Good to hear from you again Mr. Sharpco and great timing for your post! Don't know if the problem is the steel but it could play in to the equation. We've recently had two complaints from straight razor users here with exactly the same problem. Don't know what sharpening angle was used in your case but the angle used in our customer's case was 7 degrees. When the measurement was conducted successfully with these customers the edge sharpness was around 15. That's an incredibly small amount of force being applied to the edge but in some cases, apparently enough to fold and then dent the edge.
This is not a question of edge sharpness but rather one of edge stability. The sharper the edge the less force required to sever the test media. Sharper edges should make the edge less prone to folding because less force is used during the test. The scientific community measures equally sharp microtome edges every day with BESS test media with no problem. Tailmotor registers 10's with his straight razors and has done so, to our knowledge, without difficulty. We do remember though that KG sharpened a knife at 10 or eleven degrees and dented the edge during testing.
BESS test media is constructed of a blend of polymers and requires less force to sever than most sewing threads. If an edge won't cut thread without failing, what good is it? We'll tell you what it might be good for - shaving. This could be a case of "you can't get there from here". At BESS 10-15 you are already running out of scale. If the edge is so structurally weak that 15 or 20 grams of force causes it to fold, it just might be non-testable with our instrument.
Somehow Feather mass produces DE razor blades in the BESS 20 - 30 range that never dent during testing. We would be very interested, if you continue to experiment with this straight edge, in finding out what works and what doesn't. With an edge that is sub BESS 30 you only have to touch the edge to the test media before it severs. Just the weight of the razor itself should be more than enough to sever the test media assuming the edge doesn't fold over in the process.
How much is 10 grams of force? You can blow hard on the platform of a PT50A or B and get a reading of 10 grams.
(05-30-2019, 06:04 AM)SHARPCO Wrote: Today I sharpened straight razor. My customer said it was made in 1910-1945.
Atoma 400 -> Atoma 600 -> Atoma 1200 -> Spyderco Fine -> Spyderco UF -> Nanocloth strop(Tormek PA-70) -> kangaroo strop(diamond emulsion 4 micron) -> kangaroo strop(diamond emulsion 0.5 micron) -> kangaroo strop(diamond emulsion 0.025 micron)
It was very sharp. But couldn't cut test media and I have to stop testing at 155 BESS. When I checked edge, it was a little collapsed.
I think there is a problem with blade steel.
Sharpco, in my understanding it may be caused by so called “finishing burr” which sometimes occurs after stropping on leather saturated with submicron abrasives. It would be good to make sharpness measurements after honing on Spyderco UF, but before stropping.
(05-30-2019, 06:04 AM)SHARPCO Wrote: Today I sharpened straight razor. My customer said it was made in 1910-1945.
Atoma 400 -> Atoma 600 -> Atoma 1200 -> Spyderco Fine -> Spyderco UF -> Nanocloth strop(Tormek PA-70) -> kangaroo strop(diamond emulsion 4 micron) -> kangaroo strop(diamond emulsion 0.5 micron) -> kangaroo strop(diamond emulsion 0.025 micron)
It was very sharp. But couldn't cut test media and I have to stop testing at 155 BESS. When I checked edge, it was a little collapsed.
I think there is a problem with blade steel.
Sharpco, in my understanding it may be caused by so called “finishing burr” which sometimes occurs after stropping on leather saturated with submicron abrasives. It would be good to make sharpness measurements after honing on Spyderco UF, but before stropping.
Jan
Since that razor sharpening was the my first trying, you are likely to be right. But I don't know what I did wrong.
Thanks Jan or maybe what some would call a wire edge Sharpco. Some straight edge guys tell us that some straight edge guys create and then shave with wire edges. No opinion on that assertion from us. Here's a picture taken at 400X by one of these customers. By our calculation the notch created is about .2mm deep or about the diameter of the test media.
The challenge, should you elect to accept it, Sharpco is this: We know that structurally sound edges measuring 10 on the Bess can and are created. If you could determine what does and does not work with straight razors it would be very beneficial to a number of people. Perhaps the solution is just as simple as Jan proposes or perhaps there are other elements to this as well.
05-31-2019, 01:41 PM (This post was last modified: 05-31-2019, 01:51 PM by grepper.)
I have no experience with straights, but as Mr. Jan suggested, burr was my first thought too. Oddly, burr can be "sharpened" to an extremely sharp edge. That would be great if it were not so weak and flimsy. For all I know burr might be strong enough to shave with but I would think that the edge would dull/roll far more quickly than a clean edge. While razor edges are very thin and structurally lacking, it seems difficult to think that they could not cut test media without caving in.
Just out of curiosity, what is the sharpening angle?
Just for grins and comparison:
US nickel (5 cent piece) = 5 g
US dime (10 cent piece) = 2.268 g
US quarter (25 cent piece) = 5.67 g
(05-31-2019, 09:55 AM)EOU Wrote: Thanks Jan or maybe what some would call a wire edge Sharpco. Some straight edge guys tell us that some straight edge guys create and then shave with wire edges. No opinion on that assertion from us. Here's a picture taken at 400X by one of these customers. By our calculation the notch created is about .2mm deep or about the diameter of the test media.
The challenge, should you elect to accept it, Sharpco is this: We know that structurally sound edges measuring 10 on the Bess can and are created. If you could determine what does and does not work with straight razors it would be very beneficial to a number of people. Perhaps the solution is just as simple as Jan proposes or perhaps there are other elements to this as well.
(05-31-2019, 01:41 PM)grepper Wrote: I have no experience with straights, but as Mr. Jan suggested, burr was my first thought too. Oddly, burr can be "sharpened" to an extremely sharp edge. That would be great if it were not so weak and flimsy. For all I know burr might be strong enough to shave with but I would think that the edge would dull/roll far more quickly than a clean edge. While razor edges are very thin and structurally lacking, it seems difficult to think that they could not cut test media without caving in.
Just out of curiosity, what is the sharpening angle?
Just for grins and comparison:
US nickel (5 cent piece) = 5 g
US dime (10 cent piece) = 2.268 g
US quarter (25 cent piece) = 5.67 g
I just put the side of the blade on the stone and strop. I had Laser edge protractor but I couldn't think measuring the edge angle.
06-04-2019, 03:47 AM (This post was last modified: 06-04-2019, 04:45 AM by Lutejones.)
Hello guys, new member here from Spain.
First of all I’m amazed with the quality of the information on this board, the scientific approach and the will to learn even discarding common stablished knowledge.
I don’t have a BESS tester yet but it will be my next knife related purchase, thanks to KG and the correlation he created between BESS and traditional sharpness tests I can suspect than my usual edges for pocket knives are on the neighbourhood of 80-100 BESS (push cutting rolling paper with the grain) and the best I can get around 30 BESS (feathering hair but not quite crosscutting rolling paper). Anyway,
I’ve been shaving with a straight razor for 7 years now and have restored 4 of them, the problem with the OP razor could be, discarding burr remnants, that the spine is quite a bit worn, lowering the effective honing angle.
You could tape the spine to raise the angle and try again or maybe you could benefit from the micro convexing Todd S. suggests on his blog scienceofsharp stropping on a hanging strop.
Hope it helps.
Regard from Spain,
Mateo
(06-04-2019, 03:47 AM)Lutejones Wrote: Hello guys, new member here from Spain.
First of all I’m amazed with the quality of the information on this board, the scientific approach and the will to learn even discarding common stablished knowledge.
I don’t have a BESS tester yet but it will be my next knife related purchase, thanks to KG and the correlation he created between BESS and traditional sharpness tests I can suspect than my usual edges for pocket knives are on the neighbourhood of 80-100 BESS (push cutting rolling paper with the grain) and the best I can get around 30 BESS (feathering hair but not quite crosscutting rolling paper). Anyway,
I’ve been shaving with a straight razor for 7 years now and have restored 4 of them, the problem with the OP razor could be, discarding burr remnants, that the spine is quite a bit worn, lowering the effective honing angle.
You could tape the spine to raise the angle and try again or maybe you could benefit from the micro convexing Todd S. suggests on his blog scienceofsharp stropping on a hanging strop.
Hope it helps.
Regard from Spain,
Mateo
Welcome and thank you for good tip.
Now that I hear you, I think it's a mistake not to use hanging strop. It would have removed the burr more effectively than the hard bench strop.
