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How sharp is "sharp enough" for violin making?


Jeddi77
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24 minutes ago, Urban Luthier said:

I'm relying less on the wheel and compound these days.  I guess i've been a bit to aggressive but i find that after repeated honing on the wheel, my gouge bevels became rounded (dubbed?) and although razor-sharp, became difficult to use. 

I do most of my gouge sharpening on the stones now and very light honing on a leather strop. 10x mag and a bright light makes it easier to see that ones bevel goes the way to the edge of the cutting edge of the gouge

It's definitely easy to overdo the stropping. I don't have any issues with dubbing, personally, but it's possible with any non-rigid polishing stage if one isn't gentle 

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Here a couple of knives I've made using forged carbon steel from old laminated plane blades. One tested at 65 Rockwell and the other would be of similar hardness.

They have been ground down to solid hardened steel a bit less than 2 mm thick at the cutting end.

The bevels have been ground at about 16 deg. and sharpened at about 18 deg.

And, what I think is most important, the backs have been lapped smooth and flat at the cutting end.

The smaller one I did using a mixture of 1200 grit silicon carbide and 50,000 diamond paste with water on a piece of plate glass. The larger one was done on an aluminium plate down to 1200 diamond grit. It's not an easy process to lap even a small area such as this on steel this hard but I like the result.

I've tested both on some tough spruce and maple and they both show no sign of edge failure. Both were sharpened down to 5000 on a Shapton stone and finished with a cotton buff charged with chrome oxide.

 

DSC_0005.thumb.jpg.e5b145aa29f888aab2614de3924ed2a1.jpgDSC_0002.thumb.jpg.31b397bfe4f065da107980f905cde87a.jpg

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34 minutes ago, JacksonMaberry said:

Nice! But maybe grind one of them to a curved profile. I find such blades more useful for a wider variety of tasks, personally.

I've made others before out of different types of recycled steel in various shapes. A few I made from old Stanley plane blades and some of them didn't seem to hold up too well so I decided to make these.

I did make one bevelled both sides and it performs ok as well. But it is difficult to bevel both sides at a shallow enough angle to end up with an 18 deg. edge. But I'll probably try when the skin regrows on my fingertips.

I'm thinking a curved, single bevel edge might be the way to go. Of course ideally you need a left and right pair for each configuration.

 

 

 

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1 hour ago, Dennis J said:

I've made others before out of different types of recycled steel in various shapes. A few I made from old Stanley plane blades and some of them didn't seem to hold up too well so I decided to make these.

I did make one bevelled both sides and it performs ok as well. But it is difficult to bevel both sides at a shallow enough angle to end up with an 18 deg. edge. But I'll probably try when the skin regrows on my fingertips.

I'm thinking a curved, single bevel edge might be the way to go. Of course ideally you need a left and right pair for each configuration.

 

 

 

I've never cared for single bevel knives for anything in making, but other people swear by them for certain things. Different strokes is totally cool by me.

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On 5/31/2021 at 5:20 PM, Il Virtuoso said:

I own a shapton 16000 grit stone. Just dont buy it. It would make your edge worse if you do more than 10 passes on it. There is something called over honing which will make the edge very brittle. The brittle parts will break leaving a rough "saw-like" edge. You are better of buying another brand or even better some chromium buffing compound on mdf or leather.  Here's a video that demonstrates the problem I mentioned. Its about straigh razors but from experience I can tell you, that the same thing applies to the tools we use. 

https://www.youtube.com/watch?v=sn104Hib8I0

 

John Schmidt, any thoughts on why this happens?

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20 minutes ago, sospiri said:

What is happening here? Is it impurities or new agglomerates being formed?

My wild guess is that during prolonged honing, the wire edge is repeatedly produced, each time being flexed back and forth so many times that it breaks off and contaminates the sharpening stone, these larger metal pieces being what produces the trenches. I wonder it this would happen if the sharpening stone was rinsed or cleaned every few passes?

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15 minutes ago, David Burgess said:

My wild guess is that during prolonged honing, the wire edge is repeatedly produced, each time being flexed back and forth so many times that it breaks off and contaminates the sharpening stone, these larger metal pieces being what produces the trenches. I wonder it this would happen if the sharpening stone was rinsed or cleaned every few passes?

Would these metal contaminates be visible under a microscope?

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32 minutes ago, David Burgess said:

My wild guess is that during prolonged honing, the wire edge is repeatedly produced, each time being flexed back and forth so many times that it breaks off and contaminates the sharpening stone, these larger metal pieces being what produces the trenches. I wonder it this would happen if the sharpening stone was rinsed or cleaned every few passes?

David,

I agree with your explanation. I have the white Shapton glass. I notice that gray streaks quickly build up on the stones. I wipe these away with 2000 grit abrasive paper with water.

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I have a white Shapton stone which I no longer use because it just lost its cutting ability. Hard to draw conclusions about what the cause is.

As far as sharpening is concerned wide, flat sharpening bevels are not very practical especially when using finer grades of stones.

 

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I lap all my stones regularly on a granite slap using silicon carbide grit. I have no problems with my other Shapton stones but I'm skeptical about all the advertising hype and claims made around these sort of things.

I've started using a 5000 Shapton I have to finish sharpening the knives I'm making because it seems to be the best choice for that job. Some other stones are faster but they are just too soft for small blades.

 

 

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On 6/2/2021 at 2:07 PM, David Burgess said:

My wild guess is that during prolonged honing, the wire edge is repeatedly produced, each time being flexed back and forth so many times that it breaks off and contaminates the sharpening stone, these larger metal pieces being what produces the trenches. I wonder it this would happen if the sharpening stone was rinsed or cleaned every few passes?

I have a different theory, I think the Shapton 16K produces a very very fine burr which is super brittle. This burr breaks after a few passes on the stone, but not evenly, which is the reason why the edge is left wavy and rough. But then again this doesnt explain the aggressive scratch pattern on the bevel... I've heard people saying that the 16K isnt actually 16K and that it might contain a small amount of lower grit particles. Who knows...? All I can say is that i am not a fan of this stone, despite being buyest towards it (considering the amount I paid to get it).

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Shapton 16 k story.

I was in Norway when a hurricane dumped 10 inches of water on Laurinburg, NC. When I got home the water had receded. After a week, I finally got to clean everything in the shop. I found the Shapton sone in a box on the floor. Half of the stone was dissolved away. So these stones DO get dissolved by water.

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16 hours ago, violins88 said:

Shapton 16 k story.

I was in Norway when a hurricane dumped 10 inches of water on Laurinburg, NC. When I got home the water had receded. After a week, I finally got to clean everything in the shop. I found the Shapton sone in a box on the floor. Half of the stone was dissolved away. So these stones DO get dissolved by water.

Ofcourse they do which is why they are splash and go (not supposed to be soaked)...

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OK… here is my progress after NOT getting the Shapton 16000 stone. These pics are of a new Wood River 2 3/8” plane blade (1/8” thick) which I am honing for the first time. I spent about an hour with my Norton 8000 waterstone, often reflattening it. I wasn’t sure which grit to try at first, so I did spend some time with the 4000 stone, then back at it with the 8000. The back side is barely mirror-like. The bevel has seen the Tormek for a slight hollow grind, and I tried honing it as well, mostly on the the 8000 Norton waterstone. It’s definitely not ready, but I am taking off more metal in the center of the blade, and my stones are being reflattened and I am trying to evenly press on each corner of the blade. Tips? 

Since you’ve all convinced me that Shapton 16K is not worth it, I’ve purchased a variety of micro-abrasive sand “paper”… and a 10x lighted loupe. Should be arriving this week!  

QUESTION: Tormek sales video of their SJ-250 (4000 grit) waterstone/wheel says you can get the bevel to be mirror-like in ten minutes. Should I expect a hand sharpening experience on a stone to take longer? 

I’m hopeful the ‘scary sharp” papers are going to come to the rescue, with the loupe helping me check progress. I’m still wondering if the SJ-250 stone is a time saver, though. 

Thanks, all!

87B85367-4E9C-4234-A5EA-69263B12D425.jpeg

89B1AB28-6B37-4115-97BD-41E956467B5A.jpeg

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I'm still seeing a lot of grinding marks on the back of the blade. With a grind that rough, I think you'd be better off to put a micro-bevel on the back of the blade (using a shim to hone), than spending hours getting the back of the blade uniformly flat and smooth.

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1 minute ago, David Burgess said:

I'm still seeing a lot of grinding marks on the back of the blade. With a grind that rough, I think you'd be better off to put a micro-bevel on the back of the blade (using a shim to hone), than spending hours getting the back of the blade uniformly flat and smooth.

I agree, David, but I think the fundamental mistake here is not starting with a coarse grit stone to remove the grinding marks, then working up through the grits. 

It's madness to spend hours trying to flatten a blade on a 8000 grit stone.

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I think it would save you a lot of time (and frustration) to get some lower grit stones. I use 250, 1000, 4000, and 8000 grit stones. 

BC just beat me to posting, and I agree. If I'm not getting a burr in 10-20 passes I'm at the wrong grit. Generally, If I'm just dressing a blade that is still sharp I will just use the 8000 stone, Otherwise I start at the 1000, and drop to the 250 If I don't get quick results.  For your blade I would start at 250.

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I use a micro-bevel on the back of all my plane blades now, because it just takes too long to remove rounding from wear, by removing metal from the entire flat surface. This would work for the OP too, to quickly get rid of his grinding/machining ruts. No downside to doing it this way that I have been able to find.

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4 hours ago, uncle duke said:

Is that 25 or 30* bevel?  hint- make it even all the way across.

Unless the blade thickness is not the same, all the way across, in which case one would end up chasing their tail by trying to make the bevel width the same all the way across.

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13 hours ago, Jeddi77 said:

OK… here is my progress after NOT getting the Shapton 16000 stone. These pics are of a new Wood River 2 3/8” plane blade (1/8” thick) which I am honing for the first time. I spent about an hour with my Norton 8000 waterstone, often reflattening it. I wasn’t sure which grit to try at first, so I did spend some time with the 4000 stone, then back at it with the 8000. The back side is barely mirror-like. The bevel has seen the Tormek for a slight hollow grind, and I tried honing it as well, mostly on the the 8000 Norton waterstone. It’s definitely not ready, but I am taking off more metal in the center of the blade, and my stones are being reflattened and I am trying to evenly press on each corner of the blade. Tips? 

Since you’ve all convinced me that Shapton 16K is not worth it, I’ve purchased a variety of micro-abrasive sand “paper”… and a 10x lighted loupe. Should be arriving this week!  

QUESTION: Tormek sales video of their SJ-250 (4000 grit) waterstone/wheel says you can get the bevel to be mirror-like in ten minutes. Should I expect a hand sharpening experience on a stone to take longer? 

I’m hopeful the ‘scary sharp” papers are going to come to the rescue, with the loupe helping me check progress. I’m still wondering if the SJ-250 stone is a time saver, though. 

Thanks, all!

87B85367-4E9C-4234-A5EA-69263B12D425.jpeg

89B1AB28-6B37-4115-97BD-41E956467B5A.jpeg

I think you'd need to start on a 1000 grit stone to remove the mill marks before you move up to the 4K and 8K.

others have noted this above but if you put a tiny back bevel on the face of the blade (the side opposite the bevel) you can save yourself a lot of work.

some achieve this micro-bevel on the blade face by using the ruler trick - I use one of those thin rulers (got mine at Lie Nielsen) and place it under the blade at one end of the long edge of the stone and draw the plane blade up and down the length of the stone at the opposite end - this creates a micro bevel at the cutting edge because just the very tip actually touches the stone. Some pull the blade off and on the stone to achieve the same. 

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4 hours ago, uncle duke said:

Is that 25 or 30* bevel?  hint- make it even all the way across.

I wonder what others do but I now hollow grind all my plane blades at 30 degrees (even block plane blades) and sharpen free hand.

I find the a consistent blade angle helps muscle memory training. I also find it easier to get a burr honing a hollow-ground blade free hand. I've never really mastered using a honing jig - i have trouble with consistent registration in the jig and wind up with a bunch different angles on the bevel after several uses 

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