Archive for September, 2009

Taping the Spine of a Straight Razor – In a New Light

September 20, 2009

So I went to one of my knife makers yesterday in order to discuss the possibility of making a Japanese style straight razor for a member of the SRP. Everything was going fine with the design specs, and we started discussing the possible steel types, overall hardness, and thickness of the spine. This post is in relation to what happened when discussing the thickness of the spine.

Now, on the SRP, it seems a common mathematical figure that the spine of the knife should be 1/4 the thickness as the height of the blade, in other words, a blade that is 20mm high should have a 5mm thick spine. When we told the maker that we thought the spine should be 5mm thick, he said no, a 3mm thick spine should be sufficient.

Now let me just say that this maker knows his stuff. He is an expert sharpener and he really knows his steel. But like most Taiwanese people, he only shaves, well, not very often –  and he has no beard. He also revealed that he likes the Mach 3 ( the poor guy…) So my mind started to smell like smoke, and I developed a slight twitch while trying to figure out why he said only 3mm would be just fine!

At this point it should be noted that this maker, Mr. Wu (not Maestro Wu – same last name, but two entirely different people) is big on Chinese Philosophy, kung-fu and Tai-Chi. For a “blue collar” guy, trying to decipher in Chinese what he is saying is like me reading Shakespeare to him in English. His language is very high level and quite philosophical.  However, I had some help yesterday, and between us (and a handy little PDA language converter) we manged to get immediate translations. It should also be mentioned that we went to him seeking his expertise and input – I trust his knowledge and experience, and in 9 years of knowing him, he has been a constant and a huge source of knowledge.

Basically (and loosely translated) his reason was this: “Technical skills are the result of experience, and someone that has technical skills and experience doesn’t need to rely on the math. My skills are more philosophically influenced.” In other words, I’ve been making knives for a very long time, if you want a Japanese style razor that works, listen to me.

Don’t forget, we specifically wanted his input on this matter, and we opted almost immediately to go with his recommendation of 3mm.

OK, so the title of the post is Taping right? Well, in all of this discussion of the thickness of the spine, the western razor has a “built in jig”, and the 5mm thick spine is supposed to create the ideal angle of the bevel and edge. Mr. Wu’s 3mm argument was also followed by an intense discussion about edge angles on razors. Bottom line, he said that they were too thin. This made me think about another experiment with micro bevels and how members of the Badger and Blade were posting magnified edges. It is also influenced by the fact that I did sharpen up a reed knife (which this Mr. Wu makes for me) that has a 4.5 mm spine as a razor. (I know it’s a lot to take in.)

So I revisited taping because, in my mind and limited experience, taping seemed to be used to prevent spine wear, and to make sharpening faster. These reasons made using tape unappealing to me in the past – but – now, since taping can be used not so much as a micro bevel, (as the thread describes), but to purposely make the edge stronger while acting as a built in jig. (Is it really different? To me the reasoning makes it so)

I set a bevel on a Wade and Butcher wedge, did a light bread knife (ala Harrelson Stanley) Then added 2 pieces of tape (I found that 1 piece really didn’t alter the geometry “enough” for what I was attempting to do) and then set the new bevel on the Shapton 4K Glass Stone and moved on to the 8K, 16K and finally the 30K. No stropping. I did the same on the converted reed knife.

The shave with both blades was great. WTG, ATG. The beautiful part was that I usually need to use a reduced angle when shaving ATG, but I found myself just shaving, with no real regard for the edge angle to get results or to stop from ripping those stubborn hairs out from under my chin…

Looks like the 3mm will do just fine. I can’t wait to see the results of our prototypes from Mr. Wu.