lathe bit sharpening

[John HaineParticipant @johnhaine32865]

Posted by IanT on 27/08/2017 12:32:08:

the reasons I moved to inserted tooling (in a rear tool post) for larger parting cuts, the other being the shaped tip which folds the chips inward, something I never managed to grind on myself…

Regards,

IanT

This can easily be applied to an HSS parting blade (at least one ~2.5 – 3 mm wide at the top) using a round diamond needle file with about a minute's work. Clamp the tool in the vice so the flat top of the tool is just below the surface and the jaws can provide a little bit of guidance (best to use soft jaws).

[Piero FranchiParticipant @pierofranchi37209]

got an other question for ya.

When I bought my Lathe, the chap gave me a load of tooling inc tool bits,

there are some that lose there edge so much faster than others, in perticular this very dark colored bit.

its got a ever so slight bobley aperance to it, and it almost looks rusty (but its not)

it does not stand up to cutting steel at all well.

is this type of bit for cutting wood maybe ???

[mechman48Participant @mechman48]

A pic of the tool in question would help identification.

George.

[MuzzerParticipant @muzzer]

Re: back rake – I messed about with "old time" tooling angles some time back and confirmed that the back rake was key to generating (and clearing) the characteristic ribbon swarf. Take a look at the ME forum thread I posted back then.

Murray

[HopperParticipant @hopper]

Posted by Piero Franchi on 27/08/2017 19:42:23:

got an other question for ya.

When I bought my Lathe, the chap gave me a load of tooling inc tool bits,

there are some that lose there edge so much faster than others, in perticular this very dark colored bit.

its got a ever so slight bobley aperance to it, and it almost looks rusty (but its not)

it does not stand up to cutting steel at all well.

is this type of bit for cutting wood maybe ???

Sounds like an old piece of carbon steel, commonly used on metal lathes before HSS became the norm. Will work OK if you drop the rpm so it does not get overheated. Other variations between brands of HSS are common too. I have found the cheap online Far Eastern high speed steel tool bits don't last near as well as my 30-year-old Swedish, UK and Australian made tool bits from the bottom of my toolbox. Stuff from reputable suppliers seems pretty good.

[Ian S CParticipant @iansc]

A well sharpened carbon steel tool makes a good finishing tool, you can probably take a finer cut than even HSS, but for general work stick to HSS, it will do most things needed in the home workshop.

Ian S C

[VicParticipant @vic]

I've read that carbon steel can be brought to a keener edge than HSS due to the grain structure so maybe it would be good as a finishing tool on Aluminium alloy?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Ian S C on 28/08/2017 11:58:35:

A well sharpened carbon steel tool makes a good finishing tool, you can probably take a finer cut than even HSS, but for general work stick to HSS, it will do most things needed in the home workshop.

Ian S C

Quite right, but I've read you have to be careful using Carbon Steel to cut metal.

The hardness of Carbon Steel depends entirely on heat treatment and that's easily destroyed if the tool gets hot. Not very hot either – about 200C, which is easily done unless the work is flood cooled. Once a Carbon Steel tool's hardness has gone no amount of resharpening will help; the softened tool will blunt as soon as it's used again. It's also possible to destroy hardness by overheating the tool while sharpening it.

Hardness must be restored by heating the whole tool cherry red (anyone know what colour that is?) and quenching it in oil or cold water.

No wonder HSS and Carbide are so popular. Keeping cutting edges in good order knocking out piecework must have been skilled work in the old days.

Dave

Dave

[MWParticipant @mw27036]

It's important to understand there's no equity between what material you choose to cut with vs. knowing how to sharpen tools.

So learning how to sharpen and change the qualities of HSS tools is definitely worth the experience. There's no replacement of HSS when it comes to taking the finest of cuts from a sharp tool.

Michael W

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael-w on 28/08/2017 16:16:43:

It's important to understand there's no equity between what material you choose to cut with vs. knowing how to sharpen tools.

So learning how to sharpen and change the qualities of HSS tools is definitely worth the experience. There's no replacement of HSS when it comes to taking the finest of cuts from a sharp tool.

Michael W

.

I agree wholeheartedly with the sentiment, Michael; but you are showing your age [or lack of it] … Years ago, comparisons similar to those we now make between carbide and HSS were being made between HSS and high carbon 'crucible steel'.

MichaelG.

[MWParticipant @mw27036]

Posted by Michael Gilligan on 28/08/2017 18:25:59:

Posted by Michael-w on 28/08/2017 16:16:43:

It's important to understand there's no equity between what material you choose to cut with vs. knowing how to sharpen tools.

So learning how to sharpen and change the qualities of HSS tools is definitely worth the experience. There's no replacement of HSS when it comes to taking the finest of cuts from a sharp tool.

Michael W

.

I agree wholeheartedly with the sentiment, Michael; but you are showing your age [or lack of it] … Years ago, comparisons similar to those we now make between carbide and HSS were being made between HSS and high carbon 'crucible steel'.

MichaelG.

Thsnks Michael, It's good to see you back again,

Definitely a lack of age, I could muse from what I know about my rudimentary introduction in steel making, how it started off as such an unreliable process, due to the fact that iron is only ever found in an oxide form in nature.

If I were a wood worker, I would probably place my bet on carbon steel giving a nicer cut.

But for metal working, there's just something about HSS that makes it so versatile that it can be used satisfactorily for nearly any material and that's why I recommended it there and why I would recommend anyone to use HSS in a foundation sense.

Michael W

[duncan webster 1Participant @duncanwebster1]

Posted by Michael-w on 28/08/2017 16:16:43:

It's important to understand there's no equity between what material you choose to cut with vs. knowing how to sharpen tools.

So learning how to sharpen and change the qualities of HSS tools is definitely worth the experience. There's no replacement of HSS when it comes to taking the finest of cuts from a sharp tool.

Michael W

According to Tubal Cain (ours, not the yank) if you wanted the sharpest tools you should use carbon steel from old files. The disadvantage is you have to use a low cutting speed, but if the workpiece diameter is small that's not really an issue. There was an article in ME or MEW recently which went into this in more detail. I think carbide on a mini lathe is a waste of money, practice grinding your own. A loupe or a headband magnifier is a good investment.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael-w on 28/08/2017 19:58:06:

… there's just something about HSS that makes it so versatile that it can be used satisfactorily for nearly any material and that's why I recommended it there and why I would recommend anyone to use HSS in a foundation sense.

.

… Wouldn't dispute that at all.

MichaelG.

.

P.S. for more 'variations on the theme' than most of us will ever need to know … see this page:

http://www.tttg.org.au/php/ArticleView.php?id=71

Edited By Michael Gilligan on 28/08/2017 21:49:27

[Piero FranchiParticipant @pierofranchi37209]

Its a pity I didn't read these reply's before going to my workshop today (its not at my home address) or I would have taken some photos of the (what would be) soft dark brown lathe tool bit blanks.

I am Very much interested in learning tool sharpening on carbon steel and HSS tooling.

I the insert tooling is not for me or should that read, its not for my Lathe (Colchester Bantam 1600)

[Piero FranchiParticipant @pierofranchi37209]

Hi Guys

In case any of you can spread some light on the soft ish tool blanks I was talking about, I have uploaded two photos of the blanks in question into my photo album

And three photos of a harder blank I have ground my self for use in my Bantam lathe.

I tried a hand file on the dark coloured blanks, they do mark to some degree, but its impossible to describe how much,

put it this way, the blank in my tool holder that I have ground, is VERY hard to file, the dark coloured ones are hard to file but they do file slightly

ps what do you think of my grind????

I am new to tool grinding and comments are welcome

[Ian S CParticipant @iansc]

The tool in the tool post looks very neatly ground, it may need a little greater radius on the tip, but that depends on the feed rate.

If you put the softer bit of steel in the tool post and tighten the clamp screw hard, does it leave a dent? It may not even be a lathe tool. but a bit of key steel, or unhardened tool steel.

Ian S C

[Piero FranchiParticipant @pierofranchi37209]

I cant say I have used one of the darker tool bits long enough to have noticed if the holding screws mark it or not,

they do seem to be hardened to some degree, but not as much as the shiny silver one like as in the tool holder

[Author]

Posts