Bevel angle for curved scraper?

[John Torchick]

Needing to polish up my skills for the interior of boxes. Today's turning was not good and my scraper that didn't do real good, either. It is curved on the end with a bevel curving on the left side of the tool. I'm wondering if the bevel needs to be improved. Bevel at the end is 51 degrees and same for the side which only goes down the side for about an inch, has a slight negative grind on the top. I'll see if a photo will help.

 

[John K Jordan]

Don't know what will work best for you, but I grind such NRS with the same bevel on both sides (30-deg for 60-deg included angle).



I don't like the curve on the end for what I do but often use a short flat. (I do have one ground with a rounded end like you show but rarely use it.)

Note that the curve on the side of the tip is a bit longer than the one you show. To get that extra curve I have to continue the bevel grind much further down the edge of the scraper blank.

I also make NRS angled or curved grinds on the tang (Thompson steel) - I never use these tools in a handle.

Making the bevels on both sides (like a skew) let me decide which side will be up.



These work extremely well inside and outside of bowls, boxes, platters, etc.

But I think the most important thing that makes a scraper work well is the burr. I had to do some experimenting at first with the type of burnisher, the angle, and the pressure. I use only the Arno burnishers now - they have several distinct advantages. When the burr starts to lose effectiveness I use an extra-fine Eze-Lap diamond hone to refresh the edge then add a new burr. This works for maybe 4-5 times before I go back to the grinder.

If everything is right I get "whisper" shavings from the wood.

This scraper grind even works well for boxes with "egg-shaped" interiors like this:


I should mention that along with these I often use small and large curved hand scrapers.

JKJ

 

[Don Stephan]

My "lidded box" scrapers are shaped just like yours. I only grind a single bevel and hone a number of times to restore the bevel before having to go back to the grinder. You might search among the Richard Raffan Youtube videos for box scraper.

 

[john lucas]

Bevel andle wont affect the quality of cut. Shear scraping does but its hard to do inside a box. The best finish by far is using the Hunter Badger as a bevel riding cutter on tge bottom and shear scraper on the sides. Watch my box video to see how it works. Its also the best bowl bottom gouge in my opinion. The Badger demo is near the end of the video.

View: https://youtu.be/koou0WIonio?feature=shared

 

[john lucas]

Bevel andle wont affect the quality of cut. Shear scraping does but its hard to do inside a box. The best finish by far is using the Hunter Badger as a bevel riding cutter on tge bottom and shear scraper on the sides. Watch my box video to see how it works. Its also the best bowl bottom gouge in my opinion.

View: https://youtu.be/koou0WIonio?feature=shared

 

[robo hippy]

I use an asymmetrical grind for my NRSs. It is 25 for the top bevel, and 55 for the bottom bevel. Note here, on my robo rest, the settings are 30 and 60 since my angles are off by 5 degrees. My theory is that the skew chisel type NRSs doesn't have enough metal under the burr to support it which is why I like the different angles. Some, like D Way prefer an upside down approach to the bottom bevel. II remember Jimmy Clewes saying that you get a sharper burr that way, but I don't know. I may need to play around with that some more....

robo hippy

 

[John K Jordan]

My theory is that the skew chisel type NRSs doesn't have enough metal under the burr to support it

I find a 60-deg angle well supports the burr. At least a burnished burr does (grinder burr is removed first). This is with Thompson CPM10V steel if that makes a difference.