Good idea - someone showed me, took about ten minutes, and it then took
me a couple of hours of solo practice before I was grinding good working
tools, every time, by eye.
Might take me a couple of tries now to get new type of tool cutting
right, especially if I've never seen it in the flesh.
But that's all it takes.
-- Peter Fairbrother
Some of the newer grades of Carbides will withstand an awful lot more
abuse than the toughest that used to be available. Pressure upwards on
the cutting edge is a bit of a bugaboo, though!
In our shop, we have the reference manuals from four or five
companies, (Sandvik, Iscar, Seco, and a couple more I think) and one
can get lost quickly, when all one is looking for, is a tool that will
do most things reasonably well.
Add to that the plethora of shapes and geometries to choose between,
and a guy the just wants to buy a tool he can use, is gonna take up
basket weaving pretty damn quick.
It's even more confusing than grinding HSS! :-)
On or around Sun, 25 May 2008 04:01:42 +0100, "Dave Baker"
enlightened us thusly:
It depends what I'm doing. If I'm trying for a precise fit on something, I
use coolant to stop the job heating up and therefore expanding. In the
past, I've cut things that got fairly hot to an exact size (this is for
something that's a tightish push fit) and then, when it's got cold, it's not
the fit I wanted.
generally, though, I only use coolant if it seems like it needs it. Tend to
use it for parting things.
I am no turner but I couldn't agree more about diamond wheels. I got my
first one four years ago and find it invaluable for sharpening carbide
drills, carbide tipped lathe tools, and carbide gravers.
I've routinely reground (perhaps "touched up" is a better
word) inserts with a cheap diamond wheel for use in home made
I've always ground the front face only leaving the top
geometry and coating pretty well unaltered. This gets the sharp
edge but retains the low friction and chip control of any coated
top surface geometry.
All the inserts have been of unknown origin and
mostly part worn. While this seems to work pretty well my
favorite tool is still a many times reground lump of stellite
which takes a razor edge and is easily retouched.
Tell me about it. A couple of months ago I (the IT droid) was in a programming
office in part of the factory at work moaning about how their bosses wouldn't
cough up to replace the ancient industrial PCs that linked the large lathe
controllers to the rest of the world. £2,500 apiece.
I pointed out that I knew full well how idiotic the situation was, since I had
totted up that the table I was leaning on had approx £30,000 worth of inserts
neatly laid out on it :-0
That's all very well, but I personally agree with AC.
If you're a newbie who has just bought their first lathe, then the last
thing you probably want to worry about is learning to grind tools from
scratch. You want to stick some metal in the lathe, and make chips. A set of
preground tools will let you do that.
Once those pre-ground tools aren't cutting how they should, then they can
start to learn how to sharpen them, and how cutting angles work.
And your way is like telling somebody that if they want (fill in the blank)
cuisine, to cook it before they've even tasted it. Most people will of tried
what they want to cook before they try cooking it, or at least have a rough
idea of how it will taste.
True, but there's more than one route to acheive most things.
My first set of cutting tools were pre-ground.
They let me try out the lathe, and then once they started to get blunt, I
started to re-sharpen them.
After that I started to learn about cutting angles, before moving onto
grinding from blanks.
However, I now mostly use indexable tooling for easiness, but still use the
odd HSS tool mainly for profiles and flycutters.
I would personally recommend that any person new to the hobby, who hasn't
got anybody to guide/help them nearby, that they buy some pre-ground tools.
It might not be the ideal way, but it allows them to make some chips, and
provides them with a rough idea of how tools should be ground. From there,
they can go on to learning to grind them.
Except if you were to follow his plan, you would have bought
pre-ground tools, but not a grinder, because grinding tools is hard.
Point taken. Bad example, but the best I could come up with in short
Can you still buy a set of pre-ground tool that is not total shite
out your way?
Chinese, round edges, burrs, and no points, made of mystery metal, are
the best I have seen. For the most part, I would not spend the few
dollars asked for such garbage. I would never recommend them to anyone,
let alone a new user, that may or may not be able to recognise why they
would not work out of the box.
And the occasional Myford set that sells for insane prices, for no
reason that I can come up with. Them on Ebay, too. Not that they are
exactly a bargain from Myford...
Better off making your own out of old files, if you can find one that
is actually all high carbon steel, rather than just case hardened. Even
if it does mean learning to heat treat them along the way too.
My recomendation is still to learn to grind a tool right, right off.
Grinding a tool poorly, right off, is at the least, a step towards the
knowledge that will be with you for a long time!
I figure if a new owner is so lacking in skills or experience that
grinding a tool is going to be a scary thing, then that same person is
going to be pretty hard done by, when the chips start coming off hot and
Unlike AC, who was preaching that it was hard to do, and to be
avoided, I am saying that it is merely another skill to learn, that
looks daunting, until you get your hands onto it.
It's really not such a fearsome thing, to grind a decent working lathe
tool, and it should not be approached with the amount of fear that is
evident from some of the posts I have seen along the way.