Being a machine with a Vee bed, I would expect the saddle to ride on, and be located on the Vee bed, especially when using cutting tools in the front toolpost. Cutting forces will tend to push the Saddle downwards

(Tools in a rear toolpost will tend to lift the rear of the saddle. )

If, for some reason, there is excessive play, chatter would be a risk with any tool.

How much lift have you got on the Saddle?

There are probably pads beneath the front shear which can be adjusted to limit clearance, to about 0.002" (0.050 mm) or so.. Without clearance, it would be difficult if not impossible to move the Saddle along the bed, or to have relative movement between any parts of the machine.

Howard

For Parting off, put the tool upside down and run in reverse. Tool set about 0.005"above centre. Works for me and never had a dig in.

Your saddle should be adjusted as Howards advice.

Keith.

The WM180 manual shows adjustment screws and a gib at the front of the saddle, however my machine, like yours, is new, and it doesn't appear to have this arrangement. I presume there must be something like Howard suggests – maybe take the apron off to have a look.

Also, make sure that any play isn't actually taking place in the top slide/toolpost area.

A very low feed rate isn't (usually) what you want when parting off. A steady, reasonably firm feed keeps the tool cutting and doesn't give it a chance to dig in.

If you're parting off conventionally the saddle shouldn't be pushed down as it's already resting on the bed ways, the weak link with these small lathes seems to be the compound slide, I'd put money on this being the main source of your movement, as OldMart says, check your compound slide doesn't have any overhang from the base, nip the gib screws up so it's solid and try again.

Don't forget parting-off has always been notoriously difficult on small lathes!

Trouble is any movement in the wrong direction when parting-off is instantly punished, and small lathes aren't particularly rigid. I believe the DM180 is a WM180 fitted with a DRO. If so, it's a small lathe – don't expect miracles.

The best answer is to buy a big lathe, the sturdier the better. Otherwise, do everything in your power to improve rigidity.

• Part-off from a solid rear-mounted tool-post, not the towering cross-slide and front tool-post, which is bendy.
• Minimise tool overhang.
• Make sure the cutter is in good condition, is mounted absolutely square to the job and at exactly the right height.
• Lock everything that can be locked.

Then, do all the things an experienced operator does, and don't make any mistakes.

• Set RPM to optimum speed (perhaps half normal)
• Lubricate generously
• Make sure the slot never becomes choked with swarf, and Aluminium isn't welding itself to the cutter.
• Resharpen the cutter as soon as it needs it.
• Feed the cutter smoothly into the work at the optimum rate, not too fast, but never allowing the edge to rub: it must cut continuously Smooth feeding is vital: any hint of jerky hand action is liable to cause trouble. Use the lathe's power-feed if it has one.
• React quickly and in the right way to trouble – this only comes with practice.

I started with a mini-lathe. Mine parted brass OK with a narrow sharp HSS cutter, but was unreliable in my clumsy paws parting anything else. Not impossible, just needed a lot of care and had a high failure rate. On my mini-lathe it was easier for me to saw off and tidy up rather than part-off. I'm sure a skilled operator would do better than I did! (Sadly, I'm not a gifted machinist – slow, cack-handed and make silly mistakes.) I'd expect a WM180 to be markedly better at parting-off than a mini-lathe, but still tricky.

I upgraded to a WM280 because the mini-lathe was a shade too small for most of the work I do. The much bigger WM280 parts-off fairly reliably from the front tool-post and is almost idiot-proof parting off with power feed from a massive rear tool-post. Even so, the WM280 isn't beefy by industrial standards. One I know of has much the same cutting envelope as a WM280 but is three times heavier. The industrial machine is much stiffer, which means the operator has less to worry about. Operators of lighter machines have to compensate for it's shortcomings.

The need to substitute time and skill for muscle is generally true of most Model Engineers. Due to lack of space and money most of us have smaller workshops and tools than ideal. It can be frustrating. However, as a hobby, surely some of the fun is succeeding with whatever tools happen to be available…

Dave

Edited By SillyOldDuffer on 04/01/2022 10:27:35

Hello John,

Thank you for that. A neat solution well executed. Although I agree, the parts could be better made in the first place. Not exactly difficult.

I overcome the problem with the gib screws getting in the way, by using socket set (Allen grub) screws, with just enough thread for the locknuts. Then a shortened Allen key that lives in place all the time. Plus. it looks neater than sck hd cap scws. Done the same with the compound gib screws too.

I'm going to try skimming a little from the guide blocks as suggested. If I take too much off I'll reach for the shim washers. Mind you, looking at the state of those from your machine, I might just make some new ones. I like the idea of shim washers though. If they wear in the future, just re-shim.

Iain – just asking the obvious, what do Warco say?

Chris

No worries Iain, I just picked up on your comment that it was brand new, if its brand new and there is a problem the supplier should provide an answer, means, or action, (or all three!) in my book to fix it.

Chris