Abrasives and edges

[mike40]

In spite of what I said in my last post, I will be more than happy if I can do the whole job on the Tormek.  My only sharpened chisel so far sure performed much better than I even hoped it would. I will just have to get more experience to find out.

[Jeff Farris]

Interesting discussion and ideas Ken. I think I will try removing the the burr on the back with my 1200 grit diamond plate with a little water. One advantage with the diamond plate is that it is very flat and stays that way. I can't see it ruining the polished edge on the back as it only takes a very light pressure to remove the burr. If that doesn't work I will try the diamond paste on cardboard.

Here's the flaw with this approach, Mike. An edge is only as good as the surface finish on both sides of the bevel. A mirror polish on the front that meets a 1200 grit surface on the back is going to have 1200 grit "grooves" in the cutting edge. If you're not putting scratches in the surface of the back on your diamond stone, either your tool isn't flat or you're not holding it flat, and then you're definitely worse off than doing it on the wheel.

I know I've mentioned this before, but there are so many threads, and this one is really good, so I don't mind repeating myself.

Hold the back side of the tool at 9 o'clock on the honing wheel, about half an inch from the edge. Stand just above and stare straight down into the gap between the tool and the wheel. Pull the tool down slowly until the exact point where the gap disappears. STOP! Push it back up to the half inch point and repeat. Do it 4 or 5 times. Job Done.

[Rob]

My problem with working the backside on a flat surface is time. The honing wheel will remove the burr and mirror polish the back (more than it already was) in a few seconds. Doing that on anything flat is going to take longer. You're also right there -- already working on the machine...why set something else up?

If you're rounding over the backside of your tools you don't need another set up, you need to learn how to use your honing wheel.

Sorry if that sounds blunt, but the point of this forum is to teach people how to do things on a Tormek. If there was a serious issue of causing backside problems on the honing wheel, I would be the first to admit it and suggest alternatives. Heck, I don't even work for Tormek any longer. I'm here because I believe in the product.

In 1982 I went to work for Don Peschke at his relatively new magazine, Woodsmith. That's where I learned what sharp is. We used to have competitions to see who could get the best edge the fastest. The art director won consistently, but I was always in the running. Woodsmith stressed (and still does to my knowledge) backside flatness. I believe in it. I embrace it, I practice it, but I will not be convinced that I will destroy my flatness by using the Tormek honing wheel to deburr and polish. If I've shaped the back properly (usually on the side of the wheel, and btw, yes you can grade the side), the honing wheel just doesn't cut enough to alter the shape, only the surface finish.

I think everyones with you Jeff....no one wants to introduce an alternative step IF the desired edge can be achieved right there on the Tormek.  You know me...I hate the faff of changing setups, jigs etc.  But your bluntness brilliantly nails it.....is operator error causing this rounding over? I think I'm struggling to believe its the case with me given how hard I've worked to learn this procedure but I also must say....you do sound right :-)  And its certainly the most plausible explanation.  Dam...where are those chisels :-)

[Jeff Farris]

I'm not real big on stats, but I think our relatively new member Mike wins for the "fastest to 100 posts". Thanks for diving in, Mike.

[Rob]

yay....well done Mike :-)

[RobinW]

Now we all have our idiosyncrasies about how we sharpen and hone, but there is a subjective part at the end -

"How do you measure or prove sharpness?"

I have already commented that I believe that after honing my chisel edges are not as sharp as coming off a fine graded wheel. I have flattened the backs of my chisels using the side of the wheel, waterstones of various grades and polished up using the leather wheel. Ergo I believe that I should not need to re-address the backs for a while.

I then do the bevel side. Some I do as a single bevel at 25 degrees and hone up at that for paring use. Some I put a secondary bevel at 30 degrees using a fin graded wheel and then hone on the leather. I use the SE-76 jig for all operations on the bevel - I don't free hand the honing. (It's a bit a drag re-setting the usb for the stone or leather wheel, but better than what my free hand would achieve.) So I am not rounding from the back as I haven't touched it.

So how do I (or indeed anyone else) prove they are sharper by one method or another?

There is the paper cutting demo - which depends on the paper used, the angle of attack; and a matter of feel for the result.

Some years ago, I was in a test house in the USA, and one contract they had was to test samples of face shields used on fighter pilots' helmets to ensure they were meeting the desired impact standard. The test jig used a hardened pointed object (like a sharpened nail) with a specific mass attached, dropped from specific height on to the visor shield. They measured the depth of penetration for the quantitive result.

Now I do not propose dropping one of my sharpened chisels and see the penetration into my foot or other object!!!!!
I have enough inadvertent excursions without trying to formalise this one!

Anyone have any suggestions for a quantitative method of testing?

[Jeff Farris]

Robin,

Your method ignores what I feel is the most important step in producing a really keen edge.

The work you do on the bevel is going to raise a burr on the back of the chisel. You have to remove that burr from the back side. If you try to take it off from the front, you will undoubtedly round over your edge.

What you've described is perfect, except that you aren't removing the burr after working on the bevel. Given what you've said about how your back is to begin with, I am going to say you're about 30-45 seconds away from what I would consider really sharp. Just hit the back side on the leather as I described a couple posts ago, and Bob's your uncle.

What is sharp?

It will catch your fingernail and not slide.

It will cut any thickness of paper in a controlled way (I used to cut circles out of magazine stock).

Perhaps most relevant: It will cut across end-grain in softwoods without tearing.

Back in the days when prepress work for publications was done with waxed type and artboards, XActo had advertisements in the trade press that suggested you cut along a dotted line in their ad. If you didn't cut at least 3 pages below, you needed a new blade in your XActo. I'm not sure how that's relevant, but anytime the discussion about "how sharp is sharp" comes up, I recall those ads from about 35 years ago.

[RobinW]

Thanks Jeff - I am slowly putting aside a few chisels for a sharpening session, so I will report back in due course.

Just a wee distraction about stropping - when I retired from my previous career, I went to college (two years full time; two years part time) for Furniture Restoration.  The cabinet maker showed us how to sharpen chisels on a wet grinder of many years vintage; followed by various grades of waterstones. All by eye and feel - no jigs. The final process was to remove the tiny burr and this was done by (best description coming!) holding the chisel in one hand, and flicking the chisel blade backwards and forwards across the heel of the other hand. (Similar thing if you had say a wet paint brush and you wanted to get the water out of the bristles.)

Now with practice I could get my blades sharp - I spent probably hundreds of hours to get to a standard I with which I was happy. However I now get much better and consistent results with the Tormek even if I still have a burr attached!

[mike40]

Robin, as I said in another post, I tested the stropping effect by using my newly Tormek sharpened/stropped chisel all day. It still passed the fingernail test at the end of the day, but not the paper test. I then stropped it on the Tormek leather wheel only, with some diamond paste. I worked both the bevel and the back. After that it passed the paper test again. That seemed to me to be a full restoration of the edge and proof that the stropping wheel does work. One factor not mentioned in the various posts in this thread is the hardness of the steel being sharpened. Time must also be a factor here and not just technique?

[Rob]

I experience exactly that also.....can bring back a not too far gone chisel or plane edge with the strop.....I'm not even going to ask whats going on there at the microscopic level because in theory that shouldn't work right??

But......it does

[Jeff Farris]

I'm going to go out on a limb and say that microscopically, it does work.

As I understand it, two things are happening as an edge dulls...folding and crumbling...both of which are happening on a very minute level. Hitting the strop before the edge deteriorates too far is going to straighten out the folds, and if the crumbles haven't reached the size of the abrasive yet, it should deal with them just as well.

Carvers practice this approach better than any other group I've worked with.

[mike40]

That is very true about carvers Jeff. One of the best carvers in our area who frequently attends demonstration days at our local woodworking store continually strops while carving every few minutes. He doesn't use the strop when chip carving though. Instead he uses his stone to lightly hone very frequently a few very light strokes on his stone, with maybe just a minute or two intervals. If you saw his work you would immediately know that he is always working with very sharp tools.

[Rob]

that's very interesting indeed (both Jeff and Mike).  After that Canadian article which completely contradicts all of this, I have to say I was confused about what was going on.  But I also experience exactly as you describe as mentioned a couple posts ago.  This is "apparently impossible" according to the Canadian chap but clearly that's rubbish!

The very fact that an entire group of woodworkers, namely carvers routinely and successfully use this method just corroborates what Mike and I have actually experienced.  So either I'm missing some technical detail about abrasive size etc or he's got something wrong (I wonder if we could get him to join the forum and elaborate on his thinking....that would be amusing).

Again, stopping with the OCD for 1 second, on a practical level it wouldn't make a jot of difference to what I actually do because as I say, I know it works in the workshop.

[Ken S]

I met chip carver, Wayne Barton, years ago at a workshop.  The workshop was two days (a weekend). Unfortunately, I had a back injury Sunday morning, and missed the second day.  It was a good class.

Wayne uses and sold two ceramic sharpening stones.  The more coarse stone was for actual sharpening.  He described the finer stone as "refreshing" the edge.  That sound like what your local carver was doing, Mike.

Incidentally, chip carving is a good choice to add a bit of carving to projects.  The basic techniques are straightforward and Wayne only uses two tools for his work.

Ken

[mike40]

Lucky you Ken to have had a class with Wayne Barton. My son expressed interest in chip carving and I got him a book by Barton. Many chip carvers are using the ceramic stones these days with great success. I have been chip carving on some of my turnings for many years now just to add texture or a little more interest to them. This is a good idea when working with very plain woods without visible grain patterns. Nice on Birch, Linden, Basswood, etc. I can't claim to be highly skilled at chip carving, but it is definitely a good way to go for those who don't carve as their main hobby, but still want to get some enjoyment from it. I think that well done chip carving with the right patterns can be just as decorative as the acanthus style carving.

Another form of carving that can be very nice if well done is similar to scrimshaw work, only in wood instead of bone or horn. The pattern is cut (incised) with just a straight cut, maybe 1/32" in depth. Then bark sanding dust is mixed with oil and worked into the cuts to make the pattern more visible. We have some beautiful examples of such work here in Norway like the spoons below. The technique is called 'Kolrosing' her. The dark backgrounds and shaded areas are usually just a lot of straight cuts closely spaced together. Kolrosing  sounds like an easy technique, but I have found it a lot more difficult than I thought before trying it out. It is however, a lot easier than relief carving, but it requires great concentration and good  control, plus a short stout knife blade with a good handle.