jb 1/16" cobalt square graver

[monk]

anyone have a foto of the bottom of john b's bargain cobalt gravers ? how they're supposed to look . i made a few and soldered them into the 3/32" square brass tubes. i cant seem to get acceptable geometry. i'm using a grs power hone and a 600 diamond wheel. i roughed the face first with a dreml, then used the powerhone on the face, then the heels. uuugh !

 

[John B.]

Hi Monk.
The 1/16 inch round cobalt must be soldered firmly and in line to the center of the 3/32 inch brass tube.
I wonder if yours wasn't fixed and turned while being shaped and sharpened.?????
First put the brass into the V-groove of the GRS sharpening fixture and set the long axis on a zero mark.
Sharpen the face to your desired angle of pitch
Rotate the fixture to the other zero.
If it is to be a 90 degree V-graver rotate the fixture 45 degrees in the long axis of the tool on either side of the zero.
With the point of the face pointing forward set the pitch at about 2 1/2 degrees and cut a long flat for one side of the bottom of the graver.
Then rotate in the the long axis to the 45 degree mark the other side of zero and cut the other long bottom flat extended to the same exact length as the other flat.
Now you should have a V- bottom clear out to the face.
Now cut your regular lift angles on the two flats you have created and you're good to go.
These are very easy to make once you have the general idea.
I am out of town as I write and can't post a picture.
Maybe someone else can post one to help you.
Best regards Monk. John B.

 

[Powderhorn]

Monk:
I just made some of those gravers, and what I did was to:
1. ground face, at 0 deg offset
2. then ground right side angle at abt 2 deg and 45 offset
3. then ground left side at 2 deg and 45 deg offset
4 then ground 15 deg lift

they come out looking like a regular 90 deg graver, with a nice rounded top. If you are confuzziated, give me a beep.

 

[monk]

it's against the law where i live to be confuzziated. we get cornfuzed here, and yes i am cornfused. that 2 degree thing scares the crap outta me! i use the older model grs holder. it doesn't permit fine tuning left and right.

 

[msar24]

John,

Any tips on the soldering? I've done a lot of soldering but sometimes I have a hard time getting the solder to adhere to the cobalt. I've roughed up the finish, cut small grooves in it, cleaned it with denatured alchohol and of course use flux. The brass is no problem.

Thanks,

Kevin

 

[Powderhorn]

Monk:
I just eyeball the 2.5 deg, splitting the distance between 0 and 5. I put in a couple of pics hope they help.
Also my DA sharpener doesn't have any fine degree marks either, just 5 deg increments.

 

[Powderhorn]

Msar24:
I have soldered the gravers using StaBright, and silver solder. I did find that if you are off just a little in temp for the stayBright, it will not stick to the cobalt. I've had better luck using the silver solder, just make sure that you heat sink the cobalt, ie stick it in a potato, or stand it in water. After soldering let it air cool, do not quench, and do not go near the pickle pot with it , as the steel in the graver tip will contaminate the pickle. It will turn your silver pink from an iron residue.

 

[John B.]

Monk.
With the older fixture you can do 90 degree bottoms by just reinserting the brass into the V-groove of the fixture.
Just eyeball the 2 1/2 degree settings for the bottom cuts but cut both sided using the same setting before you change the fixture.
Confuzzed still ???? Hope not.
Best, John.

PS I have no problem using StayBrite after putting a couple of slot cuts on the graver shank.
Just be sure to clean everything including the inside of the tube with acetone to remove any production oil.
Flux the inside of the tube with a wet tooth pick and dip the shank of the cobalt blade in the flux.
The solder grips the brass like crazy and the flow into the slot keys stop any movement sideways or back.

 

[Tom Curran]

Make sure the steel is bright and clean.

Sometimes I tin steel before assembly, wipe excess solder with a rag or steel wool. Then the solder will wick like nobody's business.

I have been using Tinner's Fluid of late for soldering steel, and it works like no other flux I have ever used on steel. If you spill it on your bench, everything within vapor distance will be rusty. So clean up when finished! Throw away paper towels, rinse your brushes out, etc.

 

[Bob Bullard]

When I made mine I ground a couple of flats on the shank washed in acetone both pieces let dry
real good and used sta brite solder (used alu. jaws in vise for heat sink). Then to shape it put
in a N Graver tool holder(the square one) and on my power hone I use a piece of tempered plate
glass and valve grinding compoud to grind 4 flats on the round if you use a little care you end up with a nice square piece of tool steel. I use the old style of tool holder on the power hone to shape the tool steel.
Bob

 

[Tom Curran]

Anyone ever try Loc-Tite to assemble tube to cutter? if you use the permanent assembly stuff, stud and bearing mount, I bet it would work. Just be sure to degrease everything first.

 

[msar24]

Thanks everyone for the soldering ideas. Wrong solder - Duh! I'll give the Loctite idea a try too.

Kevin

 

[monk]

thanks to all for the info. the soldering is the easiest for me. i inject a bit of flux into the brass bore with a syringe. i insert the solder with forceps. i cleaned the cobalt shafts with 600 grit. the gravers are there for the duration. i must get a more advanced sharpener. thanks again to all. monk

 

[John B.]

If you don't want to use solder clean both parts well and cut a couple of slots in the shank end and cement it in to the brass tube with JB Weld.
Fill the tube with the JB Weld using a flat toothpick.
I have done this but much prefer to solder using StaBrite.
Soldering only takes a couple of seconds and no waiting for it to set.
John B.

 

[Tom Curran]

Sources of supply:
http://www.mcmaster.com/

round drill blanks, hardened M2/M7 tool steel:
0.0625" 1/16" dia. 1 7/8" long 3009A114 1.78 ea.

Square brass tube:
3/32" x 3/32" x 12" long 8859K411 13.45 for a ten pack

 

[monk]

and you know what ? these little buggers cut like crazy ! once i got the angles the way they're supposed to be. i still don't know what that 2 degree stuff is, but even without that, they cut very well. i did increase from 15 to about 17 degrees on the heel though.

 

[Powderhorn]

Monk:
So you are now un-cornfused. Pretty neat gravers, eh.