Japanese Knives

[SharpenADullWitt]

Thank you Steve!

[wootz]

Steve & Dave, please help me understand how to do single bevel Japanese knives with Tormek.
I read your comments, still cannot match it with the classic method.

True sushi chefs sharpen daily (or have their apprentices do it) on a flat waterstone - 4000, 6000 or even 8000 grit.
When I see a sushi knife it is for repair, usually at the hands of a non-Asian chef. I re-grind the bevel on the Tormek until all chips are gone, polish the bevel and return to waterstones on the flat side to finish the job.

It always seems I am late to the party.
I built Herman's HK-50 Jig and have been using it ever since with my Japanese Knives.
Both single and double bevel.
using the manufactures recommended bevel set up the Jig for the appropriate grind angle.
I use either the SG-250 or the SB-250 to establish the Knife bevel and polish the blade bevel with the SJ-250
If you polish the blade using the SJ-250 on a frequent basis you will never need to get out the SG or SB stones.
I have one really hard steel blade FUJIWARA MABOROSHI GYUTO 180MM the SG-250 would not touch the steel but the SB-250 established the blade bevel in two passes and the SJ-250 has been polishing the edge ever since.
Using the Tormek with the HK-50 jig replicates the Japanese water stone sharpening technique with the precision of the Tormek.

With classic whetstones, as I sharpen the bevelled side on coarse - medium - fine stones, before changing to the next finer stone, I do a few passes on the back side.
In other words, with each grit, having done the bevelled side, I do the flat back side, just enough passes to deburr, and then change to a finer stone and continue sharpening the bevel.
This is not practical when sharpening the bevel with Tormek, since to do the flat back side on whetstones I would have to remove the knife from the jig, and having done the back side, would have to re-mount it back in the jig to continue sharpening the bevel on Tormek finer grindwheel.

I understand you sharpen the bevelled side on TORMEK grindwheel #220, then #1000, then SJ or hone - BUT when do you deburr and hone the flat back side?

Do you prepare the flat side before going to Tormek to do the bevelled side? If you do, what grit whetstones do you use?
Do you do the flat side between Tormek grindwheels #220 > #1000 > #4000/honing while doing the bevelled side?
Do you do the flat side only after you have sharpened the bevelled side with Tormek? If yes, what grit whetstones do you use for this?

[Herman Trivilino]

Wootz, I don't see how it would be any different than sharpening a wood chisel. Assuming the flat side is, well, flat, it would never touch a grindstone. Only the honing wheel.

[wootz]

Thank you Herman.
It didn't come to me they are similar to chisels, probably because I haven't sharpened a single chisel in my all life.

[Jan]

Wootz, based on my experience with chisels, the back of a tool should have the same degree of smoothness as the bevel.

Deeper scratches on either side of the metal surface, caused by low grit stone, can serve as stress risers, which can initiate fatigue cracks or some other defects especially near the edge.

I smooth the back side of the tool freehand on the side of the stone before I start to sharpen the bevel using the jig.

Jan

[wootz]

Appreciate your input, Jan.
I thought I should ensure the flat side is truly flat before switching on the Tormek.
Now that you have confirmed this, I'll be polishing the back side on whetstones before sharpening the bevel.

One 'but' though... about the side of the stone? I tried it a few times with discouraging outcome, and then I stumbled on this Ionut's observation:
"I wouldn't flatten a tool on the side of the Tormek stone for two reasons, there are no real means to true and maintain a perfectly flat side of the stone and secondly the speed difference between the abrasive particles closer to the center of the wheel compared to the ones closer to the grinding surface would lead to uneven grinding action on the tool..."

[Jan]

I agree with you! My experience is based only on chisels where the requirements are milder. Until now I have not sharpen one sided Japanese knife. I will probably buy one as a teaching aid. 

Jan

[Herman Trivilino]

If you buy a chisel in the home center or a hardware store you'll likely see that the back has machining marks on it. These need to be removed. It's a one-time thing, and never needs to be repeated. Some find that the side of the Tormek grindstone works well enough, but others find that they prefer to use another method.

[Ken S]

I would generally recommend against buying a chisel at a hardware store or home center. All too often they are the shorter "butt" chisels, used by carpenters in the fiels for installing butt hinges. For a sharpening chisel, you will want the longer length "bench" chisel.

Avoid shiny chrome looking chisels. The intersections of the sides and back on these have a radius instead of a square intersection. The thickness of the radius must be removed in order to have a sharp edge. You probably will not live long enough to flatten these chisels.

Avoid the temptation to buy sets. You want a couple Irwin Blue Chip three quarter inch bevel chisels. Irwin is the Chinese reincarnation of the old Marples made in Sheffield chisels. I think the old Marples chisels were better tools. The Irwin are adequate chisels for sharpening practice.

If you are looking for chisels for serious woodwork, look at Lie-Nielsen or Veritas. Both are quality products. Start out with a half inch. Add other sizes only if needed.

Please read the first fixed topic in Tormek General.

Ken

[SharpenADullWitt]

On the chisels, generally you only flatten the back inch, as it would take way more time to flatten the whole back.  With bench chisels, you may flatten the back again at some other time, since they are longer then butt chisels.  (why I have seen and tried the side of the Tormek stone for flattening, as compared to a knife that is longer)
I still prefer to flatten them on my water stones, as I also like to keep them in a different area, where I tend to use the chisels.  That way I can do frequent touch ups where using a chisel and maintain practice with them.
Irwin was mentioned, and I think they are even sold in some home centers as well as places like Woodcraft, etc.  I prefer the older Marples (and have some that I picked up over the years, most of a full set), but those are not even considered good chisels, but beginners chisels in the woodworking circles I am aware of.  I picked up one Two Cherries chisel in a size I didn't have, and once picked up Narex mortising chisels when they were on sale.
Since that time and because I like refurbishing old tools, and feel the need to practice, I would say look for a garage sale chisel, personally.  A lot less then Lie-Nielsen or Veritas, and might be better then some of the bargain chisels I see out there.

[Ken S]

This topic is drifting away from Japanese knives.

We should differentiate between flattening and polishing. We should also differentiate between the back of a tool bowing inward (convex) and bowing outward (convex or having a "belly"). Having a chisel bowed slightly concavely is not a problem. Flattening is only done enough to make the top and bottom of the back coplaner. Japanese chisels are intentionally made this way.

The problem is when there is a belly in the back. When the chisel back is resting against a flat surface like the wall of a mortise, the sharp edge tends to be lifted.

The entire back does not need to be finished. SADW is correct in stating that the final inch is adequate for polishing, as long as there is no belly.

In recommending the Irwin blue chip chisels, I only mean as sharpening chisels. I would not buy a set. I bought five: two are 3/4". In hindsight, I wish I had purchased all five in 3/4". I bought them for sharpening testing, not for woodworking. I agree with SADW; I think the older Marples chihels are better tools.

My recommendation for L-N or Veritas was for one chisel, preferably a half inch. These quality tools have excellent steel, balanced nice handles, and the backs are properly flattened at the factory. I am not a believer in buying sets. I had a full set of Marples chisels. Half of them were unused or rarely used. Buy a top quality half inch chisel and only add sizes when you can identify a clear need. Having two of the most used size is not overkill. Someone correctly mentioned that the fastest reload is a second gun. The fastest sharpening in the middle of a project is having a second chisel. Having one of each of the top lines gives you an excellent comparison for when you want to add additional sizes.

If these two brands are too rich for you, the next best choice is quality vintage tools like Buck or Witherby. The Stanley 750 series is also quite good, although collectors have driven up the prices.

A sharp edge is the intersection of two planes. Both planes are equally critical. No not neglect the backs, regardless of the tool.

Ken

[Jan]

Folks, for me it is a pleasure to see the unselfish exchange of experience and opinion convergence. I think that nicely fulfills the sense of this forum and perhaps even something more. Thanks for that. 

Jan

[Ken S]

Jan,

As one of our wise members says, "Iron sharpens iron and one man sharpens another."  I believe we all grow from an open minded and courteous environment.

Ken

[Herman Trivilino]

I would generally recommend against buying a chisel at a hardware store or home center. All too often they are the shorter "butt" chisels, used by carpenters in the fiels for installing butt hinges. For a sharpening chisel, you will want the longer length "bench" chisel.

Carpenters rarely mortise for a hinge, Ken. Doors come prehung and cabinets built in the field have overlay doors. Fine woodworkers like yourself will use bench chisels. So will cabinet makers.

A few weeks ago I had to hang two replacement interior doors in existing jambs for a friend of the family. I was paid, and used a router to do the six hinge mortises. The only time I'd use a chisel would be on an existing door jamb since the door stop is in the way. Of course, a chisel still has to be used to tune up the mortises, particularly the corners. And I used a chisel to do the mortises for the face plates because there is little wood left to remove once the hole is bored.

So, yes, your comment is essentially correct in that a carpenter in need of a chisel will buy one at a home center, mostly because he's in a hurry and will already be there buying materials. The sad truth is that most of those chisels will never be sharpened. They will be used as chisels until they're too dull, then they'll live out the rest of their lives in a tool box or drawer, occasionally being pulled out to disappoint the user. Their life ends as pry bars or paint can openers.

My collection of chisels has come from those drawers and tool boxes, and thanks to my Tormek, been given a second life. I think that a 3/4" chisel is the best for these purposes, and I agree that having extras on hand is essential. Especially if you have "helpers" on the job who won't hesitate to use them to pry nails out of their way!

[Ken S]

Herman,

Sadly, I must agree with you. Of the three carpenters who worked on my house over the years, only one occasionally sharpened his chisels. The other two, who were able carpenters, considered them sharp when new and never resharpened them.

I know almost all doors are prehung today. The term butt chisel is, I believe, a leftover from another era.

Ken