grinding help

[tturley]

I have started out with new equipment, I have been working and making a blade here and there for a few years, but I made the move to doing it all out. My question is how do I get my blades thin at the edge? I get the blade started out right but I can't seem to get them thin at the edge. Any help? I am using a belt sander with 2 x 72 belts. The grinder is beaumont with a 1.1/2 motor. I have all the right belts from 40 grit up to 1200. Just seems like I have to take off a lot of metal and I am thinning too much on the back of the blade.

[ranger1]

Grinding is a practice thing. sounds like you don't have enough angle on the blade. Scribe a centerline along the edge. grind to it. I think you are flat grinding and trying to use pressure to get your angle. Try grinding the bevel without letting the spine touch the belt.
Like I said, practice,practice,practice.

[Woodchuck Forge]

If you could post pics that would help. But like Andy said practice and it will get easier.

[Ray Rogers]

I agree with Ranger1 about the practice. I would also add that you should not have to put much pressure on the blade to get the belt to remove metal. If you are using considerable pressure you're belts are too dull and you should change them more often.

Another trick that I use is instead of scribing one line down the center of the blade I like to scribe two. Set your scribe so that it is about .010 off the blades center. Run the scribe down both sides of the blade to create two lines that are about .020 apart. Now, grind each side to its line and do not cross the line!!

[Ed Caffrey]

Years ago, when I stepped up to a "good" 2 X72 grinder from an old 2 X48, I kept an empty 5 gallon bucket right beside me when grinding. After about 3 or 4 bucket fulls got hauled off to the scrap yard, I started to LEARN how to grind. I'm not making fun, just trying to illustrate that it takes a lot of time, effort, and steel to gain "the touch".

When I teach grinding, I use the words "pressure" and "torque" to try to explain it. Pressure can be in & out, or side to side, where as "torque" refers to applying a slight twisting force when the blade is in contact with the belt. If your flat grinding, whatever flat you have on the blade at the time must remain in full contact with the belt...the way to take more off the spine or the edge side is to apply more "torque" in that direction, which causes the belt to bite harder in the area where the torque is applied. Its much easier to show it...than to try to tell it, but thats how I do it.

[chiger]

First, welcome T. to the world of the possessed and insane. You've just enter a realm from which there is no safe return...knife making!

Ok, to grinding. I'm assuming your wanting a thin edge after it's been heat treated and tempered, cause like Ray said you have to leave a couple hundredths to finish grind or it'll get really thin everywhere. ;~)

I have a question and it'll stir some controversy either way you answer so be careful. ;~)

Which direction are you holding the blade? I mean edge into the rotation of the belt or spine into the belt rotation. Ed's instruction about torque kind of dovetails into it. A belt will actually bite or cut harder then slip as it trails even if you apply even pressure. His point about adding torque to counter it why I ask. If you can't get the feel one way...try the other.

I know, I know. Bad advice. You should learn to do it the right way. But I'm a firm believer that the right way is the way that WORKS for you. But, as Andy, Chuck and everyone will tell you, regardless of how you do it, it just takes practice.

Sorry guys, there are some shapes I just can't do in the same direction. ;~)

chiger,

[tturley]

Thanks guys for all the info. I think I know part of what I am doing wrong. Plus, I need more time at the grinder. To answer Chiger's question, I am grinding away from the knife edge. Mr. Caffrey, I was not thinking in terms of torque, just pressure. But I see what you are talking about. For the most part I need more time at the grinder.
Thanks
Tim

[AcridSaint]

I agree, if your grinds are going too high and your knife is not thin enough, you need to turn the edge into the belt some.

[NJStricker]

I don't have a link, but perhaps a video on grinding may help?

[M.TEX]

well I do have problems with my grindind too.... my 5 gallon bucket has only 4 or 5
knives in it.
Thanks for all info....

[ranger1]

ROOKIES!!!!!!! You need at least a 55gal barrel. Thats what I use.When its full I sell it for scrap and recoop some of my steel cost.

[chiger]

Come on Andy, you know you'll just beat it into Damascus! ;~)

chiger,