It looks like I ruffled some feathers, for that I apologize, it wasn't my intention. It also looks like this thread is going well off the track I wanted to head down, so lets all just move on. Thanks for the responses, later.
Dave
The problem with your question was that it wasn't a question that can be answered...or at least not by anybody who has thought about your question with any rigour.
If you really want to 'calibrate' your opinion of your lathe's capabilities, I reckon your best bet would be to post a video (including sound) of you taking a cut that you think you should be able to take. Make sure the video clearly shows part and tool stick out and the nature of the tooling and tell us what steel you're using for your part.
Then people should be able to hazard a guess as to what's going on and help you.
The rest of this post is for you to read or ignore as you see fit. Eh, I think it's useful information but then, I would say that.
You see there are no lathes out there like your lathe.
Okay, maybe in their hey-day, the standard production lathe manufacturers in the US and Europe (South Bend, Colchester, Harrison and the like) would have produced lathes that mostly all behaved
similarly to each other (allowing for the rare occasional QC miss) but there'd probably be enough variation
straight from the factory to mean that the lathe would need to be adjusted and set up to get the best out of it.
Not that the lathes were poorly made, they definitely weren't of course, but there would have been just enough human in the manufacturing mix to mean that they'd be unlikely to make two lathes that behaved identically.
Maybe with the likes of Schaublin, Weiler or Hardinge, the outliers would be
very rare and the differences between the lathes that went out of the doors of those companies factories would be minor; the lathes would have been
very consistent across instances.
But your lathe isn't one of those. It's almost certainly a solid, decently made lathe capable of a fair bit of precision but Taiwanese machine tools, notwithstanding the positives mentioned above were never beautifully made; just well made enough for the likes of us to use. I'd expect there to be at least a similar variation as with the standard production lathes.
Add to that the usage your lathe has experienced in its history and the way you have it set up and the tooling you're using and the fact that steel can mean anything from easy to machine 12L14 to terrifyingly difficult D3 tool steel, all means your question doesn't have an answer that will be of any help for you.
