Wanted: advice for clamp/jig for sharpening on belt grinders

MeDoctor

MeDoctor

Joined
Dec 8, 2003
Messages
279
I picked up a cheap belt grinder this week for $25 at Harbor Freight, then fired off an order to Lee Valley for about $50 worth of belts from 120 to 1000 grit, plus a leather honing belt. (Kinda like "free" puppies that you spend $500 on in veterinarian bills in the first 6 months!:D)

After getting a knife back from Ben at Edge Pro and seeing the beautifully even and symetrical edge you can get with that device, it occured to me that I might want to try building a jig for the belt grinder with a locking pivot to set the angle and a free pivot to let me move the blade into the belt once the angle is set. This would be mounted on a slider fastened to the table to permit moving the full length of the blade across the belt...

Okay, okay -- I'll say it before somebody else does -- "Why don't you just go ahead and spring for the Edge Pro, Mark, you cheap son of a gun?"

Maybe I will, but I still want to try this idea if it's feasable. And besides, I am kind of cheap! But before I set off to re-invent the wheel, I'd like to find out if there is such a creature out there on the market, or if any of you guys have made or used something of this sort.

Thanks.Shalom,
Mark
 
What size is the grinder you got? The only belt sanders that I can think of from Harbor Freight in that price are the handheld ones meant for woodworking. If that is the case I would think that they run way to fast to be of any use in sharpening a blade.

Either way if this is something you really want to try making some sort of fixture isn't the hard part. The hardest part would be getting exact angles, which is what you want to get a good edge. The other hard part would be finding a way to securley mount the jig around the moving belt. You would want the actual jig to be as close to the belt as possible, without actually touching it.

I woulod probably just make a frame out of some angle stock with a bolt as a pivot point. This would allow to adjust to various angles, and tighten in that angle nicely. HTH

If you tell me more about what you have I could try to help you a bit more.
 
I have a grinder like that, except its made by Delta. It will do a decent job of sharpening a knife. Just make sure you are real careful not to get the blade to hot. The selection of belts will also help out a bunch, I have been getting by with like 60 and 120 grit belts. Fine for a rough edge, but not any good to finish up with. You don't need to apply any pressure to the blade at all, just let the machine do all of the work.

You might not need a jig at all. The table does tilt to like 45 degrees, which is plenty of range for sharpening. I just hold the blade by hand and follow the angle on it. Sure I royally screwed up a couple of cheap knives when I started, but now I can hold an angle pretty well. Give it a shot, I think with some practice you will do better than with some home made jig.
 
Mark, if you have not done so check out the knife makers forum..

http://www.bladeforums.com/forums/forumdisplay.php?s=&forumid=741

Lots of great info from the guys who make knives.
Click to expand...

Thanks Bruz. Yeah, I've been there -- and I keep an eye on it pretty much every day. I'm amazed and blessed by the free flow of information in this community. I'm a skilled tradesman (stationary steam) who was blessed with the opportunity to move up from production work rather late in life (I was 36 when I became an apprentice -- I'm almost 50 now). I've always been baffled with the tendency among tradesmen to hold information very close to the vest. Given my limited experience I can't say for sure if what I see at my shop is typical or not, but I suspect it's pretty common. Getting "trade secrets" from most men in the other trades (pipefitters, electricians, machinists, millwrights, and others) is like pulling teeth. Occasionally, getting info out of certain guys in my own trade can be just as tough. I've also noticed that the weaker a guy's skills are, the less likely he'll be to share information -- up to a point. The really weak ones seem to want to blab everything, while the guys who are both highly competent and confident are almost always willing to share truly helpful information. I guess they've figured out that they can tell me all that I'm willing to hear -- but that won't make me qualified to steal their jobs.

Sorry... I'll stop right here, since I've gotten off into a terribly off-topic rant!

Thanks again to all. Shalom,
Mark
 
ErikD:

You've got some valid points. Maybe I'm just looking for an easy way to get better results without practicing. So far I've only worked on one knife on the belt -- I reprofiled my sons knife that had a couple of bad nicks from being used hard with a flatter edge than the steel will tolerate (it's probably 440A).

It was awkward to learn how to get an even bevel on the full length of the blade, but I got it done without heating the blade -- and I only scuffed up one small area on each side of it. I'm not yet ready to move on to working MY knives on the belt. ;) His knife was already beat-up pretty badly, and besides, when he sees the new Whisper I bought him for Christmas from John Greco he won't be as sore about the damage to his old Colt.:)

Thanks Erik. Shalom,
Mark
 
Don't worry about a jig! The best thing you coudl do is to go to a thrift store and buy a bunch of dull kitchen knvies for real cheap. Practice sharpening those knives. You'll easily be able to get even bevels in no time. I just sharpened a big santoku I made, using my belt sander and my sharpmaker. I was slicing pieces of celery thin enough to see right through!
 
MeDoctor,

I know exactly what you are going thru!

The 'trick' is getting the right gap between the spine of the knife and the belt. Then maintaining that gap, thru the straight part of the blade. Once you get to the belly you have to do a funny pull up on the handle to keep the same angle.

To compute the gap you can use my calculator: http://knives.mylamb.com/calc.htm.

To start the gap I suppose you could mount some kinda screw or something beside the platen where you can set the height to give you a visual cue as you start pass.

One thing that I personally have to do, is run the belt horizonally and away from me. Can you mount the machine that way? Many makers sharpen edge down. I can't.

The problem you are going to have is speed. So keep the pressure light.

Steve
 
I use a 2" x 36" multitool for all my sharpening work (butchers, chefs etc) and don't use a jig - it all comes down to practice and juggling the belt grits until you find the best combination. For knives I use no platen as I find this avoids heat build-up. If you do use a platen the tip is the area where heat build-up will occur first and that is where you should take most care. Don't be afraid to use your worn belts as you can get a lot out of a worn 100 grit say that you have used for heavy work and it will work like a 240 grit and so on.
 
By the time you practice enough to be good and prepare to build your jig, you will be so sick of that slappy little HF that you will take it out back and shoot it!
Or keep it for handles and kitchen knives.

If you're handy you could build a grinder, like the one on Robs site or if you're lazy like me you could just plunk down 650 for a KMG-10 grinder. SWEET!

Or 300 bucks for a Grizzly. Pretty cool.
 
Hey Mark, I have seen a jig like your wanting in one of the knifesupplies catalog, can't remember which one. I really don't think you need one though, just practice on some old knives.
 
Crayola, Steve, JD, MC, Berettaman:

Thanks guys -- you all gave me bits of helpful info.

MC: you're right -- if I choose to stick with it it won't be long before the HF grinder faces the firing squad, or gets a leather honing belt permanently mounted on it. It was a cheap way to find out if I really want to take my new fascination with knives and edges to the next step.

Berettaman: Since there possibly IS something out there I'll keep searching, but with so many guys insisting that with practice I can learn to do it freehand perhaps I should spend less time searching and more time practicing!

Doesn't look like I'll get much practice in the immediate future though. I've got a drain pipe rotted out under the concrete slab here at the house. Kitchen cabinets are all ripped out and the floor is jack-hammered to pieces to expose the pipe. Much of what was in the kitchen is now in the garage -- and it was over-stuffed before this mess started. I can barely even GET to the grinder, much less use it right now.

Thanks again guys. Shalom,
Mark
 
Oh yeah --- MC:

I'm handy enough to build a grinder but, like you, I'm also a bit lazy. Right now I wouldn't place a bet either way as to whether I'll build one or buy one if and when the time comes.

Shalom,
Mark
 
Uh-oh...

Mama spilled the beans. There's a Sears 4x36 belt grinder / 6" disc grinder coming for Christmas. My first purpose for that machine is to modify it to make a slack-belt grinder for convex edges. I love it when the spouse aids and abets my compulsions. Then she can't gripe about 'em quite as much! The old gal must be thrilled about the bucks I'm pouring into her kitchen. She'd better not get the idea that she's gonna get a room remodeled every time I want a new power toy, errr... power tool, though.

I read about this unit somewhere on these forums a few weeks ago. Sears is closing them out as a discontinued item for $79 -- a $40 discount.

Shalom,
Mark
 
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