Not the average sharpening question

[DannyEssex]

Hi all

Not a how to sharpen question but a how sharp one. How do you know when a chisel is sharp enough? For instance, if you was to run your finger over a newly sharpened tool, would it cut you? Is there a easy way to know its sharp enough or is just down to experience? Iv got the gist of how to sharpen and the old chisels Iv got are coming on OK, I think. I get them sharp to the touch and then think maybe it needs to be more, so I give it a little more and I seem to loose the really fine edge, so start again.

I hope this doesn't start a sharpening debate, I'm sure its down to experience, just hoping there's a simple answer.

Cheers
Dan

 

[MickCheese]

Does it do what you need it to do?

If so it's sharp enough.

Thought I would get that in before someone else.

Mick

 

[DannyEssex]

Does it do what you need it to do?

If so it's sharp enough.

Thought I would get that in before someone else.

Mick

I'm not sure :lol: :lol:

I don't know if its down to my beginners technique or un-sharp tools,

 

[Alexam]

Will it cut a sheet of paper sideways on with little pressure. If so, it's good to go.

Alex

 

[carlb40]

I normally try shaving hairs on my arm, if i get a continuous line of smooth arm ( blood optional :lol: ) then it's sharp enough for me

 

[DannyEssex]

Cheers guys, I'll try the sheet of paper way first :lol: :lol:

 

[Cheshirechappie]

Actually, what MickCheese said is spot on.

How sharp a chisel needs to be depends on what you're about to do with it. For very rough outdoor carpentry where nobody is going to bother about the finish, and you'll be doing the work with a big mallet, an edge from a grinder will probably do. For rather better finish, an edge from a medium oilstone would be better. For heavy chopping in reasonable quality furniture work (like mortices) the finish from a fine oilstone would do, but for end-grain paring and fitting where joints are a visual feature of the job, a polishing stone and then strop - that's when you need the armhair-shaving edges.

The type of wood affects the edge you need, too. Ironically, the softer pines (the sort with alternating bands of hard and very soft wood) need sharper edges to work cleanly, otherwise the wood tends to compress and break out. With more uniform timbers, you can get away with slightly less sharp edges some of the time - though not always!

So - there isn't really a set answer to the question. Mick's advice is sound - if it does what you want it to and gives a good finish, it's sharp enough. Just pile in and make some shavings - that's by far and away the best way to find out!

 

[MickCheese]

You need to get a 'feel' for sharp.

Try sharpening several chisels to different standards and try them one after the other cutting across the end grain.

You may then get a 'feel' for how sharp they are and what to expect.

Mick

 

[blackrodd]

When you are grinding a chisel or plane iron, when it is sharp you will notice the sparks, that have been disappearing behind the cutter etc will appear over the front of the cutter/chisel/ whatever, which is actually upside down, and towards you're thumbs. HTH Regards Rodders

 

[Cheshirechappie]

Come to think of it, there are a couple of other ways to tell how sharp a chisel (or any other edge tool, come to that) is or not.

One is to look at the edge in a good light. If it gleams at you - a thin line of light - it's not sharp. The gleam of light is the reflection from the dulled, curved surface between the bevel and the flat side. If there's no gleam of light, it's probably sharp - the flat side and bevel side are meeting at a point, so there's nothing to reflect light.

Another way is to put the edge against the ball of your thumb or a finger-end (lightly, of course!). If the edge slides over the skin, it's blunt. If it catches on the skin, it's sharp. That works on a fingernail, too - sliding over the nail means blunt, catching it means sharp.

Then there's the old 'shave hair off forearm' trick. Don't try this with an 1/8" chisel. Blood does not improve the quality of an edge.

 

[Preston]

Try and achieve this burr by honing and take the burr off on a hone-strop. If you can do that you will have mastered the art of sharpening.

 

[DannyEssex]

Thanks for all the tips, much appreciated

 

[Silas Gull]

I agree with Mick. If it'll pare end-grain then that's pretty good. For my part, I like to think I can feel when a chisel is sharp enough by lightly drawing my thumb across (not along!) The edge. If it feels ticklish and slightly 'electric', then it's good to go.

 

[RossJarvis]

I agree with Mick. If it'll pare end-grain then that's pretty good.

+1 for that

 

[bugbear]

Does it do what you need it to do?

If so it's sharp enough.

Thought I would get that in before someone else.

Mick

I'm not sure :lol: :lol:

I don't know if its down to my beginners technique or un-sharp tools,

This is where a skilled friend or a show is useful - so you can set your expectations of what a tool should/can do.

Youtube (or commercial instruction videos) can be helpful though.

BugBear

 

[Jacob]

I agree with Mick. If it'll pare end-grain then that's pretty good.

+1 for that

+1
A bit of primitive carving - you could stick bit of 2x4 in a vice and shape the end to a bullnose*, using chisels only. You would soon get a good idea of how they are working compared to each other and to the sharpening regime.

*or any shape you fancy - a little totem pole frinstance?

 

[Grahamshed]

I brought some chisels and a couple of planes from Workshop Heaven and never having sharpened anything ( successfully ) before asked Mark to put a good edge on one of them for me so I would know what I was looking for. It gave me something to aim at and while I cannot do it as fast as he did the principle worked

 

[Benchwayze]

Run your finger over the edge?
Depends on how much pressure you apply. Too much and it's an A&E job.

Some people shave a few hairs off their forearm with the edge. Some people cut a sheet of paper into strips.

If you care to believe me, when a chisel cut gives me warm glow in my chest, and I feel an uplifting of spirit, [-o< it's sharp enough. \/

Generally though, I pare the corner off a piece of the softest wood I can find. If it cuts cleanly, and leaves a single curl of waste; well.... it's sharp enough. :wink:

:ho2

 

[dunbarhamlin]

If you don't know where all that red paint came from, then it's sharp.

 

[bugbear]

If you don't know where all that red paint came from, then it's sharp.

That is indeed an excellent indicator of true sharpness, but never one I've done deliberately!

BugBear