If you can get one to fit your particular lathe I cannot recommend strongly enough to go for a rear tool post. I invested in one a few months ago and parting off ever since has been a breeze. I'm sure others can outline the theory why they do such a good job. All I know beforehand I would get chatter and snatching and every other problem that part-off can produce. As long as the tool is keen I can now part of confidently first time every time.

Hi Martin
Part from the back if you can .Tool digs out non in .no backlash on the feed screw as its pushing against the screw when parting Nobby

I was asking myself the same question recently and did a lot of research. On a recommendation from a post on this site I bought the Chronos Chipbreaker type parting tool shown HERE.

I am a novice and was dreading using a parting tool but this worked like a dream cutting 3/4" steel bar on my 5" Boxford CUD. I would have preferred one of the bigger sizes but they are out of stock. The small size that is in stock should be ideal for a small lathe and at £16 including delivery it is a bargain.

Nick

I use this tool on my small optimum lathe and it works well. The height has to be exact so you may have to experiment with some shims but when it is set up correctly it will whip right through brass and aluminium  with no problems. I have even cut stainless steel with it.

**LINK**

I bought an extra blade : one I keep with its original flat edge for recess cuts and the other one I put a sharp edge on it for parting off.

Edited By Brian John on 29/06/2016 08:21:09

I agree that the type of parting tool you might need will depend to a large extent on your lathe size and whether you have a slotted cross-slide (to mount a rear-tool post on etc).

As a general comment though, I have several sizes of inserted-type parting tools – a large one for a fixed height rear mounted holder and a smaller (thinner) one that is used from the front. Something I haven't seen mentioned is that neither require a change in height as you adjust the depth of cut. I like this, as although they both cut very well, I do not have to extend them any further than necessary to make the required cut, which aids rigidity.

In other words, once set to height, I can slide the tool in and out to suit the diameter of the material being parted without re-setting its height. Some HSS parting tools/holders use the amount of tool extension to set the tool height – which (in my view) is an unnecessary hassle. Just a thought.

Regards, IanT

I have one of the toolpost tool holder types as indicated above and they work well

If you look carefully at the original blade you can see that it has been ground to fit very securely into the holder, the top and bottom edges are not simply a plain flat blade, there is a slight angle, this is because every tiny detail helps when parting off

Fully agree with everyone advocating a Rear Tool Post. If possible, make/buy one with more than one tool position, so that you can chamfer the ends before parting off.

If in doubt, go for maximum rigidity! The greater the rigidity, the less risk of chatter. Set to centre height is taken as read.

And stating the obvious, don't let the tool rub, keep feeding it in, gently.

Howard.

As I mentioned in my post … Hemming way do a kit, comes with all castings & full set of plans, not too difficult to make

George

There's a design for a rear toolpost by my predecessor Stan Bray, which I think is meant for the ML7 or similar here:

http://www.model-engineer.co.uk/news/article/free-plan-swing-clear-rear-toolpost/18494

Neil

Normally, a parting tool, (or any other for that matter) in a rear toolpost, is mounted inverted, (ie cutting edge facing down) and the lathe is run in the normal "forward" rotation.

Various theories have been advanced as to why a rear toolpost is better, and less prone to chatter or dig ins. Most seem to revolve around the way that the forces acting in the opposite direction, affect the clearances between the dovetails.

Suffice to say that most folk seem to find that they work better, free up a space in the front 4 way!

If a lathe has a screw on chuck, WITH chuck retainers, it can be run in reverse, safely. Reverse running without them is possible, with care, but RISKY and not advised, because of the obvious risk of the chuck coming off the Mandrel.

There are various plans available for making a back toolpost, to take either a single tool, or to carry two, parting or chamfer. ( See "The Amateurs Lathe", G H Thomas etc)  Some, locate the tool at an angle, whilst others place it horizontal so that the top rake has to be ground in to the tool itself.

Howard

Edited By Howard Lewis on 30/06/2016 23:05:09