s like the slab in the above listed add^ by tshiker. You can buy them at Tandy leather stores or online I believe also.

-- I'm happiest when I have wheels on my feet or sawdust in my hair.

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