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Ron Benson

Distal taper plus flat grind

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As a rank newbie, I want to grind a distal taper on a blank. It is shaped to a drop point. I have enough 1/4" 5160 that someone gave me to make at least 8 hunter sized knives, so I'm not worried if I screw one up.  :blink: Anyway, it looks fairly straight forward - just scribe the lines and grind to them... I'd be very appreciative for any tips though, and I have watched a bunch of youtube videos.

And if I decide to go wild and also try to add a full flat grind, it looks like I would grind that taper stopping when I reach the top of the blade. I'm guessing that since the point tapers towards the center of the blade, I will have enough steel that I don't wind up grinding the edge to nothin'. Is that correct, and are there any gotchyas?

 

Thanx ~ Ron

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Posted (edited)

1/4" is quite thick for a hunter, even with distal taper. 

A blade with a drop on the spine will naturally taper if you keep your grind parallel with the edge, if you don't tilt the blade when you're at the belly. At least, that's what I figured out.

And you are correct regarding the point. 

Edited by Joël Mercier

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3 hours ago, Ron Benson said:

are there any gotchyas?

Tons of them. They will make themselves apparent soon enough!

Seriously though, Joël has clarified most of the mystery behind a distal taper when working stock removal. I forge my knives and get my distal tapers starting much further back than where the drop in the point begins. You can get the same effect with stock removal by striking a center line down the spine as well as the edge. Then you lay the blade blank (before you start grinding the bevels) flat against the platen (edge down) and slowly drag the blade from where you want the taper to start, to the point thinning it more toward the point.  Use the center line as a reference to get the tapers even. After you have ground the distal taper in, flip the blade edge up and grind the bevels in.

You do have a center line scribe tool, yes?

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3 hours ago, Joël Mercier said:

1/4" is quite thick for a hunter, even with distal taper. 

Thanx Joel. I agree that 1/4" is too thick, but it was free, and there is more room for me to correct mistakes...

3 hours ago, Joël Mercier said:

 

A blade with a drop on the spine will naturally taper if you keep your grind parallel with the edge, if you don't tilt the blade when you're at the belly. At least, that's what I figured out.

 

Sorry, but I don't understand "drop on the spine".  :huh:

35 minutes ago, Joshua States said:

You can get the same effect with stock removal by striking a center line down the spine as well as the edge. Then you lay the blade blank (before you start grinding the bevels) flat against the platen (edge down) and slowly drag the blade from where you want the taper to start, to the point thinning it more toward the point.  Use the center line as a reference to get the tapers even. After you have ground the distal taper in, flip the blade edge up and grind the bevels in.

Thanx Joshua - I have been using a drill bit the same thickness as the blank to scribe centerlines. I do flip and scribe a second centerline. Even if they don't lay on top of each other, they are the same distance from the center. For establishing the taper, I'm going to try placing a smaller bit, (maybe 3/32"), under the pointy end, and leaving the heel on the flat surface. Then take another bit to scribe the taper line. Then repeat for the other side. Does that sound like it will work?

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Joel is referring to the tip of the blade being lower (dropped) than the spine.  Often called a "Dropped point".  You get some natural distal taper simply because most points are indeed dropped a bit and are therefore thinner than the spine.  However, as Josh points out, it is often desirable to start the distal taper earlier.

Your approach will get you a good start.  The geometry of a blade is fairly complex, and I don't know that there is any quicker way to understand it than to start trying to grind one out.  You are off to a good start just recognizing that grinding to scribe lines is a good idea.  Follow Josh's approach of grinding in the taper before you start beveling, and all will be well.

Joel & Josh, I don't mean to barge in here when you guys have it under control.  I just happened along when Ron posted his reply so I thought I'd try to help out a bit. :)

(and how do you get the umlaut for your o on an american keyboard Joel?)

 

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Posted (edited)
30 minutes ago, Ron Benson said:

Sorry, but I don't understand "drop on the spine"

This is where the line of the spine begins to curve and "drop" towards the edge. I believe this is where "drop point" comes from. I am sorry not being able to explain this better due to my limited knowledge of English. 

I first noticed this phenomena when doing stock removal kitchen blades which had very pointy tips and low belly. The distal taper naturally formed while grinding if I kept grinding the blade parallel to the edge. I actually ended up with very thin tips (almost too thin). 

Edited by Joël Mercier

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16 minutes ago, Brian Dougherty said:

and how do you get the umlaut for your o on an american keyboard Joel?)

I haven't the slightest. Don't bother, I'm not the easily offended type :lol:

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23 minutes ago, Brian Dougherty said:

(and how do you get the umlaut for your o on an american keyboard Joel?)

On a windows machine, turn on num lock and then hold down the ALT key while typing 137 on the numbers pad       ë

 

And thanx for the clarification. :)

Joël - your second attempt is perfectly clear, and your English is much better than my Spanish ever was. :rolleyes:

 

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20 minutes ago, Ron Benson said:

On a windows machine, turn on num lock and then hold down the ALT key while typing 137 on the numbers pad       ë

 

download (1).jpeg

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This makes me think about how to turn the alarm off on some Volkswagen cars. You have to pop the trunk open the drivers door and turn the key to the on position.:wacko:

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If you're running an older Windows (7 or older) there are tons of ASCII tricks like Ron's using alt + keypad.  Not on newer machines, and not on phones, so unless I'm in my office on the old machine I just have to rely on Joel's goodwill. :(

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Thread is getting hijacked:D...

On phones and tablets, hold down the letter you want the umlaut on and several options should pop up (at least on iPhones and iPads...)

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Regardless of the machine you use, copying his name from the screen below his avatar and pasting it into the thread will work.

17 hours ago, Brian Dougherty said:

Joel & Josh, I don't mean to barge in here when you guys have it under control.  I just happened along when Ron posted his reply so I thought I'd try to help out a bit. :)

No worries. It's good to have people join the fray. 

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I'm having a bit of a brain-fart here.....

Putting distal taper in a tang is a bit tricky, I know one technique which I haven't tried yet.

Distal taper on the blade.......doesn't that happen by default?

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3 hours ago, Gerhard Gerber said:

Distal taper on the blade.......doesn't that happen by default?

Why didn't someone tell me... :blink:  :D

 

The distal taper turned out to be easier than I thought, but I do need to be more careful because it doesn't take but a second of inattention to grind too deep.

And I can see actually getting a flat flat grind is going to take a fair amount of practice. But then, that's exactly what I am doing now.

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Yeah, a perfectly flat grind takes practice. You think it's flat until you begin to hand sand...

Spend more time than you think you should on the higher grit belts and don't start your grind at the same place everytime. This should help with the "dips" on the blade. A disc sander also helps making a blade perfectly flat.

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Posted (edited)
On 7/11/2019 at 2:15 AM, Gerhard Gerber said:

Putting distal taper in a tang is a bit tricky, I know one technique which I haven't tried yet

The tang should be tapered in both height and thickness.Height is easy to do on the 2x72 or with an angle grinder. Just scribe a line and grind to it. Thickness is where it gets tricky, but the only real "trick" is either dragging it slowly across the platen and slowing down as you go, or using the disc and dragging it across the face. Either of these two methods will grind heavier at the distal end of the tang than at the shoulders.

The distal taper in the blade only happens by default if the spine of the blade angles down toward the edge. Even so, the taper will only begin where the spine starts to drop. The rest of the blade remains a constant thickness. This is not always desirable.

If the spine is straight, and uniform, it will remain that way unless you manually put the taper in. This can be done in the forging, or in the grinding.

Edited by Joshua States
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Thanx Joshua. That makes perfect sense. What I did, ('cause it's what I thought of), was scribe the taper lines and grind close to them moving the blade horizontally across the 2X72 grinder. Then I ground vertically with the blade flat against the platen. That got me to the same spot, but I don't have enough experience to know if it was better than your method. I do have a large homemade disc grinder that fits on my home made bowl lathe, but I haven't gotten the lathe up and running yet.

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On 7/12/2019 at 7:58 PM, Joshua States said:

The distal taper in the blade only happens by default if the spine of the blade angles down toward the edge. Even so, the taper will only begin where the spine starts to drop. The rest of the blade remains a constant thickness. This is not always desirable.

If the spine is straight, and uniform, it will remain that way unless you manually put the taper in. This can be done in the forging, or in the grinding.

Brain-fart then....makes perfect sense, thanks.

As far as the tapered tang is concerned, I was forced to do it the hard way on my 3rd knife, the method I've seen in a video is putting a horizontal hollow in the tang using a small contact wheel getting deeper to the rear.  You then grind down the tang, and I assume the hollow is a guide.....not sure at all.

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19 minutes ago, Gerhard Gerber said:

As far as the tapered tang is concerned, I was forced to do it the hard way on my 3rd knife, the method I've seen in a video is putting a horizontal hollow in the tang using a small contact wheel getting deeper to the rear.  You then grind down the tang, and I assume the hollow is a guide.....not sure at all.

Same basic concept, grinding deeper at the distal end, just that is a 2-step process.

Let's assume for a moment that you have a center line scribing tool or jig of some sort that you use when grinding the edge of the blade. Use the same tool to mark the center line of the tang. now you have  reference line when grinding the distal taper. If you set the scribing jig to be a few thousandths off center, you will end up with two lines running down the tang for reference. If you wanted to get really technical, do the math. Let's say you have a tang that is roughly uniform in thickness at 6,5 mm. You want the tang to taper from 6,5mm to half that at the distal end. Set the scribe at a little over 1,5 mm and scribe two lines (one with each side down) on each edge of the tang. You now have a visual reference to grind to.

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