lathe tools

>
>I might suggest you're not using the right carbide inserts then. To repeat,
>yet again, something I've posted many times over the years. Most carbide
>tips are designed for high powered machines and high volume work. For use on
>steel they have slightly rounded edges to create sturdiness and resistance
>to chipping and they rely on machine rigidity, horsepower and rpm to push
>them through the material being machined. What you need for small lathes and
>hobby use, regardless of the work material, is razor sharp edges which
>you'll only find on uncoated (usually) non-ferrous carbide inserts. Edges
>very similar to what you'd grind on HSS anyway. They will generally be
>bright silver or perhaps carbide grey. If the tips you are using are gold,
>black or any other dark colour they won't cut worth a damn on a small lathe
>on most materials. They'll just push off the work and tear it to shreds.
>What you have to appreciate is that what the carbide insert manuals and
>guidelines mean by finishing cuts on a CNC lathe are still probably deeper
>cuts than the roughing cuts most of us use on manual lathes.
>
>If you stick with inserts designed for aluminium you'll get perfect results
>on steel, cast iron, brass, bronze and just about anything else you want to
>tickle away at a few thou at a time on a small lathe and the inserts will
>last almost indefinitely if you don't abuse them. HSS might get the same
>finish but it'll blunt every five minutes. If you want to take 4mm deep cuts
>in EN40B then sure you need 10 hp and an insert designed for roughing steel.
>
>I use a single carbide insert turning and facing tool with non ferrous tips
>for 95% of the work I do on my Student. HSS has its uses when you need to
>grind a special shape or make a very small boring tool for a one off job but
>for most turning and facing I'd say get the largest shanked tool your lathe
>can accept, some sharp non ferrous inserts to fit it and you can forget
>buggering about on bench grinders every five minutes for the rest of your
>life.
>
>My mate's £50,000 CNC lathes can use a steel specific, rounded edge insert
>and still get a mirror finish on hard materials like EN52B and 21/4N valve
>steels. If I try to use the same insert on my Student it just buggers
>everything it touches. My 40 year old machine has 50 times the backlash his
>new ones do though, half the rpm, one tenth of the hp and no coolant. It's
>just a matter of horses for courses.
>
>If you want to spend your life learning how to sharpen tools rather than
>actually cut metal then HSS is the very thing. You'll just die very
>accomplished rather than having ever made anything.