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Chisel Flattening

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Forum topic by wilbrijo06 posted 11-20-2016 09:25 PM 1076 views 0 times favorited 16 replies Add to Favorites Watch
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wilbrijo06

8 posts in 1579 days


11-20-2016 09:25 PM

Topic tags/keywords: sharpening hand tools chisels question

Guys -

I’ve been “honing” the poo out of this 3/4” chisel I got in a set from Wood River. I know there’s better quality out there, but this is what I could afford.

Anyway, after going at it for 30 minutes with a 220 wet stone (that I just flattened) I still have low spots (see pic below). I’ve probably made a few thousand passes on the 220 stone. That’s after about 10 minutes work on the (just flattened) 1000 stone, until I realized I wasn’t getting anywhere.

Just so I can verify my technique, I’m letting the back of the chisel hang off the edge and putting all my pressure evenly, straight down on the blade. Every 50 strokes I rotate my stone to ensure I’m wearing it evenly.

A couple questions:

1. Am I doing this wrong, or is this normal?

2. Should I step down to 100grit wet/dry on granite like I use to lap my stones, or just keep going with the 220 stone? I’m not impatient (I find sharpening can be relaxing actually), but also don’t want to be wasting my time if there’s a better way.

Thanks guys! As always, as a newbie to this handtool/woodworking thing, I really appreciate your help and wisdom.

BW


16 replies so far

View paratrooper34's profile

paratrooper34

915 posts in 2792 days


#1 posted 11-20-2016 09:34 PM

BW – you are polishing way too much of the back on that. You need only polish about an inch or so (max). Try polishing to that and you should have much better luck. As it is, you are trying to polish a lot of metal.

-- Mike

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wilbrijo06

8 posts in 1579 days


#2 posted 11-20-2016 09:41 PM

Also, I wanted to add that I leave a trickle of water running over the stone as I sharpen. I heard this was a good tactic, but now I’m wondering if it doesn’t let the slurry build up on the stone necessary to do the sharpening work. Still don’t know how “wet” the stone should be during sharpening.

Thanks guys.

BW

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Tim

3684 posts in 1801 days


#3 posted 11-20-2016 09:53 PM

What Mike said and yes, go way down on your grit until you get it flat, then move up through the grits. Careful, sandpaper can round the edges. Personally though, I would take back a chisel that was that far out of flat.

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WhoMe

1564 posts in 3083 days


#4 posted 11-20-2016 10:04 PM

Instead of wasting your stones on that. Get some 180 (or 150/120 or so) grit 3×21 belt sander belts from the local big box store, some spray adhesive and a real flat surface. Slice the belt at the seam ( and cut it in half lengthwise) and glue the belt to the flat surface.
Then flatten the back of the chisel. I use simple green ass the lubricant, ymmv.
Then go to the stones.
This also works well for rehabbing old tools, repairing really damaged cutting surfaces/edges and regrinding bevels when needed.
It is cheap and saves your stones for the fine work.
I use this myself and recommend it for my sharpening class as well as general sharpening advice, especially in tool restoration.
And like the others said, you are trying to flatten to much of the back. 1” to 1 1/2” is plenty.

-- I'm not clumsy.. It's just the floor hates me, the tables and chairs are bullies, the wall gets in the way AAANNNDDD table saws BITE my fingers!!!.. - Mike -

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wilbrijo06

8 posts in 1579 days


#5 posted 11-20-2016 10:07 PM

Update:

So I think I found my problem. Cut off the running water and got a slurry going. Suddenly – my stone is cutting much faster (face palm). Forget where I read that you should sharpen under a trickle of water, but I don’t think I’ll do that anymore.

Thought it was kind of strange that my 220 stone was polishing…

Side note: I’ve had this on the stone for long enough that I’m starting to get some rust on the back where it’s not contacting the stone (you can see it in the new pic). Should I just steel wool that when I’m done?

And what do I use to oil it?

So much to learn…

BW

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bondogaposis

4483 posts in 2191 days


#6 posted 11-20-2016 10:07 PM

Use a coarser grit, you should be able to flatten it in 5 minutes or less. If it takes longer than that keep dropping grits until you get it. I use a coarse diamond stone for flattening.

-- Bondo Gaposis

View GregTP's profile

GregTP

59 posts in 783 days


#7 posted 11-20-2016 11:09 PM

I have seen mention of leaving water running on your stones also. If I’t not mistaken there was an article in Woodsmith magazine (could have been one of the others) in the recent past that had plans for making a japanese inspired sharpening station with a pump that circulated a trickle of water back onto the stone.
Not sure I agree with the method, and your results seem to prove that it was slowing you down!

-- From exercise machine warning label: "Step ladders can cause injury and even death; the ROM machine is more dangerous than a stepladder"

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mike02130

167 posts in 513 days


#8 posted 11-20-2016 11:23 PM

Hmm, two things, 1, I learned something new from WhoMe regarding the sanding belts. 2, Wilbrijo gave it a good effort before asking and was polite thanking people in advance. Not many posters seem to appreciate all the good advice.

-- Google first, search forums second, ask questions later.

View Redoak49's profile

Redoak49

2906 posts in 1829 days


#9 posted 11-21-2016 01:55 AM

The only reason to flatten the entire back is to make it pretty. I only worry about the bottom inch. Polishing the entire back will not make it any sharper. I would concentrate on the bottom inch on the back and the bevel on the front.

View Homick's profile

Homick

23 posts in 1761 days


#10 posted 11-23-2016 03:07 PM

I wouldn’t do this with a new chisel, but I’ve heard that if you are careful and your chisel is bellied, you can bend it ever so slightly in the middle. I’ve done that with some success on a plane blade; turned it into a user. I think there is some risk to that compared to just grinding it flat though; you can bend it too much too.

I was also under the impression that flattening the entire back is a good practice, so the whole surface is in plane with the sharp edge; a good feature to have if you are paring deep. Note, I’m not talking about honing and polishing the whole back, just flattening it.

View HokieKen's profile

HokieKen

4521 posts in 978 days


#11 posted 11-23-2016 06:49 PM

FWIW, I did flatten the backs all the way on my paring chisels. All others just get the inch or so at the cutting end though.

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

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Tim

3684 posts in 1801 days


#12 posted 11-23-2016 11:37 PM

Homick, I’ve bent a plane blade and a chisel carefully using the three dowels in the bench vise trick that I learned here on LJ maybe from DonW. Two dowels on one side, one on the other at the high spot and slowly close the vise just enough past where you want it to end up. If you are careful enough you can bend it just right.

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ClutteredShop

38 posts in 392 days


#13 posted 11-24-2016 04:57 AM



The only reason to flatten the entire back is to make it pretty. I only worry about the bottom inch. Polishing the entire back will not make it any sharper. I would concentrate on the bottom inch on the back and the bevel on the front.

- Redoak49


I agree with this approach, with two possible exceptions: for doing very fine paring work, and in the case of a mortising chisel, where having a perfectly flat back helps the eye determine true vertical when chopping the ends of a mortise. But for ordinary chiseling around, what you have now will be fine.

-- Cluttered Shop

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Lemwise

71 posts in 457 days


#14 posted 11-27-2016 10:08 PM

I don’t know where and when the trend of flattening the entire back started but I can tell everyone here, with 17 years under my belt as a shipwright, it’s complete bullocks. I will even say that anyone who needs a completely flat chisel isn’t much of a woodworker. Only the first and last 2-2.5cm of the blade needs to be flat. That goes for everything from fine paring work to chopping a mortise. It’s even less important for a plane blade. Stop listening to all the self professed woodworking guru’s such as Schwarz and Cosman and learn how to use a chisel.

View rwe2156's profile

rwe2156

2717 posts in 1321 days


#15 posted 11-28-2016 03:17 PM

You found the problem. I will add:

1. I agree you only need to flatten the first couple inches.

2. make sure your stones are flat & reflatten every so often during the process. And be sure whatever you’re flattening with is flat!! I bought a Norton flattening stone only to discover IT WASN’T FLAT!!

3. Like Bondo, I keep dropping grits until I get it flat – all the way to 100 grit if needed.

-- Everything is a prototype thats why its one of a kind!!

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