Microbevel

[Tiger]

Have just started using microbevels for chisels and I can see their value, but the literature is a little vague and contradictory in regards to 2 things.

At what stage of the sharpening cycle do you form the microbevel. Some authorities say use your coarse stone to do it, some say use your finest stone to form it?

When using your finest stone, how many strokes before you stop, ie do you keep honing until you feel the burr/wire edge or do you just stroke for a while and then assume it's there and then flatten it off. This too is unclear from some of the authorities including Leonard Lee.

[BobL]

Have just started using microbevels for chisels and I can see their value, but the literature is a little vague and contradictory in regards to 2 things.

Humm . . . . . I generally find the literature pretty consistent - care to quote a few of these vague sources?


At what stage of the sharpening cycle do you form the microbevel.
I presume you are referring to a fully formed, slight blunt blade that does not need a new main bevel cut? At this point you can often just get away with just touching up the microbevel? If the back needs a touch up I do that before the microbevel, and if the main bevel needs a touchup I do that first of all. If you do the microbevel first and then attend to the other things you will end up losing the micro completely.


Some authorities say use your coarse stone to do it, some say use your finest stone to form it?You can use any stone to form a microbevel - thing is, - if the grit size of the stone is significantly bigger than the grain size of the steel you're not going to get a very sharp microbevel, you will end up with a saw like or jagged edge.


When using your finest stone, how many strokes before you stop, ie do you keep honing until you feel the burr/wire edge
Yes - but the bur must be all the way along the edge.[/QUOTE]

[Tiger]

Thanks, Bob. I have looked at 3 sources. Leonard Lee, Thomas Lie-Nielsen and Christopher Schwartz. All 3 have different approaches to the microbevel. Lee uses a fine stone to develop it but there's no mention of how long to keep honing. I have tried a few strokes and I have tried honing many strokes until I get a small burr. He does not state how long to keep honing but states that a microbevel gives the fastest possible edge (I find that if I need a burr here then sharpening time is not greatly reduced, page 62 of The Complete Guide to Sharpening).

Lie-Nielsen is more vague in his Sharpening book. Page 84 just states the benefit of using a microbevel but no real instruction on how to develop one.

Schwartz (In Hand tool essentials pg 34) states to use a coarse stone to develop the microbevel and then polish it up with a few strokes. He states that you won't feel a burr but it will be there.

In my mind, they are saying different things. I am after the fastest way to sharpen and get back to woodwork.

I can appreciate that there are different ways of achieving the same end and that is a sharp chisel, but the literature is inconsistent and confusing.

[Ron Dunn]

I use one of the first-generation Veritas roller and angle-guides for sharpening chisels and plane blades.

To set a micro-bevel is easy. There is a knurled knob on the side of the roller. Click this one direction clock-wise, and you've adjusted the bevel angle by a small amount.

A few strokes on 800-1000 grit wet-and-dry to form the bevel, then a few minutes on a 6000-grit stone to finalise the sharpening, and I'm done.

[BobL]

OK assuming the back is flat and there is a well formed primary bevel you are referring to only forming the micro-bevel.

You can use a fine stone to form a micro-bevel but it will take longer than a coarser stone. Most people I have seen sharpening quickly form the micro-bevel on a coarser stone until a small burr is present all the way across the edge. Then they use the fine stone to sharpen further and then either use the fine stone or a strop or both to remove anything that remains of the burr. If you have not let the blade become too blunt it should only take 8 - 12 strokes on the coarse stone and then about the same on the fine.

The following pic might help explain the situation.
http://www.woodworkforums.ubeaut.com.au/attachment.php?attachmentid=63186&stc=1&d=1198549027
Obviously all the angles are exaggerated but if you had to reform the micro-bevel on the blunt (middle) blade with a fine stone it would take a long time.

Some woodworkers will try to never let their blades go blunt to the point that they need the coarse stone every time they reform the microbevel. However, at some point they will have to reform the main bevel as the micro bevel will eventually become too large an area and take too long to grind. Then a coarse stone will be used to reform the basic microb

[Tiger]

Thanks Bob, I had assumed that you use the coarse stone and then the fine stone for the microbevel. I do find though that with some of my chisels, I get a good microbevel after only 5 or 6 strokes on the fine stone. Others I get nothing after a couple of minutes on the fine stone.

[JDarvall]

. However, at some point they will have to reform the main bevel as the micro bevel will eventually become too large an area and take too long to grind. Then a coarse stone will be used to reform the basic microb

There's a lot of way of doing these things, so I don't want to confuse things.

But this is where you can get speed IMO. Find a way to re-grind the main bevel confidently as often as possible. Removing steel with a grinder is far faster than off stones.

For me I'd even consider regrinding when that micro bevel extends back even 2mm. Save your stones. If your using waterstones they cup (so you have to flattern). Try and keep it so when you do hit your stones your only there for a few seconds.

The main technique I use to keep this speed up on the stones is to always lap at an angle greater than whats currently present on the blade. ie. if the last lapping is at 28 degrees, set your guide to lap say 30. Just a few strokes and you'll be done, because your lapping just at the very tip. And when its starting to get too high for a BD plane just regrind to burr.

Just saying don't fall into the trap of lapping away at stones for ever.

[derekcohen]

I agree with Jake about the amount of time needed on waterstones (or whatever you use for honing).

The most efficient shape to grind a bevel is a hollow because I will thereafter predominantly hone freehand. This works for all non-laminated blades and blades for bevel up planes (where I use a flat grind and microbevel with a honing guide for a specific angle).

Ideally, the hollow grind should be taken right up to the edge of the blade. This would leave a minimal amount of metal to remove when honing. In reality this is possible on a high speed grinder but only recommended for one quite experienced (and even then it is risky). The problem is that steel heats up most where thin, and will lose its temper if overheated. Even keeping a finger on the blade at the edge of the grind will not provide sufficient warning in time. The only grinder that makes this a take-for-granted affair is a wet grinder, such as the Tormek or Triton, as these run very cool.

Using the Tormek I can grind to the very edge of the bevel. It is now a simple matter to use the two sides of the hollow as a rest when honing. The resulting microvbevel can be exceptionally small. I mean less than .25mm wide. First a swipe or two on a 1000 Shapton or 1200 King to remove the rough edges of the grinder and shape the bevel (e.g. camber it). You can stop as soon as you feel the bur forming. Then a polish on a 8000 or so stone. The final microbevel is so small it may escape immediate detection.

Using a high speed grinder, where a couple of mm should be left at the bevel edge to protect it, you have a choice how next to procede. You can hone directly on the stone as I did above. This will create a wider bevel, one that is still a microbevel by definition but now about 2 mm wide. Or you can do as Jake recommends, that is, increase the bevel angle so that you only need to hone the edge of the bevel. This will create a small microbevel, somehere in between the two above. To do this either use a honing guide or, if freehanding it, lift the handle a fraction.

Regards from Perth

Derek

[J.E. Mike Tobey]

What Derek said- emphasizing that your first MB should be a small in "depth"( thinking of the MB climbing up the main bevel), Mine are no more than.005 for the first. That is just a slight lift of the chisel, really as minimal as posssible to see the MB all of the way across.mt

[Tiger]

Good input Jake and Derek. Would have to agree and I do this instinctively whether using a grinder or coarse stone and that is, hone at an increased angle to the main bevel. I've also found that the greater the difference b/w the primary bevel and the microbevel the quicker that I get a burr on the microbevel ie if the microbevel is only a degree greater than the primary bevel then it takes longer to get the burr than it would if the difference was say 5 degrees.

[kkperth]

Tiger

No idea on this stuff myself but I thought I would add some more grist for the mill with someone else’s hard work.

I found this link somewhere on this forum and it has some exhaustive info on sharpening and explanations on micro bevels - kept me busy reading for a while!

http://www3.telus.net/BrentBeach/Sharpen/index.html

Regardless of the way in which you chose to sharpen - I found his microscope photos of different types of bevels (front and back) made me understand the results you can get with different methods.

Kirk

[Tiger]

Thanks, Kirk it's an interesting site. I'm a freehand honer from way back but the author on that site does make a good case for using a jig to hone.

[Ivan in Oz]

Good one Kirk,

I am Happy with what I see with my 30x Loupe

I'd like to be able to move up to that degree of Sharpening / Sharpness.
One day, perhaps:2tsup:

[rightendup]

Since no one else mentioned it -I post.
I use all natural Japanese water stones. The finest grit one is perhaps my most treasured tool of them all comes from one particular mountain in Japan.
When I change from the 800 grit to the superfine (don't know it's grit) I will back the iron a tiny bit and then put the micro bevel on and dress the bottom. About ten strokes, dress the bottom and then three strokes, makes a barely visible bevel, super shiny.
I have 3 stones but use only 2 the third stone (coarse) is made and kept flat and is only used to flatten the 800 grit, the 800 grit, in turn flattens the superfine by rubbing the two faces together. Not only does it flatten the stones but opens the pores and hence cuts faster.

Jay