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- Jul 15, 2009
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- 156
I’ve noticed that there isn’t much written on the subject of sharpening inside serrated edges in this forum, so I thought I’d put my two cents in and open it up for critique and questions in this How To. Here is one of the systems I use with my Edge Pro. Note: This system with minor adaptation also works well with the EZE-Sharp sharpener and can be further adapted to work with other fixed angle sharpeners. Special thanks to all of you that posted replies here a few months ago
as this is ultimately a continuation of that post.
The Problem as I See It:
Most people get frustrated trying to sharpen serrations, some to the point of not ever wanting to mess with a serrated knife at all. One method of sharpening is to sharpen behind the serrations at a very shallow angle. I consider this to be more of a method of avoiding the job of really sharpening the serration. The serrations seem to wear away quicker when this is done. Another method that is often used is to sharpen inside the serrations with a Sharpmaker / crock stick type system using the corners of the triangle shaped rods. This has issues as well. It often creates a secondary bevel inside the serration due to the angle of the rod not being exact. It will produce a sharp and workable edge, just not necessarily a professional one in a reasonable amount of time. I want one that looks as good and as sharp as many of us can get our straight edges and I want it in a short period of time.
The setup includes:
Fully adjustable hand chuck
12” drill auger bit extension
Set of aluminum rods
Wet or Dry PSA auto finishing paper
3M micro finishing film
Hand chuck:
I can’t remember where I bought this. But a quick search will reveal a few models to choose from.
Drill Bit Extension:
I use an Irwin 12” auger bit extension. It comes with two hex screws that will clamp down on anything ¼” or less. Furthermore, the extension fits the Edge Pro pivot perfectly. However, it does have a horizontal brush pattern that can cause quite a bit of friction in the EP pivot. I smoothed the length of the extension using micron belts on my belt sander. I then polished it with green micro-fine compound on a leather belt. Beyond simply polishing the tool, the wax protects the tool metal from rust. Rust can be a problem with this tool, so take care of it. Also, the hex screws can be replaced with thumb screws for added convenience.
Aluminum Rods:
Sizes of round rod are 1/4”, 5/16”, 3/8”, ½”, and 5/8”. There is an additional ½” square rod used for small and V shaped serrations. I order the rods precut at 8”. The 1” ends of each rod are reduced by lathe or grinder to ¼” diameter in order to fit into the chuck and the drill extension. This leaves a 6” workable area in the center of the rod to stick on your abrasive of choice. I use 6061 Aluminum which is a marine grade, corrosion resistant, and cold workable aluminum.
I get my rods from Speedy Metals because the prices are low, there is no minimum order, and they cut the rods to the sizes I specify. It’s a good place to get new stone blanks cheaper too. Wherever you choose to buy metals, don’t get it at your local home improvement store. The type of aluminum or steel is typically unknown. Plus, the metal will be soft and usually not straight.
Note: buying rods smaller than ¼” really requires one to use properly hardened steel rather than aluminum. However it’s rare that you would need rods that small. When I do, I just use the smooth portion of an appropriately sized chainsaw sharpening file.
Wet / Dry PSA Auto Finishing Paper:
I buy this kind of silicon carbide PSA rolls from Klingspor. The rolls are all 5 meters long and come in various widths. I use the 6” wide rolls because, duh, my custom cut rods are 6” and I can just cut tapes off the end of the roll with a cheap paper cutter. You can buy this stuff elsewhere. Automotive paint and body shop suppliers sell it. However, I haven’t found the size, grit selection, and price that Klingspor has anywhere else yet. The PSA is super strong too and wraps and sticks to the rods easily. You can buy it in 240 all the way to 2000 grit. The 2000 grit paper leaves a fairly nice shine.
Edge pro polishing tapes can be used to finish the edge even further if you already have them. I prefer to finish with aluminum oxide anyway. However, that’s expensive, the adhesive isn’t very strong, and the backing doesn’t bend easily and stay stuck on the smaller shaped rods.
3M sells micro finishing film (aka micro abrasive film) in 8.5 x 11 sheets. It is a PSA backed aluminum oxide abrasive but has the same problems bending and sticking to narrower rods that the edge pro tapes have (since it’s probably the same stuff). It’s made to be stuck to flat plate glass. I still use it, but I have to hold it onto the smaller rods while I do. It’s kind of a pain. The cool thing about it is that these abrasives go down to .3 micron. I bought mine from www.toolsforworkingwood.com. They are the only company online that I know of that sells the stuff. You can get smaller sized sheets from Woodcraft, but they don’t have the grit selection and prices are higher. Last time I checked, it wasn’t on their website. I happened to see it in one of their stores where I live in the Dallas area.
How It Works:
Fit the sharpenee in a vise. I’m using the Edge Pro scissor attachment. A good tip is to raise the left side of the knife slightly when clamping it down. This is done to make up for the fact that the pivot is stationary and on the right side of the tool table on the Edge Pro. If you are sharpening serrations using this method with the EZE Sharp, raising one side of the knife in the clamp doesn’t matter.
Next, fit one of the rods to the size serration you will be sharpening. It is best to start with the smaller serrations first as it is easier to slip out of them and into the bigger ones while sharpening. I’m not doing it this way in this tutorial for illustrative purposes. When fitting a rod to a serration, the key is to use a rod that is just big enough to fit the serration. It shouldn’t roll around inside the serration and shouldn’t just rest on the points.
Once you have a rod that fits well and have the knife at the angle you think is right, it’s time to put the tool together. Insert the one end of the rod that you are using into the drill auger extension and secure. Do the same with the other end of the rod and the hand chuck.
Then grab some 240 grit PSA SiC paper, cut however much you need off of the end of the roll, and stick it to the rod.
The next step is to use the oh so famous marker trick to make sure that you have the right angle. Take a permanent marker and color inside the first serration you will be sharpening.
Make one stroke with the gritted rod through the serration. Be sure to use a trailing stroke. Check to see if marker is removed across the entire bevel of the serration. If not, fine-tune the height of the EP pivot until you get it just right. You will need to use all trailing strokes initially until the serration is fully recut with the 240 grit. Yes, I said “recut”. This is because 8 times out of 10, serrations aren’t cut perfectly round at the factory. This will show up when checking how much marker has been removed.
Case in point…
Continue to sharpen the serration with the 240 grit until all the marker is removed and a burr has formed along the length of the serration. Use a few more very light strokes to remove most of the bur.
The rest is history.
Replace the course grit with a finer grit, sharpen, and repeat.
If polishing with micro finishing film, the pivot will need to be adjusted down a bit due to the change in thickness between sharpening mediums.
If there is any remaining bur, it can be knocked off with strop.
Here are a couple before and after pics. They aren’t the best shots. But hey, I’m not a photographer, just a sharpener.
This knife wasn’t completely dull. The small serrations were polished to 2000 grit and the large ones to 7000 (although the mirror finish doesn’t show up at all).
This knife’s serrations were used to cut shingles. Hence the entire blade, not just the serrations, is scratched up. Sad. I know.
The serrations were sharpened to 2000 grit. There is a bit of marker left on the blade. It comes off with a little lighter fluid, but I hadn’t cleaned it yet. I hadn’t sharpened the straight edge at all either.
As with most things in life, I consider this a thread a work in progress and will probably edit it in the future.
Joel
as this is ultimately a continuation of that post.
The Problem as I See It:
Most people get frustrated trying to sharpen serrations, some to the point of not ever wanting to mess with a serrated knife at all. One method of sharpening is to sharpen behind the serrations at a very shallow angle. I consider this to be more of a method of avoiding the job of really sharpening the serration. The serrations seem to wear away quicker when this is done. Another method that is often used is to sharpen inside the serrations with a Sharpmaker / crock stick type system using the corners of the triangle shaped rods. This has issues as well. It often creates a secondary bevel inside the serration due to the angle of the rod not being exact. It will produce a sharp and workable edge, just not necessarily a professional one in a reasonable amount of time. I want one that looks as good and as sharp as many of us can get our straight edges and I want it in a short period of time.
The setup includes:
Fully adjustable hand chuck
12” drill auger bit extension
Set of aluminum rods
Wet or Dry PSA auto finishing paper
3M micro finishing film
Hand chuck:
I can’t remember where I bought this. But a quick search will reveal a few models to choose from.
Drill Bit Extension:
I use an Irwin 12” auger bit extension. It comes with two hex screws that will clamp down on anything ¼” or less. Furthermore, the extension fits the Edge Pro pivot perfectly. However, it does have a horizontal brush pattern that can cause quite a bit of friction in the EP pivot. I smoothed the length of the extension using micron belts on my belt sander. I then polished it with green micro-fine compound on a leather belt. Beyond simply polishing the tool, the wax protects the tool metal from rust. Rust can be a problem with this tool, so take care of it. Also, the hex screws can be replaced with thumb screws for added convenience.
Aluminum Rods:
Sizes of round rod are 1/4”, 5/16”, 3/8”, ½”, and 5/8”. There is an additional ½” square rod used for small and V shaped serrations. I order the rods precut at 8”. The 1” ends of each rod are reduced by lathe or grinder to ¼” diameter in order to fit into the chuck and the drill extension. This leaves a 6” workable area in the center of the rod to stick on your abrasive of choice. I use 6061 Aluminum which is a marine grade, corrosion resistant, and cold workable aluminum.
I get my rods from Speedy Metals because the prices are low, there is no minimum order, and they cut the rods to the sizes I specify. It’s a good place to get new stone blanks cheaper too. Wherever you choose to buy metals, don’t get it at your local home improvement store. The type of aluminum or steel is typically unknown. Plus, the metal will be soft and usually not straight.
Note: buying rods smaller than ¼” really requires one to use properly hardened steel rather than aluminum. However it’s rare that you would need rods that small. When I do, I just use the smooth portion of an appropriately sized chainsaw sharpening file.
Wet / Dry PSA Auto Finishing Paper:
I buy this kind of silicon carbide PSA rolls from Klingspor. The rolls are all 5 meters long and come in various widths. I use the 6” wide rolls because, duh, my custom cut rods are 6” and I can just cut tapes off the end of the roll with a cheap paper cutter. You can buy this stuff elsewhere. Automotive paint and body shop suppliers sell it. However, I haven’t found the size, grit selection, and price that Klingspor has anywhere else yet. The PSA is super strong too and wraps and sticks to the rods easily. You can buy it in 240 all the way to 2000 grit. The 2000 grit paper leaves a fairly nice shine.
Edge pro polishing tapes can be used to finish the edge even further if you already have them. I prefer to finish with aluminum oxide anyway. However, that’s expensive, the adhesive isn’t very strong, and the backing doesn’t bend easily and stay stuck on the smaller shaped rods.
3M sells micro finishing film (aka micro abrasive film) in 8.5 x 11 sheets. It is a PSA backed aluminum oxide abrasive but has the same problems bending and sticking to narrower rods that the edge pro tapes have (since it’s probably the same stuff). It’s made to be stuck to flat plate glass. I still use it, but I have to hold it onto the smaller rods while I do. It’s kind of a pain. The cool thing about it is that these abrasives go down to .3 micron. I bought mine from www.toolsforworkingwood.com. They are the only company online that I know of that sells the stuff. You can get smaller sized sheets from Woodcraft, but they don’t have the grit selection and prices are higher. Last time I checked, it wasn’t on their website. I happened to see it in one of their stores where I live in the Dallas area.
How It Works:
Fit the sharpenee in a vise. I’m using the Edge Pro scissor attachment. A good tip is to raise the left side of the knife slightly when clamping it down. This is done to make up for the fact that the pivot is stationary and on the right side of the tool table on the Edge Pro. If you are sharpening serrations using this method with the EZE Sharp, raising one side of the knife in the clamp doesn’t matter.
Next, fit one of the rods to the size serration you will be sharpening. It is best to start with the smaller serrations first as it is easier to slip out of them and into the bigger ones while sharpening. I’m not doing it this way in this tutorial for illustrative purposes. When fitting a rod to a serration, the key is to use a rod that is just big enough to fit the serration. It shouldn’t roll around inside the serration and shouldn’t just rest on the points.
Once you have a rod that fits well and have the knife at the angle you think is right, it’s time to put the tool together. Insert the one end of the rod that you are using into the drill auger extension and secure. Do the same with the other end of the rod and the hand chuck.
Then grab some 240 grit PSA SiC paper, cut however much you need off of the end of the roll, and stick it to the rod.
The next step is to use the oh so famous marker trick to make sure that you have the right angle. Take a permanent marker and color inside the first serration you will be sharpening.
Make one stroke with the gritted rod through the serration. Be sure to use a trailing stroke. Check to see if marker is removed across the entire bevel of the serration. If not, fine-tune the height of the EP pivot until you get it just right. You will need to use all trailing strokes initially until the serration is fully recut with the 240 grit. Yes, I said “recut”. This is because 8 times out of 10, serrations aren’t cut perfectly round at the factory. This will show up when checking how much marker has been removed.
Case in point…
Continue to sharpen the serration with the 240 grit until all the marker is removed and a burr has formed along the length of the serration. Use a few more very light strokes to remove most of the bur.
The rest is history.
Replace the course grit with a finer grit, sharpen, and repeat.
If polishing with micro finishing film, the pivot will need to be adjusted down a bit due to the change in thickness between sharpening mediums.
If there is any remaining bur, it can be knocked off with strop.
Here are a couple before and after pics. They aren’t the best shots. But hey, I’m not a photographer, just a sharpener.
This knife wasn’t completely dull. The small serrations were polished to 2000 grit and the large ones to 7000 (although the mirror finish doesn’t show up at all).
This knife’s serrations were used to cut shingles. Hence the entire blade, not just the serrations, is scratched up. Sad. I know.
The serrations were sharpened to 2000 grit. There is a bit of marker left on the blade. It comes off with a little lighter fluid, but I hadn’t cleaned it yet. I hadn’t sharpened the straight edge at all either.
As with most things in life, I consider this a thread a work in progress and will probably edit it in the future.
Joel
Last edited:
