When my blade isn't flat and true

P. McKinley

P. McKinley

Joined
Jan 27, 2008
Messages
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This is what happens when my forged blades aren't completely flat and true and I start the rough grind on my jig:

This side looks good:


This side, not so much. You can see the line I want to bring the bevel up too. I can't get that grind line even with the blade edge and still keep a consistent edge thickness.


Spine shot(albeit blurry) of scribe lines at the blade tip...lines are further apart.


Same of scribe lines at the start of the tang ...lines are meeting:


I scribed the center lines and immediately went to the grinder without really looking at the lines. They converge about mid-blade, which means the blade isn't flat end-to-end.... the tip is thinner than the tang end(a simple, quick measurement tells me so). I realized this as I began to grind and started paying attention to the lines. Too late!!

I hate it when I try to rush and do stupid stuff!!:grumpy:
Any remedies, keeping in mind that I grind with a jig?

Thanks,

-Peter
 
The tip being thinner is natural, isn't it? With a little artful grinding, you should be able to reach your grind line. Less pressure at the start of your grind and a slight increase as you move towards the tang. Alternately, you can tilt the blade up, tip first, so you are grinding the blade almost virtually. A little practice with this method and you can correct a lot of problems. But it does take some experimenting, Peter.

But, what I find is when one side grinds perfectly, but the other does not, is I have a warp in the blade.
 
No remedies here, short of doing a full flat grind and introducing some distal taper to account for the lack of material on one side (tricky with a jig I would imagine). I'm impressed that you demand so much from a forged surface; I can only achieve that kind of flatness and parallelism after grinding.
 
I think you could at least try to freehand the grind on the right side. Since there is no belly or tip to the profile, and the spine and edge are basically parallel, just take it to the grinder and apply more pressure to the spine side of the grind to raise it a bit. You can always clean up with files and/or sandpaper if the grind doesn't turn out all that even. I think it's worth a shot at least, would be better to try than just scrapping it. Sorry if I'm misunderstanding your problem though...

~Paul
My YT Channel Lsubslimed
 
Hand forging and jig grinding aren't always compatible, bud. I once saw an episode of "Holmes On Homes"(A reality show that has a carpenter fixing up crappy jobs that other carpenters have done before him) where the "star" Mike Holmes, had to rebuild a deck. He opted not to use a level as the house itself was off a bit. He went on to explain that sometimes "true" doesn't look right and there is a time when you have to put away your tape measure and "eyeball" it.

It is hard to give advice without actually holding the piece. The only thing I can blindly suggest is to give it the old "brass hammer on a stump" treatment until is works. This may not even apply though, Pete.... sorry.
 
Cajun Kamikaze said:
Distal taper is a good thing in most blade designs. You should try and ditch the jig, freehand it.
Click to expand...

Cajun - I jig grind out of necessity as my left hand and arm sustained some nerve damage a while ago and I have trouble with the fine manipulation of the blade when free-handing. I try occasionally, but I get consistently poor results and its actually a bit scary at times. I don't mind distal taper when planned, but this is a "defect" that is hard to overcome in a brute de forge piece ground on a jig...... for me at least.

I think señor Dewey may have the solution.

Thank you folks.

-Peter
 
P. McKinley said:
Cajun - I jig grind out of necessity as my left hand and arm sustained some nerve damage a while ago and I have trouble with the fine manipulation of the blade when free-handing. I try occasionally, but I get consistently poor results and its actually a bit scary at times. I don't mind distal taper when planned, but this is a "defect" that is hard to overcome in a brute de forge piece ground on a jig...... for me at least.

I think señor Dewey may have the solution.

Thank you folks.

-Peter
Click to expand...

Def not the situation I had envisioned... Yep, back to the forge it is.
 
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