1. Scrapers It’s All About the Bur
Eric L. Krum
First State Woodturners
Acacia exelsa, Ironwood, Australia

2. What is a Scraper
As the name implies Scrapers cut wood through a scraping or rubbing action
A Scraper with a bur along the edge will cut the wood fibers
A Scraper has two components
Shape of the cutting edge
Angle of the bevel
Can remove wood where other tools cannot reach
The thicker the shaft metal is the less vibration when cutting
Note: On new scrapers use a sander to remove sharp corners to make it easier to hold

3. What is a Scraper
Scrapers come in all sizes and shapes

4. Scraping Versus Cutting
The angle of the cutting edge to the surface of the wood and the presence of a bur determines if you are scraping or cutting
A bur on the cutting edge changes the angle of the cut
Scraping is where the wood fiber is sheared off
Cutting is where the wood fiber is cut and lifted off
Scraping induces shear failure on the wood fibers, producing dust or small chips and can leave a rough surface
Cutting is where the sharp edge slices the wood fibers producing shavings and a smooth surface

5. Scraping Versus Cutting
Bur

6. Setting the Bevel Angle
Mark the angle on the side of a piece of wood
Trim the wood to the angled line
Place the stick on the grinder platform and change angle till the angled end lays flat against the grinder wheel
Store the stick for future use

7. Producing the Bur Can produce a bur by:
Grinding
Honing
Burnishing
The bevel angle is based on the diameter of the object being cut, bottom of scraper should not rub on the wood
Can put double bevel of thick shafts
Optimal bur is created when the bevel is 70 to 76 degrees
A large bur can cause problems as it is too aggressive in cutting as the bur digs in when pressed against the wood

8. Grinding Bur is created by grinder
Finer the wheels grit the finer and stronger the bur is as the metal is continuous in the bur
80 grit produces a bur that is not straight, continuous or uniform in shape
It is common practice to:
Remove the bur using a diamond hone
Hone the cutting edge to get a smoother edge
Burnish a bur on the edge

9. Honing Honing can create a small bur but it does not last long
Use a stone or diamond plate in an upward motion to create the bur
Goal is to have a bur that is straight
A bur that is curled back will cut only when head of scraper is tilted down

10. Burnishing Burnish after grinding with 120 or finer grit
Can normally burnish a new bur on 3 to 5 times before regrinding
Burnish by rubbing edge with a round piece of hardened steel
Use care not to curl the burl over if burnishing by hand
Can add more pressure by using a pivot point
Pivot point

11. Maintaining the Bur 1- Flatten top of scraper, removing dull bur
2- Grind new edge and bur
3- Hone edge and flatten top to remove small bur
4- Burnish new bur. After 3 to 5 new burs go to step 1

12. Using the Scraper
The shape at the end of the scraper determines how it can be used
Square for flat bottoms
Round for curved surfaces
Hold the scraper flat or in a downward angle
Cut on the center line
Raise the rest for deeper cuts to keep cutting edge on the center line
Try to keep end of scraper within 3” of rest or get a thicker blade

13. Round Scrapers
For a smoother cut use a scraper with a radius slightly tighter than the desired curve
Use only a small portion of the edge at a time, and by swinging the handle around you can use all of the edge at some time
Right side is used for shear scraping the exterior
Picture from Richard Raffan’s, Scrapers a Eulogy.

14. Shear Scraping Rotate scraper to an angle of 45 degrees or more
Lightly press scraper to wood and pull
Change angle till the bur engages

15. Square End Scrapers
Grind the end a little off 90 degrees so the whole surface does not contact wood at same time
Draw line across edge with marker, grind till ink on right side disappears
Cut about a ¼ inch wide section of wood at a time
Marker ink
900
900
900
minus

16. Carbide Scrapers
Carbide scrapers with flat blades are scrapers with no bur but a keen edge
Do not have to sharpen them
New models have round handles so you can shear scrape

17. Hollowing Scrapers Home made from a file Thin HSS bit
Sharpen to get bur using
Grinder
Hone
Burnish
Can remove wood where a bowl gauge cannot reach

18. Have fun with your Scrapers