The Saber Grind Struggle

S

Skullmonkey

Joined
Sep 4, 2019
Messages
9
Hello,

I am new to knife making and this forum.

But I’m hoping to pick anyones brain who can offer some help!

I’ve been using a similar jig that J.Keeton put together (2x2 piece of angle steel) with a bolt to adjust the angle.

And so far my bevels are spot on... Except when it gets to the tip of my blade where the bevel narrows or tapers.

48681301721_8990296fd9_o_d.jpg


I feel like this might be a pressure issue in that I’m not apply pressure evenly throughout the grind... Or in your experience could it be something else?

Any help would be greatly appreciated!
 
Are you hollow grinding this with a jig, or flat grinding it? If hollow grinding (on a contact wheel), the difference in height is from the changing contact point on the wheel, causing the bevel angle to get steeper as the tip drops.

If you're flat grinding the bevel on a platen, can we see a pic of the edge looking down towards the spine?
 
remember the higher you bring the grind toward the spine, the easier it will slice. saber swords are mainly for stabbing/chopping motions. the grind only goes 1/2 way up the blade because the sword is long and thin, and need that extra metal for strength so it wont bend.
 
Skullmonkey said:
But I’m hoping to pick anyones brain who can offer some help!
And so far my bevels are spot on... Except when it gets to the tip of my blade where the bevel narrows or tapers.
Click to expand...
Yes , you are pulling blade too far and maybe too late . Try to leave tip for end , grind first flat part till you get grinding line high as you want then work on belly and tip from both to get them symmetrical .....

Backyard said:
Turning/pulling the knife out too far when reaching the tip. Try just keeping it in line with the belt the whole time
Click to expand...
I would just add this .......... my grinding stop with tip in middle of belt , I never pass that point with tip of blade .
 
If your edge width is the same from heel to tip the issue is using a jig with that large belly. You will need to freehand it and twist slightly as you approach the tip.
 
So here is my jig and setup...

48686099871_91bf1d14ba_o_d.jpg


I have been trying the “arcing” of the tip in that I “arc” my handle side hand away from the grinder as I get towards the tip. And I am still using the jig for this.

48685758078_d92fcdde72_o_d.jpg


It definitely is an improvement... When I tried this arcing method I had already ground the cutting almost completely away on this knife (that’s why the tip is starting to grind away).

But I’m hoping to see some more even bevels near the tip on the next knife using this method.
 
Ok!

I definitely try to just leave the tip flat in the middle of the belt and see how it compares.

What angle do most of you guys shoot for to get the bevel roughly half way up to the spine? I’ve been measuring roughly a 6°-7° degree angle for the jig lean.
 
Skullmonkey said:
Ok!

I definitely try to just leave the tip flat in the middle of the belt and see how it compares.

What angle do most of you guys shoot for to get the bevel roughly half way up to the spine? I’ve been measuring roughly a 6°-7° degree angle for the jig lean.
Click to expand...
Don t bother with angle , angle is different for different steel width...start with low angle and change angle as you grind till you get height you want .Watching where belt remove steel will tel you what to do .When you do one side you have right angle for other side .. ...
 
This is a weakness of using a jig. You can mitigate this somewhat in your blade design. A shallower (more gradual) belly will give you more consistency but, a big belly like you have on this blade is going to do exactly what you are getting. You can redesign the knife, grind freehand or do a full height flat grind to overcome this issue.

Bob
 
Natlek said:
Yes , you are pulling blade too far and maybe too late . Try to leave tip for end , grind first flat part till you get grinding line high as you want then work on belly and tip from both to get them symmetrical .....
Click to expand...

Do you have any pics that would show this in stages like you suggest?

Sam Dean said:
Are you hollow grinding this with a jig, or flat grinding it? If hollow grinding (on a contact wheel), the difference in height is from the changing contact point on the wheel, causing the bevel angle to get steeper as the tip drops.

If you're flat grinding the bevel on a platen, can we see a pic of the edge looking down towards the spine?
Click to expand...

Sam do you have any pics of your setup? I’ve been flat grinding my bevels with the jig I post in the picture. I do have a contact wheel but I haven’t been using it very often. Would there be any advantages of using a contact wheel instead of a flat platen for a saber grind?
 
Bob Ohlemann said:
This is a weakness of using a jig. You can mitigate this somewhat in your blade design. A shallower (more gradual) belly will give you more consistency but, a big belly like you have on this blade is going to do exactly what you are getting. You can redesign the knife, grind freehand or do a full height flat grind to overcome this issue.

Bob
Click to expand...
When we know weakness there was solution ...I use light square tube as jig for that reason .......I can grind this blade shape in 5 minutes with my jig .My rest work is very precisely cut/adjusted in ANY direction and that allows me to do some things ....instead of pulling butt of jig when I get to belly I can RAISE tip to follow curve , jig only touches the edge of the side of the work rest,that s whay work rest must be precise , only touches the side but has the same angle as when on flat part .I have mark /simple wire / how much to raise jig/blade . I'm doing the same thing as we do using this jig but in opposite direction ......
JE2SPop.jpg

oT7x5ER.png
 
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Natlek said:
When we know weakness there was solution ...I use light square tube as jig for that reason .......I can grind this blade shape in 5 minutes with my jig .My rest work is very precisely cut/adjusted in ANY direction and that allows me to do some things ....instead of pulling butt of jig when I get to belly I can RAISE it to follow curve , jig only touches the edge of the side of the work rest,that s whay work rest must be precise , only touches the side but has the same angle as when on flat part .I have mark /simple wire / how much to raise jig/blade . I'm doing the same thing as we do using this jig but in opposite direction ......
JE2SPop.jpg

oT7x5ER.png
Click to expand...
But what if you want to raise the handle and move it out while you're twisting it? Sometimes this is needed... 5 axis grinding :D
 
Natlek said:
When we know weakness there was solution ...I use light square tube as jig for that reason .......I can grind this blade shape in 5 minutes with my jig .My rest work is very precisely cut/adjusted in ANY direction and that allows me to do some things ....instead of pulling butt of jig when I get to belly I can RAISE it to follow curve , jig only touches the edge of the side of the work rest,that s whay work rest must be precise , only touches the side but has the same angle as when on flat part .I have mark /simple wire / how much to raise jig/blade . I'm doing the same thing as we do using this jig but in opposite direction ......
JE2SPop.jpg

oT7x5ER.png
Click to expand...

That is quite the interesting jig!

Any chance you have some video of it in action?
 
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