Why get a bench grinder?

BenchCo Spydermade

BenchCo Spydermade

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Feb 10, 2014
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So, I have been collecting knives for a long time and have gotten pretty good at sharpening on my sharpmaker. I have a few larger, very dull blades(some even w no edge) that I can't even think about sharpening on it though. I also would like to reprofile a few of my folding blades and not spend a year doing so. I have recently seen some pretty affordable bench grinders and am very interested, but inexperienced. I would only use it for knives, as I am hardly Tim the Toolman Taylor, and was wondering if this would be a good investment, or if there are better options for my needs? I'd appreciate any advice.
 
You can spend $40 for a harbor freight grinder and another $100 on belts and a leather stopping belt and you will be good on re profiling and sharpening for a long time. Practice on cheap kitchen knives at first and move up from there.
 
jball1125 said:
You can spend $40 for a harbor freight grinder and another $100 on belts and a leather stopping belt and you will be good on re profiling and sharpening for a long time. Practice on cheap kitchen knives at first and move up from there.
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Thanks! I actually have a ton of edgeless crappy kitchen knives I plan on using for that purpose. I figure once I can get a razor edge and mirror polish on them, I'll be ready to use it on my "real knives". When I first got into sharpening, it was more like dulling, but on a grinder I figure I could really screw up a nice knife before I'm competent.
 
If you take a knife to a bench grinding wheel, you may as well just throw that knife away now and save the trouble.


Maybe as a way to spin a paper wheel, but those grinding wheels are 36 and 60 grit.
 
BenchCo Spydermade said:
Thanks! I actually have a ton of edgeless crappy kitchen knives I plan on using for that purpose. I figure once I can get a razor edge and mirror polish on them, I'll be ready to use it on my "real knives". When I first got into sharpening, it was more like dulling, but on a grinder I figure I could really screw up a nice knife before I'm competent.
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Thanks, I plan on using a paper wheel. It was actually a paper wheel thread that made me think it would be a good idea. That's the stuff I need to hear tho. What would you suggest for the lowest grit?
 
I don't use them.

I believe that they put too much heat on the fine edge and overheat the steel in the micro bevel

I believe in oil stones.
 
jball1125 said:
You can spend $40 for a harbor freight grinder and another $100 on belts and a leather stopping belt and you will be good on re profiling and sharpening for a long time. Practice on cheap kitchen knives at first and move up from there.
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I went this route at first and became quite skilled. One day I had an idea and took a hand-held belt sander, sat on the floor, held it between my feet and started reprofiling a blade. AMAZING! The handheld sander allowed me much finer control and the end product looked better than anything I'd ever done on the Harbor Freight. Just a thought...
 
Shao said:
I went this route at first and became quite skilled. One day I had an idea and took a hand-held belt sander, sat on the floor, held it between my feet and started reprofiling a blade. AMAZING! The handheld sander allowed me much finer control and the end product looked better than anything I'd ever done on the Harbor Freight. Just a thought...
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So ur saying you got better results with a belt sander than benchgrinder? Has anyone else had this experience? What other tools/machines have people used for this purpose?
 
I use a 4x36 belt sander to modify and sharpen pocketknives for whittlers, which I sell to my students.

With a little practice it is easy to avoid too much heat, unlike a bench grinder.

80 grit to rough

120 grit to finish up a bit and then a worn 400 grit before a stone and stropping. I have used the paper wheels at this point too and they are good, but too slow for drastic blade modification.

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Just a quick comment on the belt sander. I too have a belt sander. I cut a piece of plywood in a "C" shape to fit over the handle. Turn the belt sander upside down and fit the plywood over it and clamped it to the workbench. Crude but it does work. I have ground several handles this way with great success.
 
Dont get a bench grinder.. dont use a bench grinder on a knife, I have seen more knives ruined by being "sharpened" on one than i can count. Look into a Grizzly http://powertoolstores.com/grizzly-h6070-belt-and-5-inch-disc-sander-1-x-30-inch/ or something similar. You can find them for as cheap as $40 at harbour freight or as expensive as $300 at a name store. Light passes and a quick dip in water will keep them cool and give you a very good edge which you can then work with on stones.
 
tattooedfreak said:
Don't get a bench grinder.. don't use a bench grinder on a knife, I have seen more knives ruined by being "sharpened" on one than i can count. Look into a Grizzly http://powertoolstores.com/grizzly-h6070-belt-and-5-inch-disc-sander-1-x-30-inch/ or something similar. You can find them for as cheap as $40 at harbour freight or as expensive as $300 at a name store. Light passes and a quick dip in water will keep them cool and give you a very good edge which you can then work with on stones.
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Highlighted for emphasis & quoted for truth.
 
There's a world of difference between a belt sander and a belt grinder. I have a Coote (brand) belt grinder, but for blades I only use it to set the initial bevel and then only if it's a very dull blade. A bench grinder with a stone wheel is a good way to eat away a blade and not much else. For sharpening I use the cardboard wheels, but coat them with 250 and 500 grits. After you use a scrap piece of steel to knock off any rough or high spots, they end up being closer to 350 and 600. The motors for them are 1750 rpm, but without a smooth and fast pass of the blade on them, you can overheat one way too easily. Heat is the enemy of tempered steel, so learn to get it right before you really start. If I filled the rest of this reply with the word "Practice", it still wouldn't be enough. Learn to get the bevel right. When I'm done with the high number grit wheel, it either shaves or is close to it, so a few strokes on a butcher's steel finishes the job. As a rule, when I use these methods my edges look like the they did from the factory. I have years of experience doing it this way and need every bit of it every time I sharpen any knife. Now geting away from motorized sharpening, a good oil stone (Hard Arkansas) is always a good way to go. For steels like 154CM, BG42, S30V and ATS-34 (examples of your really hard stainless alloys), a diamond embedded "stone" seems to work best for me. This paragraph is just a start on what could easily become a book on sharpening. All I can do is explain what works for me and hope you take something away that works for you.
Thanks!
Bob
 
gazz98 said:
Like freak and elvis said, I think you want a belt sander for sharpening or even profiling knives. The harbor freight stuff is a popular choice for starters.

http://www.harborfreight.com/1-in-x-30-in-belt-sander-60543.html

http://www.harborfreight.com/4-inch-x-36-inch-belt-6-inch-disc-sander-97181.html

Don't forget you'll need some extra $ for belts too.
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Is the 4 inch better for sharpening because it has a much lower belt speed? Looks like about half the speed of the 1 inch.
 
Shann said:
Is the 4 inch better for sharpening because it has a much lower belt speed? Looks like about half the speed of the 1 inch.
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Most people I know use the 1 inch for sharpening. A light touch and varying grits can help offset the higher belt speed. I not sure its a huge issue when you are retouching edges. Heat might be your biggest worry, just use a light touch and most dunk the blade in water to keep it cool.

Youtube has several vids of guys using the 1 inch grinder. Check craigslist in your area too, you might find a better brand for cheap. Maybe pawn shops and 2nd hand stores too.

Sorry I'm no expert, I just know many folks use the $40 harbor freight one to get started in most cases.
 
I use a 1x42 Kalamazoo belt grinder($275) myself. I think after purchasing various belts(Trizact, Norton Blaze, 3m Scotchbrite) I probably tacked on another $125. Also replaced the stock plate with one from a member of another knife forum who cut off a section of it, making it easier to use on both sides.

This thing is handy for everything from regrinding to sharpening to polishing and refinishing. I can thin out a chef's knife, put a satin finish on the blade, and end with a mirror polished edge.
 
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