How I Flatten Chisels... What's the Catch?

**Luke Maddux** · 25th March 2016, 02:08 PM

A while back I set myself up to lap single bevel blades and plane soles. I've been doing it for a while, and I am really happy with the results.

My concern is for the fact that what I'm doing is super, super easy and quick. I can take a heavily pitted chisel and have the back flattened and the bevel sharpened in about ten minutes.

So when I see posts about how much of a dreaded task it is to flatten chisels by hand, and especially when I see the recent post about a group of experienced woodworkers brainstorming ways to do it mechanically, it makes me begin to second guess my process. So I want to outline that process and open the floor for feedback.

I have a 1.25m long piece of ground granite countertop onto which I have used contact adhesive to glue P80 sandpaper. The yellow stuff that comes in the 100mm x 5m rolls. I have been liberal with the contact adhesive and pedantic about attaching it so as to ensure that the sandpaper is not bubbling up in front of the leading edge of the tool I'm lapping.

So the steps are:

1. I put on a glove, as it generates a bit of heat
2. I apply firm, uniform pressure on the chisel, backside down, and push it about a 1m stroke forward, then wipe it, then pull it backward. Then wipe it. I repeat this process until the pitting/rust/patina is removed from the back. I clean up about the first two inches of the blade like this.
3. ~30 strokes forward and back with coarse diamond stone on the first 1" of the chisel
4. step 3 on fine diamond
5. step 3 on extra fine diamond
6. step 3 on 4000 waterstone
7. step 3 on 8000 waterstone

At this point, I'm about 5 minutes into the process (worst case scenario) and I have a mirror polish. According to my high dollar try square, the chisel is flat. I have yet to have one go through this process and not come out flat.

I then grind and hone the bevel (easy) and I'm done. From my perspective, I have the results I want, and I'm getting them every time.

The part that worries me is the fact that this is, again, extremely easy. It isn't a process I dread, nor is it something I feel the need to further engineer. It's just a minor step in something I love to do, which is restore old chisels.

So why haven't more people done this and put an end to the woes of chisel flattening? Or, more importantly, have people actually tried this and decided that, for some reason, it is inadequate?

Interested in any feedback.

Thanks in advance,
Luke

**Pagie** · 25th March 2016, 02:20 PM

Sounds good to me. Maybe some people don't like to do things the easy way.

**jhovel** · 25th March 2016, 02:34 PM

I think the important part of why your method is easy is the "1m stroke" part.
If you have only 200mm long stones/laps/surface plate, then each of your strokes equals 5 of ours....
I really like your method I have to say.
An alternative equivalent would be to have the sandpaper move over a very flat and hard surface and the chisel stay still - they call that a linisher. Most of those move too fast though (designed for surface prepartaion, not precision flattening). So if you used a variable speed linisher (or belt sander) running on a granite or dead flat steel backing plate, that might be a really good option.
What do you think?

**rob streeper** · 25th March 2016, 02:50 PM

Great method Luke. I have a section of granite and am inspired by your description to use 3M spraymount and WD paper to achieve the same end.

Cheers,
Rob

**Luke Maddux** · 25th March 2016, 02:55 PM

Originally Posted by jhovel

...that might be a really good option.
What do you think?

I think it might be a winner, but, before engineering anything like that, try the manual method. I think you'll be happy with it, but I would really like someone else's take on the process after trying it.

**FenceFurniture** · 25th March 2016, 02:56 PM

C'mon Luke - time to fess up to being 2.8m tall and a metre across the shoulders...

I must confess that the contraption I made was purely academic for me, as my chisels are already done. Maybe some others can get some benefit from it, but I don't see myself using it much.

It's been a while since I've used a method similar to yours, and I didn't have the luxury of a run that long. As I recall (and it's faint now) I was getting a bit of dubbing on the leading edge (could have been inexperienced technique).

I have a lapping plate on order from the USA which is CBN 60 grit one side and 100g the other, so it will be interesting to see how that goes.

**Luke Maddux** · 25th March 2016, 03:01 PM

Originally Posted by FenceFurniture

I have a lapping plate on order from the USA which is CBN 60 grit one side and 100g the other, so it will be interesting to see how that goes.

I'd be interested to hear how that goes as well. Is it a fairly standard (200mm) size?

**FenceFurniture** · 25th March 2016, 03:03 PM

O'course much of the ease or difficulty depends on the type of steel and how well it's been heat treated. My tool steel Irwin bangers weren't too hard to flatten, but getting the residual surface grinding marks out of the HSS M2 Harold & Saxons was a whole 'nutha story. Both types of chisels above were new at purchase.

Yes, the plate is 200 x 75mm, ¼" thick. You'll probably hear more about it "elsewhere".

**Heavansabove** · 25th March 2016, 04:03 PM

I suspect Luke is somewhat younger than many members of this forum... The problem with sandpaper (and this sounds like cloth backed Zirconia) is dubbing, I admire Luke's ability to avoid this - not just on chisels but also on plane soles, where most people end up with convex soles*. I do use such paper for very rough initial flattening of very bad chisel backs, and then move to my preferred method explicated in other threads, ie Dremel grinding.

cheers
Peter
* drawfiling the middle of the sole before the paper treatment works wonders to avoid convex soles; skilled operators may run the middle of the sole over a linisher wheel

**Luke Maddux** · 25th March 2016, 04:53 PM

It's a heavy paper on the back. I'm not sure what the material is.

I've given most of my lapped chisels away, but I'm going to try one soon and see if I've just overlooked some dubbing. Note the wiping of the blade at the end of each front and back stroke. I do this in an effort to prevent as much "slurry" (the wrong word since it's dry) from dubbing the edges as possible.

Good observation about my age. I'm 30. This is a major part of why it concerns me to see guys with as many woodworking years as I have life years not using a method like this...

Cheers,
Luke

**rob streeper** · 26th March 2016, 12:52 AM

Another question occurs to me: Your first post suggests that you move the chisel along cutting edge first. Do you swap the chisel around and push it handle end first as well?

**derekcohen** · 26th March 2016, 02:53 AM

Hi Luke

I wrote about this many years ago. There is an article on my website from 10 years back ...

This popularised the use of a magnet to hold the blade.

The lapping plate is 1m long glass on MDF on a flat bench top.

Regards from Perth

Derek

**FenceFurniture** · 26th March 2016, 07:42 AM

Hi Derek

I can see how the magnet would hold a large surface area like a plane blade, but how does it go with the narrow tops of a chisel blade?

**Luke Maddux** · 26th March 2016, 12:36 PM

Originally Posted by rob streeper

Another question occurs to me: Your first post suggests that you move the chisel along cutting edge first. Do you swap the chisel around and push it handle end first as well?

Hi Rob,

Sorry, I see how that was unclear. I have the bladed edge parallel to the push and pull direction, so as I push forward the right side of the chisel is the leading edge, and as I pull back the left side is the leading edge.

Hope that helps.

Cheers,
Luke

**Luke Maddux** · 26th March 2016, 12:38 PM

Originally Posted by derekcohen

There is an article on my website from 10 years back ...

Hi Derek,

Would you mind posting a link? I'd like to see what you have to say about this method.

Cheers,
Luke

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