Breaking graver tip

[vanknife]

Good day to all,
I have been practicing the last couple of weeks on sharpening gravers properly and put them to use, I have learned a lot and again thanks to all who shares so freely. I have one problem that I come across frequently and that is when I do tight scrolls the graver tip break very easy (110 Deg) full relief heel 15 Deg.Lindsay point. Do I do something wrong? or do I have to accept it as an injury timeout of this game.

PS. "Good judgment comes from experience, experience comes from bad judgment " (Author unknown)


Thanks

"VAN"

 

[jlseymour]

I'm using colbalt 3/32 square and 2mm colbalt drill bits hammered into 3/32 square brass and use the Hamler sharping tool... Not had the problem... John B has Info on the sq brass and 12" rods on Sam's and Paul Hamler has pic and info on Steve Linsley's forum...
Good Luck
JL Seymour

 

[jimzim75]

Hi,
Tip chipping or Spalding. Understanding the forces at work in necessary.
130° with a 15° lift should be a fairly hardy graver even with sharp scrolls.
The shear point pressure should be lower than a 90° blade because the
cross section is bigger.One engrave told that by slightly dulling the point
thus making the graver shape more like a carbide lathe cutting tool you
could reduce the shear point pressure. Shear is when you have two things
going in the opposite directions. The graver is the only thing moving but
it still works that way.Spalding or the cracking of the point edge in a C
shape is what happens.
Personally I don't dull my tips, I feel it has to do more with speed
that the gravers is traveling through the material and how hard your pushing, or speeds and feeds. When your cutting straight lines the geometry of the graver is ideally suited to the job. All the pressure is at the
very tip. When you make a turns the pressure goes from the tip to
side of the blade. The side of the blade will actually be traveling at a
slightly faster rate, but the shear pressure can be double or triple that in
a straight cut.
The cure is a combination of things.
1.Higher stroke speed to shorten the distance the graver is cutting.
2.Less hand pressure or a light touch.
3.On deep cuts can mean, multiple recuts to lesson pressure.

Your tips will still break but hopefully not as much. One more thing,
stay away from diamonds. They break a tip every time.

Jim

 

[Mike Bissell]

It seems that I have had this happen a time or two. Simply stated this usually happens when ending a curved cut and the ball rotation continues after the forward movement of the graver has stopped.

Mike

 

[vanknife]

Thanks for responding to my needs

Thanks for the advice and Mike is right it happens on the end ball of the scroll. I will have to take some time and analyze were I apply the pressure and move the force in the right direction, that is if I understand the explanation that is given by Jim, seems to me the cobalt trick maybe the answer

"VAN"

 

[Sam]

Graver point failure is a fact of life for hand engravers. Some things to remember:

* Inexperienced engravers often apply more stress to gravers than an experienced engraver who has greater control and finesse.
* The rotational speed of the vise increases when cutting smaller and/or tighter curves. This is often a problem area for engravers with less experience, and can lead to point failure as control diminishes.
* Wider-than-90 degree gravers are stronger than square gravers, but they can still fail.
* Increasing face angle a few degrees can strengthen the point, but be prepared for the graver to feel and behave differently.
* Gravers fail more in hard metals than softer metals.

 

[vanknife]

Thanks for the advice SAM, I guess the old saying "practice makes perfect" is what it is all about.
Much appreciated

"VAN"

 

[Raul Hinz]

Van I notice that if the work is not secure the vibration will cause the graver to brake. Slowing the stroke
will help. Letting the graver do the cutting not pushing, also works for me.

Raul HInz

 

[vanknife]

Thanks Raul will have to try and find the right way of doing engraving as I said more practice

cheers

"VAN"