On shaving hairs and high angles

Re: On shaving hairs and high angles

paul womack

>Is it normal for a high angle blade to shave not as well?

Wouldn't surprise me. Bevel angle is a factor in cutting action, as any carver will tell you.

There's more to blades than an edge.

BugBear

Re: On shaving hairs and high angles

Derek Cohen (in Perth, Australia)

>Denis

In my experience there is a significant difference in cutting with different bevel angles. Take, for example, the extremes of a scraper and a low cutting angle plane. A high angle blade gets increasingly closer as the cutting angle rises.

My favourite demonstration is to use three equally sharp chisels of the same width, but one with a 20 degree bevel, another at 25 degrees and the third at 30 degrees. Use the same piece of end grain, and you will easily feel the difference in terms of resistance.

For woodworkers, however, sharpness is only part of the equation. Durability of the edge is another. Perhaps others will chime in here with their opinion.

Have a read of Leonard Lee's "The Complete Guide to Sharpening".

Regards from Perth

Derek

Re: On shaving hairs and high angles

Todd Stock

>Denis:

I have an acquaintance that offers professional body hair removal services with laser, chemical peel, and for the more traditional (or those bound by religious preference), the well-honed blade. I queried her re: your problem, and she had the following comments:

1. In general, a lower bevel angle is best for fine, straight-body hair.

2. Coarser, curly hair really demands a higher bevel angle

3. Interlocking, really dense mats of hair may produce quite a bit of blade chatter - even with the higher bevel angles

4. Combination skin can make chosing a bevel angle a real gamble

My friend also mentioned that the amount and density of back hair was the usual metric employed by those in the industry to make a final determination as to blade bevel and desired alloy.

Unfortunately, I won't be able to follow up with her on your particular problem, as she's at Seven Presidents Beach in NJ doing on-site research comparing cryo and non-cryo treated blades. With so much back hair in one small area, she'll likely be gone most of the summer.

Hope this helps...

Todd

Now that's funny ;> ) rotflmao..

Victor Parisian

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Re: On shaving hairs and high angles

Gump in Renfrew

>Hi Dennis,

If you want to borrow LL's book, let me know and I can bring it for you on Wednesday.

Where are ya gonna start shavin' when the arms are done? Forget it, I don't want to know.

Gump

Why, the back, of course!

Denis Ch�nard, Orl�ans, Ont.

>You dirty mind... ;-}

DC

Yes, I'd like to see LL's book, thanks for the offer...

Re: On shaving hairs and high angles

Alan Hamilton

>Denis,

Into the breach once more!

Along with about everyone else, I will apply edges to arm hairs. But I've found that shaving my arm is NOT a very good test for sharpness. A pretty dull blade will still shave hair. I liken it to a razor: a razor that's too dull to take anywhere near my throat will still shave hair!

The best test I've found is the "Newton" test--the old business of looking at the edge with a light behind me to check that my edge appears as a very narrow black line. If it shows any white at all it isn't sharp.

With my rapidly fading eyesight it's getting harder and harder for me to test edges this way. But I've found if I use my most powerful glasses, and a 10x field lens, I can still manage it--but only just.

Alan

Higher angles don't shave as well

Steve Elliott

>I have a fair amount of recent experience testing blade sharpness using different methods, and I've done some tests of different bevel angles in the last few weeks.

The hair-shaving test is a pretty good one for distinguishing between sharp and somewhat-sharp blades because there is a gradient that goes roughly like this:

1. The hair pops off as the blade first touches it.

2. The blade cuts cleanly without pulling.

3. The blade scrapes the hair off.

4. The test is too painful to continue.

More acute angles test much sharper on this scale than equally refined edges at greater bevel angles. So your sharpening technique is probably fine--I'd just try the blade out actually planing some wood, that's the real test.

Looks like you're right

Denis Ch�nard, Ottawa, Ont.

>I popped the blade in, and tried it on bird's eye, curly maple. That should be a good test...

Came out, no tearout, smooth as a baby's bum, shavings under a thou...

Man, that LV LA jack is impressive...

DC

Hear, hear!

Don Thompson - Cutler Ridge, Florida

>I have long suppressed the urge to comment that the ability to shave arm hair is a limited means of testing sharpness. Yeah, it shows that the blade is sharper than a butter knife...

And you see this demonstrated in videos, etc., all the time. Phooey!

Re: Hear, hear!

Sgian Dubh

>You may doubt the sharpness demonstrated by the arm hair shaving test Don, but I've been using that test off and on for thirty years now.

I spend my working life working wood and teaching others how to work wood, and if I can't stone up a blade and have the plane reassembled and working in less than 2-1/2 to three minutes I'm not working efficiently enough.

True, I can use ever finer grits to get that perfect edge and the back of the blade shiny enough to see my face in, and probably add about four or five minutes to my sharpening time. The end result might be an infinitesimal amount sharper than my workaday sharpening technique, but time spent getting that sort of perfection is time wasted.

Not only that, but a couple or three strokes along the wood with a plane sharpened to that level and the thing's no sharper than the edge I get in the first place with just an 800 grit stone.

Sometimes-- almost always in my case, it's a matter of sharpening to the point of good enough rather than sharpening for the sake of sharpening. It depends I suppose on what motivates someone to use and sharpen woodworking tools. Slainte.

Re: Hear, hear!

Don Thompson - Cutler Ridge, Florida

>I understand what you are saying; I should have elaborated on the point.

What I object to is the representation that an edge that will cut arm hair is perfectly or ultimately sharp and refined. I do not believe this to be the case. A ragged, moderately sharp edge that will disintegrate rapidly can cut arm hair. A wonderfully-prepared edge will also cut arm hair. The arm hair test does not well differentiate between the two.

Cheers.

Re: Hear, hear!

Greg Sloop, Portland Oregon

>Kind of like saying... "My car can spin the tires on dry pavement. It's a hot car." While it might be, I can probably get a Geo Metro or a run-down Yugo to spin the tires on dry pavement. DAMHIKT

So likewise, IMHO, it is simply a poor measure of how well the edge has been sharpened.

Unfortunately, there seem to be no really good and easy tests to determine this.

Cheers,

Greg

Re: Hear, hear!

Sgian Dubh

>Don, you might like this tale from way back in the dark ages when I was just a daft laddie, ha, ha. Slainte.

A Lesson in Sharpening.

A perennial subject in woodworking magazines is that of sharpening techniques. No other furniture making topic seems to generate so many words, resulting in the publication of innumerable articles detailing �infallible� or �sure fire� methods of doing the job.

Naturally, the subject is of interest because blunt tools aren't much use. The opening preamble to many of these articles often cause a wry smile for they bring back memories of my initiation into the 'dark' art. Many authors make points about those that struggle at it, and possess a workshop full of dull tools. Conversely, it is often said that those that can do the job tend to be fanatical about grits, slurries and bevel angles. My experience is that there are really only two types of people when it comes to sharpening.

1. Those that can�t.

2. Those that can.

In the first group, those that can't, you'll sometimes see every sharpening system known to man arrayed around their workshop gathering dust. They have oilstones, water stones, ceramic stones, diamond stones, guides, pieces of sandpaper, jigs, etc.. Usually, every hand tool they own is chipped, dull and mostly useless.

In the second group, those that can, I haven�t observed much fanaticism about slurries, grits and bevel angles. In all the workshops I�ve worked in the only concern is to get the job done. It�s a case of, "Plane�s blunt, better sharpen it." Dig out the stone, sharpen the blade, shove it back in the plane, and get on with it. The equipment is minimal. A grinder, a stone and lubricant along with a few slips for gouges and the like.

Going back to the early seventies when I trained, learning how to sharpen tools was undertaken within the first few days. I don�t now recall precisely the order of my instruction, but it went something like this. I was handed a plane by the cabinetmaker I was assigned to and told, "Get that piece o� wood square." I didn�t know why, but I�d done a bit of woodworking at school, so I had a vague idea what to do. I fooled around with that lump of wood for twenty or so minutes, and got it something like. All this under the watchful eye of the crusty old guy and his ever present roll-up hanging out of the corner of his mouth.

"Okay, I�ve done that." I said, "Now what do you want me to do?"

I was told to hang about for a minute whilst he picked up his square and straight edge and proceeded to scrutinise my handiwork, which was followed by a non-committal grunt and some desultory foot sweeping of the plentiful shavings on the floor. (The wood was probably only about eighty or so per cent of its original volume.)

"Now sonny, let�s do the next job," he announced. "Pull that jack plane you�ve bin usin� apairt and let�s have a look at the iron." I did.

"Hold the iron up so�s yuh can see the cuttin' edge," he instructed. (He was a Scot.) Again I did as I was told.

"Now, can yu� see it? Can yu� see the �line o� light� at the shairp end there?" he wheezed, as he tapped a line of ash onto the floor and stood on it. He was referring to the shiny reflection visible when cutting edges are dull.

"Aye," I said, after a little eye narrowing, and other pretence of intelligence.

"How shairp does it look to you boy?" he enquired.

I thought about this for a moment or two, seeking the right response to my tormentor, for I hadn't really got a clue what he was talking about, and finally replied rather hopefully and a bit brightly, "Pretty shairp, I�d say."

He laughed out loud, and hacked a bit. "Dinnae be the daft bloody laddie wi� me son. If yu� can see it, it�s blunt. I could ride that bloody iron y'er holdin� bare-ersed to London and back and no cut ma�sel�. Get o�er here an� I�ll show yu� something."

You can probably guess. Out came the oilstone from his toolbox, and quick as a flash the iron was whisking up and down the stone, flipped over, the wire edge removed, and finally it was stropped backwards and forwards on the palm of his hand. You could shave with it. I know, because he demonstrated how sharp it was by slicing a few hairs off his forearm. On went the cap iron and the lot was dropped back in the plane followed by a bit of squinting along the sole from the front whilst the lever and knob were fiddled with and that was it. He took a few shavings off a piece of wood and it went back in his toolbox. It took, oh,�......a few minutes.

"Now son, that�s a shairp plane. It�s nae bloody use to me blunt. Yu� may as well sling a soddin� blunt yin in the bucket fur'all the use it is to me." He explained with great refinement. "I�ve aboot ten mair o� them in that box, an� they�re all blunt. Ah�ve bin savin �em for yu�. There�s a bunch a chisels too. Let�s get yu� started."

For what felt like forever I sharpened his tools for the one and only time he allowed me to under his rheumy eyed and critical stare, and things gradually got better. After a while he stopped telling me what a "completely daft stupit wee bastit, " I was, and a bit later he started offering grudging approval. I had to sharpen some tools more than once because he kept on using and dulling them. When I�d done the lot we stopped and surveyed the days work.

"Aye, nae too bad fer a daft laddie's fust effort," he commented darkly, sucking hard on his smoke, "I think ye�ve goat whit it takes. Time�ll tell sonnie. Remember, ye�ll never be a bliddy cabinetmaker if yu� cannae even shairpen yer fuckin� tools. Lesson over. Dinnae ferget it."

I haven't.

Well done!! Great writing!

Luke Herzberg

>

Great story!

Don Thompson - Cutler Ridge, Florida

>One question: what is a soddin� blunt yin?

Re: Great story!

Sgian Dubh

>soddin' = a sort of Brit substitute for f**kin'.

Blunt. easy enough I'd guess.

yin = one.

Slainte.