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Going from one water stone to next leaves a very odd scratch pattern

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Forum topic by Burgoo posted 01-09-2019 12:35 AM 473 views 0 times favorited 15 replies Add to Favorites Watch
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Burgoo

9 posts in 653 days


01-09-2019 12:35 AM

Topic tags/keywords: question sharpening chisel plane iron honing water stone flattening

Hi all;

I’ve been trying to work on my sharpening technique, and I’ve come across an odd occurrence. I’m re-establishing the edge on one of my (new version) Stanley Sweetheart chisels, and in general I use a combo of medium and high grit sandpapers on a granite block (120, 220, 320, 400, 600, 800, 1500, 2000, 2500), Norton water stones (1000, 4000, 8000), and a strop—although for this job I’m not going back as far as the sandpaper. Before starting I used the 1000 and 4000 stones to flatten each other, and verified using pencil lines that both surfaces were dead flat.

I started by doing the back again just so I can say I did the whole job (I’ve done it once before, and I know that the back only needs to be done once, but still…). Using the 1000 stone and moving side-to-side I got a good scratch pattern all the way across the edge and at the base end as well after just about 30 seconds.

When I moved up to 4000, however, I found there was only a kind of oblong area along the edge that was polished, and somehow there isn’t a place at the base that has quite the same polish from the 4000 as the place at the edge.

Since the 4000 and 1000 stones flattened each other, I can’t work out how these patterns could be so dramatically different. And, why isn’t the base as polished as the edge? Shouldn’t it touch in the same places as on the 1000 stone?

I included two pics to illustrate what I’m seeing, one that I’ve captioned and one with Sharpie marker showing the wear pattern.


15 replies so far

View TungOil's profile

TungOil

1254 posts in 883 days


#1 posted 01-09-2019 12:43 AM

I suspect your stones are not really flat. One could be concave while the other is convex. Perhaps get a diamond plate to flatten them?

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View Breeze73's profile

Breeze73

102 posts in 1069 days


#2 posted 01-09-2019 12:47 AM

Looks to me there is a twist in the steel, but more likely a twist in your stone. Based on what your saying, the 1000 grit stone appears to be wearing the 4000 grit stone unevenly. My guess is that the 4000 grit stone is softer than the 1000 grit stone. I would recommend getting a Trend Dia-flat plate to use as your stone flattener.

-- Breeze

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MPython

129 posts in 200 days


#3 posted 01-09-2019 01:01 AM

Why are you flattening the whole back of your chisel? That’s asking for trouble. You only need to flatten the back next to the edge. I flatten anywhere from 1/2” to 1” of the back at the edge. I’ll never sharpen that much of the edge away, so that’s more than enough. The rest of the back doesn’t matter.

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Aj2

2266 posts in 2186 days


#4 posted 01-09-2019 01:28 AM

I also think your shooting yourselve in the foot trying to flatten the whole back side of the chisel. The swarf from the finer grits will make almost impossible to keep things flat.
Just try for a inch.

-- Aj

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Andre

2615 posts in 2194 days


#5 posted 01-09-2019 03:33 AM

Depending on the chisel flattening the entire back is not a bad thing, but after it is flat leave it be! Stones can not flatten other stones! get a flattening stone or a diamond stone. I do a rough flatten on 220 grit sandpaper then move to a 1000 WS then finish with a hone/polish on a 8000/1000 WS. Always on a hollow grind except on small detail chisel.

-- Lifting one end of the plank.

View Smitty_Cabinetshop's profile

Smitty_Cabinetshop

16125 posts in 3006 days


#6 posted 01-09-2019 03:53 AM

If I comment on what may be going wrong, I feel it’d only be furthering this madness re: flattening the entire back of your chisel(s).

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View Kirk650's profile

Kirk650

643 posts in 1136 days


#7 posted 01-09-2019 02:51 PM

Don’t flatten the entire back. No need to do that. I just do about an inch or so of the back.

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Burgoo

9 posts in 653 days


#8 posted 01-09-2019 03:14 PM

Thanks for the replies everybody. I understand that as long as there is a polish along all of the edge, that’s all that is technically needed on the back side to have a sharp chisel. Maybe it’s my OCD with tools, but I like knowing that my chisel backs are flat—at least once. It’s not something that gets done at every sharpening.

I went ahead and ran my stones over some 400 grit on my [certified flat] granite block, and a pencil line grid did show that two opposite corners were not precisely flat—but it was veeeeery close.


... Stones can not flatten other stones! get a flattening stone or a diamond stone.

- Andre

I see your (and everyone else’s) point about having a flattening stone that gives a definite reference, and it’s probably a more reliable method, but I don’t agree that stones can’t flatten other stones. After putting a pencil grid on both surfaces, the grid was completely removed on both of them, and contact suction was achieved—that can’t happen unless the two surfaces are true to each other. Even if the coarser stone started out not flat, it couldn’t transfer that imperfection to the finer stone because as they get worked in circles and back and forth and all over, any contours—on either face—would be worn away. If not, a pencil grid wouldn’t be completely removed.

In any case, I think I will get a diamond lapping plate to save me the hassle of getting out the granite and going through a full sheet of sandpaper every time I need to flatten a stone. I appreciate everyone’s input! Happy woodworking everyone.

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Andre

2615 posts in 2194 days


#9 posted 01-09-2019 11:49 PM

After putting a pencil grid on both surfaces, the grid was completely removed on both of them, and contact suction was achieved—that can’t happen unless the two surfaces are true to each other.

Harder surface will always wear softer surface, How do we know surface was flat to begin with?
Pencil grid only works when we know one surface is absolutely flat, any high spots will still remain on harder stone which while will flatten softer stone to a degree, usually creates ridges also, so unless it is flattened on a proven flat harder stone which is why the diamond stone is the chosen method to flatten WS. IMHO!

By the way no the complete lengh of thechisel need not be flattened but IMO looks nicer and gives me a warm and fuzzy feeling when paring 4 or 5 inchs with my 720’s LOL!

-- Lifting one end of the plank.

View Aj2's profile

Aj2

2266 posts in 2186 days


#10 posted 01-10-2019 01:53 AM

In any case, I think I will get a diamond lapping plate to save me the hassle of getting out the granite and going through a full sheet of sandpaper every time I need to flatten a stone. I appreciate everyone s input! Happy woodworking everyone.

- Burgoo

Check out Hap’s Diamond plates. I have one of his old versions and its still working. I wish it would stop working so well then I could justify a new one :). https://nanohone.com/

-- Aj

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jmos

913 posts in 2757 days


#11 posted 01-10-2019 12:57 PM

Not that I would dissuade you from getting a diamond plate for flattening, but you shouldn’t be running through a sheet of sand paper every time you flatten a water stone on a granite reference plate.

I usually use a sheet for many, many flattenings before it cuts so slowly I toss it. If you are working that hard to get your stone flat I’d suggest you’re waiting too long between sharpenings.

-- John

View bondogaposis's profile

bondogaposis

5398 posts in 2739 days


#12 posted 01-10-2019 02:33 PM

You only need to flatten the front 1/2” of the chisel. Flattening the entire back serves no purpose.

-- Bondo Gaposis

View Andre's profile

Andre

2615 posts in 2194 days


#13 posted 01-11-2019 05:07 PM



You only need to flatten the front 1/2” of the chisel. Flattening the entire back serves no purpose.

- bondogaposis

What? Tell that to my set of 2 Cherries I dare you! LOL!

-- Lifting one end of the plank.

View SMP's profile (online now)

SMP

1034 posts in 293 days


#14 posted 01-11-2019 05:43 PM



You only need to flatten the front 1/2” of the chisel. Flattening the entire back serves no purpose.

- bondogaposis

I wonder how long 1/2” will last. I have 100+ year old planes with original blades. My oldest chisels are only 50ish.

View diverlloyd's profile

diverlloyd

3500 posts in 2245 days


#15 posted 01-11-2019 06:53 PM

Nice name op shows where your from.

I have nothing to add everyone has already chimed in.

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