How to check if a chisel (or angled cut) is square

[Paddy Roxburgh]

This is a follow up on Petey83's post about his AI chisels being out of square. I have decided to post it as a new thread as I don't want to get bogged down in whether he should have made the post, or whether it matters if a chisel is perfectly square or which shoes can be compared to which chisels, this is more about technique when checking for square on anything with a bevel.
When I got in the workshop today I grabbed a square and checked a chisel out of curiosity having read Petey83's post about his chisels. I initially did it as he did in the photo ashley-isle-s-chisels-so-dissapointed-t104570.html and it looked pretty out of whack. I then slightly wiggled the square and it looked much better (although still not perfect). This is due to resting the square against fine lands which are difficult to register the square on. If the the square is not completely in line with the cutting edge of the chisel it will appear to be out of square when it is not due to the bevel dropping away. The same is true with angled cuts when checking the none beveled direction for square.
The correct way to check for square (in my opinion) is to register the chisel with the face towards you (face means the non bevelled side, sometimes referred to as the back) and to move the square up until it reaches the cutting edge. As it is registered on a flat surface the problems of the bevel making it look out of square do not occur.
The same approach should be adopted for checking for square on a bevelled (angled) cut, something I am always careful to do as I have (many moons ago) been caught out by this and spent ages adjusting my table saw, when It was cutting perfectly well.
I am not saying that Petey83's chisels were not out of square, simply that the photo is the wrong way to measure for it. I am making this post in order to prevent people from falling into trap of incorrectly concluding that a bevelled cut or tool is out of square when it is not (or indeed concluding that it is square when it is not)
Paddy.

 

[Corneel]

Also, a lot of my vintage chisels and plane iron don't have parallel sides. So you get a different reading from either left or right.

 

[Paddy Roxburgh]

Hi Corneel, As soon as I posted that occurred to me, a square would not be the correct tool to check a tapered mortise chisel. I suppose you could use a sliding bevel, but I think the most suitable tool for that job is your eyes (unfortunately I have vintage eyes so need to put glasses on, maybe I should shop around for some boutique eyes).
Paddy

 

[bugbear]

Also, a lot of my vintage chisels and plane iron don't have parallel sides. So you get a different reading from either left or right.

I once ground a Bailey blade (with parallel sides) perfectly square, only to find the bedding was slightly skewed.

BugBear

 

[undergroundhunter]

Also, a lot of my vintage chisels and plane iron don't have parallel sides. So you get a different reading from either left or right.

I once ground a Bailey blade (with parallel sides) perfectly square, only to find the bedding was slightly skewed.

BugBear

This exact thing happened to me with my 4 1/2 plane. I spent ages getting it just so to find out I had made the problem worse.

Matt

 

[D_W]

Your eye will tell you whether or not a chisel is square enough. I know I have a bias when honing on the diagonal that will cause a chisel to start to look out of square to the naked eye (which doesn't take much once your eye is trained). It's no issue at all to grind it with a bias to work that back out.

I've never seen it actually cause an issue in use, even when I see that it's a little out of square.

 

[Lons]

(unfortunately I have vintage eyes so need to put glasses on, maybe I should shop around for some boutique eyes). Paddy

I'd suggest rose tinted glasses maybe Paddy :wink: :lol: If related to another thread.

 

[cowfoot]

I think this question was asked (but not answered) in the Ashley Iles thread -
does it even matter if a chisel isn't perfectly square?

 

[AndyT]

I think this question was asked (but not answered) in the Ashley Iles thread -
does it even matter if a chisel isn't perfectly square?

Let's answer this straight away before we get to 11 pages... Yes it was answered, No it doesn't matter.*

*In all normal woodworking procedures. You could probably come up with some extreme case where it would, but this is a woodworking forum, not a court of law.

 

[bridger]

Also, a lot of my vintage chisels and plane iron don't have parallel sides. So you get a different reading from either left or right.

I once ground a Bailey blade (with parallel sides) perfectly square, only to find the bedding was slightly skewed.

BugBear

Adjust the frog.

 

[David C]

Azimuth error.........

I teach a sharpening , plane tuning and planing technique course.

On Monday afternoon, when looking at grinding, I show how to correct a chisel which has been ground slightly out of square.

This is done in an Eclipse type guide, on a coarse stone. (I use an 800 grit King stone).

Differential finger pressure is used to square the edge.

It's nice to have fairly sq chisels but not essential.

Mortice chisels I would prefer to be square.

Best wishes,
David

 

[swb58]

The correct way to check for square (in my opinion) is to register the chisel with the face towards you (face means the non bevelled side, sometimes referred to as the back) and to move the square up until it reaches the cutting edge. As it is registered on a flat surface the problems of the bevel making it look out of square do not occur.
The same approach should be adopted for checking for square on a bevelled (angled) cut, something I am always careful to do as I have (many moons ago) been caught out by this and spent ages adjusting my table saw, when It was cutting perfectly well.
I am not saying that Petey83's chisels were not out of square, simply that the photo is the wrong way to measure for it. I am making this post in order to prevent people from falling into trap of incorrectly concluding that a bevelled cut or tool is out of square when it is not (or indeed concluding that it is square when it is not)
Paddy.

If I've got something of an unknown quantity, chisel or plane iron, I use the square from both sides and draw a pencil line from both sides. If the sides are parallel then the lines are 'in line'. If the sides aren't parallel mark them so the lines roughly intersect in the centre of the blade, then just assess by eye.

 

[ED65]

Apologies for the diversion but an 800-grit stone is considered coarse now??? That's equivalent to P1000-P1200 paper :shock:

 

[bridger]

Apologies for the diversion but an 800-grit stone is considered coarse now??? That's equivalent to P1000-P1200 paper :shock:

800 is coarse for a finisging stone. I'd call it midrange. Much coarser and I'd be eyeing the bench grinder

 

[David C]

My sharpening system has 3 bevels. How outrageous is that?.............

For a chisel say, grind 25 degrees, raise wire edge on 800 stone at 30 degrees and polish at 32 degrees on an 8 or 10,000 grit waterstone.

800 grit stone is plenty coarse enough for this function.

best wishes,
David Charlesworth

 

[woodbrains]

Apologies for the diversion but an 800-grit stone is considered coarse now??? That's equivalent to P1000-P1200 paper :shock:

Hello,

Japanese 800 grit King stone is not measured using the same system as 800 diamond plate, which is likely American CAMI system.

The Japanese 800 is a bit coarser, but neither fine enough for the finishing stage of honing.

Mike.

 

[ED65]

800 grit stone is plenty coarse enough for this function.

Coarse enough I get David (I mostly hone now on a #1000 plate) just in the context of the previous post it was implied it was outright a coarse stone.

Japanese 800 grit King stone is not measured using the same system as 800 diamond plate, which is likely American CAMI system.

Thanks but I know, I was using a cross-system comparison table. Two actually, Norton's and one of the ones drawn up by knife enthusiasts. That's why I hedged the abrasive paper equivalent because the two tables didn't tally exactly (a common frustration).

The Japanese 800 is a bit coarser, but neither fine enough for the finishing stage of honing.

How standards have changed from the days of a single oilstone in the workshop!

 

[woodbrains]

How standards have changed from the days of a single oilstone in the workshop!

Hello,

Or how some are not duped by this myth.

Mike.

 

[Paddy Roxburgh]

Guys, I know being the OP doesn't make me "king of the thread", however could we possibly avoid descending into a pointless edgy (see what I did there) sharpening debate.
Paddy

 

[woodbrains]

Guys, I know being the OP doesn't make me "king of the thread", however could we possibly avoid descending into a pointless edgy (see what I did there) sharpening debate.
Paddy

Hello,

Don't worry, I'm not going there, it was just a matter of semantics, and clarification. And we know ED65 uses a strop, so we know his comment about single stones is a throwaway​ one anyway.

As far as square edges on chisels etc, I've never tested with a try square in my life, judgement by eye is good enough. It is surprising how close to dead square you can judge and correct as you go if necessary.

Mike.