Belt sander for sharpening?

buck91

buck91

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Just wondering who here uses a belt sander for sharpening tools? Recently picked up an el cheapo 1x30 from Menards to profile a few axes and hatchets and am really happy with it. Can't believe I spent so many years avoiding this purchase! Progressing from 80,200,400,600 and eventually 1000 grit belts I can get even my Harbor Freight axe shaving sharp. Sharpened my Esee 6 today and found that trying to maintain an even grind angle on the longer blade much trickier- probably not unrelated to the vertical orientation.

For those that use belt sanders for sharpening, did you find it worth while building a horizontal mount? What type of abrasive belts do you use and how high do you go on grit? Also, does anybody use those leather strop belts? Wondering how well they work compared to hand stropping.
 
I haven't tried it for tools so much, but I've got one of these for knife sharpening and I've been able to put an edge on ones that I could never get done with a lansky stone set.. My filet knives are the sharpest they've ever been.


I love it, but the fine belts don't last very long, so plan on having a few on hand.
 
Do you turn the edge towards the belt direction turning in to the edge or the knife edge away from the belt?
 
Never have used one for sharpening. I like the sharpener listed above though. Glad it has worked for you. I haven’t used a belt sander since I was in 9th grade and done wood shop lol.
 
I have used one plenty, but can achieve much better results by not using one. The belt does not sit perfectly flat on the sander, it bunches up a little bit just before it. If doing chisels, its basically impossible to get the bevel flat. its always rounded and mekes precision chiselling much more difficult as the chisel can rock when placed on that rounded side which should be a flat bevel..

Can certainly get them sharp, for a little while, but the more one uses a belt sander on a chisel the worse and worse it gets. I still use it, on my harbor fright chisels that i don't much care about, but the chisels I do care about I have jigs and various grits of wetsandpaper adhered to flat plate glass. The difference in planer blades and chisels with the latter method are night and day compared to the quick and dirty belt sander, but each have their time and place and both can be done well, or quite poorly.

I'd not get too excited over the belt sander method, and think twice about using it on quality steel.
 
If we're talking chisels, or plane blades, then, yes, a belt sander is too crude.

My approach to chisels and plane blades: Flatten back on a fine diamond plate. Polish back on Japanese water stones of 1000, then 4000 grit. Hollow grind the bevel on an 8" fine grinding wheel (low speed 1750 RPM). Hone edge on water stone of 1000 grit. Micro bevel at 4000, then 8000 grit.

Razor sharp. Easily done. The hollow ground bevel allows the blade to be sharpened with a minimum of material removal. The micro bevel is a very thin (1/64") edge that can be done in just a few strokes on the finer stones, again, minimum material removal, and to a very fine surface finish.

Keep the water stones flat on the diamond plate for best results.

But that Worksharp belt sander I've got for knives really works well. Consistent angle, and a progression of grits, allows for a very nice edge on knives and scissors.
 
buck91 said:
For those that use belt sanders for sharpening, did you find it worth while building a horizontal mount? What type of abrasive belts do you use and how high do you go on grit? Also, does anybody use those leather strop belts? Wondering how well they work compared to hand stropping.
Click to expand...

This is a long answer to a very faceted question that is extremely non linear and conditional. Personally I have designed, made, used, maintained and reconditioned pretty much every type of cutting tool known to exist for pulp/paper and machining and have worked with all the major manufacturers such as Simonds, IKS, Lennox, Kennametal and a lot of others over the decades. I point this out because I have seen about every type of technology there is and they all have strengths and weaknesses on sharpening despite all the various "opinions" out there.

You need a firm rigid mount- no human eye and muscle/joint structure can hold a proper rigid angle ( and slope of the angle) along the cutting surface against resistance. ( let me get the comparator or microscope and show those who think otherwise). Just because it cuts "good" when first used is NOT an indicator of proper edge geometry.

Belts are good for general purpose but you have to use a relative equation all moving backward from the "correct edge" ( a subject all of its own)

Micro abrasives get you closest ( lapping and such), hard wheels get super close, belts get "good enough" and so forth- they are all relative to the condition of the current edge when starting as to which is the best method or even capable. ( you will take years to "polish" out a bad profile but a belt will do it in a few seconds and so forth)

The true choice of method is determined by the steel and edge design as to which is best.

Basically on the shaping, you have 3 choices: laterally ( side-to-side, rubbing, sawing and other terms), cut toward edge, cut away from edge.

How bad the current geometry will determine which is best but generally laterally is best for straight edges because of the long run and cutting toward the edge is normally superior to cutting away from the edge. ( that's a CONDITIONAL answer with special cases)

The reason cutting toward the edge ( cutting edge facing away and drawing blade toward you) is best has nothing to do with the angle ( both ways will get that equally) but with micro fatigue and work hardening in the critical angle zone.

All abrasives gouge metal as opposed to peeling like a lathe tool ( different type of chip evaluation) so as the metal gets thinner, the force to mass increases so there is microscopic work hardening. ( not unlike changing RPM on a CNC when getting near hole end)

In general belts are more uneven/random in abrasive distribution so they will dig in and damage the leading edge wen cutting into the edge.

For mechanics use, use the method you feel most comfortable with

That's a short general primer for a very detailed and complex subject.
 
Goes back to the old razor stropping on leather. My grandfathers both always shaved with a straight razor. A belt won't keep a surface flat, but it can be sharp at the edge, not microscopically sharp but sharp enough.
 
Microscopically sharp is sharp. Your grandfather's strop was getting that blade microscopically sharp.

Not microscopically sharp is, well...dull...and, depending on what you're doing with the blade, like cutting apples, may work fine for you.

But if you're using a plane or chisel on end grain of maple, or oak, well, then, you need genuinely sharp tools.

If you're interested in the science of sharpening, I recommend this book: "The Complete Guide to Sharpening" by Leonard Lee.
 
Farnsworth said:
Goes back to the old razor stropping on leather. My grandfathers both always shaved with a straight razor. A belt won't keep a surface flat, but it can be sharp at the edge, not microscopically sharp but sharp enough.
Click to expand...

The strop works in that application because of the geometry of a straight razor, blade thickness ( and durability at that thickness) combined with an almost invisible beta difference between the primary and secondary edge ( if there was one to begin with, many razors don't have both))

The trade off is they dull quickly and need to keep being honed. ( but you could cut hair lengthwise with good ones)
 
I have the Ken Onion Worksharp, it was scorned upon by a blade-making buddy. I think it is wonderful, in a few hours I had everything in the house and garage very sharp. It does have adjustable angles and guides, properly used you can maintain an angle, but the blade profile will be ogive due to belt deflection. If you can't live with that, it's not the tool for you.
 
Even though it will work fine, and produce an extremely sharp edge on a tool, a belt sander will not provide the proper profile for an axe edge. There is a bit more to axes that appears to the casual user. An ax, once it penetrates the wood, must release easily so the next swing can be made, and not bounce out. I straight sided bevel is ideal for this. A belt will flex and provide a very sharp CONVEX edge, which will limit penetration. A hollow ground edge will have a CONVEX edge which will stick in the wood. (BTW, I picked this info up years ago, I am NOT a lumberjack).
Probably fine for lawnmower blades, some knives, etc. but NOT an ax.
 
I am far from an expert or even amateur lumberjack but like to keep my axe and hatchet sharp and ready for the next job. I use a stone and follow the method described at the link below. IMO a sander or flapwheel is fine for mower blades but not axes or knives.

www.knivesandtools.com

How do you sharpen an axe? Knivesandtools explains

Anything you want to know about sharpening axes ✓ The best sharpening products for axes ✓ All sharpening stones and sharpening machines tested and in stock
www.knivesandtools.com www.knivesandtools.com
 
Some really informative posts above. I use this https://www.edgeproinc.com for knives, planer blades, jointer knives, chisels, etc... Less precise sharpening like axes and lawn mower blades get a belt sander!
 
In the most general terms relative to edge formation and taper and omitting all things regarding what makes the proper edge to begin with- grinding is and always will be superior to any belt operation for any edge because of the rigidity/geometry of the media relative to the surface contact profile over the travel.

Additionally the wheel breaks off and replaces the sharp edges better than a belt giving less heat transfer and work into the edge.

Belts can adequately work for "refinishing' an edge and are easy and great for 'edge maintenance" ( to a degree) but will always have a limit as to what they can do.
 
ABN_CBT_ENGR said:
In the most general terms relative to edge formation and taper and omitting all things regarding what makes the proper edge to begin with- grinding is and always will be superior to any belt operation for any edge because of the rigidity/geometry of the media relative to the surface contact profile over the travel.

Additionally the wheel breaks off and replaces the sharp edges better than a belt giving less heat transfer and work into the edge.

Belts can adequately work for "refinishing' an edge and are easy and great for 'edge maintenance" ( to a degree) but will always have a limit as to what they can do.
Click to expand...
A grinding wheel is too harsh for an unsupported edge like we are talking about here , compared to the belt. I know this from experience. I did a lot of work over many years fabricating optical materials like quartz. Using a Levin lathe with the Levin grinding attachment, with the wheel perfectly trued, it is still far too crude and there is always machine induced vibrations that break off the unsupported edges. I had to cut a piece of diamond file cemented to a metal block to mount rigidly to the cross slide to be able to get a better edge,. In this case the surface had to be flat to the very edge not rounded so a soft belt wouldn't work. This was done observing with a Zeiss stereo microscope mounted over the lathe bed. A belt, like a leather strop, flexes and absorbs vibrations and of course it is not taking off much material, just at the important very tip of the edge.
To get a microscopically sharp edge, to near molecular sharpness, the edge needs to be supported from both sides. The supporting pieces must be in molecular contact to the knife edge material to reduce the gap in the assembled piece. Otherwise the edge still breaks off. Not an easy thing to do. Lot of tricks involved.
 
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"To get a microscopically sharp edge, to near molecular sharpness, the edge needs to be supported from both sides. The supporting pieces must be in molecular contact to the knife edge material to reduce the gap in the assembled piece. Otherwise the edge still breaks off. Not an easy thing to do. Lot of tricks involved."

On that note, just for fun, which material can be sharpened to the finest edge?
Answer, Obsidian. A natural stone that can be shapened to nearly one molecule of width. Look up Obsidian Scalpels. Not cheap.
 
Farnsworth said:
A grinding wheel is too harsh for an unsupported edge like we are talking about here , compared to the belt. I know this from experience.
Click to expand...

Your experience on "polishing" materials like quartz is nowhere the same as grinding metal and not applicable as well as out of context with the premise of the thread. (I guess which is why the entire blade making industry grinds rather than uses belts even up to carbides and other hard materials) ( grinding in this context includes soft polishing wheels charged with abrasive)

Yes all roads have an ogive and molecular edges are a different animal but not the subject here so not a valid comparison.

They aren't tricks per se, they are techniques required depending on the angles/edge required and finishing process.
 
My tools get a coarse grit sharpening.

My fillet knives get the same. Much better performance and edge retention for real cutting tasks.

EDC knives and such get the fine rods. I’ve stopped using ultra fine rods.They are still shaving sharp and I can push a knife through a receipt in any direction.
 
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