Which tools should retain a burr after sharpening?

[George Pagliarulo]

I know I have been asking some pretty basic questions. Thanks for your indulgence and thoughtful answers.
I am much more familiar with sharpening plane blades and woodworking chisels than lathe chisels. When sharpening these tools you sharpen until a wire burr is raised and then remove the burr. The only time a burr comes into play is with a card scrapper.
After reading a lot of sharpening posts I have a question about burrs and my understanding of them when it comes to lathe chisels. This is what I've picked up about burrs:

• scrapper chisels are treated like card scrappers, raise a burr and then leave it, it shouldn't be honed off.
• when a scrapper gets dull, rather than grind it, use a burnisher to raise another burr. Grind only when you can't burnish a burr.
• after grinding a skew, hone off any burr

What about other cutting tools like gouges? I assume that the bur is removed. Is that correct? What about parting tools?
-

 

[hockenbery]

You have good grasp on it
You will get different answers.

Most will agree on skews and scrapers
Skews - they need to cut both ways so the burr must be honed off.
Scrapers use the bur so it must be left from the grinder or raised mechanically.

For gouges you will find some who hone the burr off.
Gouges - I use off the grinder with the burr left.

Parting tool I use off the grinder burr up. I try to us it in a peeling mode most off the time

 

[Rick Urban]

I know I have been asking some pretty basic questions. Thanks for your indulgence and thoughtful answers.
I am much more familiar with sharpening plane blades and woodworking chisels than lathe chisels. When sharpening these tools you sharpen until a wire burr is raised and then remove the burr. The only time a burr comes into play is with a card scrapper.
After reading a lot of sharpening posts I have a question about burrs and my understanding of them when it comes to lathe chisels. This is what I've picked up about burrs:

• scrapper chisels are treated like card scrappers, raise a burr and then leave it, it shouldn't be honed off.
• when a scrapper gets dull, rather than grind it, use a burnisher to raise another burr. Grind only when you can't burnish a burr.
• after grinding a skew, hone off any burr

What about other cutting tools like gouges? I assume that the bur is removed. Is that correct? What about parting tools?
-

George,
I think of it more in terms of when does the burr matter and when it doesn't.
Skew: matters. Remove it (usually).
Negative Rake Scraper: matters. Keep it.
Others: doesn't matter (usually).

 

[Dean Center]

I have a suspicion that coming to woodturning from being a carver is a disadvantage. You may be thinking about edges similarly to carvers.

Imagine you have a 12" blank on the lathe, spinning at 1200 rpm, and you engage your cutting tool. In 3 seconds, your tool has cut 132 feet of wood. How long would it take you to cut 132 feet of wood with a plane or bench chisel? More than 3 seconds, I bet.

As Al says, scrapers keep the burr from the grinder or have one raised with a burnisher. Skews get the burr honed off. Gouges don't need the burr removed because when you use it, the burr is gone within seconds. Some folks prefer to hone it off anyway. It's a choice.

 

[George Pagliarulo]

“Gouges don't need the burr removed because when you use it, the burr is gone within seconds.”

Good point Dean. I never thought of it that way.

 

[Roger Wiegand]

None. Scrapers work better and longer if you hone the usually huge, ragged grinder burr off and then form a stronger, more uniform, more controlled one with a burnisher.

In a class I took a while ago we looked at gouges in a microscope after a little use. The burrs remained on the modern tool steels after quite a bit of use, contrary to expectation. At least in fine finish cuts it's possible to feel and see the difference that honing the burr off a gouge makes; the cut is smoother and the shavings less ragged.

 

[robo hippy]

With the skew, you can't 'hone' the burr off, unless your sharpening stone goes up into the 16000 range. You have to 'strop' it. For me, this is usually a piece of plywood or softer hardwood like alder with some stropping/polishing paste applied to it. With some metals it is possible to bend it back and forth several times and the burr will break off. Many will use leather as a stropping surface. You can go to a saddle shop and find boxes of scraps. Kangaroo, if you can find it, tends to compress less than other leathers. I would expect auto upholstery leather, which has 'fillers' in it would work well also. No need to get fancy for this. Big box stores have 'polishing' compounds. I think the black stuff is around 800 grit.

For scrapers, it depends. For most woods, the grinder burr is fine, and you can burnish it down and back up a couple of times before needing to go to the grinder. However, on some really hard woods, it works better if the burr is honed and stropped off. Saw a demo where the finish cut on some hard maple was done with a scraper that was treated this way. The surface was glass smooth.

For bowl gouges, I don't strop, hone, or burnish. A quick trip to the grinder works best for me. Most of the time, I use the 180 grit CBN wheel. Some times for softer woods, I go to the 600 grit wheel because it does make a small difference.

I have been venturing into flat work again, and hand planes and bench chisels. Many ways to do it, but all of those edges are stropped, and they are at a level of sharpness that would not work with turning tools.

robo hippy

 

[Dean Center]

In a class I took a while ago we looked at gouges in a microscope after a little use. The burrs remained on the modern tool steels after quite a bit of use, contrary to expectation. At least in fine finish cuts it's possible to feel and see the difference that honing the burr off a gouge makes; the cut is smoother and the shavings less ragged.

This kind of evidence based information means I'll have to reconsider my thinking. Thanks, Roger