Sharpening with a 6" bench grinder?

myright

myright

Gold Member
Joined
Jan 31, 2008
Messages
5,145
Hey everyone

I've got a variable speed 6 inch Craftsman benchgrinder that I use around the garage for a lot of different projects. I've got a hard wheel on one side and a wire wheel on the other side.

Would it be reasonable to think that I could sharpen my knives on this grinder? I know I'd have to get new wheels so what types of wheels would I need?

Also - Is it worth it or will I just butcher my knives? I would consider my sharpening skills to be moderate.
 
myright, it can be done, but i don't really suggest it. if you really want to try it, check out leevalley:
http://www.leevalley.com/wood/page.aspx?c=2&p=43080&cat=1,43072

i use regular coarse stones on my cheap bench grinder for really course grinding, like regrinding badly damaged chisels and other things that i don't necessarily care about. with a good tool rest, you can do some pretty good things with a round stone grinder, especially with a slow-speed option.

i suggest at least getting a hard felt wheel for a power strop. if you want you can make one by stacking several 6" discs of cardboard, that's what i did. load it with compound and it really works wonders, especially if you use different grit compounds. they are great for polishing out a bevel or even resharpening if you have a coarser grit.

wanted to add; for powerstropping of general purpose knives (not recurves) i suggest using the widest strop you can (stack felt wheels or use extra cardboard discs) to increase surface area and polish faster.
 
I don't really want to "try" it on my knives :)

I have used the grinder, like you said, on my chisels, mower blade, etc.

I guess I could just get off my butt and send them to you :)
 
myright, grab a gas station knife or get a few kitchen knives at the dollar store or consignment shop and give it a go on those...

when i use the bench grinder i use a file or coarse bench stone after to even out and flatten the bevels.

since i got my belt sander though i usually use that for heavy metal removal, since it has the flat platen and a slack area.
 
smitty0331 said:
More than likley, it will definately ruin a knife.
Click to expand...

Only if the user had no idea what they are doing. I have a number of grinders that I use. Two are used for various grinding wheels, one used with only various wire wheels, one for cloth and paper buffing wheels, and one is a portable table top wet grinder. Three of the five are just motors with the proper arbors attached. None are variable speed and range from 1750 to 3600 RPM with different load resistance. I have been using these for many years with no problem. The secret is to practice with inexpensive knives and work your way up to harder and better steels. Practicing on lawn mover blades and such works well. Even more important is the safety aspect. ALWAYS wear eye and hand protection. I also use a face shield as none of my grinders have shields or guards. I know I should have them but I can not utilize enough of the wheel with the guards on and my home made grinders never had any. I have been using grinders for 35 years. I ALWAYS have eye, face and hand protection. I also have a fire extinguisher nearby as different materials throw hot sparks. Titanium is loads of fun to grind:D. I also have it handy as my welding bench is never far from my mounted or handheld grinders. Richard J and others are great sources on the forums here for wheels and grinder techniques.
 
Last edited:
check out a set of the sharpening wheels. you can put them on your grinder and they will work just fine. with some practice on some cheap knives or even an old hack saw blade you can soon get you knives sharp. here is a link to a knife i made and sharpened with the wheels. i used a belt sander to work up a burr but removed it with the paper buffing wheel. i have a few vids of how to use the wheels that i can send you. http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=43364157
here is thread i started about the wheels http://www.bladeforums.com/forums/showthread.php?t=578787
 
I have a 6" 3500rpm grinder with a very coarse wheel. I usually set all my edges with a file. The only time I used it on a knife is to put an edge on a large Okapi that for some reason left the factory unground, and to remove the hump on a 6" Old Hickory butcher. Use light pressure and dunk the blade in water every second or less. Watch out when you get to the tip because thats's the easiest part to overheat.
 
its still not a good idea to use a regular grinding wheel. its too easy to mess up quickly. it also takes a lot of life out of a knife by removing a lot of metal quickly. you might not think so but it does.
 
Last edited:
In a word no don't sharpen knives on a bench grinder. They are too coarse, and run hot enough to ruin temper in a blink of the eye. The reason is that knives are thin and heat up too fast, and the edge will be very coarse and will need to be brought up to a finer finish on a stone anyways. So use the stone instead.

However, for heavier blades such as axes for splitting wood, and even lawnmore blades, a bench grinder can produce a decent edge.
 
Bufford said:
In a word no don't sharpen knives on a bench grinder. They are too coarse, and run hot enough to ruin temper in a blink of the eye. The reason is that knives are thin and heat up too fast, and the edge will be very coarse and will need to be brought up to a finer finish on a stone anyways. So use the stone instead.

However, for heavier blades such as axes for splitting wood, and even lawnmore blades, a bench grinder can produce a decent edge.
Click to expand...

With the proper wheels a bench grinder is not too coarse or hot. I use a bench grinder with paper wheels to put the final buff on my knives. After that is strop is all it takes to keep the edge razor sharp.
Just because you don't know how to do it is no reason to tell others that it won't work.
 
Thanks everyone.

Richard - I'll shoot you a PM for those videos. That knife slicing the paper is wicked sharp.

I'm lucky to get my knife sharp enough to shave my arm hair using my Sharpmaker. In fact, I've got a Razel from the Graham Bros in S30V that I can't get sharp to save my life. Really - If my life depended on getting that blade sharp I would have been dead a while ago.

I would love to be able to sharpen my own knives effectively and not have to send them out to anyone. I have a bunch of cheapo knives that I could practice on. Is it reasonable to think that I could set up the grinder with two different wheels and be fine or would I need more wheels and have to change them out to get the knife perfect?

Here is the grinder that I have:
http://www.sears.com/shc/s/p_10153_...&cName=Bench+Power+Tools&sName=Bench+Grinders
 
Last edited:
about changing wheels-i typically leave my coarse and fine hard buffing wheels (powerstrops) on the grinder 95% of the time. i only use them after i have set the bevel and done some polishing with the belt sander though, so that impacts it.

if you set up the grinder with a fine stone and a coarse buffing wheel, that would probably cover you well. after that it would just take a dozen or 20 passes on a strop to remove the burr and make the edge wicked sharp.
 
What is a good online retailer for these wheels? How fine of a stone would the fine stone need to be?

What purpose does the buffer wheel serve for the blade?
 
with the paper wheels, you can have a knife sharp in under a minute if its slightly dull. when i would set up at a fundraiser, i could sharpen about 30 knives in just over a half hour and you only need the 2 wheels.
 
I'm going to order some wheels and try messing around with some of my cheaper knives and see how that comes out.

Worst case - i ruin a cheap knife :)

Thanks for the info.
 
get a hacksaw blade or some scrap bandsaw blade to practice on. both are good steel and will sharpen up just like a good knife.
 
Will do.

I'll call Mike tomorow to see about ordering a set. Once I get them and have them installed I'll post. I'm sure I'll have some questions so I may end up giving you a holler to talk through it.
 
You must log in or register to reply here.
Back
Top