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Warco Lathe setup

Vertical play in the saddle

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iain hale 103/01/2022 18:25:47
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14 forum posts

Please can anyone help me resolve the issue of play in my Warco DM180 lathe saddle.

When trying to part off using a small parting off tool and taking the feed rate very slowly the cutting tool is forced down and below the centreline of the work.

It appears there is a small amount of play in the saddle, I am at a loss as to how to rectify. The lathe is brand new only had a few hours of running.

Happy New Year to you all

Iain

Bo'sun03/01/2022 18:35:59
617 forum posts
2 photos

Hello Iain,

Strange, but on my WM250 there's a gib at the back of the saddle but nothing at the front.

Howard Lewis03/01/2022 18:41:47
6305 forum posts
15 photos

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

David Ambrose03/01/2022 19:21:54
28 forum posts
3 photos

Have you minimised the overhang of the tool and toolpost, and locked the carriage? The WM180 carriage lock clamps the carriage to the bed.

KEITH BEAUMONT03/01/2022 20:20:58
173 forum posts
43 photos

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.

Niels Abildgaard03/01/2022 20:26:57
430 forum posts
163 photos

My 180 parts of well(most of the times)

Give us a picture of your setup

Rigid tools

iain hale 103/01/2022 20:31:59
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14 forum posts

Gentlemen Thank you all for your quick responses to my query..

Howard :The lift on the saddle is enough to be able to see the saddle move slightly.

David: Yes minimised the overhang, but not locked the carriage on the basis I didn't know you could!!!

Keith: I thought about turning the tool upside down but how do you centre it, am I missing something here?

iain hale 103/01/2022 20:35:10
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14 forum posts

I will post up a video clip of the setup tomorrow,

Andy Stopford03/01/2022 20:44:02
165 forum posts
25 photos

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.

old mart03/01/2022 20:56:48
3892 forum posts
268 photos

It's always a good idea to lock the saddle when parting off, and set your compound for minimum overhang. Also make sure the compound gibs are preventing any noticable play.

When I made a rear parting off block for industrial blades, I added a rear lock to the saddle so not only are there 2 locks, but the only play will be in the cross slide.

Pete.03/01/2022 23:57:35
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815 forum posts
245 photos

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.

Bo'sun04/01/2022 09:45:27
617 forum posts
2 photos

I'm interested in Howards comment regarding adjustable pads. My WM250 doesn't appear to have any adjustment at the front of the saddle, or have I missed something? I have around 0.06mm of noticeable lift at the front and 0.01mm at the rear, which has a gib strip.

SillyOldDuffer04/01/2022 10:26:43
Moderator
8875 forum posts
1997 photos

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...

devil

Dave

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

Journeyman04/01/2022 10:38:49
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1174 forum posts
236 photos
Posted by Bo'sun on 04/01/2022 09:45:27:

I'm interested in Howards comment regarding adjustable pads. My WM250 doesn't appear to have any adjustment at the front of the saddle, or have I missed something? I have around 0.06mm of noticeable lift at the front and 0.01mm at the rear, which has a gib strip.

The WM250 has a couple of guide blocks at the front just behind the apron. Not adjustable and one (as image below) also forms the saddle clamp, which on the older WM250 at least can't possibly work unless the block is left loose. It is possible to adjust the fit by either filing or using abrasive paper on a flat plate. I played with mine to re-make the saddle clamp *** See Journeyman's Workshop ***.

saddleguide.jpg

It occurs to me that on the OP's WM180 with DRO the saddle clamp screw may be hidden beneath the scale depending upon how it is fitted.

John

Bo'sun04/01/2022 17:51:18
617 forum posts
2 photos

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.

Andy Stopford04/01/2022 19:16:20
165 forum posts
25 photos

On the WM180 the saddle clamp screw is indeed inaccessible unless the cross slide is wound far across. Easily fixed by replacing the cap screw with a hex head (with a little packing piece in the counterbore to keep the head above the surface).

ChrisH04/01/2022 19:26:19
1018 forum posts
30 photos

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

Chris

iain hale 104/01/2022 19:44:48
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14 forum posts

Hi Chris

Thanks for the question and to be honest I never thought of asking Warco, but I will now. Being a newbie all the suggestions and advice is most welcome so thanks again to all who have offered advice.

I have now found the saddle lock bolt and will be carrying out a mod to turn up a new threaded bolt to attach a handle so the cross slide issue is no more.

Having broken the tip off the parting tool, resharpened it swopped out all the shims used to pack it up with and milled up a piece of steel to fit, moved the blade as far back into the holder as possible. This time it all worked very well just as I expected in the first place.

No substitute for experience and making a few mistakes, but heh that was only one cut better see if I can do it again consistently.

ChrisH05/01/2022 17:53:25
1018 forum posts
30 photos

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

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