flattening chisel backs with lapping film

[carlb40]

Slight concavity, apparently standard practice with Axminster cheapos, and with various Stanley, Marples, Footprint bits n bobs over the years.

I take it "apparently standard practice" is extrapolated from a small sample?

BugBear

Well I've certainly noticed it often before and it makes good sense - easy to sharpen and self flattening. It was the first thing I noticed about the cheap Axminster set I bought some years back.
So perhaps chisel makers know more about it than we gave them credit for. Except for Lie Nelson who recommend a long-winded tedious flattening procedure! Somebody should tell them. :lol:
And I bet Narex are better than Matthew thinks and they also don't need flattening.

PS My sample size; perhaps a dozen chisels new from 4 or 5 different makers. And jhwbigley's green handled Marples example which I have yet to sharpen.

If you watch Mathew's narex chisel sharpening video, he states that the narex come with a slight concavity on the back. He then just removes the machining marks on the tip and edge

 

[GazPal]

I tend to think the majority of good chisel manufacturers deliberately "create" a degree of lateral concavity within their blades behind the leading edge. The majority of new chisels I've bought over the years (45 + chisels by Marples, Stanley, Bahco, Footprint, etc.) have been slightly concave laterally behind their leading edges by a fraction of a mm, but seldom - if ever - been concave longitudinally.

The degree of concavity being similar in form to that found with Japanese chisels, but much more subtle.

 

[Jacob]

........

I take it "apparently standard practice" is extrapolated from a small sample?

BugBear

Well I've certainly noticed it often before and it makes good sense - easy to sharpen and self flattening. It was the first thing I noticed about the cheap Axminster set I bought some years back.
So perhaps chisel makers know more about it than we gave them credit for. Except for Lie Nelson who recommend a long-winded tedious flattening procedure! Somebody should tell them. :lol:
And I bet Narex are better than Matthew thinks and they also don't need flattening.

PS My sample size; perhaps a dozen chisels new from 4 or 5 different makers. And jhwbigley's green handled Marples example which I have yet to sharpen.

If you watch Mathew's narex chisel sharpening video, he states that the narex come with a slight concavity on the back. He then just removes the machining marks on the tip and edge

That's allright then! I tend not to watch these videos through - too many old blokes fiddling about in sheds. :roll:

 

[GazPal]

If you watch Mathew's narex chisel sharpening video, he states that the narex come with a slight concavity on the back. He then just removes the machining marks on the tip and edge

Precisely what's been suggested all along

 

[Corneel]

That's allright then! I tend not to watch these videos through - too many old blokes fiddling about in sheds. :roll:

Wouldn't the internet be much more interesting if we could watch nice young ladies fiddling around in old tin sheds?

 

[GazPal]

That's allright then! I tend not to watch these videos through - too many old blokes fiddling about in sheds. :roll:

Wouldn't the internet be much more interesting if we could watch nice young ladies fiddling around in old tin sheds?

That's a totally different forum :lol:

 

[Jacob]

Here's jh's chisel before and after. Old stock but unsharpened and with a cap to keep it in good nick. Ground at 25º

Distinctly concave along the length and slightly across the face so a paring cut will dive in a bit. It's not sharp so the result is more of a scrape

The kit; 2 oil stones and one strop;

The pink stone and 15 seconds later it's sharpish and machine marks almost gone (from the edge). Rounded bevel started so it's caught at the heel as well as the edge. Eventually after many sharpenings the whole bevel will be rounded with an edge at 30º;

The face near the edge is flattening out and shows up;

Another 30 seconds on beige stone and strop and it is sharp with machine marks gone (from the edge);

A planing/paring cut will pass over the surface without diving, unless you press it down near the edge and it will take off fine parings;

That's it. Say one minute in all, not counting getting the kit out and cleaning up. If you wanted it extremely sharp another 30 secs on a finer stone would do it. As the rounded bevel extends it will take a bit longer to hone which means spending longer on the coarser stones to back off the bevel.

It's self flattening - every time it is honed the flat area gets extended a touch and there's certainly no need to deliberately flatten or polish

Perfectly good chisel, well worth £1 + postage! Thanks jh.

 

[Jelly]

Thats an awfully no-nonsense approach, definately maximises productive time... though I guess that's the point!

 

[Corneel]

I have two vintage Sorby paring chisels like that. They also took less then a minute to get sharp. Brilliant. All the other stuff which finds its way into my shop is nowhere near like that. Always bellied, backbeveled, drooped corners and/or haevy pitting.

Oh well, I guess that's the kind of punishment I deserve.

 

[GazPal]

Here's jh's chisel before and after. Old stock but unsharpened and with a cap to keep it in good nick. Ground at 25º

Distinctly concave along the length and slightly across the face so a paring cut will dive in a bit. It's not sharp so the result is more of a scrape

The kit; 2 oil stones and one strop;

The pink stone and 15 seconds later it's sharpish and machine marks almost gone (from the edge). Rounded bevel started so it's caught at the heel as well as the edge. Eventually after many sharpenings the whole bevel will be rounded with an edge at 30º;

The face near the edge is flattening out and shows up;

Another 30 seconds on beige stone and strop and it is sharp with machine marks gone (from the edge);

A planing/paring cut will pass over the surface without diving, unless you press it down near the edge and it will take off fine parings;

That's it. Say one minute in all, not counting getting the kit out and cleaning up. If you wanted it extremely sharp another 30 secs on a finer stone would do it. As the rounded bevel extends it will take a bit longer to hone which means spending longer on the coarser stones to back off the bevel.

It's self flattening - every time it is honed the flat area gets extended a touch and there's certainly no need to deliberately flatten or polish

Perfectly good chisel, well worth £1 + postage! Thanks jh.

Wondering what on earth all of the fuss was about in the first place, as it looks like a pretty decent chisel. :-s The polished flat will naturally expand further along the blade with repeated whetting.

Jacob, judging by feedback from sharpening, how do you think it's edge will hold up during normal use?

------------

In essence, the end result tends to be much the same regardless of whether we use abrasive papers, oil stones, water stones, diamond plates, grind wheel systems, or voo doo to prepare for and produce a finished edge. Although timescales may vary, a sound cutting edge - at a practical degree of finesse - capable of performing the tasks demanded of it can be produced with minimal financial investment. Flatness shouldn't be an issue with new tools and - quite obviously - flies out of the window when dealing with gouges and carving chisels. Flawed tools can be returned for refund or replacement, but there is a very real danger that newcomers can be misled into thinking perfectly sound tools are somehow flawed because they've read somewhere that a fully polished and flattened blade somehow makes a tool outperform the rest, or can enhance skill sets that only tend to improve with lots of practise.

Try to resist the temptation to spend a small fortune on sharpening kit until you've uncovered - for yourself via practical application - whether or not further refinement is justified. Sharpening needn't be and isn't rocket science, but it does take practise for one to obtain a sound working edge each and every time you re-hone an edge. Sharpening is as fundamental a skill set as sound tool handling technique when it boils down to successful woodworking.

 

[Jacob]

............
Jacob, judging by feedback from sharpening, how do you think it's edge will hold up during normal use?
..........

I did a few end grain paring cuts and noticed one or two very fine lines appearing which means flaws in the edge, or insufficient honing. Either way I'd expect these to disappear after a few more sharpenings, except for normal wear and tear.

 

[GazPal]

Not too much of a problem then. It should be ready for anything once you've had a chance to raise a true wire edge.

My son brought home a set of four el cheapo chisels (Less than £5) for rough use and I was pleasantly surprised to find they take and hold a flawless edge, plus feel good in the hand. I sent him back to the shop for another set, as I intend to convert the second lot into fish-tails for him. Otherwise he'll try to nab my old ones for work. :lol:

 

[Fromey]

I dug out an old Marlpes blue handled firmer chisel on the weekend. It was seriously out of square, so I set it to rights and sharpened it to within a micron of its life. I then set to cutting a mortice and immediately cut into a large staple that was hidden in the wood. Doh! Serves me right for using reclaimed wood. But it was good sharpening practice.

 

[GazPal]

I dug out an old Marlpes blue handled firmer chisel on the weekend. It was seriously out of square, so I set it to rights and sharpened it to within a micron of its life. I then set to cutting a mortice and immediately cut into a large staple that was hidden in the wood. Doh! Serves me right for using reclaimed wood. But it was good sharpening practice.

I hate those heart sinking moments when you feel or hear a sharpened edge unwittingly strike a UHO (Unidentified Hidden Object). Especially if miles from a bench grinder, or after forgetting to return the saw file to your tool box before leaving for work and with another seven hours of a shift remaining.

 

[jhwbigley]

Perfectly good chisel, well worth £1 + postage! Thanks jh.

Glad to see you getting on with it, looks a craker. . . Probably should get roubd to sharpening the one I kept for myself now!

JH

 

[Jacob]

Perfectly good chisel, well worth £1 + postage! Thanks jh.

Glad to see you getting on with it, looks a craker. . . Probably should get roubd to sharpening the one I kept for myself now!

JH

It's a nice chisel - good quality, properly shaped and average or better degree of finish.
I thought you might be sending me some sort of horrible corkscrew as a challenge!

 

[bugbear]

It's a nice chisel - good quality, properly shaped and average or better degree of finish.
I thought you might be sending me some sort of horrible corkscrew as a challenge!

If those marks really came out in 60 seconds, I think that chisel's a little soft.

Still, at least the back is flat (to "Stanford" tolerance )

Better a soft flat chisel that a soft bananna.

BugBear

 

[Jacob]

It's a nice chisel - good quality, properly shaped and average or better degree of finish.
I thought you might be sending me some sort of horrible corkscrew as a challenge!

If those marks really came out in 60 seconds, I think that chisel's a little soft.

Not so. Hard enough steel. NB the marks were only taken out in the vicinity of the edge - the face is slightly hollow and the bevel is rounded and just touches at the edge and the heel. And yes the marks came out easily in 60 seconds. Actually quite a lot less but I didn't want to appear to exaggerate.
The thing is - freehand rounded bevel is very fast and energetic. You can do 20 energetic strokes on the bevel in 10 seconds, then spend 20 seconds working the flat face (alternating face and bevel to take off the wire edge), and you are nearly there, with 30 seconds to spare!

Still, at least the back is flat....

Wasn't that flat - visibly concave along the length. But the functional flatness is in the end 10mm or so which becomes co-planar with the other end near the handle.

Better a soft flat chisel that a soft bananna.

BugBear

This was a hardish banana.

PS I realise that a lot of people want to believe that sharpening is difficult and they'll never be convinced otherwise. :roll:

 

[bugbear]

The thing is - freehand rounded bevel is very fast and energetic. You can do 20 energetic strokes on the bevel in 10 seconds, then spend 10 seconds working the flat face (alternating face and bevel to take off the wire edge), and you are nearly there, with 30 seconds to spare!

Nobody uses a jig for flat side (obviously?), so bevels (convex or otherwise) and the whole jig vs freehand spat are irrelevant to this point.

The claim remains that a Norton fine stone (with whose properties I am familiar, it's an abrasive I use for various purposes) removed the grinding marks from the "flat face" in sub 30 seconds.

I'd call that soft steel, at least softer than I'd prefer. Makes for easy flattening though, which I suppose is a benefit. The egyptians cuts dovetail joints with copper chisels, so anything's possible.

I once had a slightly convex I Sorby blade that was so hard I gave up trying to flatten it with the abrasives I had.

I gave it (posted it) to a professional plane maker friend who flattened it in 10 minuites using suitable waterstones. He said it was an excellent piece of steel.

BugBear

 

[Jacob]

The thing is - freehand rounded bevel is very fast and energetic. You can do 20 energetic strokes on the bevel in 10 seconds, then spend 10 seconds working the flat face (alternating face and bevel to take off the wire edge), and you are nearly there, with 30 seconds to spare!

Nobody uses a jig for flat side (obviously?), so bevels (convex or otherwise) and the whole jig vs freehand spat are irrelevant to this point.

You've missed the point again! Not using a jig means you can alternate instantly between bevel and face as often as you like, and as necessary, rather than having to take off the jig and make it into two separate processes.

The claim remains that a Norton fine stone (with whose properties I am familiar, it's an abrasive I use for various purposes) removed the grinding marks from the "flat face" in sub 30 seconds.....

So you are calling me a liar? Fine, that's what I expected from you! I 'd be disappointed otherwise. :lol: :lol:
NB if you read more carefully you will see that marks were removed only from the vicinity of the edge. The face is concave.

PS I'd also point out that it's never so easy to sharpen a chisel as when it's brand new and untouched. It gets a bit (not a lot) harder subsequently.