Jump to content
Maestronet Forums

How sharp is "sharp enough" for violin making?


Jeddi77
 Share

Recommended Posts

Hi, everyone! I've been enjoying reading tips and insights from this forum. I've never made a violin, but played one for many years, even a number of "new American" violins. I've been preparing to make violins myself (gathering tonewood, tools, books, patterns), but a main detail I've not been able to achieve is what grit of stone will give me tools that are sharp enough to do high level work as a luthier of violins? When I look for "sharpening" threads here, I'm overwhelmed by the amount of times that word is used!

I'd like to have the fastest way to a sharp, repeatable edge. I do not enjoy sharpening for a long time, although I have spent hours in learning what not to do! I think I have enough gear to do it (perhaps too much), but maybe not: 

Off-brand diamond stone: 300/1000

Norton sharpening stones: 250/1000 and 4000/8000 + flattening stone (which I had to flatten with my diamond stone)

"old" green Tormek grinder with basic gray stone (250 - 1000), with leather stop wheels and "metal polish" paste. Many jigs, too!

"Green" polishing compound stick for strop. Currently, I am making "another" strop because I'm not sure the first one I've made is adequate (soft-ish leather)

NEW "accu-finish" 6-inch diameter diamond wheels: 60 and 100 grit that I've built a station for, including a hand grinder and tool holder.

 

I have been doing... 

GRINDING with the tormek (coarsest grade)

HONING with the diamond/norton stone 1000, then 4000, 8000

and not very clear on how to use a strop effectively. 

I think POLISHING with home-made strop and green compound could work. I haven't figured out whether I like the strop wheel on the tormek. Any tips would be helpful if anybody here uses one. I "fear" I have put the wrong kind of paste on the leather wheel and ruined it, but I don't know. 

 

The tormek could possibly be sold if my hand grinder came into play (60/100 grit diamond), then do the rest on the stones. 

 

I'm fairly good with my hands, but having never needed to sharpen tools before, I'd like to zero in on...

What can I do without from my current gear? 

Is 8000 grit good enough?

Is a stop with compound a decent substitute for a higher grit stone (like 16000+)?

 

Thanks, all!

 

Link to comment
Share on other sites

  • Replies 106
  • Created
  • Last Reply

Top Posters In This Topic

Personally I find the very best tool is a 5-10x loupe and a bright light - you can easily see whether you have an consistent scratch pattern at the cutting edge and that the burr has been removed.

For sharpening  I don't think you need a lot. I find the Tormek useful for grinding back and shaping tools to the desired angle and or shape. A 1000 grit stone for honing, a 4000-8000 one for polishing and the green compound with a leather strop for final polishing. I use  1000 and 16000 shapton glass stones. 

Link to comment
Share on other sites

13 minutes ago, Urban Luthier said:

Personally I find the very best tool is a 5-10x loupe and a bright light - you can easily see whether you have an consistent scratch pattern at the cutting edge and that the burr has been removed.

That's what I put high reliance on, too. A burr can cut hair really well, but will bend over or break off when subjected to serious wood-cutting duty, instantly producing a messed-up cutting edge.

Link to comment
Share on other sites

16 hours ago, Jeddi77 said:

 

 

I have been doing... 

GRINDING with the tormek (coarsest grade)

HONING with the diamond/norton stone 1000, then 4000, 8000

and not very clear on how to use a strop effectively. 

I think POLISHING with home-made strop and green compound could work. I haven't figured out whether I like the strop wheel on the tormek. Any tips would be helpful if anybody here uses one. I "fear" I have put the wrong kind of paste on the leather wheel and ruined it, but I don't know. 

 

The tormek could possibly be sold if my hand grinder came into play (60/100 grit diamond), then do the rest on the stones. 

 

I'm fairly good with my hands, but having never needed to sharpen tools before, I'd like to zero in on...

What can I do without from my current gear? 

Is 8000 grit good enough?

Is a stop with compound a decent substitute for a higher grit stone (like 16000+)?

 

Thanks, all!

 

I wouldn't want to be without my Tormek for grinding/reshaping.

The approach you describe sounds perfectly reasonable. You certainly don't need a stone that's any finer than 8000 grit. Not convinced stropping would improve on what you'd get with the 8000.

I just do 600/1000 diamond followed by strop or 8000 stone. 

I agree with the guys above about the wire edge, although I don't do a visual inspection.

 

Link to comment
Share on other sites

How well a tool will cut is solely a function of geometry. If you have two  flat planes which meet at a consistent angle all the way to the edge of the tool then it will cut. The exact angle required to cut with minimal force is determined by the nature of the material being cut and the angle of approach. There was a discussion here some time ago concerning this which delved fairly deeply into the mechanics.
 

The equipment you describe is more than adequate to sharpen wood working tools. The finer grit stones are only to remove microscopic variance in the angles caused by material being either broken or torn away from the edge or bending away from the edge instead of being removed cleanly (wire edge). However any rounding of the angles no matter how small will make the tool cut less well. I recommend looking at a book on basic machine tool technology for explanations of the geometry which is of course much more crucial and unforgiving in metal cutting than in wood.

Link to comment
Share on other sites

Not too experienced, but I find a 1000 stone followed by stropping to be perfectly adequate. I think the properties of the tool itself are more important. Is it soft enough that sharpening doesn't take all day, but hard enough to retain an edge? Is the angle of the grind appropriate for the intended use? Et cetera.

Link to comment
Share on other sites

1 hour ago, Urban Luthier said:

Personally I find the very best tool is a 5-10x loupe and a bright light - you can easily see whether you have an consistent scratch pattern at the cutting edge and that the burr has been removed.

For sharpening  I don't think you need a lot. I find the Tormek useful for grinding back and shaping tools to the desired angle and or shape. A 1000 grit stone for honing, a 4000-8000 one for polishing and the green compound with a leather strop for final polishing. I use  1000 and 16000 shapton glass stones. 

Will i be able to see a burr that i can't feel with my thumb? I might purchase a triplet loupe if this will assist.

When i finishing sharpening i was always taught to feel and make sure their was no burr.

Link to comment
Share on other sites

"I find a 1000 stone followed by stropping to be perfectly adequate"

It's possible that you may not know what you're missing. I do a hollow grind with a white aluminum oxide wheel, followed by 1000, 4000, 8000, 12,000, and a quick stropping with green chrome oxide. Done properly, it doesn't take more than a minute or two with each grit. It's sometimes hard to quantify sharpness but this test has been discussed here:

"Make a loop 40 weight rayon thread and attach it to a weight (say 60-100 grams). Twenty U.S. nickel coins or 40 pennies weigh 100 grams. An edge that cuts the thread (without slicing) at 65 grams is super sharp, sharp enough for easy woodcarving. 85 g. is sharp enough for almost any woodworking task."

I go for 65 grams force. With a properly tuned plane, and a super sharp blade, I can cut ribbons that you can easily read print through.

Link to comment
Share on other sites

43 minutes ago, CaseyLouque said:

Will i be able to see a burr that i can't feel with my thumb? I might purchase a triplet loupe if this will assist.

Absolutely, with a little practice. A burr that is big enough to feel with your thumb is a mega-burr.

Link to comment
Share on other sites

1 hour ago, nathan slobodkin said:

How well a tool will cut is solely a function of geometry. If you have two  flat planes which meet at a consistent angle all the way to the edge of the tool then it will cut. The exact angle required to cut with minimal force is determined by the nature of the material being cut and the angle of approach.

I very much agree on focusing this idea of surfaces meeting.  And, the use of a 10x loupe and strong light to see what's going on.

As an aide to seeing progress, I also often blacken the surface I'm working.  This can be helpful, but not always. The loupe is more certain for confirming things.

I also distinguish between the different tasks of making the two surfaces meet well at a good angle, and making those surfaces very smooth -- between sharpening and honing is how I think of it.

I think working the surfaces truly is much more important.  I do like also getting the surfaces stroped and smooth to make a bright mirror surface, but I don't mind scratches from earlier grits remaining to some small extent.  Completely removing scratches seems like the least significant detail, and it can cost a good deal of time.

The last detail of my sharpening is perhaps just ritual. I've no idea how much it really matters.  But when I strope, I count the strokes on each surface of the blade, then switch sides.  And I reduce the count on each side as I finish.  So it might go something like 16 16 8 8 4 4 4 4 2 2 2 2 2 2 1 1 1 1 1 1.

I fancy that switching sides and countinh down helps reduce chance turning the edge.

But I don't trust that really, so I check the cutting and check with a loupe.

It all goes very quickly.

Link to comment
Share on other sites

1 hour ago, FiddleDoug said:

"I find a 1000 stone followed by stropping to be perfectly adequate"

It's possible that you may not know what you're missing. I do a hollow grind with a white aluminum oxide wheel, followed by 1000, 4000, 8000, 12,000, and a quick stropping with green chrome oxide. Done properly, it doesn't take more than a minute or two with each grit. It's sometimes hard to quantify sharpness but this test has been discussed here:

"Make a loop 40 weight rayon thread and attach it to a weight (say 60-100 grams). Twenty U.S. nickel coins or 40 pennies weigh 100 grams. An edge that cuts the thread (without slicing) at 65 grams is super sharp, sharp enough for easy woodcarving. 85 g. is sharp enough for almost any woodworking task."

I go for 65 grams force. With a properly tuned plane, and a super sharp blade, I can cut ribbons that you can easily read print through.

I like the thread test approach Doug that would be easy to reproduce. 

My wife might be happy if i am cured of my Left arm pattern baldness that seems to appear. Always checked its ability to shave a patch of my arm hair in one swipe.

Link to comment
Share on other sites

14 minutes ago, David Burgess said:

Absolutely, with a little practice. A burr that is big enough to feel with your thumb is a mega-burr.

In this case 'seeing is really believing'. I got the idea of using a loupe from one of your posts a while back. I couldn't figure out why my block plane blade was dull after a few passes over ebony. Answer was simple - poor sharpening routine led to a 'false' sharp - as David notes above - a burr will dig into your nail, cut hair, newspaper and wood - but a burr means your blade isn't fully sharp and will also dull your cutting edge really quickly - you can see the affect through a loupe.

For what it is worth I find the Shapton glass stones do a good job of quickly removing the burr. I like these threads, I learn something new every time.

Link to comment
Share on other sites

19 hours ago, Jeddi77 said:

Hi, everyone! I've been enjoying reading tips and insights from this forum. I've never made a violin, but played one for many years, even a number of "new American" violins. I've been preparing to make violins myself (gathering tonewood, tools, books, patterns), but a main detail I've not been able to achieve is what grit of stone will give me tools that are sharp enough to do high level work as a luthier of violins? When I look for "sharpening" threads here, I'm overwhelmed by the amount of times that word is used!

I'd like to have the fastest way to a sharp, repeatable edge. I do not enjoy sharpening for a long time, although I have spent hours in learning what not to do! I think I have enough gear to do it (perhaps too much), but maybe not: 

Off-brand diamond stone: 300/1000

Norton sharpening stones: 250/1000 and 4000/8000 + flattening stone (which I had to flatten with my diamond stone)

"old" green Tormek grinder with basic gray stone (250 - 1000), with leather stop wheels and "metal polish" paste. Many jigs, too!

"Green" polishing compound stick for strop. Currently, I am making "another" strop because I'm not sure the first one I've made is adequate (soft-ish leather)

NEW "accu-finish" 6-inch diameter diamond wheels: 60 and 100 grit that I've built a station for, including a hand grinder and tool holder.

 

I have been doing... 

GRINDING with the tormek (coarsest grade)

HONING with the diamond/norton stone 1000, then 4000, 8000

and not very clear on how to use a strop effectively. 

I think POLISHING with home-made strop and green compound could work. I haven't figured out whether I like the strop wheel on the tormek. Any tips would be helpful if anybody here uses one. I "fear" I have put the wrong kind of paste on the leather wheel and ruined it, but I don't know. 

 

The tormek could possibly be sold if my hand grinder came into play (60/100 grit diamond), then do the rest on the stones. 

 

I'm fairly good with my hands, but having never needed to sharpen tools before, I'd like to zero in on...

What can I do without from my current gear? 

Is 8000 grit good enough?

Is a stop with compound a decent substitute for a higher grit stone (like 16000+)?

 

Thanks, all!

 

The way I check if my tool is sharp is I run the edge of my fingernail over the edge of the blade cutting edge. Not for the faint of heart, but you can get much more information about the edge this way than you could get by shaving arm hair or cutting paper. If there are any nicks or worn out spots you'll be able to spot them as the nail will "grab" onto them.

Also if your edge is properly sharpened it should feel like glass as your nail runs over the whole edge. If it's anything but absolutely smooth and glassy you either have a burr or you need to go to a higher grit stone. I guess you could use a loupe too, I have a zeiss stereoscopic microscope that I use from time to time but honestly I don't even bother any more. The finger nail method is  good enough for me.

Link to comment
Share on other sites

2 hours ago, FiddleDoug said:

"I find a 1000 stone followed by stropping to be perfectly adequate"

It's possible that you may not know what you're missing. I do a hollow grind with a white aluminum oxide wheel, followed by 1000, 4000, 8000, 12,000, and a quick stropping with green chrome oxide. Done properly, it doesn't take more than a minute or two with each grit. It's sometimes hard to quantify sharpness but this test has been discussed here:

"Make a loop 40 weight rayon thread and attach it to a weight (say 60-100 grams). Twenty U.S. nickel coins or 40 pennies weigh 100 grams. An edge that cuts the thread (without slicing) at 65 grams is super sharp, sharp enough for easy woodcarving. 85 g. is sharp enough for almost any woodworking task."

I go for 65 grams force. With a properly tuned plane, and a super sharp blade, I can cut ribbons that you can easily read print through.

Doug,

Of course I agree. 65 gram weight and 40 wt rayon thread. This is an objective measure that will keep you honest.

26 pennies is 65 grams.

Link to comment
Share on other sites

21 hours ago, Deo Lawson said:

Not too experienced, but I find a 1000 stone followed by stropping to be perfectly adequate. 

I was curious about this so did a quick test. I sharpened a chisel using a Shapton 1000x waterstone (removing the mirror polish I had on the back of the chisel). Then stropped it 10 times on each side using a leather strop loaded with Micro-Gloss polish. This edge easily passed the 65 gram test using 40wt rayon thread mentioned above. Then I made 20 cuts on the end of a soundpost (all cuts were clean with no scratch lines) and it still passed the 65 gram test. Then I made another 20 cuts on the end of a soundpost but this time chiseling down onto a green cutting mat. After that I was able to lift the 65 gram weight off the bench about an inch before it broke. I then stropped it 5 times on each side and it easily passed the test again. The test was very limited but the edge did seem "perfectly adequate" as Deo said. I might try sharpening some other tools like this and see how they do under more real world usage.

Link to comment
Share on other sites

3 hours ago, DarylG said:

I was curious about this so did a quick test. I sharpened a chisel using a Shapton 1000x waterstone (removing the mirror polish I had on the back of the chisel). Then stropped it 10 times on each side using a leather strop loaded with Micro-Gloss polish. This edge easily passed the 65 gram test using 40wt rayon thread mentioned above. Then I made 20 cuts on the end of a soundpost (all cuts were clean with no scratch lines) and it still passed the 65 gram test. Then I made another 20 cuts on the end of a soundpost but this time chiseling down onto a green cutting mat. After that I was able to lift the 65 gram weight off the bench about an inch before it broke. I then stropped it 5 times on each side and it easily passed the test again. The test was very limited but the edge did seem "perfectly adequate" as Deo said. I might try sharpening some other tools like this and see how they do under more real world usage.

For the two surfaces to make a perfectly straight approach to edge, so for actual sharpening, the coarser work is the most important.  Your coarse sharpening should be perfect.

As the grits get finer, the more it's about smooth the surface rather than perfecting the shape and approach to the edge.  And the greater the chance that your work will round the edge rather than perfect a straight clean approach.

I always sharpen to over 1000, and usual to 2000 or 3000.  Then I strope.

I agree that 1000 can be quite serviceable and durable.

Link to comment
Share on other sites

My general routine these days is to go from honing on a 2000 Shapton stone, directly to a strop. I have courser stones than the 2000, but have not found that they remove metal any faster, just leave deeper scratches.

Yes, any sort of stropping will round the edge a little bit, but if it isn't taken too far, I have not found it to be a problem

Link to comment
Share on other sites

On 4/22/2021 at 10:09 AM, David Burgess said:

 ( ... ) A burr that is big enough to feel with your thumb is a mega-burr.

Thank you for this post.

In the first shop I worked in, there were only occasional spot checks of tools. My work was checked but never critically. When I started cutting posts, it was apparent that the burrs were not managed correctly.

Link to comment
Share on other sites

18 hours ago, GoPractice said:

Thank you for this post.

In the first shop I worked in, there were only occasional spot checks of tools. My work was checked but never critically. When I started cutting posts, it was apparent that the burrs were not managed correctly.

Thread tests. arm shaving and loupe and light can be useful but ultimately how the blade cuts is the only thing that matters. If you are used to very sharp tools you quickly notice when they become dull but unless you already know the feel of sharpness you can’t feel the difference.

Link to comment
Share on other sites

Glad to see a sharpening thread pop up. I think it's always worth revisiting, because it's the foundational skill of the work. If you cannot sharpen well and quickly, everything else will be a frustration. Thanks to all for your thoughts. Some good info in here. 

Sharpening can become something of a religious obsession. Most critical is to arrive at an easily reproducible, successful method, and stick with it.

Link to comment
Share on other sites

Getting a good edge on gouges and chisels depends on a few basic fundamentals. Chisels are fairly straightforward but it is very important to get the underside of the blade flat and smooth.

Old forged firmer and carving gouges were ground slightly hollow behind the cutting edge so that a slipstone could be used to prepare for honing or remove wire edges after honing. That hollow surface has been lost on a lot of old gouges but they can be restored by grinding if the rounding over is not too bad.

In the pics you can see how the slipstone has worked right up to the cutting edge. I use the aluminium discs with diamond powder and kero to flatten chisel backs. The coarsest grit I use is 325. They do need flattening occasionally but it is not hard to do with silicon carbide sheets.

 

DSC_0007.jpg

DSC_0005.jpg

DSC_0010.jpg

869120772_DSC_00052.jpg

Link to comment
Share on other sites

1 hour ago, Dennis J said:

Getting a good edge on gouges and chisels depends on a few basic fundamentals. Chisels are fairly straightforward but it is very important to get the underside of the blade flat and smooth.

Old forged firmer and carving gouges were ground slightly hollow behind the cutting edge so that a slipstone could be used to prepare for honing or remove wire edges after honing. That hollow surface has been lost on a lot of old gouges but they can be restored by grinding if the rounding over is not too bad.

In the pics you can see how the slipstone has worked right up to the cutting edge. I use the aluminium discs with diamond powder and kero to flatten chisel backs. The coarsest grit I use is 325. They do need flattening occasionally but it is not hard to do with silicon carbide sheets.

 

DSC_0007.jpg

DSC_0005.jpg

DSC_0010.jpg

869120772_DSC_00052.jpg

This is one of the countless reasons Karlsson makes the best gouges available today - they grind in that hollow. All the big name western european manufacturers I can think of do not.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.




×
×
  • Create New...