lathe chatter

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You join the rest of us who find parting off tools a bloody nightmare. I've snapped more of those than you can shake a stick at. Best advice I can give is to make sure the cutting edge is razor sharp with lots of side clearance and front edge not parallel to the work i.e. ground at an angle to the lathe spindle. Whether you choose to have the chuck end or tailstock end cutting first is up to you.

Also try and eliminate any source of play in the toolpost or toolpost slide. Nip up the gib screws before using it for parting off. Part off as close to the chuck as you can so the job isn't vibrating all over the place.

Even so I still generally just part off a couple of mm deep to give me a datum notch and then hack away with a hacksaw while the job is spinning which is a major no no and I wouldn't dream of telling you to do. However it works for me and so far I haven't lost any hands, eyes or hacksaw blades :)

1. You'll always get some squeaking noises with brass.

1. Try the Q-cut parting off tool - I was persuaded by a lesson from a fellow member in my engineering club - he made me part off from some 1" stainless steel bar - I was hooked! (ISTR Greenwood Tools"

2. The only problem I've had with the Q-cut is when the supporting plate wasn't dead square on to the chuck.
3. I was as nervous as you before buying the Q-cut - perhaps I read the same books!

1. "Lathe Chatter"? Sounds like what this NG ought to be!

In article , snipped-for-privacy@tiscali.co.uk writes

You did remember to sacrifice the small bat, and dip the tool in chicken entrails, right? ;^)

Parting-off seems to be a bit of a black art. I'm now a convert to the use of a parting-off tool with carbide inserts, it makes the whole process *much* easier.

what lathe do you have

-- bolma

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Eddie,

I don't know what lathe you have, but it might be an idea to try a rear toolpost for the parting off tool if you can rig one on your cross-slide. The parting tool is held upside down behind the work so that the lathe still revolves normally to do the cutting. This can cut out a lot of problems with chatter.

Another thing you might want to try is to make the tool work harder. I find that I can often get better results by being a bit more 'firm'' with the feeding in and the machine quietens down and cuts better.

Jim.

Yes! I remember that that was part of the lesson!

I think you will find that improvement can be obtained with a stiffer parting tool assuming your saddle/crosslide/tool post are all set up well without play. I changed to the Greenwood tool (no connection usual disclaimers etc) a long time ago which has a carbide insert tip but its secret I believe is the very deep vertical tip holder which eliminates the tendency for the tool to tip down on cutting then spring up and so on thus creating the chatter. This very small movement is the bane of all parting off.

With this tool I can part off at speed brass or MS although brass is a little more difficult as it needs a really sharp cutting edge otherwise it sort of rubs and then bites. Of course the work needs to be rigid too. Parting off away from the chuck will give problems unless support is given by the tail stock.

Hope this may help you.

Alan

I use the Greenwood carbide insert parting tool in the rear toolpost on my Taig lathe to good effect - you need to use plenty of cutting force, in brass it works particularly well if you crank it in good & hard. If you are too genteel with it you get all sorts of nasty noises; these change to a very satisfying "eeeeeeee" accompanied by lots of chips as you take courage and crank on the cut. Seems to work equally well with free cutting steels & such.

It is probably a bit heavyweight as a solution for such a light lathe, and I occasionally worry about what it is doing to the cross slide leadscrew, but it seems to work better than any other tool I have used to date..

Regards, Tony

I found that most of my parting off problems went away when I made a rear tool post - well worth the effort.

AWEM

I go with the "Q" cut option. I've had very few problems with it and those that I have had are generally of my own making :-)

Cheers

Peter

instead of making a rear tool post.... why not mount the tool upside down and run the machine in reverse? you have the advantage of the swarf falling into the machine instead of all over you as well

In message , Jim Guthrie writes

A rear parting tool solved my problems when I had a beat-up old Boxford. The reason seems to be that the work is being pressed down toward the bed rather than lifting away from the bed.

In message , Tim Bird writes

Most saddles are constrained vertically at the rear of the bed. If so, then running in reverse with an inverted tool will tend to raise the saddle.

Be careful of that suggestion, depending on the machine you are using...

Why???

Because, for example, Myford and Boxford as well as other lathes, you could very easily unscrew the chuck.

When parting off brass, there should be no top rake on the parting tool, else it is more likely to snatch. Do not have too much tool sticking out. Move the top slide so that the tool is as much over the top slide bearing surface, so that there is more stability under the tool. If appropriate, support the work. (Center, steady etc.) else position the work to be cut closer to the chuck. Ensure there is a clear pathway to the nearest toilet, as when it does snatch and break...

H>> snipped-for-privacy@tiscali.co.uk wrote:

one word HACKSA

-- krame

----------------------------------------------------------------------- kramer's Profile:

Q-Cut insert parting tool (Greenwood).

Hold in a back toolpost if possible.

Run fast and feed fast and firm.

Don't, repeat, don't run the lathe backwards with tool held upside down. You will unscrew the chuck and disaster will surely follow!!!!

As an idea of speeds and feeds I would part off 1" dia brass bar on my Myford Super7 running at top speed (2200RPM) with a Q-Cut tool in the rear toolpost and feed in as fast as I can. Same with free cutting MS. I might drop the speed a bit if i was parting off silver steel or stainless.

snipped-for-privacy@tiscali.co.uk wrote:

Practice on aluminium, about 2" diameter. HSS blade; about 30 deg rake, very little clearance; side rake; very sharp; tool just below centre; right way up and lathe running forward. When you can do that, nothing else is a problem!

Ensure the chuck cannot become unscrewed!

Four words UNCONTROLLED LINE OF CUT