TandyPro - 35mm Japanese Style Flat Knife - Any Good?

[CalgaryJim]

On 2/12/2024 at 7:36 AM, Mablung said:

Those kinds of high-ish carbon stainless steels generally benefit from a higher-grit polish before stropping. I don’t know exactly why, but the ones I have used respond better to one more polishing increment before stropping. So, I’d polish it on an 8000-grit stone before taking it to the green compound, as you’ll reduce the scratch size imparted by the 4000 and then be able to smooth them out better on the strop. Also check the bevel angle to make sure it’s consistent. A loupe is very helpful for an edge like this that needs to be uniform. 

Thankss, good to know. I have been using a 1000/4000 stone set but I'll source an 8000 now as well.

[CalgaryJim]

On 2/12/2024 at 2:38 PM, Mablung said:

Appreciate the vote of confidence, and the point about the heat treatment is an important one that I omitted.  If the heat treatment is like that of my Stohlman-branded round knife from Tandy, it's a bit finicky.  That knife requires a great deal of polishing to get a really good edge.  I'm not sure whether it's 9Cr13MoV like the skiving knife you're looking at, @CalgaryJim, but the characteristics are very similar to a 8Cr13MoV folder I have (only slight differences in chemistry, but enough to make the 9 a bit tougher).

Something else I thought to add to my explanation, above, is to make sure you check the back side of the blade for a burr.  Be very consistent with the main bevel, but also be sure to remove the burr from the back of the blade.  Because the bevel is a chisel-grind, i.e., a single bevel, you won't take the burr off when you sharpen the other side of the bevel, because there isn't a second bevel.  Leaving that burr will cause issues swiftly.  As long as you're careful with the sharpening process, it ought to sharpen up decently.  Whether it retains the edge is a different matter, but smooth skiving seems to require a mirror-like polish on a carefully tapered edge.

Thanks for this also. What are the pros for a single bevel, if any?

[Mablung]

11 hours ago, CalgaryJim said:

Thankss, good to know. I have been using a 1000/4000 stone set but I'll source an 8000 now as well.

Norton makes a good 8000-grit waterstone, which I use. You can also consider a hard Arkansas stone. I have a couple Arkansas stones as well, one of which is an Ultra-hard black stone I use for final polishing on blades I want exceptionally sharp. Those aren’t measured by grit but by specific gravity and separated into hardness grades that correspond to the specific gravity. 

11 hours ago, CalgaryJim said:

Thanks for this also. What are the pros for a single bevel, if any?

A single bevel is helpful for something like skiving, where the back of the blade can lie more flat to the surface of the leather and slide along it while the cutting bevel pushes the cut leather up and away. A double bevel pushes the leather away in two directions, which is also workable for skiving. However, some people like a single bevel for skiving for the reasons I mentioned. A single bevel can also make it easier to cut along a straight edge, arguably; I do fine with a double bevel along a straight edge, but some people like having the flat blade back to place along the straight edge. 

[MarshalWill]

I made two skiving knives. One with a single bevel and one with a double bevel. They both work great but the single bevel seems to work better pushed along an edge, although I can use either.

[CalgaryJim]

1 hour ago, MarshalWill said:

I made two skiving knives. One with a single bevel and one with a double bevel. They both work great but the single bevel seems to work better pushed along an edge, although I can use either.

Thanks, good to know.