Recommend parting tools?

[prepman]

ha ha I should really use the auto feed on my lathe but I am a mere novice never used a lathe before until I got mine 2 years ago. I like to feel what is going on

I thought you were an exspurt.

 

[123hotchef]

I thought you were an exspurt.

Far from that I am a expert chef!

 

[prepman]

Well sadly the parting tool failed a few hours later trying to take a higher feed rate. The insert broke, but in the process damaged the blade notch. The consequence being that next insert flipped out with a bang. Confidence shattered. Used other end with manual feed to finish job and arranged for replacement on warranty. So it is possble to break one.

 

[prepman]

As I said, Tang grips need to be fed harder and it does not suit every lathe. I had a lot of use out of mine but when the tip went it took the blade too.

What lathe is it? If its using 250-200 holders or bigger the tang grip is probably ideal.

Blade holder, get a two part clamping block. Lots on ebay.

Same here tip and tang gone. Back for replacement/refund. Student on 250 holders.

 

[Munkul]

I don't get this nonsense that is parroted on here about "feeding parting blades as hard as you can!"

Never had a lathe or a job that warranted destruction of perfectly good parting blades. Not even on an old clapped out Student. Sure you don't tickle it, but nor do you ram it in. If it feels like it's going to break, it probably is.

As far as I'm concerned, it's BS. Stop it, you're just breaking stuff.

 

[8ob]

I don't get this nonsense that is parroted on here about "feeding parting blades as hard as you can!"

Never had a lathe or a job that warranted destruction of perfectly good parting blades. Not even on an old clapped out Student. Sure you don't tickle it, but nor do you ram it in. If it feels like it's going to break, it probably is.

As far as I'm concerned, it's BS. Stop it, you're just breaking stuff.

I am no latheist but I found I was rubbing out tips, @Hood advised going in a bit harder and the improvement was dramatic.

Bob

 

[Hood]

If possible you want to feed a parting tool hard enough to curl the swarf into tight curls. When this happens the geometry of the insert is working properly, that is assuming it is an insert with proper geometry the swarf is being reduced in width as it folds in the middle, and due to that, and the curls, it ejects from the cut easily and doesn't mar the surface. Obviously you do not want to ram it in if it is not wanting to feed, you will soon know the difference between the pressure of an insert that is cutting and one that is being forced.

Vid showing the curled swarf.

 

[prepman]

I don't get this nonsense that is parroted on here about "feeding parting blades as hard as you can!"

Never had a lathe or a job that warranted destruction of perfectly good parting blades. Not even on an old clapped out Student. Sure you don't tickle it, but nor do you ram it in. If it feels like it's going to break, it probably is.

As far as I'm concerned, it's BS. Stop it, you're just breaking stuff.

Hmmm. I don't think it was a case of as hard as you can. Used many different styles of parting tools over many years, with varying results. Best are HSS with correct holder (Soft stock). The holder I have has the rake built in which in IMHO is a liability. I say this because if it bites and dips then it will dig in further. A parrallel holder with the rake (if any) ground in is preferential IMHO. The hot rolled bar stock I have a lot of doesn't seem to be uniform throughout. Inserts ARE designed to be heavy fed at high speeds. Which is an issue with light weight lathes.

 

[Seadog]

A 2" piece of tough steel parted at 400rpm with a 2mm GPN insert. Slight chatter until I get the load on. It was one handed by the way. (Boxford AUD)

 

[prepman]

A 2" piece of tough steel parted at 400rpm with a 2mm GPN insert. Slight chatter until I get the load on. It was one handed by the way. (Boxford AUD)

I've been trying to analsye the issues with part jams and breakages both HSS and Inserts. It seems to very dependent on material and feedrate (no brainer), but why exactly?. I think what's happening is that with low feedrates (below optimum) the action produces grains rather than chips or swarf and this jams the blade. Too high with either can cause gouging and breakage. The sweet spot varies with materials from brass to hot rolled en3 as is well known.
Ground a groove in the top of my flat profile 1" hss tool, this had a significant beneficial effect.

 

[prepman]

I feed my parting tools as per robins advice and I've never had an insert snag. They've only ever gone dull or chipped once when I didn't take the tailstock away soon enough.

Robin?

 

[slim_boy_fat]

Robin?

@Hood

 

[prepman]

@Hood

Ah...of course....