Why are bench grinders unsuitable?

Status
Not open for further replies.
B

barney fife

Joined
Mar 23, 2013
Messages
6
Noob question: I have read that bench grinders are "worthless" for blade grinding yet I repeatedly see videos of Italian and Spanish and other Euro guys using them to make blades. These guys are usually older and have been making knives for generations. Usually their stone wheels are quite a bit larger then bench grinder wheels.

The blades I see them making are usually medium to small size rather than big Bowies for instance.

I'm interested in making rather small blades for slip joints and am wondering if a bench grinder(s) with assorted grit wheels, (along with assorted files and sandpaper/stones) would be advisable? Why are people down on stone wheels?

thx, barney
 
I am far from an expert but I know a regular bench grinder can have a large learning curve when it come to making even smooth grinds . Don`t ever let someone tell you things can`t be done but making things easier is usually better. Also I would think if one could find a nice 20" water cooled grinder; I for one would give it a go.
 
years ago I cut a number of lathe tools on a bench grinder, so I am certain they can work. But a belt grinder offers the latitude to work wood as well as steel, to change out the belts quickly, to have a large number of belts available for hogging metal through polishing. I've heard that the belts will run cooler.
 
You know, a little searching in Shoptalk could answer this question rather exhaustively... it's not uncommon.

Short answer, no- not suitable. Can it be done? Yes, but that does not recommend it.
 
I use a bench grinder to profile the blade after cutting it to shape and before using files. I use an angle grinder for the bevels and later files and sandpaper. Those tools are definitely not ideal but they work for a hobbyist.
 
It really all comes down to preferences. The idea of bench grinders being junk is far more opinion than fact. What tool or machine is only dead weight to one maker may be worth that weight in gold to another, because there are many ways to make a good blade - but which way you get a piece of steel there will determine what tools will or won't be of use. I did have a bench grinder, but have moved on to using an angle grinder since I can do much more with it and get more uniform tapers. HOWEVER; while I did have it, I used it for so much of the profiling and thought it was the greatest machine I could ever have in the workshop. I didn't stop using it becuase it was "worthless", only because my process had changed so my equipment needed to change with it if I wanted to keep improving. If you know someone who has one, ask if you can try it out first to decide if it really is a tool for your process.
 
The idea of bench grinders being junk is far more opinion than fact.
Click to expand...

Sorry "Ninja Blacksmith", I didn't realize I was speaking to the angle grinder crowd. If you'd used a real belt grinder, I believe your "preferences" would lean heavily in that direction.

No one is calling bench grinders worthless, but like angle grinders too, they are not a tool particularly suited to making knives. Especially not grinding bevels. Save 'em for metal fabrication. Buy a Craftsman 2x48 to start out with.
 
the shop benchgrinder you would have does not compare to those truck tire sized stones the old world dudes use. A benchgrinder is VERY hard to grind anything that needs to stay flat. Every little imperfection in that wheel is gonna make your blank jump all over the place. It will be extremely frustrating. Ive used benchgrinders, angle grinders, files, and belt grinders and the worst by far is the bench grinder. Impossible? No, but it is the furthest thing from ideal.
 
A few of my personal observations about an average (6" Craftsman) bench grinder.

I started off with that as my only grinding tool (apart from files and sandpaper). It had two wheels... coarse and medium. I quickly learnes that that translated into Coarse and Coarser. Anyway, they did help me profile a few blades.

However, as for actually grinding the bevels, the problem I had was that the stones wore down where I used them most. This tended to be the outer edges, leaving the grinding surface domed. A domed grinding surface makes it very difficult to get anything like a flat surface on a bevel. Losing the edges of the stones so quickly made it all but impossible to get a clean plunge with them.

Sure, you can try to "dress" the stones to regain that edge, but that takes a lot of time that could be spent grinding the knife instead.

Also, the average bench grinder is powered by a 1/3 HP motor, which means it bogs down every time you press into the work more than just a little. I could keep my wheel spinning, but by no means at a constant speed. That means even under the best circumstances it was grinding irregularly.

So I will be among those that say the bench grinder has a place in knifemaking, but it's a VERY, VERY limited place. In my case it was limited to profiling ONLY, and that was before I got the metal cutting bandsaw to do my profiling. If you have a 30 inch or larger stone it may be a lot more suited to some tasks. But the average Joe with a 6" bench grinder will find the tool all but useless.
 
I have used a 6" bench grinder to grind bevels before, many years ago. After that I got a 4x36 belt sander, then eventually a 2x72 grinder. The 4x36 was about as much of an improvement over the bench grinder as the 2x72 was over the 4x36. Personally, if I had to grind bevels on a blade and only had files and a 6" bench grinder to do it with, I would use the files.
 
If you don't already have a bench grinder, Skip the bench grinder.
That $ would get you almost half way to the Craftsman 2x42 belt sander.



If you already have a bench grinder, then no matter what we say you will want to use it.

Just try it once, you will bounce that blade off the wheel a thousand times and achieve anything but a flat surface.

If you already have one try using the rubber sandpaper backing discs and abrasive paper
 
Last edited:
I have 3 bench grinders in my shop and use them quite often. Of course I took the stones off and replaced them with paper wheels, buffing wheels, and wire wheels.
 
jawilder said:
I have 3 bench grinders in my shop and use them quite often. Of course I took the stones off and replaced them with paper wheels, buffing wheels, and wire wheels.
Click to expand...

+1

I find wire wheels really useful for fabrication, cleaning up screw threads, rusty stuff.
 
So to sum up, it's kind of like the "Rambo forges a bowie over a campfire" scenario.
Yes, if you desperately need a knife, any knife, it can be done...no, it's not an easy way to do it...it's likely to be pretty frustrating and the results aren't likely to please you.
The reasons are: The stones spin too fast. They wear quickly and unevenly. The tool rests are almost always horrible.
And you know what? I've done it, and at the time I was pretty happy with it.
But the fact that the OP is on a forum where you ask questions of some really top drawer metal engineers and bladesmiths kind of implies that he's at least a little interested in doing it right! Best of luck, and happy knife making!
 
A real good use for a 100 dollar 8 inch bench grinder with nice new wheels is to make a few hollow ground knives before the wheels get all rounded off. If you came up with some nice bevels by the last of your test knives you can now spend large sums of money to get better equipment and have more fun. Your grinder now will have other uses. If you cant get a decent bevel by the end of your test knives you have not spent a ton of money and you made a few knives. Just one opinion from the rookie end of things.....
 
Bench grinders are only really useful for shaping a blade blank - round off sharp edges after using a band saw, and stuff like that. I have successfully ground bevels with them before, but it sucks doing it that way. You'll be so tense trying to hold the damn blade still that you'll be sore for a day afterwards. And if you lose concentration for a moment, Whoops! There goes all your work down the drain.

And if by some miracle you get it done, you'll still need a belt sander to clean up the cuts that a grinder wheel leaves. Hand sanding that out just isn't realistic.
 
An inexpensive 6" bench grinder is completely different than a kaiten toishi or similar grinding wheel.

I suppose someone might be able to make a knife with a bench grinder, but it would be very difficult and inefficient.
 
Status
Not open for further replies.
Back
Top