My Blade Grinding Jig

jhiggins

jhiggins

Joined
Jul 11, 2003
Messages
3,258
Hi buddies!

I've been working on a blade grinding jig that would encompass both fixed and folding blades. The main problem I was experiencing was how to design a jig that would be effective, yet flexible. After several prototypes, I think I'm close to getting what I want. The following pic is the basic jig. Its made from a chunk of 2" angle iron. It features a big knurled knob and a knurled nut for setting the depth. A series of threaded holes provides many choices to hold the blade in position.

Jig_001.jpg


This is a view of the business side. Note the threaded holes - they are all 6-32.

Jig_002.jpg


Side view. The brass fixture you see is for holding fixed-blades.

Jig_003.jpg


Bottom view. The small white thing at the bottom is actually a Delrin swivel on the end of the knurled bolt. Note the corner of the angle iron has been smoothed.

Jig_004.jpg


This is a better view of the knurled bolt and jam-nut setup. The tall nut is called a coupling nut. Please don't laugh at my weld. I had to grind it smooth because it was so ugly - I was running out of argon when I welded this!

Jig_005.jpg


This one shows a fixed blade installed and ready to rock.

Jig_007.jpg


This is a view with the jig tilted a few degrees. You can see that its possible to dial-in a nice even grind on both sides of the blade!

Jig_008.jpg


In this pic, my pencil is pointing to the eccentric. This is merely a thin piece of a 3/8" rod drilled off-center. The eccentric helps to put the blade into exact position to keep the bevel precise.

Jig_009.jpg


Last but not least, here is a view of the keeper for the tang end of a fixed blade. It's milled to provide a snug fit for a 1/8" thickness, and the top screw is to take up any slop.

Jig_010.jpg


I had the angle iron kicking around the shop, but the hardware was ordered from McMaster-Carr. If anyone needs a parts list, I can probably find the old invoice and list the part numbers here.

Thanks for looking!
 
I really like machining stuff and this looks cool. Now I have a coupla questions.

How do you deal with the curve up front?

Does this run along the tool rest? If so it must be a nice big one like on the KMG... The little dinky thing on my BIII is a waste,

Do you do the whole grind on one side at a time? I've been told one should alternate sides frequently to ensure no undue stresses build up in the steel. It's probably not too hard to switch sides but how hard is it to get everything positioned just right each time?

Nice post, I'd like to see this baby in action. Making stuff is cool!
 
I am interested in seeing it in action as well as the parts list! That looks rather interesting, and ingenious too.

Doc
 
That is so tricky ya just gotta love it!!! :D Thanks for posting the pix.
 
Originally posted by ddavelarsen
How do you deal with the curve up front?
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It depends on the design of the blade. A nice straight back like the blade in the pics lends itself very well to this type of grind. We have a lot of Finnish families here in the area - many of whom are my friends. The puuko is a predominate style and sometimes I just make a few. I will admit that I do have to finish the tips by hand, but this jig really sets a perfect angle. I've tried it with hollow-grinds also... it works, but I like freehanding them better.

Does this run along the tool rest? If so it must be a nice big one like on the KMG... The little dinky thing on my BIII is a waste.
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Yes it does, Dave. I have a BIII also, and the first thing I did was ditch the dinky little tool rest. I made a bigger one with more mass to it and covered it with 1/4" G-10. The jig slides along that G-10 like butter.

Do you do the whole grind on one side at a time? I've been told one should alternate sides frequently to ensure no undue stresses build up in the steel. It's probably not too hard to switch sides but how hard is it to get everything positioned just right each time?
Click to expand...

Yes I do the whole grind at once on one side. I'll dip the entire jig and blade into my slack tub and keep going. I've never noticed any undue problems related to this practice, and I've used many different steels with no ill-effects noted.

As far as getting the positions correct from each side, I simply make a measurement on the spine of the blade to the top of the jig. When I flip the blade, I match those measurements, and boom! There you go. In an earlier prototype, I made a little protractor and placed it on the side. That sucker took more time to make than the rest of the jig! It was really nice to record what degree each blade was ground, but as luck would have it, I dropped the jig and the protractor was f.u.b.a.r... So I left it off this one.
 
I have been using a mirror grinding block for years. The only thing I can see on yours that mite be difficult would be getting that concentric disc the same spacing on the other side when you flip the blade. Maybe you could use a dowl pin in the center, that would support the blade and make it easy to flip from side to side while keeping the same grind line even.
 
Jeff, that's pretty neat! I gotta say, you sure take excellent pictures,too. Thanks for the great post.I have been trying to figure a jig, yours looks really good.
 
Originally posted by Jim Smyth
The only thing I can see on yours that mite be difficult would be getting that concentric disc the same spacing on the other side when you flip the blade. Maybe you could use a dowl pin in the center, that would support the blade and make it easy to flip from side to side while keeping the same grind line even.
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Good observation, Jim. In fact, that's almost what I do sometimes. All of the threaded holes are perfectly aligned, and what I do is install a socket-head cap screw in the middle row. This act s asa a dowel pin and stays tight. I showed the fixed-blade rigged on there because its the hardest to setup. Still, its relatively easy to get a good even grind on both sides - I just have to use the calipers and record the height of each end.

The real beauty in this that once one side is all dialed-in, the flip side is all set and takes much less time to grind.
 
Originally posted by John Andrews
Jeff, that's pretty neat! I gotta say, you sure take excellent pictures,too. Thanks for the great post.I have been trying to figure a jig, yours looks really good.
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Thanks, John! I use a Sony Mavica 5 megapixel camera. All my shots are off-hand. imagine what they'd look like from a tripod!

On the jig: This is a fancy jig compared to others. I know some high-end folder makers who machine many of their blades or use jigs for grinding, etc. There's no shame in it. Heck, my favorite example is Ron Lake. If you can even get one of his knives, you are spending beaucoup bucks for it. Point is: He machines almost all of his knives. Howard Hitchmough also uses a jig to grind his blades, and his knives sell for many $1000's. Know what he uses? A door hinge!
 
Originally posted by Chris Crawford
Hey Jeff, did you happen to get the idea for the jig from this post?
http://www.ckdforums.com/showthread.php?s=&threadid=18725&highlight=grinding+jig

Here is another post from nearly 2 years ago with the same info:
http://www.bladeforums.com/forums/showthread.php?s=&threadid=194164&highlight=grinding+jig

-chris
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Chris, before I saw your jig, I was using an angle-iron with a plate attached to the grinder-side via a piano hinge. Then I used just the angle, but I had a nylon bar attached to the back with two screws to set the degree of bevel. When I saw your jig, I immediately went back to the drawing board and made this current model. So yes, your jig does have some influence on mine, and I apologize if I did not recognize you right off. However, many different makers and their gear have their influences in this jig. Kind of like a salad bar - you take what you like and leave the rest, huh? :D
 
aaahJIG :eek: :barf:
what's the world coming to :D
I free hand but I have been thinking on
a jig but when I do it it's going to do both
sides at the same time and water cooled.
so that means I'm going to build a new grinder.

if I'm going to make inexpensive users I'm not going to spend
a lot of time grinding them. but mean while it's by free hand here.
don't get me wrong
I have nothing at all against jigs ,,
as long as a maker can free hand.
just a pet peeve of mine.;)
 
Originally posted by Mark Williams
Let's not even get started in that discussion:D

Dang stock removers:footinmou
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:D
hey I'm resembling that remark a lot .:confused: :D
I forge too just not a lot :p
 
Its all stock removal in the end, and if your smithy is nothing more than a pile of rubble after last year's snowfall, then you tend to only forge in decent weather. Grrr! I'm still p-o-ed about that.

So, I placate myself by making little knives and folders and crap I can sell until I get another shed or something out there I can smack some hot steel around in. Thing is, I think we are going to sell here and buy another house so even that may have to wait a while. I want me a big ol' barn this time with plenty of room for my machine shop, too!
 
I thought a grinding jig was what you did when your finger gets between the belt and the workrest?

Steve
 
Holy Caramba!!! And I mean that!

Anyone who can spell "beaucoup" is a freakin hero in my book.

My hat is off to You, man-oh-man. Hell, My whole scalp is off to you!!!!

YeeHA!

Okay, back to your normally scheduled sedate conversation...

DDave

:D
 
Originally posted by jhiggins
Its all stock removal in the end, and if your smithy is nothing more than a pile of rubble after last year's snowfall, then you tend to only forge in decent weather. Grrr! I'm still p-o-ed about that.
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Snowfall? Did someone mention snowfall? I have heard of such. I was out in the shop last night in a shortsleeve shirt. It does get cold here every once in while, mainly in the summertime when the AC is running.

Actually, in the winter, it does get rather cold, it may even get down to 30 on a real bad day.

But oh, I do envy you guys in the northeast in the summertime, well, not really. :)

Craig
 
Craig
the last few days here in the morning it's been all most 100 deg lower than your lowest :(
- 26 F but I've seen it lower than -40 F
 
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