Turning aluminium with carbide inserts

I use a Tangential for most of my turning but have always used the standard grind. I have wondered if you could grind a "chipbreaker" on the tool but the bit is a bit too small to handle apart from when it's in the standard grinding jig.

Rather presumptuous.

As it happens I use inserts for most general turning. But I use HSS, or even carbon steel, for specials. I don't need fancy facilities for grinding tools, just a small bench grinder my father bought 50+ years ago; all my grinding is done freehand. The only exception is if I need an accurate shape, in which case I CNC mill the profile. On my repetition lathe, which is aimed squarely at production, I exclusively use hand ground HSS.

Tool grinding isn't difficult, basic tools are just three angles and you don't need the fancy grinders or the holders/guides that sometimes appear in the magazines. But sometimes it seems to be regarded as some sort of black art that takes decades to learn - no wonder people are put off.

Andrew

Unlike Andrew I only rough grind by hand HSS tools on the rare occasion I use them but do use a Quorn to grind the finished surface to obtain the exact angle required.
Most of the turning work I do is on cnc lathes so changing inserts is the best system for that use, little or no tool compensation is needed in the program, unlike if removing a HSS tool to grind and re-fitting in the turret or holder requires tool offsets re-setting.

Emgee

Edited By Emgee on 19/01/2019 11:57:56

I've turned HSS on my lathe with carbide tools but have any of you milled HSS tool bits with a carbide end mill? Just wondering if it's preferential than grinding the initial shape in some cases?

Vic,

Read Andrew’s post just above yours. That should make it clear enough.

Vic,

You could grind a chipbreaker into the tool but I doubt it would work well. Wrought aluminum doesn't break up for me. I notice the polished inserts for aluminum don't have a chipbreaker. Cast aluminum does break chip fairly readily. Unfortunately the high silicon content dulls HSS quite rapidly.

Vic,

Something I forgot to mention: the way a tangential tool is positioned it might be difficult to get an effective chipbreaker. There is a very small clearance angle on the tool. If you ground a groove for a chipbreaker I suspect there might be interference between the ridge behind the groove and the work. Be advised that my conclusion was arrived at in my recliner, not in my shop.

Yep:

Involute form milled on the end of a 1/4" square HSS toolbit with an uncoated 3-flute carbide cutter, for use with a slotting head to cut an internal gear. Relief and rake angles were ground by hand afterwards.

If I need to remove a lot of material to get the required shape I'll rough out with a carbide cutter to start with. Way quicker than grinding.

Andrew