Sign in to follow this  
NCLuthierWyatt

Scroll Gouges

Recommended Posts

I'm finding it helpful to have a scrap of spruce to test gouges on as I sharpen.  The tool should slide through with minimal effort and leave a perfectly smooth surface behind.  If there is any resistance or lines/grooves left in the surface then it could be sharper. 
Both sides of the edge should look like a mirror.  
 

Share this post


Link to post
Share on other sites
15 hours ago, Nick Allen said:

I find that that way of testing sharpness to be very unreliable. If there is high humidity about, or you are sweating, you could shave your arm hair with a spoiled cucumber just about as easily. 

Agree.

Shaving hair can be done with almost any shaped edge polished bright. Cutting wood requires accurate geometry to allow tool control and create proper chip curling. Even the slightest rolling of the edge creates an area where the wood must compress to allow the edge to cut.

 

 

 

 

 

Share this post


Link to post
Share on other sites
1 hour ago, nathan slobodkin said:

Agree.

Shaving hair can be done with almost any shaped edge polished bright. Cutting wood requires accurate geometry to allow tool control and create proper chip curling. Even the slightest rolling of the edge creates an area where the wood must compress to allow the edge to cut.

 

 

 

 

 

Nathan, please talk a little more about this. I am not sue about what you are saying. Thanks.

Share this post


Link to post
Share on other sites
17 hours ago, Nick Allen said:

I find that that way of testing sharpness to be very unreliable. If there is high humidity about, or you are sweating, you could shave your arm hair with a spoiled cucumber just about as easily. 

I have found it to be quite reliable. When one has done it enough times, one learns the differences between cutting wet hair, dry hair, and the different pressures required to cut the hair between a less sharp tool, versus a more sharp tool. It's an acquired skill which benefits from practice, not unlike so many other skills in our trade.

11 hours ago, violins88 said:

I use loops of 40 wt rayon embroidery thread attached to a 65 gram weight..

 

see this:  https://youtu.be/1Ve5ZjHNit0

Wouldn't that require multiple thread cuts to test all along the length of the blade? How long would that take?

Hair shaving, testing every part of the blade takes about 5 seconds or less. Wanna race? :)

Share this post


Link to post
Share on other sites
3 hours ago, violins88 said:

Nathan, please talk a little more about this. I am not sue about what you are saying. Thanks.

Unfortunately I still don't have the ability to draw using the computer so I will try to describe this in words.

A cutting tool is essentially a wedge which divides the material being cut into two parts; the part which you wish to keep and the waste you are removing which is technically called a chip. As the chip separates from the work there is a friction caused by the wedging action directly behind the actual ,microscopic level, cutting edge. If the chip is thin and therefore flexible it will curl away from the work relieving the friction and lessening the force required to push the tool. The included angle of the  two faces of the tool can affect how much the chip rolls and also can break the chip further relieving the friction.If the part of the tool (blade) facing the work is not 100% flat then in order for the cutting edge to follow a line the material just behind the  edge must actually be compressed before the cutting edge engages the work.

If you think of driving an axe  90 degrees into a tree the axe will simply stick and no chip is formed. If you tilt the axe 45 degrees or so a chip will be broken out leaving a clean cut on the other side. If you tilt the axe far enough you get progressively thinner chips until the point where the flat side of the axe is parralel to the side of the tree and no cutting is taking place.

As I said this is easily seen from a picture but a bit hard to describe. Just to head off some argument axes and scrapers are actually sharpened completely differently than chisels or plane blades but I hope the above explanation is clear enough

Share this post


Link to post
Share on other sites

Nathan,

Wow. You painted a great picture with words. I now understand. Thanks for taking the time.

Are you a machinist? Engineer?

Share this post


Link to post
Share on other sites
47 minutes ago, violins88 said:

Nathan,

Wow. You painted a great picture with words. I now understand. Thanks for taking the time.

Are you a machinist? Engineer?

Neither. Just a guy who paid attention in junior high shop class and have made many millions of chips over the past 50 years. There are some basic metal working texts that describe this stuff beautifully. I am not in my shop right now but I know there is one which I think is called "Machine tool practices" and also a wonderful little pamphlet from the South Bend Lathe Co. about lathe use. Wood is of course much more  forgiving than metal but the mechanics are the same and can be applied to both.

Share this post


Link to post
Share on other sites

I think bald patches on the arm make you look like you have some unpleasant skin condition.  I test sharpness by testing the angle the blade makes as it begins to catch on the surface of my thumb nail.

Share this post


Link to post
Share on other sites

Even fairly roughly sharpened or worn edges can shave hair just like well worn disposable shavers will. Might be a bit rough but still do the job. The best test I've found is to slice through newspaper by holding the sheet in my left hand and push the blade away in a slicing action. Because newspaper is a bit floppy and rough only a well sharpened blade will slice through it smoothly. Any small nicks along the edge will stop the blade cutting. Of course a lot of people don't buy newspapers so they might need to find something similar. I judge the sharpness by the sound produced by the slicing action. The better the edge the quieter the sound it makes is and I've found it to be the ultimate sharpness test. I can fairly reliably tell quite small differences in sharpness or quality of the edge by this method. It is not as practical a method with gouges, but sharpening requirements for those are not as straightforward either. I'm happy to get an even smooth edge with them. Sharpened properly they are a pleasure to use.

 

 

Share this post


Link to post
Share on other sites

To test the sharpening I prefer to observe the cutting edge with a magnifying lens to see if there are irregularities and if the stones have actually touched the edge giving it a mirror finish or not. But I think the only definitive test is in the real situation (which is what matters) by cutting the wood by feeling the flow of the cut and if the actual force necessary to push the tools into the wood is fine for the task they have to carry out. However each test is fine if you know its limits, but you need experience to know how to interpret it and to judge the difference between a tool that simply cuts and one that cuts more, so in the end you will notice it only when you use the tool in the real situation.

Share this post


Link to post
Share on other sites

This is a great thread and really shows MN at its best: basic, critical skills being shared by people with years of experience.

I used to use the hair method until I sliced off a substantial strip of skin while distracted. >ouch<

A piece of scrap wood now serves the same purpose. If the chisel cuts as described by Nathan, it is sharp enough.

 

Share this post


Link to post
Share on other sites
1 hour ago, ctanzio said:

I used to use the hair method until I sliced off a substantial strip of skin while distracted. >ouch<

 

That's why I use the cat. :D

Share this post


Link to post
Share on other sites

As for your arsenal of scroll gouges, don’t forget to add some palm gouges. I have good luck with Flexcut and Japanese Power Grip. The latter are very inexpensive and sharpen nicely.

Share this post


Link to post
Share on other sites

I am actually surprised at the answers of some experienced people. I use the tool. If it is sharp enough it is sharp enough. If not, I sharpen it.

Since I don't cut hair or string with them, those tests aren't  really relevant to me.

Share this post


Link to post
Share on other sites
13 minutes ago, Michael Darnton said:

I am actually surprised at the answers of some experienced people. I use the tool. If it is sharp enough it is sharp enough. If not, I sharpen it.

Since I don't cut hair or string with them, those tests aren't  really relevant to me.

My preference is to get an idea of the sharpness of the tool, before screwing up any work.

On some things, like a roughing gouge, there is little potential to mess up the work. On other things, like cutting the inside radius of the outer edge, the first cut with a dull gouge can mess things up, so I prefer to go in at least semi-informed.

Whatever an individual finds to work for them is fine with me.

Share this post


Link to post
Share on other sites
9 hours ago, David Burgess said:

That's why I use the cat. :D

I no longer have a cat.

I tried using the dog, but he saw what happened to the cat and stays out of the workshop.

Share this post


Link to post
Share on other sites
1 hour ago, Michael Darnton said:

I am actually surprised at the answers of some experienced people. I use the tool. If it is sharp enough it is sharp enough. If not, I sharpen it.

Since I don't cut hair or string with them, those tests aren't  really relevant to me.

It probably comes somewhere on the obsessive compulsive  disorder spectrum. I don't worry about chisels and gouges but I often check plane blades before I refit them to make sure I've got it right. I find it takes just about as much time to take the stones or steel plates and accessories out as it does to do the sharpening. I regrind the primary bevel regularly to keep the honing bevel narrow. It doesn't take more than a few seconds on the bench grinder and saves a lot of sharpening time.

 

 

Share this post


Link to post
Share on other sites

I just wanted to thank everybody who responded to my question re sharpening (geigenbuaer, it was very kind of you to provide those links).

Isn't it interesting how everybody has different ideas and practices? 

Share this post


Link to post
Share on other sites
On 3/25/2020 at 4:03 PM, David Burgess said:

I have found it to be quite reliable. When one has done it enough times, one learns the differences between cutting wet hair, dry hair, and the different pressures required to cut the hair between a less sharp tool, versus a more sharp tool. 

I guess I just cut some wood to test it. If it cuts nice, then it's sharp. But that's just what works for me. 

Share this post


Link to post
Share on other sites

To the question originally posted, I bought a Stubai set before going to school -- probably on the advice of [redacted name drop].  I still don't use all of them, though I am of the school that appreciates having a wide range of options among my tools. And they look nice on the rack, which, after all, is why we buy tools, isn't it?  :D

But were I to do it again, I would buy perhaps 4 or 5 good gouges of the needed sweeps, bearing in mind that you will be making a cello at some point at VMSA.  Then, when you are finished with school, you can sell those to a school noobie and trade "up" to a set if you want.  Or you will have become so adept at making scrolls with a handful of gouges that you can spend your shekels on other cool stuff.  Sometimes I think it would be ideal to be able to make with a minimal tool collection,...Nah!

Share this post


Link to post
Share on other sites
3 hours ago, Julian Cossmann Cooke said:

To the question originally posted, I bought a Stubai set before going to school -- probably on the advice of [redacted name drop].  I still don't use all of them, though I am of the school that appreciates having a wide range of options among my tools. And they look nice on the rack, which, after all, is why we buy tools, isn't it?  :D

But were I to do it again, I would buy perhaps 4 or 5 good gouges of the needed sweeps, bearing in mind that you will be making a cello at some point at VMSA.  Then, when you are finished with school, you can sell those to a school noobie and trade "up" to a set if you want.  Or you will have become so adept at making scrolls with a handful of gouges that you can spend your shekels on other cool stuff.  Sometimes I think it would be ideal to be able to make with a minimal tool collection,...Nah!

I only use like 3 for violin and viola. But depending on the style of scroll you may need more. Strad style scrolls seem to want more variety with all of the different radii needed to be carved. I wouldn't be surprised if DG used like one gouge to do the whole job, though. 

Share this post


Link to post
Share on other sites
1 hour ago, Julian Cossmann Cooke said:

To the question originally posted, I bought a Stubai set before going to school -- probably on the advice of [redacted name drop].  I still don't use all of them, though I am of the school that appreciates having a wide range of options among my tools. And they look nice on the rack, which, after all, is why we buy tools, isn't it?  :D

But were I to do it again, I would buy perhaps 4 or 5 good gouges of the needed sweeps, bearing in mind that you will be making a cello at some point at VMSA.  Then, when you are finished with school, you can sell those to a school noobie and trade "up" to a set if you want.  Or you will have become so adept at making scrolls with a handful of gouges that you can spend your shekels on other cool stuff.  Sometimes I think it would be ideal to be able to make with a minimal tool collection,...Nah!

I use 9 or 10 gouges and 4 or 5 chisels for violin and viola scrolls, why use less when you can use more?:lol:

Share this post


Link to post
Share on other sites
2 minutes ago, Davide Sora said:

I use 9 or 10 gouges and 4 or 5 chisels for violin and viola scrolls, why use less when you can use more?:lol:

That's the spirit!

 

Share this post


Link to post
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...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.