Is this a Warco / Metric thing...or am I just out of date?

Finally got to do some serious turning on my new WM250V...but have been scratching my head why I can't seem to take the right size cut. Never had this problem during the 40 years of using my old imperial Sheldon....

At first I thought it was my unfamiliarity with metric units and me constantly looking up imperial equivalents in my Zeuss book. Finally dug out my imperial dial gauge and took some measurements as I wound the cross feed table in and out.

So when did the cross feed dial indicator change to show total reduction of diameter rather than amount of movement of the table??? On my old lathe, if I wound the table in by 20 units on the dial, it would move in by 20 thou of an inch and take 40 thou off a diameter.

With my Warco, if I wind the cross feed in by 0.8mm on the dial, it actually takes 0.8mm off the diameter. i.e table only moves in by 0.4mm (or 16 thou inch on my imperial dial gauge in the photo)

I appreciate the latter set-up is more useful. But when did this convention change? Of maybe there is no standard at all...

Some do, some don't...

As I understand it, the Americans tend to use the "total reduction in diameter" whereas here in the UK we use "tool distance". Other countries just seem to have picked whichever they prefer.

I may be wrong.

Rob

China's biggest market is the US, they don't do the two times table.

Hello Paul,

I think I prefer the actual tool movement, although I'm getting used to the total reduction WM250.

What I am struggling with though, is the 0.04mm graduations.

Been like that forever. Diameter more likely in the US and rest-of-the-world lathes than the UK, but both ways of graduating the dial have co-existed since Maudsley.

Of the two I prefer diameter because it saves having to do mental arithmetic which I usually manage to cock-up. Most of the time I turn to a diameter, not to a radius, so the calculation is unnecessary.

The UK preference may be related to when much turning was done to fractional dimensions, a system that often mades dividing and multiplying by two easy. Sadly, the need for higher accuracy broke fractional dials during the 19th century, when engineering switched to thou. As decimal numbers aren't quite so easy to multiply by two in your head, having the dial do it helps. I suspect the radius method was retained because old-school machinists found it too difficult to accept a new-fangled improvement.

Does cutting in slices of radius have an advantage? If so, I've missed it!

Dave

And yet my 80 year old Sheldon was a Chicago made lathe....

Absolutely! It's crazy, isn't it? I'm ok with 0.4 and 0.8 which are marked and I can just about find 0.6, but 0.65 would challenge me.

Interesting, my somewhat elderly WM250 has a similar arrangement which I am now used to but the graduations are in 0.05mm which is slightly more useful. The dial also lets you know it is referring to diameter by the ⌀ symbol.

John

My 40 year old UK built industrial lathe uses diameter, much more useful in my view.

Andrew

To Paul W - When I was training, thousands of years ago it seems, a very experienced and smart workshop instructor said "assume nothing - when you walk up to a machine you don't know, set up a dial indicator and check distance moved vs the handwheel graduations on every axis" and then "check it in both directions you lazy ba%6^%ds to see what the backlash is like". Words to live by. I've remembered that and have done it since. Just food for thought.

This topic has come up in forums across the pond and even there, most lathes use the movement of the cutter rather than the diameter change. I want to know how deep the cut is and have never had difficulty converting the radius change to diameter change. If I was stuck with a cross slide like that, the dial would be re engraved pretty quickly.

I would prefer it to be a radius dial because that's what I'm used to but I can live with it as-is. If I was using a milling attachment, then it would be awful....

Thanks for all your comments.

As if my brains weren’t scrambled already, my Warco is set up for metric and imperial.

I have a Boxford and a Colchester. They differ. Keeps me on my toes!

Very interesting! Which Warco lathe is that? Is that something you did or does it come as standard on the bigger models?

It freaked me a bit at first on my Warco, but you can get used to anything. If I'm milling or co-ordinate drilling using the crossslide I double the metric offset I dial in. What complicates it more is that my vertical slide's a Myford Imperial.

I know I could buy a DRO set, but (a) I'm a cheapskate, (b) too lazy to want to go through the learning curve to fit and calibrate the things, and (c) believe in maintaining the mental calculation exercise.

I've had it 8 years and so far I've coped.

It’s the GH1322, the imperial lead screw version, as far as I know, it was manufactured that way.

My first lathes were Myfords, all with "tool movement" calibrations. Made a lot of sense when the lathe plus vertical slide was also used for milling. Current lathe is an old-but-good Smart and Brown 1024 which is calibrated in diameter. However, the transition was significantly eased by the fact that it came with a DRO which, like many, has a radius/diameter button. It means that I work in diameter - take a cut, measure, set DRO to that diameter, and then machine down to required diameter. Yes, you still have to do the right thing with depth of cut, but the sums are easy enough (and simpler than the imperial DoC to metric equivalent for which I still have little feel). Can't remember the last time I read a feedscrew dial...

Having used a Metric GH1330 (same lathe different bed length) I can confirm it came new with that double system dial.

The metric leadscrew imperial dial reads out to an impractical number of thou per revolution, I presume your imperial leadscrew metric dial does the same but for twentieths of a mm.

Edited By Jelly on 18/04/2023 21:44:21

Odd graduations on the habdwheel dials drove me nuts when I first got my Chinese lathe - so much so that one of the first jobs was to make some new ones!

Edited By Andy_G on 18/04/2023 21:19:49