- Joined
- Sep 23, 1999
- Messages
- 5,855
Hey Forumites, I got another email from Jerry, and it is packed with great info on grinding blades!! Thanks again Jerry!!!!
Michael,
A very common problem with polishing is not the polishing but the grinding.
It is quite possible that what you are trying to polish out are 60 grit
scratches that are sitting in low areas of the grind. That is the most common
issue with what looks like a polishing problem. Your 400/500 grit belt just
doesn't get to them. I almost always double grind at 120 grit (ie, grind out
all the scratches, put the blade down, then at a later time go back and do it
again). You will often see, on the second grind, what I am talking about.
I normally grind 20-30 blades at a time. The first one or two are always
rougher than the rest. By randomizing the regrinds I am able to smooth them
out so that when I finally get to that 400 grit belt, they are pretty easy to
finish. I grind to a smooth (worn belt) 120grit before heat treating, then
start at the same place or a 220 grit after heat treating. (CPM steels don't
apply - they change everything) I'm convinced the more belts you use (ie the
more regrinds and smoothing) the better the results. At the end of the drill,
I'm sure it's faster than fighting those scratches that are driving you
crazy.
Let me know if I can help any,
Jerry
------------------
"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
Michael,
A very common problem with polishing is not the polishing but the grinding.
It is quite possible that what you are trying to polish out are 60 grit
scratches that are sitting in low areas of the grind. That is the most common
issue with what looks like a polishing problem. Your 400/500 grit belt just
doesn't get to them. I almost always double grind at 120 grit (ie, grind out
all the scratches, put the blade down, then at a later time go back and do it
again). You will often see, on the second grind, what I am talking about.
I normally grind 20-30 blades at a time. The first one or two are always
rougher than the rest. By randomizing the regrinds I am able to smooth them
out so that when I finally get to that 400 grit belt, they are pretty easy to
finish. I grind to a smooth (worn belt) 120grit before heat treating, then
start at the same place or a 220 grit after heat treating. (CPM steels don't
apply - they change everything) I'm convinced the more belts you use (ie the
more regrinds and smoothing) the better the results. At the end of the drill,
I'm sure it's faster than fighting those scratches that are driving you
crazy.
Let me know if I can help any,
Jerry
------------------
"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
