Sharpening flints?

[mhb]

I've been saving 'tired' flints with the intention of trying to sharpen them for re-use, if I could find a suitable diamond-impregnated wheel or disc. I also want to try the same method for correcting 'humped' flints which do not fit the **** properly.
Yesterday, at the estate sale of an advanced (really!) lapidary/rock hound, I acquired a diamond disc machine made for grinding glass, which I think will work equally well for flint. My question, then is: have any of you tried sharpening flints by diamond grinding, and with what results? I am aware of the need to control dust, so all grinding will be with water on the operation.
From a few experiments with diamond files (really labor intensive and slow!), I believe the method is worthwhile, but want to compare notes with anyone who has some experience with grinding, rather than re-knapping, flints.

mhb - MIke

 

[andy52]

Sounds like a worthwhile experiment to satisfy the creative juices but practically speaking it seems to me that just buying extra flints would be much easier.

 

[mhb]

Sounds like a worthwhile experiment to satisfy the creative juices but practically speaking it seems to me that just buying extra flints would be much easier.

You are probably right about the easy thing to do. But I already have a pretty large supply of flints, and, every time I order new ones, a fair percentage are not properly shaped to begin with, but could be improved by the proposed method. And many flints, used until they no longer produce good sparks, are still large enough to be restored to a good working edge. I've tried re-knapping, but it is difficult to get consistent results. So, I have hopes that grinding the flints will prove workable in saving flints for longer service.

mhb - MIke

 

[Omahkapi'si]

Curious myself. I save all the old ones once they stop sparking.

 

[Grenadier1758]

I think the diamond disc machine would be great for grinding the humps off to get a flat top and bottom. The edge can be sharpened by grinding, but the sharpest edge is done by percussive flaking.

 

[Bassdog1]

You have the equipment I think its a great idea. Waste not Want not. I agree diamond files are a lot of work.

 

[flntlokr]

I would think that by the time a flint has been reknapped and used to the point of being un-knappable, yer done. To grind/cut a usable edge would reduce the core so much that there might not be enough to hang on to in the jaws. I have found that as one gets back into the core, you get fewer good strikes form a new edge (too thick?). with 100 or more shots from a rock, why go to the bother? I give most of my cores to folks who use them for fire lighters, or toss them on the ground for the amusement of future archaeologists: 'Look Dr. Oldigger, a worked piece of stone! There must have been a primitive village on this site, and they must have been lead miners judged on our other finds! These small pieces of carefully worked flint were possibly used as currency to purchase those small beads we occasionally find!' And thus a whole new civilization is created.

 

[Dusty_Traveler]

I'm interested to see how you knock that hump down. I have a whole bag I need to do that to.

 

[Grimord]

I have been using a diamond wheel (Harbor Freight) on my variable drill for years now to remove the humps on flints so they fit better in the jaws and to sharpen badly worn flints. In the field, I carry a small diamond file to touch up the flint if needed. I find that my flints last much longer and stay sharper longer cause I can keep the bevel angle. I never was very good at knapping, and ruined way to many flints in the attempts. since using the diamond wheel, I have sharper flints, and they last much longer. When the large filints get worn down to the point that I can no longer use them in the gun they were designed for, I can sometimes use them in other guns that require smaller sized flints. It is important when using the grinder to wear a mask and eye protection and to go slow.

 

[Rich44]

I'm interested to see how you knock that hump down. I have a whole bag I need to do that to.

Add me to the interested.

 

[Dusty_Traveler]

I have been using a diamond wheel (Harbor Freight) on my variable drill

is the flint in some kind of fixture, or do you just hold on to it?

 

[Grimord]

is the flint in some kind of fixture, or do you just hold on to it?

I have a small vise that I put in my larger bench vise to hole the flints. I use pieces of inner tube in the vise jaws to hold the flints for working.

 

[hawkeye2]

"I have been using a diamond wheel (Harbor Freight) on my variable drill for years now to remove the humps on flints"

Grimord, which HF wheel do you use?

 

[Grimord]

"I have been using a diamond wheel (Harbor Freight) on my variable drill for years now to remove the humps on flints"

Grimord, which HF wheel do you use?

Not really sure of the make, but it is about 2" in diameter and about 1/2" thick.

 

[mhb]

is the flint in some kind of fixture, or do you just hold on to it?

I've thought about a fixture, but do not as yet have one - I think I can do what is needed by holding the flint at the proper angle manually. I might ultimately find or make a fixture for the job.

mhb - MIke

 

[mhb]

Here are photos of the gadget. It was exactly what I was looking for, and it came with 5 extra diamond impregnated discs, 4 brand new, of grits from 170 to 1200, and a water drip outfit (for another, similar machine) which can be adapted for this one. In addition to the disc, there is a drum which attaches to the motor shaft. The disc spins at quite high speed, so should be efficient in removing material. I am hopeful this will work as desired... I have used the small diamond wheels which you can get at Harbor Freight, etc., for use with a drill, but they are really too small, and dust control is impossible.

mhb - MIke

 

[smo]

I use a Dremel with a small green rock too remove the humps..
I put the flint between my 4” vice jaws in a piece of leather prior too grinding down the hump..
I’ve never re beveled a flint edge with one.. but it might work .. once.

Use PPE while grinding

 

[M. De Land]

I've been saving 'tired' flints with the intention of trying to sharpen them for re-use, if I could find a suitable diamond-impregnated wheel or disc. I also want to try the same method for correcting 'humped' flints which do not fit the **** properly.
Yesterday, at the estate sale of an advanced (really!) lapidary/rock hound, I acquired a diamond disc machine made for grinding glass, which I think will work equally well for flint. My question, then is: have any of you tried sharpening flints by diamond grinding, and with what results? I am aware of the need to control dust, so all grinding will be with water on the operation.
From a few experiments with diamond files (really labor intensive and slow!), I believe the method is worthwhile, but want to compare notes with anyone who has some experience with grinding, rather than re-knapping, flints.

mhb - MIke

A water lubed diamond wheel such as is used for opal work should be superb for shaping hump back flint! I have and use a green wheel dry on a double wheel shop grinder that works well for hump removal but one must grind in short spurts so as not to overheat the flint and crack it.
Flint edges are stronger and last longer if knapped because of the serrated edge.
Serration also extends frizzen life as it keeps changing the impact area more often than does a ground edge .

 

[Rock Home Isle]

I've been saving 'tired' flints with the intention of trying to sharpen them for re-use, if I could find a suitable diamond-impregnated wheel or disc. I also want to try the same method for correcting 'humped' flints which do not fit the **** properly.
Yesterday, at the estate sale of an advanced (really!) lapidary/rock hound, I acquired a diamond disc machine made for grinding glass, which I think will work equally well for flint. My question, then is: have any of you tried sharpening flints by diamond grinding, and with what results? I am aware of the need to control dust, so all grinding will be with water on the operation.
From a few experiments with diamond files (really labor intensive and slow!), I believe the method is worthwhile, but want to compare notes with anyone who has some experience with grinding, rather than re-knapping, flints.

mhb - MIke

My dad is going to try this as well…let you know how it goes.

 

[hanshi]

Interesting discussion! There seem to be three kinds of flint shooters. 1. Those who knapp only. 2. Those who only grind their flints. 3. Lastly, There are those who do some combination of both. I knapp flints until there's nothing much left for the **** to hold onto. Old, used flints go into a separate box waiting to be called back into action. I've struggled with the humpbacks and have yet to find a "quick & easy" way to flatten them and so far the ways I've tried turned out to be neither quick nor easy. A diamond wheel of some type is obviously what is needed. But we'll see.