Homemade chisels.

["John Klassen" <jaklassen2001@zzzzzzzzzzzz>]

Hello All,
Over the past week I have been investigating the possibility of making carbide tipped chisels. A lot of this has been on the sidelines as a result of an original question about some strange chisels that I picked up at a flea market.  Those chisels seem to be metal working chisels that could be used for soft stone like limestone and marble, not granite.  I had asked about inserting carbide tips and was advised not to bother and use those chisels for softer material.

My next line of thought was "What about making my own carbide tipped chisels?".  The problem, for me, was to find out the problems that stone workers have and to pose those questions to engineers and specialty metal workers that are friendly to me.

Some of the problems were.

The carbide tips wear down too fast.
The tips fall out.
The tips shatter.
What metal to make the shank out of?
What type of carbide to use? Hard, Medium or Soft?
Can this be done by the home enthusiast?

I'm hoping that some of the great people on the list can help answer these questions.

I am coming to the realization that this investigation might not help me in working with the granite blocks that I have come across.  Hopefully someone else can use this info because it sure has been fun trying to sort it out.

What  I have become to realize(with the help of many people) is that for softer stone like marble or limestone, the metal of the shank doesn't matter that much. You can pick up a piece of any steel round bar that's handy(construction rebar, for example), silver solder a piece of carbide into a slot in the end,  shape it a bit, sharpen it and go to town.

Please remember, that I am only trying to get to the bottom of the technical question of making a carbide tipped chisel for the home enthusiast.

I have made 2 chisels out of stainless steel shanks with solid carbide silver soldered into a slot in the ends.  The carbide comes from broken, cold cut, metal saw blades that have been collected over the years.  So far, they seem to stand up pretty well.

2 Pictures can be seen at
http://public.fotki.com/JohnKlassen/

For now, I would suggest to any one willing to try it out, to make the tolerance of the slots as tight as possible and to try to get the bottom of the slot and the piece of carbide as closely fit as possible. Silver Solder is relatively soft and will compress and move around with the continuous impacts if there is too much solder between the insert and the bottom of the slot.  Any compression of the solder at the bottom of the slot could cause shearing of the solder joint at the sides of the insert, resulting in the insert falling out.  It seems that ,the harder the grade of carbide, the more prone to shattering.

Please, wear a respirator when cutting or sharpening the carbide. Supposedly, the dust could be cancer causing.

Through experimentation and consultation,  solid carbide seems to be able to be TIG welded.  I tried a piece with stainless filler wire and it welded OK.  My friend "Kevin" tells me that extended high heat welding can make the carbide brittle.  Not too sure how this can help the purpose yet but will continue to look into it.

This is about as far as I have gotten so far in this and would love to have as much input as possible.  Hopefully some one could add to this.

My friends have told me to "get off my wallet" and buy some pro made chisels.  My response is that there is too much fun to be had in figuring out something new.

Any help?

John Klassen