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Chisel Sharpening Frustration

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Forum topic by todd4390 posted 06-10-2015 01:31 AM 1365 views 0 times favorited 15 replies Add to Favorites Watch
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todd4390

130 posts in 935 days


06-10-2015 01:31 AM

Let me preface this by saying that I’m fairly new to hand tools and sharpening. I just got done spending an hour and a half lapping the back of this chisel and this one corner at the edge isn’t getting hit by the 300 grit diamond stone that I’ve been lapping with. It went pretty well at first but then spent about 45 min with what appears to be no progress. I have successfully lapped the back of a plane iron so I’m hoping this isn’t my technique. Do I have a bad chisel (Marples), am I doing something wrong, is something wrong with my stone? I tend to lean toward this being a chisel issue. Or does it just take this long to do the initial lap on new chisels? If so I’m not really digging that too much.


15 replies so far

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hhhopks

645 posts in 1844 days


#1 posted 06-10-2015 01:40 AM

I feel your pain. It takes longer because you have more surface area to grind off as you come closer of getting the back of the chisel flat. I would consider of grinding the chisel back from the front edge so that corner low spot would disappear.

-- I'll be a woodworker when I grow up. HHHOPKS

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tomd

2027 posts in 3237 days


#2 posted 06-10-2015 01:41 AM

That looks like a grinder mark, a chisel problem for sure. Depending on how deep it is you may have to go to a much coarser grit.

-- Tom D

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Ross

142 posts in 1440 days


#3 posted 06-10-2015 01:52 AM

When lapping the back of a chisel you only need to lap about an inch up from the cutting edge. There may be a slight twist in the chisel iron up towards the handle. Try lapping just the 1st inch. When I have to lap new chisels or plane irons I start with my work sharp 3000 and 150 grit A/O working my way up to 400 grit A/O then I switch to the stones. 1000 to 2500 then I polish with a leather strop?
Hope this helps

-- "Man Plans and God Laughs"

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todd4390

130 posts in 935 days


#4 posted 06-10-2015 02:37 AM

The marks at the edge is black sharpie I used to mark progress not grinder marks.

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Andre

1023 posts in 1273 days


#5 posted 06-10-2015 03:04 AM

I usually start with 180 – 220 grit sand paper then go right to a 1000 water stone followed by 8000 polish.
In some cases like rust or pits, start with 100 grit. Blades are hollow ground and only need a few strokes
on the 1000 water stone then 8000 polish. Nothing like honing blades for hours on end to make you appreciate
real quality tools!

-- Lifting one end of the plank.

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BubbaIBA

383 posts in 1844 days


#6 posted 06-10-2015 10:19 AM

Todd4390,

Unless you are very careful when lapping, the leading edge can be “rounded”. It doesn’t take much for that to happen, then you end up with what is in effect a convex back. A convex back is very hard to flatten. The Japanese work around the problem of convexity by grinding a hollow on the back forcing the back to be concave.

You might try using a grinder or a Drimmel to grind a shallow hollow on the back (see a Japanese chisel), it doesn’t take much to be effective, so you are only lapping a small area.

ken

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PatrickH

51 posts in 1355 days


#7 posted 06-10-2015 11:03 AM

Is this a new chisel? If so, I’d try returning it? Definitely a chisel problem. I had the backs of 5 Lie Nielsen chisels glowing in under an hour.

-- http://bloodsweatsawdust.com

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rwe2156

2200 posts in 948 days


#8 posted 06-10-2015 11:52 AM

I disagree with the post on lapping only 1 inch on a chisel because when paring you need a flat back way more than 1”.. Its ok on a plane iron, but not a chisel. You need at least 2 – 2/12” of flat bearing surface if you ever want a chisel to perform well. Personally, I try to flatten a chisel even higher than that (like 3/4 the way up the back).

I think what you’ve got here is a manufacturing defect. You’re going to see this a lot in the cheaper chisels. I started out with a set of Irwin Marples and as I recall the 3/4 and 1 inch chisels were a bear to flatten. But surprisingly, after I got them tuned up, they are not bad chisels – no good for dovetailing but good for anything else.

I have had to resort to actual grinding on couple chisels that were really bad, but you have to be willing to throw it away if you fail, and I don’t recommend anyone do this (wink, wink) OK?

My rec on this one is to go with sandpaper in a super coarse grit, maybe even 80 and work up from there. I would be prepared to wave the white flag on one like this and instead just go buy another chisel and use that one for scraping glue or whatever. There is a point of diminishing returns before you decide you’re wasting valuable time.

How big is your diamond stone? Maybe its the photo, but is looks kind of small.

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

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todd4390

130 posts in 935 days


#9 posted 06-10-2015 05:47 PM

The diamond plate I’ve been using is the Trend 300/1000 combo plate that’s not in this photo. In all the stuff I have found on the web about sharpening I haven’t seen anyone recommend lapping only the first inch of the chisel.

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rwe2156

2200 posts in 948 days


#10 posted 06-10-2015 06:11 PM



The diamond plate I ve been using is the Trend 300/1000 combo plate that s not in this photo. In all the stuff I have found on the web about sharpening I haven t seen anyone recommend lapping only the first inch of the chisel.

- todd4390

Sounds like you’re doing everything right. You’ve just got a bad chisel there.

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

View bobasaurus's profile

bobasaurus

2675 posts in 2651 days


#11 posted 06-10-2015 06:23 PM

The trend plates don’t remove metal very quickly, I have the same one. Maybe try with coarser sandpaper on granite or on a jointer/table saw bed.

-- Allen, Colorado

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Holbs

1379 posts in 1496 days


#12 posted 06-10-2015 07:29 PM

For new chisels / irons, I go to sandpaper first. 8” x 10” sheets are ok, but sanding belts are better. I too, have diamond stones. You only have so much real estate to work with on diamond stones. 8”x 10” sandpaper sheets are better. 4”x 48” sandpaper for belt sanders are the best because SOOO much real estate to work on (also depends what you have under the sandpaper). For really bad looking chisels/irons, I actually start at 80 grit, then 120, then 220, then 400… then I start using my diamond stones after that.
So work on 80 grit sandpaper until pattern marks are uniform. Then enjoy the climb up the grits.

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

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Holbs

1379 posts in 1496 days


#13 posted 06-10-2015 08:50 PM

Also, you can take a flat edge along the backside of the chisel and see just how far you have to go to make it all flat. If it’s visibly bent or damaged, that will give you answers. If it’s flat, you know you are SO close :)

-- Yes, my profile picture is of a Carpenter Bee! The name is derived from the Ancient Greek "wood-cutter"

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TheFridge

5765 posts in 953 days


#14 posted 06-10-2015 09:13 PM

I have 3 new old stock marples that I flattened. 3/4&1-1/2 took an hour apiece start to finish and the 1/4 took a lot longer. I ended up just grinding off a 1/4” off of it because I didn’t feel like lapping anymore. The only dead flat chisel I’ve worked with was a LN 1/2. It was pretty much perfect.

I never realized how much easier it was to lap irons and chisels with sandpaper and a hunk of granite.

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

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bandit571

14638 posts in 2150 days


#15 posted 06-11-2015 12:04 AM

Worked on this German Chisel that came from Ebay the other day

Muller 22mm-7/8” wide. Needed abit of work. There was two bevels on the edge, even.

Main tool of choice to flatten the back, and redefine the bevel? A 1” x 30” belt sander. Got both the back flat, and the bevel back to a single bevel. Then it was off to a stone ( 600 medium India) then some wet-n-dry 1K-2.5K paper, the stropped with a dry leather belt.

Seemed to do just fine. When i use that beltsander, I keep a bowl of water nearby. Fingers will tell me when to dunk a part. Grit on the belt? unknown, as it is quite worn from use.

-- A Planer? I'M the planer, this is what I use

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