[gandrfab]

As a career welder grinding is one if not the most hated part of my job.
But I have been threatening to cold grind, sand and make a knife out of a file for a few years.
The plan has been for no heat treatment.

A buddy gave me 4 of these files his company uses a bunch of them as a backing for knurling RF label making.
I'm not sure how it works and would be more confusing trying to explain, the knurling gives a foil the perfect texture in a press and each file is good for a few thousand hits.
So his scrap has been sitting in my shop for a few years.
Here goes one.

Air die grinder and then bench grinder to get this shape.

Then to the belt sanders...started free hand on the 1"x42"

Then altered the 4"x36" for more even sanding

At this point the spine is .21" thick
.050"ish thick at the edge ±.005"ish
Primary inclusive grind is 9°

Spine to edge is 1.16"


Started the grind on a 1"x42" belt sander and that seemed futile trying to keep the primary bevel/grind even.
My 4"x36" belt sander didn't have the relief allowing room for the blade heel.
So, I added a plate to the 4" belt sander and have been sanding with 80 grit since.

Any recommendations for target thickness behind the edge? C
Or guesses where I'll give up flat grinding and convex the the grind to the edge?

This is more for fun than weapon, no feeling hurt if this is moved.

 

[brownie]

Did you anneal the file before grinding? Nice project

 

[gandrfab]

I did not anneal had no plans to over heat grinding or heat treat after.

 

[Rick McC.]

I did not anneal had no plans to over heat grinding or heat treat after.

I made a hunting knife out of a file for my Dad years ago with no before or after heat treat.
It broke a couple of years later when he was chopping palm fronds with it in the swamp.
He’d done the same many times before and got away with it; until the last time. Files are pretty brittle.

Here’s a knife that Mike (LionTribe) made me from a file:

I’m pretty sure that he anneals them first; then re-tempers when the shaping’s all done.

 

[brownie]

I made a hunting knife out of a file for my Dad years ago with no before or after heat treat.
It broke a couple of years later with he was chopping palm fronds with it in the swamp.
He’d done the same many times before and got away with it; until the last time. Files are pretty brittle.

Here’s a knife that Mike (LionTribe) made me from a file:

View attachment 79902 View attachment 79904

I’m pretty sure that he anneals them first; then re-tempers when the shaping’s all done.

He's likely taken some of the temper out of the file during grinding. It'll be brittle as your dad found out. Files are usually rockwell'd to 72 where working blades are as low as 55 and normally in the range of 57-59.

 

[gandrfab]

Right or wrong it's in the shop toaster oven holding 375° to 405°f
This pic is at 1/2 hour in.

 

[gandrfab]

hmm, time stamps may not equal actual time. 2 hours in and now slow cooling.
Plan on a 2nd toaster oven cycle

 

[gandrfab]

Scotch-brited the color off and now in for another heat cycle.
I sanded the grind, large flat of the blade until the edge thinned to .040"
FCC's thoughts on finished edge angle?

 

[brownie]

0.35 mm is a perfect thickness for a carving knife. For a chef's knife that deals with more pressure, the thickness can be a bit higher: 0.45 mm is then still perfect.

 

[BeerHunter]

Scotch-brited the color off and now in for another heat cycle.
I sanded the grind, large flat of the blade until the edge thinned to .040"
FCC's thoughts on finished edge angle?
View attachment 79922

I'm not expert but the default on my Spidey Sticks provides a 40 deg angle for the edge of my EDC blades. I think there's a 30 deg angle, too, but remember being told to only use the 40 deg edge, except for "XXX," which I only remember didn't apply to anything I needed to keep sharp.

 

[gandrfab]

Edge is currently thinned to .040" and blunt
I'm thinking 20° - 25° edge bevel.
If I leave the grind alone that may make the C dimension above .050" 🤷‍♂️


Was half tempted to keep sanding the grind to sharp but that edge might fold over cutting cardboard.

 

[BeerHunter]

Edge is currently thinned to .040" and blunt
I'm thinking 20° - 25° edge bevel.
If I leave the grind alone that may make the C dimension above .050" 🤷‍♂️


Was half tempted to keep sanding the grind to sharp but that edge might fold over cutting cardboard.

Just to be clear, that 40 deg edge bevel I mention is the total angle.

 

[gandrfab]

Thanks.
2nd cycle, didn't get as hot as the 1st round and Scotch-brited
+ a tip drop on to the concrete floor from 3'

 

[Rick McC.]

Just to be clear, that 40 deg edge bevel I mention is the total angle.

20 degrees per side?
20-22 sounds pretty good to me.

 

[BeerHunter]

20 degrees per side?
20-22 sounds pretty good to me.

Yes, I was referring to the angle from the guide on the Spidey Sticks base; 40 deg edge bevel = 20 deg either side of center (probably not explaining in technically correct "knife maker" terminology).

 

[gandrfab]

20° angle per lansky 120 grit stone, edge still blunt. Sharpening is on hold until a holder is made.

On the fence, tempted to hammer out a metal sheath (do we call it a scabbard this small?) or have a leather one made.

 

[Caleb]

Looking good so far!


Sent from my iPhone using Tapatalk

 

[brownie]

Handle portion seems too thick to me. Are you going to grind on that end to attach handle slabs or leave the handle that thick which will be quite thick in the hand with scales put in it.

 

[mario]

Nice Job! Reshaping file hard steel into that knife is quite an accomplishment

 

[gandrfab]

Handle portion seems too thick to me. Are you going to grind on that end to attach handle slabs or leave the handle that thick which will be quite thick in the hand with scales put in it.

On the fence about scales too.
After handling like it is so much I have been knocking edges off the handle on the bench grinder as I go, minimal and evenly on both sides.
My forefinger landing or (quillon?) is still a hot spot.
If nothing else the file teeth make outstanding jimping.