Ugh!!..Nail nick problems again

J

John L

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Oct 28, 2004
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Nail nick problems seem to plague me on my slipjoints. I really want a fly cutter style nick..one that is long and skinny. I just cannot figure out the geometry of the cutter. Clearly one edge is ground to give a near vertical wall and the other angled. What should the relief be? The way most fly cutters are made..almost no relief is possible as the angle allows it...but I continually break the points no matter what the relief. I am using standard 3/8 or 5/16 square lathe bit stock. Is there a better material? Do any of the carbide tipped standard lathe bits work such as AR, AL, BR, BL, C, D, E? I am at a total loss right now and it is gettin to me!! The blade is well supported in a vise directly on the horizontal table of my Benchmaster horizontal mill...no give that I can discern. RPMs are slow...about 200RPM. I cut about 50 thous into material and then it breaks. Is the steel work hardening or??? Does lubrication make a big difference?...none that I can tell. Any help here is appreciated. I cut a variety of materials...CPM154, D2, primarily. Thanks
 
I tried the flycutter route and had the same troubles your having. I went to a stone and solved all my problems. One really nice thing is you can grind it in after the heat treating is finished. Simply dress the stone down to the about a 4" diameter and dress a knife edged 45 degree angle on it.
 
Bruce: Are you doing this on a surface grinder? If not..is the stone a cup grining type stone? Are you dressing bottom of the stone on a diamond point? Just a bit curious on exactly how you are dong this. Many thanks.

John
 
Bruce, what kind of stone? Size, brand, grit, hardness.

Oh, sorry to hear about your trouble John, thought you had it figured out with the H-mill.
 
Hmm. I haven't has any problems cutting in the nail nicks at all. I run my mill on the slowest it can go. In my archived build off page I have some pics going through the process of making the knife. About half way down is the section on the nail nick.

http://knives.mutantdiscovery.com/buildoff.html

Here is the actual cutter I use though.

IMG_2168.JPG
 
Don: I'm down here in Mexico making do with ....well...Mexican stuff. I never have the right stuff down here and nowhere to buy anything. Oh well...next trip! Fishin also BAD:eek:
 
Here is a couple shots of my method. I hope you can see well enough. The neat thing is it is very precise and the stone can be touched up with a diamond file for the last few clean up grinds.

I use a surface grinder but theres no reason you can do this same thing in the milling machine vertical instead of horizontal like this.

100_7325-1.jpg


100_7326-1.jpg
 
Don Hanson III said:
Bruce, what kind of stone? Size, brand, grit, hardness.

Oh, sorry to hear about your trouble John, thought you had it figured out with the H-mill.
Click to expand...

Hi Don,
I cant tell what grit it is but its a Norton I think about an 80grit. It is only .150" thick and I dressed it down from 6" to 5". I dressed the angle on with a diamond file to about 35-40 deg. angle. I played around with different angles on scrap steel until I liked the width of the nick
 
John send me a bit and i will grind it for you. Carbide breaks easy. I may cut one or 12 before i resharpen. You want to flood the material or dont use cutting flood at all. Go .005 deaper than center. It took me a year to work it all out. Your nick will look very large but you will grinding half of it off. I mill is running 1000rpm. Feed is about .0005 at time. It seems to cut well at even higher rpm if you are useing good cutting flood.
 
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I use a stone in the mill Norton 38A100-IVBE.
P1010042.jpg


Dress the angle with a sine dresser. I got mine from CDCO Machinery $90.
P1010043.jpg


Blade mounted to a plate held in the vice and cut the nick.
P1010003.jpg


The holder if anyone wants to make one.
P1010013-1.jpg

P1010015.jpg
 
It works good for me Bruce. A little coolant in a spray bottle and cut them in.

I have used a tool post grinding wheel the same way. Made a mandrel from a bolt and washers on each side of the stone. I think MSC has a 4 inch tool post wheel with a 1/2 inch hole.
 
Rick: Very nice of you to offer to grind a cutter for me. I am going to grind one that looks like yours and see what happens. I have a horizontal mill in St. Louis that has a lathe bit fastened to the 1" arbor, right thru the arbor, and it sticks out at a 90 degree angle. It works great. I just cannot get a bit sharpened correctly that fits in my fly cutter down here in Mexico. I am going to set it up vertically and try itlike yours. This mudda is not going to defeat me...although it very easily could:eek:
 
Although my setup is is for small nail nicks, I might try making that arbor to hold bigger stones. I used scrap around the shop to make a holder that gets held in place my the lathe toolholder, and I c clamp the balde to it. I spin a 1" dovetail cutter. Only drawback is you have to do it pre HT. Oh, and since my lathe is tiny I can only do blades up to 3".

nickcutter1.jpg


nickcutter2.jpg


nickcutter3.jpg
 
Since a lot of you guys are forgers, why not just stamp the nick in?
 
I use a setup similar to gixxer's, a dovetail cutter, but I use a mini mill.

Bill slipjoint blades are generally stock removal, although I guess someone out there may forge them.

Sean
 
Regardless of stock removal or forged, nicks are traditionally forged into blades. Simply make a nick-shaped punch, harden it, and stamp the unhardened blade. Finish as necessary.
Machining the nick is fine, but unnecessary.
 
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