Worn headstock bearings is one thought. Noel.

Lots of advice already discussed on this forum but are your slides tight and are you using lubrication to start with, need more details.

Tony

P S

A centre held in a 3 jaw WON'T be on centre, unless myou nhave an exceptional chuck.

It is likely to run out by anything up tom 0.005" on a reasonably good chuck, more non a worn one..

You should set to a centre, located in the 2MT bore, and recently trimmed up.

Use a 2 MT centre, not a parallel one in a 3 jaw!

You would spend time profitably, making a Centre Height Gauge, It would aid setting tools to centre height considerably.

This might be part of your problem! (Looks to be on centre but may not be . If too high will cause problems)

Let us know how you get on

Howard

Edited By Howard Lewis on 03/08/2022 18:43:33

Although I mostly use mine with a round nosed insert it does get used for parting or grooving sometimes.

Seems OK on the Warco front mounted in a QCTP, 15mm mild steel, 450rpm 0.0025" /rev feed. Nice bright short curly chips rather than long swarf when run at this sort of finer feed rate.

Chris,

I used to have lots of problems when parting off, I tried carbide and HSS but had some expensive foul ups, my conclusion was that model engineers lathes are inherently unstable because they flex too easily when under pressure such as parting off. My approach to reduce the problems that I was having was to check that everything on the lathe was adjusted correctly, that means making sure the gibs are adjusted nice and snug, when you are making the cut make sure you have locked the top slide and the carriage, my carriage lock was useless so l made a new lock which firmly clamps the carriage to the bed. My next idea was to always use lubrication when parting off, it’s surprising how much difference that can make, when cutting make sure that you advance the tool at a constant rate, be sure and firm with your movements. I still have problems if I use carbide tips, it is as though I am not running the lathe fast enough, I chicken out on running fast on parting off so for now the carbide tips are put to one side and I only use HSS, I am surprised at how much easier that the operations are now that I have incorporated the ideas mentioned above, I used to dread parting off and would in preference reach for the hacksaw but now my confidence has been rebuilt and I am using my parting tools again. One point I use as thin an HSS parting tool as I can, I find it is easier and more forgiving. Dave W

Re set the tool so that it is 5-10 thou above centre. 5 thou should do, but if the tool and compound are dipping with load, the higher amount might be needed. .

This is more important with carbide parting inserts than with HSS. The very last thing you want is for the work to climb over a carbide parting tool. Instant failure.

I've got one of these; I've found it to be very fussy about feed and speed. My lathe has variable speed control so I can twiddle the control knob to find a speed that works. The feed needs to be pretty brutal – anything less and it will chatter badly and the swarf comes off as a powder. When you get it right, it works well, but most of the time I find an HSS blade less hassle.

edit: I think the insert on mine is different – it has a shallow groove in the top, which I can't see in your photos, and its single-ended.

Edited By Andy Stopford on 03/08/2022 21:21:52

I do parting at 800 RPM, 0.02 mm/rev, use lubrication and the powerfeed. I have 1.2 mm HSS and 2 mm carbide (SP200) parting tools.

I don't part off the last 0.5 mm when parting steel.
I can only do parting on both my lathes when the tool is mounted upside down and the rotation is reversed.
I check the height of the tool by facing an aluminium bar.

The stickout of your parting tool is very long!

Could possibly be your three jaw chuck is worn bell-mouthed and allowing the job to move, causing jams. Try on a piece of material held in the four jaw chuck and see if it works better.

From looking at your pic, it may be that your parting tool is not set perfectly square to the lathe axis. Check it with a dial indicator. With a bit of practice you can line the tool up by eye with the edge of the cross slide.

On my ML7 I have found the T section HSS parting tool from Eccentric Engineering works brilliantly and even better mounted upside down in the rear toolpost. It has a nice sharp cutting edge that requires less force and thus creates less flex in these lighweight lathes than a carbide insert tool. See this thread here LINK

Edited By Hopper on 04/08/2022 03:04:02

DC31k

Don't demand your money back.

Read the various pieces of advice to grind a V in the top of a HSS tool, or examine your carbide tool.

(I think that either Edgar Westbury, or Arnold Thorp gave this suggestion; so not a new idea. )

By having a V in the top of the tool, it should have, effectively, two cutting edges, and so will produce two streams of swarf, each narrower than the width of the slot that has been cut, so reducing the risk of swarf jamming.

Having had bad experiences with a Garmin tool, I have never plucked up courage to use my Q Cut. I just stick with my 3/32 wide HSS , with no top rake, mounted inverted in the rear toolpost, and increasingly use power feed. .

One bit of information that i do lack is the author of the quotation that "Sarcasm is the lowest form of wit" can you help?

Howard

Edited By Howard Lewis on 04/08/2022 05:20:24

“Sarcasm is the lowest form of wit but the highest form of intelligence,” wrote that connoisseur of wit, Oscar Wilde. (Scientific American)

And G H Thomas also recommended grinding a small groove in the top surface of the parting tool, not to produce two separate streams of swarf but to produce one ribbon of swarf that was curled inwards so was narrower than the width of the groove being cut/parted.

The Eccentric Engineering T section HSS blades have the top surface hollow ground slightly concave so the ribbon of swarf comes off curled slightly narrower than the groove it is from.

Chris, is this your first attempt at parting off or have you been doing it before? If you did do it successfully before what tooling did you use?

I don't have problems parting off and never have, I use a bog standard HSS parting tool mounted in a Dickson holder on both my Super 7 and all other lathes I have. Not saying its wrong but I have never used power feed for parting off, I like to have the "feel" of the tool during this operation.

Worth noting Chris is using an ML7 and no power cross feed is available ! I do have a tool of the type you are using , tried it and it was OK but did not cut as well as the HSS, considerably more pressure required to make a cut.

Pretty much everything else has been said, make sure the machine is adjusted correctly, main bearings in particular, tool to be "tad" above centre, plenty of lube and a steady feed — with hand feed do not dwell at the end of the cut — feed in and back off, feed in and back off. If you leave the tool touching the work it will induce chatter and don't be too gentle with the feed – its all about "feel" !

To get the centre height correct a tool height gauge is well worth making but in the absence of one just face a piece of stock leaving a tiny pip at the centre to set your parting tool to.