Making a Strop got a few questions

I had some comments for an alternative strop until I saw Vassili's movie. Wow. . . . Wow. I pulled out my pocket knife which I sharpened 2 days ago and tried it (hair is abundant from the top of my head :(). Can't do it. I'll try with my chisels and marking knives, tonight (considerably sharper), but WOW.

Anyway, I'm a little embarassed to mention my alternative . . . but will anyway. A High Pressure Sodium Bulb. I carry one around in my pocket when I'm in the shop and have one in my kitchen drawer. If it's the smooth kind, it will take the burr off of most steels and leave a razor sharp ( hair shaving, not hair whittling . . . WOW) edge. These are the lights you see on highways and street corners. Once the lamp goes out, the 4-6" in bulb inside can be used for this purpose. Some are slick, some are rough. The slick ones are the ones I'm speaking of.

Electricians and maintenance folks at large commercial/industrial establishments and city street departments would probably pick a few up for you. These things touch up blades similar to a 4000 mesh waterstone and strop.

Hair whittling. I now have a good reason to clean my shower drain . . . abundance of hairs for whittling :)

cinteal
 
I like that knife, buck strider of some sort? I have the folder version and like it immensly, didn't know they made big fixed blades.
Is it just me or are buck knives great at taking an edge?
 
I got wowed by Vassili's hair whittling and I forgot to mention the thing I wanted to in my post . . . edge durability.

Vassili mentioned rolled edge/bevel vs. flat/straight edge/bevel. Flat edges are sharper but rolled edges are more durable. Durability is a very important aspect for edged tools in woodworking and is a function of stropping. For an extreme example, turning gouges do not have a straight bevel, the whole bevel is rolled. A straight bevel on a gouge would bend while turning, even with super hard, powder metallurgy, HSS.

Now we move down to the microscopic edge of a knife or fine chisel/plane. We use our best stones to put a perfectly flat bevel on the tools, abrading the metal to the finest point possible. By some means, we remove the burr and are left with the microscopic edge. It sounds (and looks) like Vassili can do this without a rounding of the bevel on a microscopic level. Supersharp! However, though I may not be able to whittle hair like Vassili, I bet my edges stay sharp longer than Vassili's because I PURPOSELY roll the bevel on a microscopic level while stropping. After removing the burr, producing a more durable edge is the secondary purpose of stropping. Hair is tough, relatively speaking. Though a perfectly straight bevel on a Barber's razor would be sharper, to keep that edge, he would have to sharpen constantly, not just strop. But the microscopically rolled bevel established by the initial strop and maintained by routine - not constant - stropping (until it's complete rolled over and dull) maintains a "good enough, very good enough) edge. That's why Barbers used the free hanging leather strop. If you've ever seen an old man roll the edge of a recently sharpened blade over the palm of his hand, I bet in his youth he was a barber. What he is doing is adding an ever so small "roll" to his perfectly flat bevel. Vassili's edge would bend like the straight bevel turning gouge.

Now . . . I'm going home to make a stretched leather strop from the thinnest leather I can find, keep my bevel perfectly flat on the strop, finish up with the lightest strokes possible, whittle some hair, and post a reply tomorrow disagreeing with this cinteal guy.

cinteal
 
Well, leather will make edge convex, like you or not. It is soft - even hardest and thinest leather. Rolling out edge in my terms is actually rounding edge - edge with no sharp angle. So the point is to keep that angle on the very edge while convexing it by leather. In my case this was too much pressure on too thick leather - I have polished by 0.15microns diamond and get round edge in result, because on very edge leather bend under blade as an pillow dulling it!

Of course if this round edge is thin enough it will do cutting, but it will be less sharper then after stones - better polished but round edge. I saw this with my sharpness test many times - sharpness goes down after leather, while edge looks like a mirror. It drove me crazy, until I found solution.

To see all results I have - initial sharpness and edge holding for different steels, you may check this thread - I keep all my test data there:

http://www.bladeforums.com/forums/showthread.php?t=509097

Thanks, Vassili.
 
Ted,

Vassili explained what I was talking about. When you take a blade off the finishing stone (side sharpening at 8000 - 16000 removes any burr without stropping) it is as close to a perfectly flat/straight bevel as possible. This edge is super sharp but not that durable - it bends/deforms with the slightest cutting force. Stropping makes the last few micrometers of the bevel slightly convex AKA rounded, rolled - increases the angle of the very tip of the bevel without putting on a true Microbevel.

Let's say our edge, in gigantor terms, looks like the Roof of a House. It starts at the botom and comes to single point at the crest. On a knive/chisel this is the sharpest attainable edge, but the least durable. To beef up the edge, some put on a microbevel. In house terms, start at the bottom, but just before you get to the crest, reduce your pitch and make a crest with not so steep an angle. This is the second sharpest edge but more durable than the single bevel. Then there's the stropped bevel. It would look more like a archway to a catherdral - still comes to a singular point, but instead of having a flat bevel, it has two convex bevels. This edge on a knife is not as sharp as the first example but probably pretty close to the second example - but even more durable. Structurally, a Triangle is a very strong design, but an Arch is stronger (from multidirectional force, anyway).

That's what I mean by "rolled edge". Please forgive my limited vocabulary. I think Vassili is making a convex bevel, as well. He's just able to produce that convex shape much closer to the edge than I can, thus his blade is sharper and can whittle hair.

When I look at reflections in my chisels sharpened on synthetic waterstones, over the majority of the bevel I see perfect reflection, like looking into a perfectly flat mirror at an agle. However, just before you get to the edge, if you twist the chisel just right, you can see a thin, brilliant line of reflection across the width of the blade. That's from the stropping. The ever so slight convex bevel at the very edge. Not to be confused with an edge that reflects light. Of course, if you can see light reflecting of the cutting edge, that edge is not sharp. You can read a book though the long shavings these chisels produce. They're sharp, but they retain their edge longer than when I was simply removing the burr with the stone and not stropping. One of my favorite things to do is shape a long chest leg with my timber slicks right after I've sharpened them. They actually sing while producing the finest shavings . . . and I can complete the shaping of two legs before sharpening where prior to stropping I might not be able to finish one.

Another treatise, sorry.

cinteal
 
nozh2002 said:
No it does matter because most what good strop system need to is preenting edge rolling out. So for this reason soft or thick or glued leather will not work - it will work to some extent. But to make edge hair whittling you need to be very careful. If it is not glued then it can absorb some move which otherwise will leed to edge being rolled out.

I can prove that my strop work, and before with "HandAmerican stroppng leather" glued to flat wood I was not able to make edge better then 70 gramms on thread test. Actually measurements shows that in many case I loose sharpness after this stropping (while it continue shaving arm).

Prove: http://www.youtube.com/watch?v=sI_iqAyb3xA

I can speak only about my experience. If someone else can whittle hair like I do and made it different way - I'll be happy to see this. Please post you whittled hair picture.

Thanks, Vassili.
Click to expand...



I use a knivesplus strop block, and the leather is glued. the trick for me is pretty simple, I hold the strop in my hand as, so I can keep the pressure very light and let the surface move as I pull the blade along it. I wouldn't expect to get the same from laying it down and making it completely rigid.

please excuse the pic, cheap camera and lousy photographer behind it :)
 
hardheart said:
..........

I use a knivesplus strop block, and the leather is glued. the trick for me is pretty simple, I hold the strop in my hand as, so I can keep the pressure very light and let the surface move as I pull the blade along it. I wouldn't expect to get the same from laying it down and making it completely rigid.

please excuse the pic, cheap camera and lousy photographer behind it :)
Click to expand...

That is precisely what I do. I hold the strop in my left hand and can vary the angle of attack with both hands. I also push and pull the knife while simultaneously pushing or pulling on the strop.
 
hardheart said:


I use a knivesplus strop block, and the leather is glued. the trick for me is pretty simple, I hold the strop in my hand as, so I can keep the pressure very light and let the surface move as I pull the blade along it. I wouldn't expect to get the same from laying it down and making it completely rigid.

please excuse the pic, cheap camera and lousy photographer behind it :)
Click to expand...

Good idea. I did not think about it. It lowers the pressure and also absorbs overpressure if you accidentally apply too much.

Thanks, Vassili.
 
Thanks for all the info guys!

I scored a some leather scraps from Tandy's, some are thin others thick (1/8"). I cut a thick piece for using on a hard surface and made a large strap out of some thin leather. Both seem to work quite well, I got my axe sharp enough to shave arm hair.

I cant get a straight razor sharp enough though, any tips?
 
sketchbag,

If you're using the razor to shave - leave the burr on and shave on that side. Micro-burr, like the one left from 4000 - 8000 grit, not the one left by 220. Stropping can keep it a little longer but too much stropping will remove the burr. That's simply how I got my razor to shave my face. Worked well. Not well enough to throw away my Gillette. Any barbers out there I'm sure can give you better tips on the subject, just telling what I've experienced.

Aside from that, I don't know.

cinteal
 
You must log in or register to reply here.
Back
Top