Blade Grinding Questions

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Dixieblade57

Joined
Jun 20, 2007
Messages
1,361
I am asking this because I am in the planning stages/ securing all my material for building a KMG clone, and a question has arose in my mind.
I don't know this answer because up this point all my knives have had the material removed at the grind area by roughing with a side angle grinder, file and sandpaper, in other words a flat cut on the bevel.
So I assume using a wheel to produce a hollow grind the girnder is turning towards yourself / counterclock wise or into the material. Therefore you are grinding blade up or looking into the blades edge as you grind.
I also understand that is the reason for the centerline on the edge to allow for you to watch that you don't take off to much. Since grinding in this position means you are blind to the back / spine edge of the blade cut.

I am I misunderstanding the rotation of the grinder or the blade up approach?

How do you know that you are not taking off too much at the back / spine of the grind line?

Do you just mark it and keep grinding into the spine until you reach the mark?

I know these sounds like elementary questions to some but it just struck me a while ago when I was thinking over the hollow grind process! Any advice would be appreciated.
 
I haven't even tried to hollow-grind yet, but the process isn't all that different from the mild-convexes I'm working on. Yes, I almost always grind edge-up.

Dixieblade57 said:
How do you know that you are not taking off too much at the back / spine of the grind line?

Do you just mark it and keep grinding into the spine until you reach the mark?
Click to expand...

A) Watch your angle and check every few passes. Or maybe make a jig?

B)Yup, pretty much. Just check often and watch your angle so you don't actually grind the plunge right into the spine, and make it thinner than the tang/ricasso. Then you'll have to flat-grind the tang/ricasso to match the plunge again, or else it looks stooopid. Don't ask me how I know. :o
 
Hollw grinding in my opinion is easier than flat grinding. But the only way to not bust the spine is practice, practice and more practice..
 
I'm a beginner, so take what I say with that little fact in mind, but here's what I do. (I'd add pictures but I'm not at home where I could do so:( )

After profiling a blade blank and deciding to use a hollow grind, I take a sharpie to my edge. I take the whole edge and darken it up, so I can take a scribe to it. Using a center scribe (this one here) I mark my edge. I'm not fancy about it, I just guestimate something that looks about right for a edge thickness and go from there. If I don't like it, I adjust my scribe, re-sharpie and go again.
Then I grind a pretty obtuse angle going right down to that mark on my wheel, about a half inch high. From there I go back into that groove, and lightly lean the spine in towards the wheel, raising the grind line higher and higher with each pass. I alternate sides with each pass, to try to keep the bevels on each side even.

Hopefully that makes sense, and it is a good way to go about things (Experienced makers, please tell me what I could fix if I'm wrong somewhere with this)
 
Dixie,
If you ever want a video completely detailing the process of the hollow grind I would highly recommend "How to build a sub-hilt fighter" with S.R. Johnson. Mr Johnson does a superb job of explaining EXACTLY what he is doing to get the desired result while grinding his blade. He grinds the entire blade start to finish in real time explaining every step along the way so you get an idea of the time involved also.

Just thought I'd mention this to ya for future reference cuz IMHO this video was the best hollow grinding learning material available.

Sounds like you've got the basics down. From my limited grinding experience it's not too difficult to walk your grind towards the spine a little at a time even though you cant see that side of the blade while grinding. Where I, and I suspect many newbies, get in trouble is when 95% finished attempting to get a perfect match from left to right. It goes something along these lines-

A little higher on the right, oops to much :(
just a touch higher on the left, crap ! :(
(Aproaching spine) back to the right for 1 pass, son-of-a.......

It's fun stuff :D I believe Dan said it best "practice, practice and more practice.. "

-Josh
 
Thanks everyone you see I am not totaly lost here just seeking a little guidance. I have a construction background and have building things all my life. So often before I get into something while still in the planning stages I go over and over things in my mind. Hopefully to avoid as many screw-ups because, "I done been there, done that"!
This question just got into my mind and the more I thought about it, the more I was realizing that spine side of the cut had to be a blind process. Which leads me to commend those that get it right all the time. I know its practise, practise,etc...!!!!!!!!
Once again thanks for the info from evryone! As money is tight, as I know it is evrywhere this grinder maybe a slow process. I am oredering some new steel to build knives from! I hope to sell them to finance the grinder, and then start the whole process again. You know, robbing Peter to feed Paul! :D
 
I not only scribe my centerline on the blade ede I also figure out how high i want my grind to go then I dychem the side of the blank and scribe a line on both sides.Then when grinding I just work myself up to the line and my grinds are the same on both sides.I use my dial calipers and set them for one side and follow the blade edge.
Stan
 
A little higher on the right, oops to much
just a touch higher on the left, crap !
(Aproaching spine) back to the right for 1 pass, son-of-a.......
Click to expand...

Josh, you haven't been watching over my shoulder, have you?
 
Ahhh,
Being a newbie and shooting for perfectly matching grinds and plunges :eek:

Pretty sure most go through or have gone through this senerio on an occasion or 12. :D

-Josh
 
You don't need to see what you are doing. You can feel when the wheel is riding in the bevel. Then you can can steer it around. It just takes practice.
Watching Steve Johnson's video instantly improved my grinding. He does a great job of explaining everything.
 
RUGUR said:
You don't need to see what you are doing. You can feel when the wheel is riding in the bevel. Then you can can steer it around. It just takes practice.
Watching Steve Johnson's video instantly improved my grinding. He does a great job of explaining everything.
Click to expand...

Ok, you and Josh both recommended the Steve Johnson video but when I googled it I ended up with a link back to the forum on another thread but noting about where or how to order this video.
So does anyone know how or where to order this video?
 
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