Scraper sharpening, of all the woodturning tools, is probably the easiest tool to sharpen. But there are a few details to be aware of during the sharpening process.
How do I sharpen a scraper woodturning tool? The front bevel edge needs to be sharpened at a precise angle and should get the most attention during sharpening. However, the top surface needs to be honed flat to create an ideal cutting edge.
Extreme Angle of Attack
The angle of a scraper bevel is vital to understand and get right.
Think of a 90° bevel angle as the bluntest scraper angle. If a scraper bevel is 90° and contact is made with the wood bowl blank surface, the wood surface will not fair well.
A blunt impact may remove wood quickly, but it will also rip and deeply tear fibers away. This would not leave a pretty surface.
On the opposite side of the spectrum, a steep scraper angle like 20° makes for a very unsupported delicate scraper edge.
Presenting a scraper angle, this extreme into turning wood fibers will not do much besides scratch the surface. Within only a few moments, the skinny tip would be dull and curl under.
Ideal Scraper Bevel Angle
As you might imagine, we don’t want the scraper bevel angle to be too blunt nor too steep. Somewhere in the middle will work better.
We are looking for a blend of sturdiness from the tall upright angle but with enough angle to present a firm cutting edge and create a nice cutting angle.
Some people recommend a 85° scraper bevel angle while others favor a 70 or 60° angle. The range seems to be between about 85° (the steepest) to 45° (the most extended) scraper bevel angle.
My round nose scrapers and flat scrapers are sharpened to about 65 to 60-degree bevel angles.
An angle around 65 to 60-degrees works for me, however, you might find a different angle works better for you.
The real answer to the scraper bevel angle is to try an angle that works for you and stick with that angle.
And keep this in mind, when you see a video or watch a demo, and the presenter says your scraper bevel angle must be X degrees. Just smile and know that your angle works just fine, even if it is different than their angle.
What Is Cutting?
Before we go any further, it’s essential to understand what is actually doing the cutting.
We are essentially introducing a hard steel edge into a turning chuck of wood fibers. While the technique for using a scraper is important to understand and spelled out here in this article, we need to know what is happening.
Based on the angle of approach and the type of wood, we can expect the steel tool to do far more damage than good. But it doesn’t, why?
The answer is at the micro level, with the tiny burr that is formed at the top edge of the bevel. This burr acts like a miniature knife and slices at the wood fibers.
Burr From Where?
The burr at the cutting edge of a woodturning scraper tool can be made one of three ways;
We will talk more about how to establish a burr in a moment, but for now remember, we need to know a burr is necessary to cut fibers instead of just scraping or ripping them away.
Before You Sharpen
We need to clean up the edge a bit before we begin scraper sharpening.
Because the burr on a scraper edge does not last long and deteriorates quickly, we need to clean and clear away the old burr area.
Clearing the burr area away makes the bevel edge ready for a new fresh burr to be applied.
Using a diamond honing card here’s a link to the one I use, hone flush across the top edge of the scraper for a few seconds.
This flush honing action will remove the remains of the previous worn out burr.
If you are happy with the angle of your scraper tools, simply match that angle at the sharpening grinder wheel.
Use the flat platform support on the vari-grind sharpening system to support the scraper during sharpening.
Want to learn more about setting up the Oneway Vari-Grind Sharpening System? Check out this detailed article.
With the sharpening grinder wheel off, I usually loosen both the platform and sliding arm locks to freely move the platform to the desired angle.
Then I hold the scraper on the platform and adjust the position until the front bevel angle is flush against the sharpening wheel surface.
Checking Scraper Sharpening Angle
Take a marker and mark the front bevel surface of the scraper.
Turn the grinder on and gently touch the scraper bevel to the sharpening wheel. Look at the bevel edge.
A full stripe of marker color should be removed from top to bottom edge of the scraper’s bevel.
If only an area on the top or bottom of the bevel was stripped from color, then adjust the platform further until the bevel is flush with the sharpening wheel.
Also, it can be helpful to bring a light source close to check for any gaps between the scraper bevel and the sharpening wheel.
Adjusting New Angle
If you want to intentionally change your scraper bevel angle, use a protractor with a locking mechanism, like the one I use, here’s a link.
Measure the current angle of you scraper bevel angle first and make a note, if necessary.
Now, adjust the protractor to the angle you would like to change the scraper bevel and lock the protractor.
With the new angle locked in, position the protractor at the bevel edge of the scraper and take a look at the gap created.
This new edge will require grinding more material on either the top or bottom edge of the bevel. Transfer the new angle to the grinding wheel platform.
Use the more coarse grinding wheel to shape the scraper and the finer sharpening wheel to sharpening the final edge.
Once the sharpening platform is set to the desired angle and the top surface of the scraper has been honed smooth, it’s time to sharpen.
Place the scraper firmly to the platform and simply contact the scraper bevel edge to the sharpening wheel gently. You do not need to apply force while sharpening.
For flat scrapers, slide the scraper bevel edge left and right across the platform.
Round nose scrapers need to be evenly pivoted from left to right matching the curved shape of the tool nose.
Once a new, fresh, shiny edge is applied to the bevel edge of the scraper, the sharpening process is complete.
Important Side Note – Wear your protective safety glasses and respirator while doing any work at the sharpening station. Wood dust is hazardous and must be avoided. Metal dust from the sharpening wheel is even more hazardous. Protect yourself. Here’s a link to the respirator I use and here’s an article explaining how to take care of your respirator.
The sharpening process itself will apply a small burr to the scraper edge.
You can test this yourself by running your finger over the front top cutting edge of the tool before and after you hone it smooth and after you sharpen on the sharpening wheel.
Of the three ways to apply a burr, the sharpening wheel process probably makes the smallest burr, but a burr is created.
After only a short time on the lathe, this small burr will deteriorate and need to be reapplied.
Honed Scraper Burr
Because the burr wears down so fast, there usually isn’t a need to return to the sharpening wheel every time to reapply a burr. The bevel edge of the scraper is generally intact. It’s only the burr that needs to be recreated.
Instead of going to the sharpening wheel, you can manually apply a burr one of two ways.
Use the diamond honing card to apply a burr by holding the card flush with the bevel edge and make up and down motions.
The advantage of applying a honed burr is that the process is quick and removes only a fraction of steel from the scraper bevel compared to the sharpening wheel.
Run your finger across the top edge of the scraper to confirm the burr is ready.
The final way to apply a burr is by far the most effective and reliable method.
Use a hardened steel burnishing tool, like this one I use, to apply a burr, here’s a link to check it out.
The process for using the burnishing tool is to pull the device across the top edge with force once or twice.
Instead of stroking the edge as we’ve done with the honing card, the burnishing tool needs to be applied only once or twice with even applied pressure.
I hold the scraper and pull the burnisher across the edge similar to the way I peel a potato with a peeler.
My thumb is positioned to support and brace the motion, and the rest of my hand pulls the burnisher across the cutting tip.
Again, run your finger across the top surface to confirm the burr is in place.
Scraper Burr Advantage
The burr is critical for making clean cuts, yes “cuts,” with a scraper.
Think of the burr as a little knife mounted to the microtip of a stable platform, because…well, that is what it is. Ha!
We really don’t want to depend on the blunt force of that chunk of raw metal against our wood turned piece.
On the other hand, we do want the stable, secure characteristics of that metal, but with a sharp edge as well.
A scraper with a fresh burr can make cuts as smooth as a bowl gouge.
I find that pulling a burr with a burnishing tool makes a better burr than the one coming straight off the grinder wheel, or the hand-honed burr.
So when do I return to the sharpening wheel instead of honing or hand burnishing a burr?
That’s a great question.
Usually, I will wait to return to the grinder until the bevel edge is looking pretty worn or uneven.
The honing card can quickly clean up the edge and freshen up the burr between more thorough trips to the sharpening wheel.
Only a light touch at the wheel should quickly return a clean, smooth bevel.
If it takes longer to clean the bevel, I will shorten the time between return visits to the wheel and hand hone or burnish the rest of the time.
Scraper Sharpening Wrap
The process of scraper sharpening is not complicated, but each step is essential.
Remember to clean up the top surface of the scraper well first, hone or sharpen the bevel, then apply a fresh burr, and you are on your way to making smooth, clean scraping cuts with your scrapers.