Micro-Bevels

[Saint Simon]

When using a sharpening system, like the Veritas, that allows the application of a micro-bevel, what happens the next time you sharpen the tool? Do you sharpen to the basic angle taking off the m-b and then reapply it or do you just apply the micro bevel again, leading to a larger and larger m-b? The former seems hard work and a waste of tool steel and the latter makes me wonder why have a basic angle at all. Help please.

 

[bugbear]

When using a sharpening system, like the Veritas, that allows the application of a micro-bevel, what happens the next time you sharpen the tool? Do you sharpen to the basic angle taking off the m-b and then reapply it or do you just apply the micro bevel again, leading to a larger and larger m-b? The former seems hard work and a waste of tool steel and the latter makes me wonder why have a basic angle at all. Help please.

Half way between the two (as you observe, the two extremes are poor).

The purpose of the primary bevel is to keep the secondary (Veritas call it micro) bevel small. It does not form the cutting edge.

As such, it can be worked with coarser abrasives.

The primary bevel should never be worked until it meets the cutting edge, since this removes valuable tool steel, and shortens the working life of your tool.

Honing of the actual edge is done on the micro bevel - since this is small it can be worked rapidly, even with fine abrasives, leading to a fast sharpening system.

In fact it is not even neccessary to work the primary bevel every time you sharpen, speeding things futher.

Some people prefer a triple bevel system, where there is a primary (or relief) bevel, worked with very coarse abrasives (or even a grinder), a secondary bevel (quite) small, and a third bevel (micro bevel?).

In this approach, the secondary bevel is worked all the way to the edge (but ONLY to the edge), using a "medium" abrasive, and a tiny microbevel formed afresh at each sharpening.

BugBear

 

[woodbloke]

Some people prefer a triple bevel system, where there is a primary (or relief) bevel, worked with very coarse abrasives (or even a grinder), a secondary bevel (quite) small, and a third bevel (micro bevel?).

In this approach, the secondary bevel is worked all the way to the edge (but ONLY to the edge), using a "medium" abrasive, and a tiny microbevel formed afresh at each sharpening.

BugBear

...which is my preffered approach with A2 steel blades
Primary grinding bevel - 23deg (Tormek)
Secondary bevel - 30deg (Green DMT stone)
Micro bevel - 32deg (10000g spyderco ceramic) - Rob

 

[Derek Cohen (Perth Oz)]

Just to complicate matters - demonstrating that everyone and his dog has an opinion about what is right when it comes to sharpening - I prefer to create a microbevel that is coplanar to a hollow grind for chisels and BD plane blades. I prefer to freehand such blades.

In doing so, using the Tormek, I hollow grind to the very edge of the steel (in opposite to BB's advice), and only ever use one secondary microbevel angle (in opposite to Rob's advise). Typically 25 degrees. Having set up a blade this way, it takes just a couple of swipes on 1000 and 12000 Shapton waterstones to get an edge.

I do use a different secondary/microbevel system for BU plane blades. Here I will create it on the Veritas Mk 2 Honing Guide.

The thing is, a microbevel is generally bad news if you use stropping to maintain an edge between honings. I described why in detail here:

http://finewoodworking.taunton.com/item/8521/a-sharpening-strategy-beyond-a-sharp-edge

Regards from Perth

Derek

 

[lurker]

I'm with BB on this (as per usual)

Unless I ding a blade I never have cause to re-hone the Primary bevel.

Which is why I can't understand why some on here, have such a lot of honing paraphanalia.

When I have a job on the go I don't need to get sidetracked with blade honing other than a few secondary bevel strokes now & then on a fine "scary sharp" plus a few strops.

I have enough plane blades & chisels to put a dinged one to one side for a "once every few months Sharpening session". Even then I rarely take a blade to a grind wheel these days.

 

[woodbloke]

Unless I ding a blade I never have cause to re-hone the Primary bevel.

Which is why I can't understand why some on here, have such a lot of honing paraphanalia.

Eventually the secondary bevel will get so large that honing becomes difficult so then it's time to regrind the primary so as to reduce the width of the secondary...and so the cycle starts again.
My paraphanalia is an Eclipse cloned guide (Mr C. modified) the projection board, some DMT's, the Spyderco and a strop. I always use the guide and it takes barely longer to set up the guide (using the 'bench hook' projection board) than it does to do it freehand. The beauty of using a guide (for both BU and BD blades) is that the chosen angles are accurately repeatable - Rob

 

[lurker]

Rob

My stuff & technique is virtually identical except for DMTs & Spyerco (where I use Traditional oil stones & scary).

Maybe I ding blades frequently enough :roll: that I never get a big unwieldy secondary.

 

[lurker]

The beauty of using a guide (for both BU and BD blades) is that the chosen angles are accurately repeatable - Rob

And thus you grind away less "meat" per resharpen

 

[woodbloke]

Rob


Maybe I ding blades frequently enough :roll: that I never get a big unwieldy secondary.

Don't ding your blades then!! :lol: :lol: :lol:
Seriously...if you do get a 'ding' in a blade (and it happens from time to time) then you've got no recourse but to grind down the primary bevel past the 'ding' to new steel- Rob

 

[bugbear]

In doing so, using the Tormek, I hollow grind to the very edge of the steel (in opposite to BB's advice), and only ever use one secondary microbevel angle (in opposite to Rob's advise).

Surely Tormeking (new verb!) nearly to the edge would have the same result (in the terms of secondary bevel size reduction) and extend (a bit) the life of the tool?

Admittedly, if you're being careful (and knowing you, I suspect you are), your "all the way" and my "nearly" may be very similar.

BugBear

 

[Derek Cohen (Perth Oz)]

Hi BB

How much is nearly (to the edge)? I would not go all the way to the edge with a dry grinder - I have a half speed 8" with a 46 grit 3X Norton wheel that is fairly cool grinding - however the Tormek makes this a safe process, and I stop once a slight wire edge begins to form.

I have not experienced any difference in edge holding when comparison is made to a thicker edge.

I do find that there is a significant reduction is speed and effort when honing freehand on the thinner edge. The 1000 grit Shapton requires no more than 3 strokes to straighten the end, while the 12000 grit needs 5 strokes maximum to remove any scratches.

Since this removes very little metal, I am guessing when I say this but I probably get about 3 or 4 more sharpenings before reaching the position I would have been in if using the dry grinder.

Regards from Perth

Derek

 

[bugbear]

Hi BB

How much is nearly (to the edge)?

.2 mm - .3 mm

I just don't want to remote ANY "edge", but I do want to make the final bevel as small as practically possible.

I'm doing this by hand on 80 Grit AlZi, so I can get pretty close, safely.

So I think we're doing practically the same thing.

BugBear

 

[Anonymous]

After half a dozen times sharpening (honing secondary), it's over to the grindstone for 30 seconds to grind away the secondary and start the process again.

I use a very cheap Tormek 1206 (found it under a pile of dust in a shop and made a silly offer that was acepted ) and the seondary is cut on 15 micron, then 5 micron, then 0.5micron paper from Veritas glued to a surface plate I had lying around.

I use the veritas mk2 for curved blades and the large Richard Kell for straight blades.

Takes less than 30 seconds to set up the blade in either jig - for info, I would rate the Veritas as considerably better than the Kell in use but neither is 'bad'

 

[ivan]

I thought the 3 bevel system would be an over-elaboration till I tried it out, urged by one of David Charlesworth's books. For a typical blade, he says grind at a bit under 25 deg, to within say 0.5mm of the existing edge (to keep the shape you like, straight or cambered) then raise a burr at say 32-33 deg (I use 600 grit diamond here) and then polish at 35 deg (I use 8000 grit waterstone for this) where I find half a dozen polishing strokes will usually do the job. When the edge gets dull, a few strtokes at 33 deg on the diamond to raise a burr followed by a polish at 35 deg takes very little time with a jig (as DC suggests) and the shallow under 25 deg grind lasts a longer time too. If you woodwork all day every day then learning to sharpen without a gude is probably more practical.

 

[Derek Cohen (Perth Oz)]

Ivan

The question I ask of those that use multiple secondary bevels angles to sharpen is "how easy is the blade to re-sharpen or maintain an edge between sharpenings?" What is the procedure and how long does it take?

Regards from Perth

Derek

 

[woodbloke]

I thought the 3 bevel system would be an over-elaboration till I tried it out, urged by one of David Charlesworth's books. For a typical blade, he says grind at a bit under 25 deg, to within say 0.5mm of the existing edge (to keep the shape you like, straight or cambered) then raise a burr at say 32-33 deg (I use 600 grit diamond here) and then polish at 35 deg (I use 8000 grit waterstone for this) where I find half a dozen polishing strokes will usually do the job. When the edge gets dull, a few strtokes at 33 deg on the diamond to raise a burr followed by a polish at 35 deg takes very little time with a jig (as DC suggests) and the shallow under 25 deg grind lasts a longer time too. If you woodwork all day every day then learning to sharpen without a gude is probably more practical.

The method you use hear is almost the same as mine except the angles I use are slightly less (see previous post) Doing your honing this way is dead easy with a guide (of whichever denomination) but very hard to do accurately and repeatably freehand - Rob

 

[ivan]

I guess the 33 - 35 deg(as DC suggests for LN blades) could be 30-32 deg or less, according to steel and species, start low and increase if edge not retained to your satisfaction. Once you have the grind (or primary bevel) it only takes me a few moments to put the blade in my LV II guide, and if you sketch it out on paper, you can see that very little metal has to be removed at 33 deg. The LV guide has quick way of adding 2 deg by rotating a knob - say 5 secs - and then half a dozen strokes on the 8000 grit waterstone. Creating /maintaining a camber on the 600 grit would take a bit longer for additional inspections.

I have tried using the 10" wetstone hollow grind to support thick blades for hand (guideless) sharpening but the above seems to work beter for me (retired from day job and in workshop 2-3 days a week)

 

[ivan]

Derek, having thought of it overnight, I think the DC method scores with repeatability - it was first time I could g'tee continuous, curly end grain shavings every sharpen.

Perhaps I should have tried using the hollow grind to support the blade (guidless) on 600 grit, and instead of doing the same on the polishing stone, raised it by eye/feel a couple of degrees. Funnily enough I do something like this on my LN 9 blade at ~20/22deg (although the 10 deg backbevel gets its polish in the guide) As most of my bench planes have been fitted with LN 4.5+mm blades (from Nos 8 or 9) and so have big bevels, I could manage this, but I don't have the skill to replicate this on blades of more standard thickness. And of course you'd need to grind on the tormek more often than with DC's method.

 

[Derek Cohen (Perth Oz)]

I think the DC method scores with repeatability - it was first time I could g'tee continuous, curly end grain shavings every sharpen.

Hi Ivan

No, I cannot accept this is more repeatable than honing freehand on a hollow grind. To achieve repeatability first you need to set up the blade in your honing guide at the desifred angle. Then you need to freset this for a second - and perhaps a third! - microbevel. How long does that take you? All I need to do is hold the bevel on the hollow and stroke it sideways a few times.

And of course you'd need to grind on the tormek more often than with DC's method.

You'll have to explain this as I do not follow what you are saying.

Regards from Perth

Derek

 

[Jeff Gorman]

Would sharpening talk be clearer if we used two traditional terms - Grinding angle, honing angle and the new(ish) microbevel?

Grinding angle - usually about 25deg

Honing angle - about 30deg

Microbevel - couple of degrees higher than the honing angle to form a very narrow bevel that can be honed (polished?) with fine abrasives with minimal effort.

I think this system implies a pretty accurate and repeatable honing system.

Jeff
www.amgron.clara.net