Rolled Bevel vs Micro Bevel vs Hollow Grind

[Pedro Reyes]

My curiosity on the pigstickers is piqued. The way the rounded bevel tends to clear the mortise is by pushing the chunks of wood into a void as the mallet strikes. It may be that a slight round to the bevel facilitates this better than a flat or hollow ground bevel.

Jim,

Pure speculation on my end, but I suspect that the rounded (convex) bevels on those chisels is the result of frequent sharpening freehand, likely on the job site, more so than a desired feature, I may be wrong. It is not an exaggerated curve, just off from flat. Being on the convex instead of the concave side also supports the "better edge retention". Levering against the bevel, would also seem to be better with a convex bevel.

/p

[David Weaver]

It can be difficult to get an idea of how a chisel, etc, was used professionally, regardless of the origin. Warren Mickley (and I'll paraphrase) mentioned a while ago that the tools he has found that were either lost or put away shortly after new are maintained often much differently and much more precisely than a lot of the same tools that have been used hard and put away. There's no guarantee that the last person who used the tools knew what they were doing, and often the last user is someone who doesn't and who uses the tools until they've gotten them into a condition that they can't really be used.

To get an idea of how tools were set up, we would probably have to find a tool box that was known to last be used by a master, and not be used or fiddled with since, or find period literature with the tools in use. If you ask warren what the right way is to set up a mortise chisel, I'm pretty sure I recall him saying that it is with a single flat bevel, and he works wood by hand professionally.

[Jim Neeley]

I agree with you, David. Further, I think some fall into the trap of hating the idea of the ruler trick based on the concept of not having a flat back rather than the magnitude of the impact. To make my point I'll share the way I use it and a few quick calcs on the magnitude of the "error", assuming you start with a well machined chisel and not a banana-shaped imitation thereof.

My choice of plane blades are the Lie-Nielsen and Veritas which come flat but unpolished. There are no doubt many other makers who also provide such products.

I use a 4" wide 1000 grit diamond (coarse, 14.7 micrometer) stone and my ruler is 001" thich and 3/8" wide. I grind a back-bevel of 1/16" to 1/8". As a result of this, the tip of my blade is (mathematically) out of plane by 0.00015" to 0.0003" (yes, that is 15 to 30 one-hundred-thou). I then take it to my (2.76" wide) 16k & 30k Shaptons and remove just enough to get rid of the previous scratches.

Even assuming that the scratches in the steel were 1/2 the diameter of the 1000 giamond grit, those scratches would be only 0.00025".

Adding the two together your maximum "out of plane" amount would only be about half a thou.

If I could get my resulting work to within half a *hundredth* it would be amazing and even then my tool would be 10X as accurate as I was.

This reminds me of the old off-color story of the engineer and the physicist stuck on a desert island. With lots of time on their hands, their conversation turns to, well, women. The engineer asks the physicist:

"Imagine you awake and see a woman at the other end of the beach and you start running towards each other and every 10 seconds you cut the distance between you in half. What do you think of that?"

The physicist replies: "That's horrible, to be so close but never get there. What do you think of that?"

The engineer replies "I may not get there, but I'll get close enough!!"

Can you tell I'm an egineer? <g>

Jim

[Winton Applegate]

Bruce,

Thread Tools Drop Down

Thank You.
It would help if I would take the time to look through all the things like that here.
I have been too busy "talkin'".

[Winton Applegate]

I must be tired. I am tired but
Where is the decimal point on your ruler thickness spec ?
Are you really intending to say your ruler is .001" ? One one thousandth of an inch thick ?

Well stand back bubba, while I whip this out.
Mine's bigger :
.02" two one hundredths of an inch thick. See photos.

Plug that in your spread sheet and smoke it.

Am I the only sharpening snob here that thinks going from a (he sniffed as he said it with his nose in the air, eyes all a flutter) harumph . . . 1000 diamond stone.
scratchy, scratchy, scratchy, . . . scratch, . . . scratch to a . . .
excuse me . . .
16,000 Shapton in one fell swoop is bordering on useless.?
I bet I could see the trenches left n the metal from across the room. Maybe your intent is a mini "toothing" blade and I missed that.

What is the point of the 30,000 ? That is for like surgical instruments.
Is it really, really true that you can hear angels sing when you use it ?
I do want one. Can I have yours ?

PS: A couple of times I have considered doing the math but without coming up with relatively meaningless numbers I know the actual results while planing the HARDER wood.
Have you actually used blades sharpened this way in the wood I suggested and compared it to the results of the flat facet and flat back alternative ?
. . . or are you just playing poker ? The latter I think.

Don't take my swaggering too seriously but really
I think you can have a better time planing with a little more attention to the finer points.
Who knows . . . you may even be able to get that

if I could get my resulting work to within half a *hundredth* it would be amazing

to work out for you.
To be an everyday ocurrance as it is for me.

[David Barnett]

Well stand back bubba, while I whip this out. Mine's bigger

I just had a Blazing Saddles moment.

Am I the only sharpening snob here that thinks going from a (he sniffed as he said it with his nose in the air, eyes all a flutter) harumph . . . 1000 diamond stone.
scratchy, scratchy, scratchy, . . . scratch, . . . scratch to a . . .
excuse me . . .
16,000 Shapton in one fell swoop is bordering on useless.?

Makes sense to me. I routinely go from 600 grit poly diamond to 14,000 grit paste. Works.

[David Weaver]

I also go from medium to fine, about that interval, on just about everything.

[Roger Nair]

I'd like to thank everyone for the kind welcome and gentle words because I know how we all can be very demanding when working in our own ways.

[Roger Nair]

I agree with you, David. Further, I think some fall into the trap of hating the idea of the ruler trick based on the concept of not having a flat back rather than the magnitude of the impact. To make my point I'll share the way I use it and a few quick calcs on the magnitude of the "error", assuming you start with a well machined chisel and not a banana-shaped imitation thereof.

I got to reply, from a timber framers pov, that I love my vintage laminated framing chisels with the convex back for several reasons. The set up of the chisel is simple, I only concern myself with flattening the back about 3 inches in from the tip. The convex back creates clearance for the socket and handle which allows the chisel to be used freely as a paring chisel or even to be configured as a slick with the addition of a long handle. There is a tendency for straight back chisels to dig in towards the back while making deep mortises, the convex back chisel seems to be somewhat self correcting in that regard, by introducing a counter force to the tip with each mallet strike. Plus the older chisels taper in width from tip to heel, that taper will help mitigate jamming in deep cuts. Taken as a whole, the vintage chisel has more subtlety of design than the ever so straight modern ideal. So honestly I'm a little lost when the discussion gets into the effect of such minor deviations.

[Winton Applegate]

Blazing Saddles moment

Ha, ha,
you got it partner.

600 grit poly diamond to 14,000 grit paste. Works.

ohhhhhh, no, no, no
Blasphemous temptations !
This is Satan's work !
I won't let my self hear this; la, la, la, la . . .
here I went to Shaptons so I could fill in between the 4000 Norton and the 80000.
This is crazy talk, crazy talk I tell ya'

PS: when I saw the youtube where he goes to town for thirty strokes on the strop I had two thoughts :
Why would I want to cramp up my hands like that when I could be using a jig ? ( I often sharpen six wide blades at a time)
and
For the same number of strokes I could take six strokes each over five more stones (which would be excessive) and have a better edge.

[Chris Griggs]

Makes sense to me. I routinely go from 600 grit poly diamond to 14,000 grit paste. Works.

+1 I currently go 800 grit to 8k and I'd have no qualms with going bigger than that. I'm a big fan of big leaps. Works fine. Particularly if to use hollow grinds or micro bevels.

[Chris Hachet]

I prefer to NOT use a micro-bevel for one reason only.... I find it difficult to do free hand and I am usually in a hurry. As such, I prefer a hollow grind. To micro-bevel, I end up using a jig and I have not set anything to allow me to very very fast drop something into the jig so that the angle is perfect. I really probably should do that.

Now, that said, my Lee Valley PM-V11 chisels came with a micro-bevel, and they are really sharp from the factory. I have not found it in myself to slap them on my Tormek to add a hollow-grind just so I can free hand them.

I am ginding the hollow grind really helpful, and am planning on getting a Tormek

[Charlie Stanford]

I am ginding the hollow grind really helpful, and am planning on getting a Tormek

If you have plain Jane Stanley/Record irons you might find that the hollow produced by large diameter wheels is less useful, and less longer lasting, than the hollow produced by smaller diameter wheels. You need to be able to refresh the hollow without going all the way to the cutter's edge. Large wheels make this a little harder to do, at least for me. I'm no virtuoso grinder operator though -- just sump'n I've noticed over the years using different equipment in a few different places.

[David Weaver]

For anyone who doesn't burn edges on a regular basis, I don't see a virtue in a tormek over any powered 6 or 8 inch grinder with decent rests.

I personally would rather have any decent (foreign or domestic) dry grinder than a tormek because it's quicker, no fiddling with water, abrading the surface of the stone is certain and takes seconds and the hollow is longer lasting.

I had one (Tormek supergrind) for a while and eventually got tired of looking at something I didn't use and put it in a box and sent it to someone else.

[Derek Cohen]

Just to demonstrate that it is all about choices and preferences, and that there are no "right" answers, I am going to disagree with both Charles and David.

I have both the 10" Tormek as well as a 8" dry grinder with a 48 grit white Norton wheel. If one simply compared the speed with which the dry grinder removed steel, the Tormek is not in the running. The Tormek is quicker than most realise when the wheel is clean and used at the lower 220 grit. However, it is still going to hollow grind the steel from a 2" O1 plane blade in about 3 minutes versus the 1 minute for the dry grinder.

The large Tormek also creates a shallower hollow, actually quite shallow - it is possible to hone away the hollow quite quickly. The up side of this is that one can use it on laminated steel without removing the backing layer. One needs to refresh the hollow after about 4 or 5 honings, but this is quick thanks to the angle setter, and the only steel removed is inside the hollow, not from the length of the blade.

So far the dry grinder seems to be the winner. However, there is another factor, and this is where the Tortoise overtakes the Hare.

The Tormek, being a wet grinder, runs very cool. You can grind to the very edge of the blade without fear of burning the thin steel there. You can also hollow grind laminated Japanese blades without fear of affecting the hard steel layer. By grinding to the edge, it take one or two passes on a 5000 or 6000 grit waterstone to create a micro bevel. It takes about 5 passes on a 13000 waterstone to complete the polishing stage. And you are ready to go. This process takes about 30 seconds.

On a dry grinder one would have to stop about 2mm from the edge to avoid heat damage. At this point you need to begin with a 1000 grit waterstone to create a larger micro bevel (not sure it it is a "micro" bevel any longer), and I'd estimate that this takes about 2-3 minutes. And then you still need to move to the 6000 and 13000 stones, each of which takes many more passes than on the primary hollow from the Tormek as the primary bevel is wider.

Furthermore, the hollow grind on the Tormek is controlled by the guide, and it ends up being very even in width. The hollow on the dry grinder tends to be made freehand. I am quite decent at this, but still end up with an edge that needs to be straightened on the 1000. This adds to the time in preparing the final working edge. Remember, it is the time in achieving a working edge that determines the speed of the machines, and in this manner you will find that the Tormek is the faster machine overall.

Lastly, a further advantage of a clean hollow is that it makes it easier to freehand if, as I do, one uses the hollow as a jig. Grind the hollow primary at the angle desired, and freehand directly on this. Quick and easy. But not for everyone.

Regards from Perth

Derek