HSS or Cobolt

[DanielW]

I've never tried turning with Cobolt,always HSS.

I was looking to purchase some blanks for making a series of screw thread bits,came across three pieces of cobolt blanks near enough the same price as I'd pay for the HSS.

Whats cobolt like to grind down and turn with on the lathe?

 

[DanielW]

....or even Cobalt.

 

[doubleboost]

HSS
Is much easier to work with
Cobalt is very brittle

 

[awemawson]

Not turning I appreciate, but I've just been utterly impressed by cobalt drills. I had a particular HT bolt to drill out of a machine casting, and brand new quality HSS drills wouldn't touch it. First Cobalt drill that I tried went through like butter. Now as I have to replace drills any newly bought ones will be cobalt !

 

[hotrodder]

Cobalt is HSS, it's included in at least two flavours usually described as HSS-Co with the common suspects being M35 and M42 which are ~5% and 8% Co respectively. Most of my lathe blanks are M35, not really any different to basic HSS to grind but it retains it's hardness to higher temps so you can work faster and/or don't need to resharpen as often

As far as i can figure cheapnese HSS-Co tat is responsible for the 'very brittle' association, especially cheap cobalt drills with fancy coatings that are junk compared to decent quality plain ol' HSS... harder/stronger virtually always = more brittle but HSS-Co is tough compared to carbide

 

[Shox Dr]

Not turning I appreciate, but I've just been utterly impressed by cobalt drills. I had a particular HT bolt to drill out of a machine casting, and brand new quality HSS drills wouldn't touch it. First Cobalt drill that I tried went through like butter. Now as I have to replace drills any newly bought ones will be cobalt !

I used to buy 8mm Coblat drills from the local tool dealers, to make parts for MTB suspension, at £12 a pop they were not cheap, but lasted better than HSS cutting 316, however they still broke, and blunted with use, too quickly.

Went to MM for something and bought a full set for 20quid (1-10mm) for £19.95, still have them some 20yrs later. And still going strong.

 

[the artfull-codger]

I use hss for a large proportion of my turning but I use crobalt bits which are a lot tougher & longer lasting than hss & can cut at higher speeds.

 

[hotrodder]

Some of the flavours of HSS (including colbalt) that Presto use... http://www.etc-ltd.co.uk/documents/presto/tables.pdf

 

[brightspark]

colbalt???

Some of the flavours of HSS (including colbalt) that Presto use... http://www.etc-ltd.co.uk/documents/presto/tables.pdf

colbalt similar to cobalt is it

 

[hotrodder]

Grow up

 

[brightspark]

Grow up

awww cant u take a joke NO WURRY some cant

 

[rory1]

That's quite a handy reference table that you've linked there hotrodder, thanks

 

[hotrodder]

awww cant u take a joke NO WURRY some cant

Part of growing up is developing a sense of humour beyond that of a two year old...

 

[brightspark]

Part of growing up is developing a sense of humour beyond that of a two year old...

u wouldnt last 5 minutes on site believe me

 

[ajlelectronics]

Pot, kettle, black anyone?

 

[brightspark]

Pot, kettle, black anyone?

the forum english teacher strikes again

 

[the artfull-codger]

Some of the flavours of HSS (including colbalt) that Presto use... http://www.etc-ltd.co.uk/documents/presto/tables.pdf

I use crobalt bits [with an r] not cobalt

 

[brightspark]

I use crobalt bits [with an r] not cobalt

here http://www.eccentricengineering.com.au/index.php?option=com_content&view=article&id=32&Itemid=46