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If you grind your Japanese chisel on loose diamonds will the diamonds imbed themselves in the softer iron part of the chisel. When you then go to higher grit loose diamonds, or paste, diamond against diamond will knock the lower grit out and it becomes a wild grit. I can't think of a reason that this would not happen. Also if you went from diamonds to a natural stone the imbedded diamonds would do a job on you stone. Can you tell me about that scenario?
Jim
I don't have that much experience with Japanese tools (I have a set of HAP40 chisels, but that's about it) so I'll defer to Brian there.Quote:
Originally Posted by James Pallas
I will say that this isn't exclusively a concern with Japanese tools. Some older Western plane irons (some pre-1930 Stanleys for example) have welded inserts in mild steel bodies. Similarly many chisels and plane irons (both older and current) are only hardened for the first couple inches, such that the remainder of the tool is effectively annealed tool steel.
This also isn't exclusively a concern with diamonds. You can easily transfer loose grit from water stone slurries, for example. In general you have to mitigate for cross-contamination with any medium that has either a loose binding (waterstones, compounds) or friable abrasive (SiC sandpaper, some papers with alumina-ceramic grains).
I deal with it in two ways:
1. If I'm just doing quick sharpening and I want the speed of diamond then I use lapping film.
2. When using anything that "sheds" I use a contamination control process. In the case of coarse grits you can easily feel any residual abrasive, so I run my finger over the relevant parts of the tool and remove anything I find. When going to the finest grits I clean the tool with a low-particle-count wiper (TexWipe 604, about $0.02 each) and acetone. If there's particular concern then I may clean unhardened tool surfaces with a fine brass plater's brush and using mineral oil as a solvent before the wiper, but I seldom do that. I'm pretty sure I'm overdoing it, but I haven't had scratch problems since I got serious about the process, so I'm sticking with it.
Frankly the bigger problem is environmental contamination of the finest-grit lapping plates themselves rather than direct transfer via the tool. Cleaning measures are similar to the ones described above.
I don't use loose diamonds much, and have avoided using them on Japanese tools for that reason, in afraid that will be the result.
If you do get contamination in a JNat (whether from external sources or because of the inevitable imperfections of quarried rock) can you just remove it using a Nagura, or is there more to it than that?Quote:
Originally Posted by Brian Holcombe
If it's a line then some guys will just chisel it out, but if it's just a rogue particle I'll normally just rebuild the slurry (I use a diamond plate) and the contamination will disappear. It happens from time to time.
That is in line with what I think. Just think, if you use loose diamonds then water stone, you could be flattening as you sharpen.:eek:Quote:
Originally Posted by Brian Holcombe
Jim
To reiterate something I said above, if you're using waterstones then you already have this problem. Diamonds are the hardest abrasive, but that distinction is mostly relevant only when working hard steels and carbides that approach or exceed the hardness of other abrasives. The slurry from your coarse stones contains loose abrasive particles that are effectively "infinitely hard" compared to the iron parts of your tool, and that will transfer and create coarse scratches (unless the coarse stone is also natural, in which case the abrasive particles are probably too "round" to embed). The only real difference is that the diamonds will continue to cause mayhem longer than other abrasives once they've been transferred to your polisher, but it's best (and quite feasible) not to let that happen at all.Quote:
Originally Posted by James Pallas
If you use Silicon Carbide anywhere in your workflow then that's particularly problematic, because it forms sharp "shards" that embed deeply in iron, more so than diamond in my experience. This is why people get very fast results with loose SiC grit on iron laps. The most involved part of my own cross-contamination process is cleaning my iron laps after I resurface them using SiC grit.
You need good cross-contamination control period. There's nothing terribly unique about diamonds.
Brian, am I correct in inferring that you're using a diamond plate in place of a Nagura, or does the Nagura still serve some other purpose?
BTW, diamond plates "shed" grit (see before and after comparisons here), so if you're using a diamond plate to surface your waterstone then you need to carefully inspect afterwards and extract any rogue particles. I do so with my synthetic polishers, and I don't think it's a big issue because it's fairly easy to mitigate, but I'm bringing it up to reinforce my point that transfer via compound is also not a big or unique issue :-).
Good point, they can lose abrasives.Quote:
Originally Posted by Patrick ChaseTo reiterate something I said above, if you're using waterstones then you already have this problem. Diamonds are the hardest abrasive, but that distinction is mostly relevant only when working hard steels and carbides that approach or exceed the hardness of other abrasives. The slurry from your coarse stones contains loose abrasive particles that are effectively "infinitely hard" compared to the iron parts of your tool, and that will transfer and create coarse scratches (unless the coarse stone is also natural, in which case the abrasive particles are probably too "round" to embed). The only real difference is that the diamonds will continue to cause mayhem longer than other abrasives once they've been transferred to your polisher, but it's best (and quite feasible) not to let that happen at all.Quote:
Originally Posted by James Pallas
If you use Silicon Carbide anywhere in your workflow then that's particularly problematic, because it forms sharp "shards" that embed deeply in iron, more so than diamond in my experience. This is why people get very fast results with loose SiC grit on iron laps. The most involved part of my own cross-contamination process is cleaning my iron laps after I resurface them using SiC grit.
You need good cross-contamination control period. There's nothing terribly unique about diamonds.
Brian, am I correct in inferring that you're using a diamond plate in place of a Nagura, or does the Nagura still serve some other purpose?
BTW, diamond plates "shed" grit (see before and after comparisons here), so if you're using a diamond plate to surface your waterstone then you need to carefully inspect afterwards and extract any rogue particles. I do so with my synthetic polishers, and I don't think it's a big issue because it's fairly easy to mitigate, but I'm bringing it up to reinforce my point that transfer via compound is also not a big or unique issue :-).
I use it just like a nagura stone, in tradition polishing work the nagura stones are used to build a slurry and in doing so can bring out different characteristics of various natural stones. They are also sometimes used in and of themselves as polishing stones. There is a book on traditional sword polishing that you may find very interesting especially to the degree that they use abrasives to bring out certain characteristics in the steel.
All of the natural stone efforts are grounded in traditional sword polishing, as with most things that people pursue they're originally for military efforts. Sword polishers worked to bring out the steel's character allowing the smith to further analyze the quality of his efforts.
Diamonds are imbedded into COPPER laps by lightly tapping the round lap ,while rotating it,with a hardened steel hammer. This is done over a steel surface with the diamonds are thinly spread. Then,the lap would be used to lap a hole smoother. The hardened steel hammer doesn't get any diamonds embedded into it. The soft copper does. I doubt that your chisels would get any diamonds embedded into it.
i don't think that diamonds or sic would get into the hardened steel but into the wrought iron lamination.Quote:
Originally Posted by george wilson
Jim
For a Western-style chisel, no. The only time I've ever seen that happen was with one chisel that had a particularly roughly-ground hollow that straddled the hardening boundary. When I moved from a fairly coarse grit of diamond paste to a finer one I noticed that scratches were developing between the hollow and edge and nowhere else even though I had cleaned the chisel with acetone. Working the hollow with a brass brush fixed the problem, so I think that it's reasonable to conclude that the rough unhardened steel in the hollow had trapped some particles.Quote:
Originally Posted by george wilson
James is concerned about a laminated Japanese tool, though. IIRC those are prepared without secondary bevels, so in the process of working the bevel you inevitably bring both the hard steel "bit" and the soft backing in contact with the lap/stone/whatever. I think there is a legitimate cause for concern there, but I also think that it can be mitigated by following reasonable cleaning procedures.
My thinking goes "stay with the stones" and leave the loose stuff out of it. Adding risk and mitigation to the process just adds time. There is of course the risk of wild or rogue particles to stones also but not imbedded diamonds or sic in the iron backing.Quote:
Originally Posted by Patrick Chase
Jim
For some sharpening is a chore they would rather avoid if at all possible.
For some sharpening is a pleasing break in their woodworking routine.
Then there are those who approach the refinement of their edges as if it was a modern religion and every commandment must be followed to the Nth degree.
To me, sharpening is usually a pleasant task without the complications of scientific sizing of various media.
Keep It Simple Sherlock and it will get done.
jtk
- Sherlock was substituted for the word that is normally used at the end of KISS.