Good results in cold rolled mild steel bar

[Shawn]

I have always had less than great results turning cold rolled steel bar and have used a shear tool when I wanted a nice finish. I was watching a few videos showing a couple YouTube regulars having a bit of a tool grinding, removal rate competition and thought I would have a go grinding a chip breaker into a tool. I had to double check that it wasn't 12L14 I was turning by mistake!! The results probably aren't all due to the chip breaker but it did show me I have a lot left to learn about grinding lathe/shaper tools 

[PixMan]

You are finding what works for you and your machines. Cold rolled 1018 is FAR more difficult to get a good finish than 12L14, and it seems the lighter your depth of cut, the worse it is.

A chipbreaker in the tool always helps keep stringy chips from getting caught between the tool and work because they just curl up and drop the chips. The leaded 12L14 is better at breaking chips than 1018 CRS, I love it. It's also pretty easy on tools.

So was it the Keith Fenner vs. Abom videos of using HSS that you watched? That was entertaining, though neither guy really uses HSS all that much. They both have bigger machines and workpieces than most of us and can push some insert tooling pretty hard. That's more like what I prefer to do when making axles for motorcycles out of the 316 stainless, because I'm impatient and want to get the 1" (or bigger) stock down to the 10mm or 12mm finish diameter in minutes rather than hours.

The shear tools work great just for finish cuts. You can see now that with the right tool geometry you can get good finishes with a deeper cut too.

[DaveH]

Looks good Shawn . One thing to bear in mind, sharper the HSS tool the better the finish.
 
DaveH

[PixMan]

(01-27-2015, 11:53 AM)DaveH Wrote: Looks good Shawn . One thing to bear in mind, sharper the HSS tool the better the finish.
 
DaveH

And the sharper the HSS tool, the faster it wears.

Always the quandary.

[DaveH]

(01-27-2015, 12:41 PM)PixMan Wrote: And the sharper the HSS tool, the faster it wears.

Always the quandary.

That's true Ken,
so keep sharpening it - which is a bit of a pain   or keep one or two for finishing only.

DaveH

[PixMan]

And that's why I choose to use coated carbide inserts or uncoated cermet. Beautiful finishes at 3 or 5 times the speed with virtually NO tool wear!

[DaveH]

(01-27-2015, 02:13 PM)PixMan Wrote: And that's why I choose to use coated carbide inserts or uncoated cermet. Beautiful finishes at 3 or 5 times the speed with virtually NO tool wear!

And me

DaveH

[Shawn]

I was thinking it was probably how sharp the edge was with the added angle of the chip breaker that made the difference. What I did learn for sure was I need to keep tweaking my tool grinding skills and experimenting with different geometry. I might be sick but I actually enjoy grinding HSS bits, requires some concentration and provides me with instant gratification. I have a lifetime supply of high quality HSS/cobalt blanks so I will be grinding for years yet, will definately give inserts a go at some point though.

[DaveH]

Shawn, nothing wrong with grinding your own lathe tools ............ every credit to you.  

Not everyone's 'cup of tea' though.

 
DaveH