Hafco AL-250G thread cutting limitations
I'm currently looking to replace my third lathe (AL-50G) that I've just sold. I've narrowed it down to the Workman 10x20 (same as Grizzly), the Paramount 610x280, impala 550x250 and Hafco's AL250G. All have 25mm or better spindles, 250 swing or better and 500 centres or better. The paramount has a reverse gear as an added extra as does the Impala, (I think); however, parts for the first three may prove problematic. Hafco have excellent spares availability, even for some of their now defunct machines. The Hafco rep advised me the AL-250G would cut imperial threads, I was (nearly) satisfied with that, until I took a look at the threading chart on the headstock and pulled out my calculator. He was partially correct: For example the finest thread it will cut is (metric pitch) .035, in imperial threads that's 725 TPI. Perhaps there is an imperial thread that fine, but I think you'd need a microscope to see it and so it goes for the next 15 or so pitches. The finest thread I would use ( metric pitch .70) is around 36 TPI. The remaining nine or so metric pitches are useable, but when converted to imperial TPI, the conversion matchups are exceedingly rare. Unless my maths aren't up to speed (and feel free to correct me) the AL250G is basically useless for cutting imperial threads. Hafco have nothing between the AL50G and the AL320 that's suitable for me, so, I'll have to again look at the other brands that I've already mentioned. All three look alright on paper, except for requiring the use of the half nuts for auto feed and suspect spare parts availability (half nuts):C. Although much cheaper than Hafco, and, with a long list of standard accessories, such as a stand, 4 jaw chuck, live centre, etc, the (un) availability of spares could turn all three into expensive boat anchors. Now the question is: Can I get by with just metric thread cutting? Oh whoa is me, what a quandry. Will someone please prove my maths wrong on the AL-250G's thread cutting limitations.