Defective Waterstones??

[Matt Z Wilson]

I probably should have been more clear, I'm referring to only modern medical instruments. It is my mistake if you are refering to historical examples. However we should be clear in our distinctions. My straight razor has a polished edge, my disposables not so much. Surgical steel is all stainless, mostly 440 but some 410 depending on the instrument. I've never seen a high carbon steel scalpel in modern use. Undoubtedly scalpels used historically were carbon steel. Previous surgeons also did not have the benefit of electrocauteries, and used a scalpel for all cutting maneuvers and therefore sharpened their own instruments and probably stropped them. I've never been in a situation where a "toothed" edge similiar to a kitchen knife would have been helpful. The cleanest cut and the most control possible are paramount. Medical sterilization is undertaken with high pressure, heat and steam and would ruin what most of us consider a well honed edge. Scalpel blades used in modern medicine are all disposable, due to the possibility of various rare infections that can survive the autoclave (a different topic entirely). In fact, most of them are made from the scrap from decomissioned Navy submarines because of their high quality and consistent steel. Amputations are usually done with an oscillating bone saw, another item that does not have a polished edge, merely a machined one. Bone chisels have a high angle of about 45 degrees and are sharpend the same way as disposable scalpel blades, ground on a high grit wheel. In this case is boils down to economics, polishing an edge on a medical tool that has to be disposed of anyway is not economically sensible, especially when the tool gets dull, it can be replaced in a few seconds.

[george wilson]

Yes,my observations ae mostly based on historic examples due to my museum tool maker background. I bought a brand new bone chisel off of ebay last year. It is VERY soft,and not real sharp.It is probably 410 stainless. I'll never use it,having experimented with it. Months later,a guy came into my shop who was modifying a bone chisel for someone,and we got into a discussion of their requirements as to edge,hardness,etc..I refused to re temper the tool for him due to liability should anything be wrong with the temper in a surgical application later,which I might not have qualified to be messing with.

I had done resharpening of iris scissors,bone chisels,and a few other tools for a surgeon friend. The cost of resharpening those items was very high if you sent them back. I felt more confident in that situation,with the surgeon's direct instructions as to what was needed. And,I wasn't re hardening anything.

The responsibility of working on tools that are going to actually be used on a human weighs heavily.

[Wilbur Pan]

Wilbur,you did notice that the edge became smoother with finer acting stones used?

Yes. Did you notice that the finest scratch pattern was left by the natural Japanese waterstone, which leaves a matte surface to the face of the bevel? The Shapton 15000 and 30000 grit stones, which leave a mirror finish on the tool, and which left coarser scratch patterns than the natural Japanese waterstone, have abrasive particles that are about the same size as stropping compound, so one can conclude that the Japanese waterstone leaves an edge at least comparable to one achieved with a strop, even though one looks polished and the other does not. That's also been my experience trying tools sharpened with both techniques.

Are you defending waterstones that you spent a lot of money on?

I don't know why you are resorting to calling my motives into question, since I've been trying to provide real data to this conversation, but for the record, the most I've ever paid for the three fine grit natural Japanese waterstones that I have is $110. Whether you think that's a lot of money is a matter of opinion, but it seems to be in line with other fine grit manmade waterstones on the market. The natural Japanese waterstone I like using the most cost me $60.

Look, I'm not saying you can't achieve a very sharp tool edge by polishing with a strop. What I am saying is that you can get an equally good edge on woodworking tools with other sharpening techniques that also happen to leave a non-polished appearance to the bevel of the tool. I don't understand why you insist on denying this. Your method of sharpening must be very good to get the results that you do. There are other methods that are just as good.

By the way, as a physician, I also use scalpels on a regular basis, although not daily like Matt does. At work today, I checked the OR stockroom to see where our scalpels are sourced from. Some are made in the US, some are made in Mexico, some are made in India, and some are made in China. They all work equally well. I also checked the edges with a microscope and they seem to be sharpened by a grinding process, as Matt said -- not polished.

So you may want to rethink your crack about non-polished Chinese made blades. They work quite well in a hospital setting, and there is nothing about being made in China that precludes quality manufacturing. I find such sweeping remarks to be a reflection of being quite ill-informed.

[george wilson]

My remark was a joke,Wilbur. As I discussed with the other surgeon,surgical instruments seem to be in a separate class of requirements. He admitted that their edges would not be regarded as good by woodworkers,and they did not last long.

Razor blades are stropped,but you completely ignore that. As far as what you want to do with your edges,have at it. You and I do not seem to think the same way,so we should stop debating,don't you think.

I am certainly not ill informed about woodworking tools.If you have followed my posts,and looked at my work,you could see that for yourself. I am putting you on my ignore list,so keep on with your rather unique opinions. I will not see any of your replies.

[Mike Henderson]

I am putting you on my ignore list,so keep on with your rather unique opinions. I will not see any of your replies.

Wow - that seems pretty extreme. Wilbur simply has a different opinion from you but has been polite in expressing his point of view. I've always found Wilbur to be reasonable and more than willing to listen to opposite points of view.

We all learn by hearing rational, reasonable points of view, especially when they differ from our views.

Mike

[george wilson]

Mike,I think you are a nice person,and do not mind debating with you. But for him to call me ill informed was ill informed of him. I have a very long record of work,and results that I stand upon. Let's all end this silly discussion.

[michael osadchuk]

I started out sharpening with King stones but was not satisfied with the results I was getting. I eventually wound up with Shapton stones and a couple of DMT diamond plates and am reasonably satisfied with the results I'm getting now.

But it's hard for me to know if my initial dissatisfaction was due to my lack of skill or to the stones. I still have the King stones and will go back and sharpen on them to see what difference I see now between the King and the Shaptons.

Sorry I can't answer your question but I'll do some investigation with what I have. I understand your point that your skill is constant across the use of the two stones.

Mike

Mike,

Maybe you can add another "data point" to the discussion, if you have very fine grit Shapton stones (say 16k or 30k). Have you noticed the degree of matte/vs. shiny or mirror finish such Shapton stones leave, especially if you have ever sharpening a blade on the King manmade stones and then continued on to the very fine grit Shaptons?


I ask the question out of 'almost idle' curiosity (smiley, realizing how 'vigorous' the discussion has been).
I have same or similar experience as Wilbur Pan regarding very fine grit Japanese natural polishing stones leaving a matte finish, after previous sharpening steps on King 4000 and 8000 grit stones leaving mirror finishes; the edge from the Japanese natural polishing stones, though noticeably more matte than mirror, appear to be a bit sharper (especially when planing very difficult wood or trimming end grain) and seems to leave a more durable edge.

thanks

michael

[Mike Henderson]

Mike,

Maybe you can add another "data point" to the discussion, if you have very fine grit Shapton stones (say 16k or 30k). Have you noticed the degree of matte/vs. shiny or mirror finish such Shapton stones leave, especially if you have ever sharpening a blade on the King manmade stones and then continued on to the very fine grit Shaptons?


I ask the question out of 'almost idle' curiosity (smiley, realizing how 'vigorous' the discussion has been).
I have same or similar experience as Wilbur Pan regarding fine very grit Japanese natural polishing stones leaving a matte finish, after previous sharpening steps on King 4000 and 8000 grit stones leaving mirror finishes; the edge from the Japanese natural polishing stones, though noticeably more matte than mirror, appear to be a bit sharper (especially when planing very difficult wood or trimming end grain) and seems to leave a more durable edge.

thanks

michael

Michael - the finest Shapton stone I have is an 8,000. My next down is a 5,000. It's funny, but I often get a better shine off of the 5,000 than I do off the 8,000. I think it's due to what Jim K. was pointing out. You see a black slurry form on the stone which is actually a mixture of steel and broken off stone. If you keep working on the stone, without cleaning the slurry off, you'll get a good shine on your edge. [side note: I find the 8,000 Shapton to be "sticky" meaning that the iron (especially when doing the back) will stick to the stone when pushing the iron across the stone. The 5,000 doesn't do that.]

Often, I stop at the 5,000 stone. But that does depend on the tool - a smoother iron seems to benefit from a really good, finely polished edge, while a chisel used for chopping does not.

Sometimes I'll hone with green paste on leather which gives a really good shine.

Mike

[george wilson]

Mike,does stropping get the edge sharper? Of course,it partly depends upon correct stropping technique,which I am sure you have.

I strop on the hair side of calfskin glued to a board.The green compound is fine. What I do is change angles as I strop to prevent the build up of tiny ridges,and further reduce the "mountain chain" on the edge of the tool. I do not strop long enough to round over the edge,and I think any kind of buffing wheel,leather or cloth,ruins the sharper edge I got by hand stropping. They keep a Tormek out at the Woodcraft store.I ruined my pocket knife's edge twice on their leather wheel. Now,I leave it alone.

[Mike Henderson]

Mike,does stropping get the edge sharper? Of course,it partly depends upon correct stropping technique,which I am sure you have.

I strop on the hair side of calfskin glued to a board.The green compound is fine. What I do is change angles as I strop to prevent the build up of tiny ridges,and further reduce the "mountain chain" on the edge of the tool. I do not strop long enough to round over the edge,and I think any kind of buffing wheel,leather or cloth,ruins the sharper edge I got by hand stropping. They keep a Tormek out at the Woodcraft store.I ruined my pocket knife's edge twice on their leather wheel. Now,I leave it alone.

I sort of doubt if it does, George, and there's always the risk of dubbing the edge.

I do sharpen my carving tools on a powered leather wheel with that green paste and it works well. Of course, the primary angle on my carving tools is small so a bit of dubbing doesn't make the tool into a really high angle tool (for example, my primary angle may be 20* and the dubbing makes a 30* "microbevel"). And I just haven't found another way to sharpen carving tools as quickly and easily as that. Through time and experience I think I can control the dubbing somewhat - but it is always there.

But for plane irons and chisels, I prefer to use them straight off the stone.

Mike

[george wilson]

I know others that think dubbing results from stropping,and it does,if you don't use due care,and a minimum of stropping. Pfiel carving tools arrive with pretty sharp edges,but they are really dubbed from the factory use of buffing. I always have to redo their edges,though they are my favorite carving tools.

[Wilbur Pan]

Michael - the finest Shapton stone I have is an 8,000. My next down is a 5,000. It's funny, but I often get a better shine off of the 5,000 than I do off the 8,000.

Another funny thing/coincidence: today I picked up a replacement Hock blade for some Stanley planes I have, and used my Shaptons to get them sharpened up. I had exactly the same experience. The 5000 Shapton left a nice shine, the 8000 Shapton left an "oily" appearance to the shine.