Parting off – Left over nib

[Blue HeelerParticipant @blueheeler]

Is there a way when parting off to have the left over nib (that at least I always get) stay on the piece that’s in the chuck and not on the piece that’s been parted off?
I’ve tried adjusting my parting tool every which way over the years and never managed to have that nib not end up on the parted piece.
Anyone have any hints?

[Colin HeseltineParticipant @colinheseltine48622]

Nikcole Mini Systems do some very nice parting and grooving tools the indexable carbide tips are as thin as 0.7mm and can be obtained for right hand or left hand holders. The actual tips can cut a flat bottomed groove or can cut minutely tapered so the pip can be on the part held in the chuck or on the piece parted off.

I am very impressed by them and I use the 8mm square holder on my Cowells lathe. I have the next size up holder for use on Myford.

[Colin Heseltine]

On Colin Heseltine Said:

Nikcole Mini Systems do some very nice parting and grooving tools the indexable carbide tips are as thin as 0.7mm and can be obtained for right hand or left hand holders. The actual tips can cut a flat bottomed groove or can cut minutely tapered so the pip can be on the part held in the chuck or on the piece parted off.

I am very impressed by them and I use the 8mm square holder on my Cowells lathe. I have the next size up holder for use on Myford.

Just Googled them Colin, nice looking tooling but they only make micro cutting tooling?

[howardbParticipant @howardb]

The traditional way to grind a parting tool, either made from square HSS tool bit stock, or a HSS parting tool blade is to grind the tip of the tool to a slight angle, so that the “pip” is left on the bar stock in the chuck, rather than on the workpiece being parted off.

The slight angle can be 10-15 degrees on a short stumpy parting tool, but on the blade-type don’t go more than about 5 degrees or the angle can deflect the blade sideways, resulting in the parted off face on the workpiece being concave.

[JasonBModerator @jasonb]

If you go with Nicole then get a handed parting insert rather than a flat bottomed one.

If you are using GTN style inserts then the N is for Neutral, you can also get R & L depending what side you want the pip left on. Same for most other types of insert, get the handed ones if you want the pip on a particular side

Both these have the same effect as grinding the end at an angle. Only down side is that it can make the cutter more prone to wandering off to the side

[Bo’sunParticipant @bosun58570]

Concur what howardb says.  Keep the angle and blade stick-out as small as possible.  Even so, still check for any curvature of the cut face if it’s important.

[Nigel Graham 2Participant @nigelgraham2]

Another problem by excessive angle across the tool face is the chip being wider than the cut, so more prone to jamming.

Many insert tools have a Vee-profile to curl the chip inwards and to give a better rake angle to the cut; and though that will not prevent leaving a pip on the parted-off piece, that is usually the lesser problem

[Blue HeelerParticipant @blueheeler]

Cheers one and all, appreciated.

[Wink HackmanParticipant @winkhackman25989]

Is there a UK supplier for the Nikcole inserts and holders?

[JasonBModerator @jasonb]

MSC Direct, though they now brand them under one of their own makes.

[Colin HeseltineParticipant @colinheseltine48622]

Yes there is a UK supplier for Nikcole.  They have a larger variety of stock than MSC.

Newcomer Ltd.,

Black Horse Road,

Coventry,

CV7 9FW

Tel: 02476 363535

 

Ask for a lady called Nina in Sales, she was very helpful.  Tell her they are for hobby use, helped on prices.

Colin

 

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