Thread: The Burr

I too wondered if what Martin is doing is creating a fine toothed-iron (which is the implication of Truckjohn's post). Going from 80 grit to 2u grit in a single jump would take an unbearably long time to get rid of the grooves from the wheel, so it seems plausible that the result is a finely toothed blade, much finer than a deliberately toothed one, of course, but 'toothed' nevertheless. However, in many situations and with many of our hard woods, a toothed blade may well be preferable to even the most highly honed iron. As Tj says, whatever works for you, works.

Toothed blades have not had a big resurgence, despite a few attempts to revive the idea (and sell a few more blades) over the last 40 years. I have often thought of having a serious play with the concept, just haven't got the round tuit, yet. The explanations I've read of how the toothed blade 'works' have never been completely satisfying to me so it's something I'd like to investigate for myself.

Now I can make acceptable blades at very little cost, I don't have many excuses for putting it off, though one thing I will need is some decent magnification gear so I can see what's actually happening at those edges and on the wood surface....

Cheers,

Originally Posted by IanW

I too wondered if what Martin is doing is creating a fine toothed-iron (which is the implication of Truckjohn's post). Going from 80 grit to 2u grit in a single jump would take an unbearably long time to get rid of the grooves from the wheel, so it seems plausible that the result is a finely toothed blade, much finer than a deliberately toothed one, of course, but 'toothed' nevertheless. However, in many situations and with many of our hard woods, a toothed blade may well be preferable to even the most highly honed iron. As Tj says, whatever works for you, works.

Toothed blades have not had a big resurgence, despite a few attempts to revive the idea (and sell a few more blades) over the last 40 years. I have often thought of having a serious play with the concept, just haven't got the round tuit, yet. The explanations I've read of how the toothed blade 'works' have never been completely satisfying to me so it's something I'd like to investigate for myself.

Now I can make acceptable blades at very little cost, I don't have many excuses for putting it off, though one thing I will need is some decent magnification gear so I can see what's actually happening at those edges and on the wood surface....

Cheers,

They were offered here by LN as a solution. LN either didn't know the cap iron works or wanted to advise against it, instead offering frogs and toothed blades. toothed blades work, but a jack plane with the cap iron set is more practical. If the wood is too hard for a full width shaving, just less width.

One of the professional woodworkers here in the states talks about using a jack with the cap set often, but it does create some extra effort on a jack where the shaving is stiff - but he may have less rank set geometry than I do. I usually feel like if I have to resort to it, it's going to be a rough day working from rough.

I haven't ever seen a vintage toothed plane iron that was intended for roughing work, though - just scuffing irons on veneer planes held near vertical.

Hi All

Not convinced I know what I am doing either ...

In terms of time I don't spend long on the MDF disk is powered on a drill. The grind is at 25 degrees, the polish is at a higher angle aiming for a curved bevel starting in the low 30 degrees. The polished section is only 0.2 to 0.3 wide. In terms of process, spend 10 seconds or less on the grind - (the opposite side if the disk) and then polish for the 30 seconds at a higher angle, slightly increasing the the angle towards the end of my 30 second count. Have bright light on the disk so I can see the bevel / disk angle easily. At the end I inspect the slim edge to see if that narrow strip has reached the base of the scratches. That strip while narrow is very reflective, flaws are easy spot. If I see one I polish again.
At the end the blade backside is also given quick polish.

Note is parallel to bevel- (largely) - the polish normal to the bevel - generally- (generally as it is a disk)

Timber surface is smooth - Don't think the actual edge is serrated.

Judge the new edges of slightly sharper. This is an empirical judgment, the new edges produce a "slightly" more flawless finish on hardwoods. Tts that slight shift in finish that I notice. For now my theory is I was doing something less than perfect prior, as mentioned,.


Wild Speculation
Ok - now for a clutching at straws hypothesis , building on the TJ's serrated/ toothed idea and Ians expansion...



Maybe, just maybe, effectively - accidentally I will add- lazy, in fact- I created a toothed bevel. And perhaps the timber "sees" the scratches behind the lead edge and consider the to be lower angle, hence sharper blade - see low angle razors. Then maybe this "toothed bevel" offers enough strength so does deflect/ deform on contact with the timber. Now then, and yet another maybe, the net average of these high/lower bevel angles is what I am feeling as a sharper edge.

Ok thats about as speculative as I can get. This is pseudo science at best. But,with a developed and considered approach to making toothed/ scalloped bevel,
it might be possible to make a sharper blade with adequate durability.
Just tried pushing a "toothed" bevel blade and polished bevel and the toothed one did seem easier...... very empirical, not controlled, utterly inadequate test.


Lets see what you gentlemen make of this conjecture.

Cheers M

Originally Posted by MartinCH

Hi All

Not convinced I know what I am doing either ...

In terms of time I don't spend long on the MDF disk is powered on a drill. The grind is at 25 degrees, the polish is at a higher angle aiming for a curved bevel starting in the low 30 degrees. The polished section is only 0.2 to 0.3 wide. In terms of process, spend 10 seconds or less on the grind - (the opposite side if the disk) and then polish for the 30 seconds at a higher angle, slightly increasing the the angle towards the end of my 30 second count. Have bright light on the disk so I can see the bevel / disk angle easily. At the end I inspect the slim edge to see if that narrow strip has reached the base of the scratches. That strip while narrow is very reflective, flaws are easy spot. If I see one I polish again.
At the end the blade backside is also given quick polish.

Note is parallel to bevel- (largely) - the polish normal to the bevel - generally- (generally as it is a disk)

Timber surface is smooth - Don't think the actual edge is serrated.

Judge the new edges of slightly sharper. This is an empirical judgment, the new edges produce a "slightly" more flawless finish on hardwoods. Tts that slight shift in finish that I notice. For now my theory is I was doing something less than perfect prior, as mentioned,.


Wild Speculation
Ok - now for a clutching at straws hypothesis , building on the TJ's serrated/ toothed idea and Ians expansion...



Maybe, just maybe, effectively - accidentally I will add- lazy, in fact- I created a toothed bevel. And perhaps the timber "sees" the scratches behind the lead edge and consider the to be lower angle, hence sharper blade - see low angle razors. Then maybe this "toothed bevel" offers enough strength so does deflect/ deform on contact with the timber. Now then, and yet another maybe, the net average of these high/lower bevel angles is what I am feeling as a sharper edge.

Ok thats about as speculative as I can get. This is pseudo science at best. But,with a developed and considered approach to making toothed/ scalloped bevel,
it might be possible to make a sharper blade with adequate durability.
Just tried pushing a "toothed" bevel blade and polished bevel and the toothed one did seem easier...... very empirical, not controlled, utterly inadequate test.


Lets see what you gentlemen make of this conjecture.

Cheers M

if you can make 1 or two thousandth shavings that don't break, you don't have any serrations. Serrated edges from coarse shaprening actually fare better at same angles in a knife slicing test, but in pushing (like planes), the edge life is reduced significantly.

Your process sounds good to me. You can also run your fingernail across wood sideways - anything that would be visible in any light will click as your fingernail goes across it.

I have no idea why knives last longer, but in push cuts, toothing results in less lateral support - whether it's just damage that occurs from that and erosion from the damage that shortens edge life, I don't know. but there's a drastic difference in edge life even if the "teeth" are just five micron diamond grooves and all of the burr is cleanly stropped off.

From the sound of Martin's description, he's just using a diamond charged MDF wheel to install a micro-bevel.

That takes me back to the "Diamond cuts old, low alloy, high carbon tool steel like it's grating cheese" hypothesis. Remember that those old irons sharpened reliably on silica abrasives - that's Mohrs 7. Most everything these days really wants at least aluminum oxide if you want to finish in any reasonable amount of time.

My guess is that you could do pretty much the same diamond wheel thing with most any modern, commercially produced iron.

what size diamonds are we talking about here? diamonds won't do too much to cut deeply in steel if they are on an MDF backer. per size, they'll be less aggressive than alumina in a stone.

here is 1-3 micron bonding grade diamond grit (this is grit that is not tightly graded like lapidary, which also makes it really cheap). It's intended to be bonded to diamond tooling.
https://i.imgur.com/PqCGuQi.jpg

compare it to the shapton cream, which is pretty loosely graded in terms of abrasive. I'm convinced they graded it loosely to quote the average particle size (1.12 microns) while getting the speed of something more like 3 microns.

the actual scratches look similar to something like an 8k waterstone like king or kitayama.

1 micron diamonds in my planed length test (on cast iron at that, about as aggressive as you can make them) will outlast a shapton cream edge planing by a pretty sizable amount. Cream/8k waterstones have about the same edge duration as a black arkansas.

The difference in diamond behavior based on substrate is massive, but if diamonds are too brash, the answer is always just use finer diamonds. Even on the softest steels, and the most plain, diamond lapidary can outdo anything made in stone form.

to your last point - I noticed no difference in sharpness (and visually no difference to the limits of visible light) with M4 or O1 with 1 micron diamonds - it definitely just kind of does the same thing on each steel type up to at least 10v (10v isn't a very good steel for plane irons - it does something strange as it wears that I can't tell what it is visually, but it picks up a shaving less well than some other highly alloyed steels. 52100 does the same thing compared to O1, too, no matter what hardness I make them, and I can't see why, but the difference is pretty stark.

10V will not sharpen to a visual polish under the microscope if diamond isn't used, but with diamond, it'll look like anything else. And then still wear weird. I could draw conclusions about why it behaves that way when it looks better under micrograph photo than V11 (XHP) and V11 doesn't do it, but it would just be contradicted. 52100 has chromium carbides like V11 and yet it still behaves in terms of snappiness starting a cut more like 10V. It's the kind of stuff a catra tester will never notice slicing cards, but it's stark 1/3rd of the way through the edge life in a plane iron - A/B testing, it will actually lead to surface differences in terms of fineness on something difficult to plane.

O1 is very good at picking up a shaving as it's dulling, V11 is (though edge stability for V11 isn't as good as O1), 26c3 (like file steel) also very crisp. W1, not quite as good - no clue on that one either, but both W1 and W2 are good to use, but they lack that crispness as they're dulling.

TJ - here's a fun picture...I misread your comment earlier at first, which is why the response first probably sounds like a rebuttal and then agreement. figured I should mention that - work is busy lately and my brain is fried.

but the hard cutting nature of diamonds on a new 400 grit monocrystalline plate. Similar to dmt, and like dmt, this is before those initial high sitting diamonds leave the building - but they will after this and the cut will be about 1/4th as harsh.

https://i.imgur.com/qi56cb1.jpg

if you look, you can see the odd tall diamond's really large row peeled out - and this is carbon steel that's >60 hardness. I just don't remember which one.

When people pine for the initial fast cutting version of a diamond hone, I think they'd change their tune for daily sharpening. I'd need to go from this to a medium stone that has some aggression at the very least. when they settle in, they may not be faster at fast work, but they save time in subsequent steps.

it almost looks like someone dragged a stick through clay.

I had a 60 hardness 10V iron and I rehardened it to 64 after breaking the iron to look at the microstructure and then grinding it back. 60 isn't hard enough for 10V - it's crunchy peanut butter at that, and I asked the maker here in the states why they chose that ...DFM toolworks or something, and they said they wanted to see if there was a market before the committed to a big batch, and they didn't want to do it with irons that would chip - fair point.

At 64, it still had that same weird wearing property I mentioned, but had I thought about it, i would've run this same test on the 64 hardness 10V - the vanadium carbides would not stop the diamond from cutting a clean groove, but the groove would almost certainly be a lot shallower.

I took this picture because Bill Tindall mentioned displaced steel sounding like a myth, and I figured we'd see. the red arrow shows steel that looks (could be an artifact of something else) like it was literally plowed up like clay and laid over.

...wait...we're in luck. I do actually have picture not of high carbide steel, but another well worn diamond hone of the same type on the 400 grit side.

https://i.imgur.com/wxMr2Fl.jpg

And another with different light:

https://i.imgur.com/yNk4iVT.jpg


I believe the ripple at the end is related to burr formation, but not sure.

All are carbon steel to my recollection, but not soft carbon steel. hardness of carbon steel even will make a big difference on groove depth - just as a matter of physical work.

Hi all

Hypothetical Bevel....

Avoiding the actual edge for a second - consider the bevel angle just behind the edge- say starts at 32 degrees then adjacent it is 25 degrees then rises back uo the 32 and so on. Deep toothing glo oves on bevel , with the valley's at lower pitch and the ridges at a higher pitch all meeting at an apex. The edge itself is smooth and collinear as feasible.

The wood might effectively consider such a "toothed bevel" to have lower angle. Also becasuse the bevel is now effectively "sloped' to the wood such a bevel would apply some force transversely to the grain which is weaker. The resulting theoretical bevel may feel sharper...



TJ, the MDF disk has oil spread on it surface and the 2 micron diamond dust rubbed in. Just a smear. Seems to cut well for say 20 or 30 sharpening - not a huge number. When it stops cutting, spread oil on again and its reinfected with diamond dust.


Cheers M

So... Comparing the power wheel to a stone...

Assume a 200mm diameter and 1,750 rpm. 1 minute = 1.1km travelled. A 10-sec pass is 183m linear distance of contact.

so, on a 200mm long stone, assuming your passes only get like 180mm worth because of the ends... so to get the same 183m of contact, round numbers, 1,000 passes on the stone. So even a 2 micron abrasive eventually gets there because it doesn't break down in practice.

And that math is why I love power sharpeners.

Hi TJ

I wouldn't spin that fast, a tad more controlled.


A few shaving photos - sheoak and Blackwood, the finish - and the ugly sharpening of the blade

IMG_6495.jpgIMG_6496.jpgIMG_6491.jpgIMG_6492.jpgIMG_6493.jpgIMG_6494.jpgIMG_6490.jpg


Cheers M

Why woods like that don't yield nice lacey thin shavings isn't really going to register with most of the folks working medium hardwoods. There are some here in the americas like that, but mostly in mexico and central america. they are just too brittle or something to form a nice thin shaving, and even when the shaving is thin, the density prevents it from looking like it's see through.

David,

The " nice lacey thin shavings" doesn't really register with me. I work the local woods generally. The brittle, hard, tearout out prone joy's that they are. Even common statements like plane with the grain don't not always translate - foe some woods it more like- if you plane that direction it is slightly better than planing the opposite.
And not using a sledgehammer to pound in a chisel. Amazing - slight exaggeration but I have used one a few time's to cut mortises.

These are "thin" shavings, you can see that are tapering to the edges. I don't typically obtain intact shaving that stand upright and relatively intact. Thats new to me. Usually they curl up and are stringy and break easily. It is a surprise that they looking at all like the intact shaving that imported timbers/softwoods offer.



Regards M

I don't know how many stars and stripes folks are here. I'm one, though not particularly the flag waving type - but you get what I mean. if you run into us or maybe some english folks used to planing cherry and beech and stuff, some will think your shavings represent dull work.

I know better. Sometimes those more dense than water and crossgrain but not visually so obvious types of woods are OK if you can get them just a little bit damp or air dried, but they all go the same way if they're interlocked - perplexing. The shavings are crunching, the wood is disagreeable and even the sharpest edge will result in a bunch of dust as the shaving breaks itself around being cut.

Just to plane a wood like that with any plane is success.

Well if your talking planing beech I need to hold on to my planes. Otherwise that will take off and fly across the room... I have plane beech a few time's levelling woodies and it it an effortless process- but sometimes the smell of the century old wood isn't great..

Sketch of what a grooved bevel might look like face on

toothed bevel.jpg

Presents to the wood a fair amount a sloped surface which might applies force to the traverse as it lifts of the shaving- like how a scrub plane does or a skew or spewed plane, not sure such a bevel would make a difference but lowering the bevel does make for a sharper edge.

Might look at putting a 36 grit belt onto an awful old belt sander I have in deep storage, and see what happens of point a polished lead to the resulting deep scorched bevel. A deliberate effort rather than chance.

Cheers M