Thread: Negative rake scrapers.......

G'day smiife. I sharpen my NRS at about the same angle as the skew, 30 deg on each side. Sharpened this way it wont hog off wood but when it's sharp it cuts fine wispy little shavings that will blow in the wind. Only use it for removing tool marks or tear out prior to sanding.
I have a look on the sawmill creek site occasionally and this topic comes up from time to time. One of those things where everyone has their own opinion about what works best. I don't have enough NRS's to have different grinds and have stuck with the angles that it came with as that works for me. But what you have done obviously works, cant fault the finish.

Tony

Much the same as Tony, used to remove tool marks and tearout. Kept sharp, whispy shavings, more a finishing tool then a hogging tool for me.

Several NRSes are my normal finishing tools on hard stuff (soft wood is either a bowl gouge if I am on top of my game that day or a sheer scraper). I like scrapers!

And they (along with several carbide tools and some skews used as NRS scrapers) are my go-to for turning resin, which I do a fair bit of.

Cheers,

Danny

Originally Posted by tony_A

G'day smiife. I sharpen my NRS at about the same angle as the skew, 30 deg on each side. Sharpened this way it wont hog off wood but when it's sharp it cuts fine wispy little shavings that will blow in the wind. Only use it for removing tool marks or tear out prior to sanding.
I have a look on the sawmill creek site occasionally and this topic comes up from time to time. One of those things where everyone has their own opinion about what works best. I don't have enough NRS's to have different grinds and have stuck with the angles that it came with as that works for me. But what you have done obviously works, cant fault the finish.

Tony

Originally Posted by Pat

Much the same as Tony, used to remove tool marks and tearout. Kept sharp, whispy shavings, more a finishing tool then a hogging tool for me.

Originally Posted by rtyuiop

Several NRSes are my normal finishing tools on hard stuff (soft wood is either a bowl gouge if I am on top of my game that day or a sheer scraper). I like scrapers!

And they (along with several carbide tools and some skews used as NRS scrapers) are my go-to for turning resin, which I do a fair bit of.

Cheers,

Danny

Hi guys , thanks for your replies , I found that the edge didn, t last too long , so lots of trips to the grinder , but certainly worth the effort I found ,
I feel a lot more confident now with a scraper than I did before , wish I had done it years ago

Interesting. Something I must turn (pun?) my attention to shortly. The correct use of scrapers and angle options, sharpening etc. Just now getting pretty good with sharpening and using my bowl gouges. Forget the skew chisel. So much to absorb.

Originally Posted by smiife

Hi guys , thanks for your replies , I found that the edge didn, t last too long , so lots of trips to the grinder , but certainly worth the effort I found ,
I feel a lot more confident now with a scraper than I did before , wish I had done it years ago

Yep, one or two passes, sometimes I cheat and touch the edge up with a #600 hone, is working on a soft wood. Eucy's are grinder retouches only.

I was going to make some comments but then decided what would be more useful is to provide links to Doc Green's excellent articles on scrapers and scraping.

Scrapers Part 1

Scrapers Part 2

Scrapers Part 3

IMO, his articles are well informed and full of sound advice.

If I have any quibble with anything in his articles it is his mention of using old files as scrapers. Scraping puts far less pressure on the tool than other methods, but blank HSS is so relatively cheap now, so why take any risk at all.

Myself, I use a shear scraper for final finishing 'cuts' with an included angle of less than 35°.

Originally Posted by NeilS

Myself, I use a shear scraper for final finishing 'cuts' with an included angle of less than 35°.

G'day Neil, an interesting read. How do you present your shear scraping tool to the work ?
I use a shear scraping technique based on one of Robo Hippie's vids. I use a regular curved scraper with a single bevel angle about 75 degrees. Tool is tilted to about 45 degrees and handle dropped probably at about 45 degrees as well. Tool is lowered onto the wood so the bevel is riding and then rotated until the edge just starts to cut. I raise a burr on the tool when shear scraping.

Tony

[QUOTE=Hardenfast;125485ting. Something I must turn (pun?) my attention to shortly. The correct use of scrapers and angle options, sharpening etc. Just now getting pretty good with sharpening and using my bowl gouges. Forget the skew chisel. So much to absorb.[/QUOTE]

Hi Wayne , yeah , It, s a lot to take in , but interesting too!

Originally Posted by Pat

Yep, one or two passes, sometimes I cheat and touch the edge up with a #600 hone, is working on a soft wood. Eucy's are grinder retouches only.

Hi Pat , I didn, t try the diamond card , have to remember next time .....

Originally Posted by NeilS

I was going to make some comments but then decided what would be more useful is to provide links to Doc Green's excellent articles on scrapers and scraping.

Scrapers Part 1

Scrapers Part 2

Scrapers Part 3

IMO, his articles are well informed and full of sound advice.

If I have any quibble with anything in his articles it is his mention of using old files as scrapers. Scraping puts far less pressure on the tool than other methods, but blank HSS is so relatively cheap now, so why take any risk at all.

Myself, I use a shear scraper for final finishing 'cuts' with an included angle of less than 35°.

Hi Neil , that was very Interesting , thanks for the links , I hadn, t heard of him before , when you say included angle of 35º, does that mean equal angle on each side ?

Originally Posted by tony_A

G'day Neil, an interesting read. How do you present your shear scraping tool to the work ?

Approximately 45°, Tony.

Handle on the level.

Originally Posted by smiife

...when you say included angle of 35°, does that mean equal angle on each side ?

The term included angle refers to the angle between the two bevels.

https://www.mathopenref.com/angleincluded.html

See the first image under the heading Scraper with 35° Included Angle in Doc's Part 3.

Scrapers Part 3

The scraper on the right side of that image has an included angle of 35°, as illustrated.

My included angle can get down as low as 25°.

The burr is very fragile at such a low included angle so I raise and refresh it with a fine grit diamond plate, while standing at the lathe, which partly acts as a burnisher that gives a more resilient burr.

Some time ago I posted on this forum my test results on the durability of various burrs and magnified images of them. I'll see if I can find it and provide a link, although I expect the images will have gone in the 'big image vanishment'.

Bringing the top bevel to a very high level of polish before raising a burr is definitely beneficial to the durability of the burr. Once done it doesn't have to be done again for a very long time unless you are of the school that wants to remove the burr before raising it again, of which I've never been a member.

Originally Posted by NeilS

Some time ago I posted on this forum my test results on the durability of various burrs and magnified images of them. I'll see if I can find it and provide a link, although I expect the images will have gone in the 'big image vanishment'.

As expected the images are no longer there, so the thread has less value without them, but for what it is worth, here is the link.

A brief history of the burr

Originally Posted by NeilS

Approximately 45°, Tony.

Handle on the level.

Thanks Neil. Will give this a try.

Tony

Originally Posted by NeilS

As expected the images are no longer there, so the thread has less value without them, but for what it is worth, here is the link.

A brief history of the burr

PS - post #16 has just a few of the retrieved images, which I resurrected back in Sept 2018.

I seem to be starting to repeat myself..... that's a worry for all concerned!!!