why would you want a reversing motor on a lathe? I thought you only cut in one direction? but I can see a variable speed, one direction motor being useful..
obviously I know less than nothing about metal lathes and their proper operation.. some reading material is certainly needed...
I'm a little late to the party but didn't see much input on all this. It was mentioned that a reversible motor was related to threading but more specifically metric threading. When cutting metric threads on an "American" lathe you can't disengage the lead screw once it's engaged with the first cut.
So to make that work you pull back, stop the lathe while it's in gear on the lead screw, run it in reverse to get back to the face of the part then run everything back to your zero point plus however much you want your next cut to be.
When cutting "standard" threads it's not needed because you just engage it on the correct point of the lead screw each time and it stays in time.
So if ya' want to cut metric threads some day you need reverse. If not then you don't. Oh and yes you always cut parts with the chuck spinning towards you. Even CNC lathes run this way but since the tooling is generally on the opposite side of the chuck it sits in it's holders upside down to what we're used to on a conventional lathe.
hmmm, I wonder how important/nice self centering chucks are... pretty low price on this 8".. but i don't think it's self-centering...
http://www.ebay.com/itm/METAL-LATHE...6?pt=BI_Tool_Work_Holding&hash=item4abf3a182c
This is really a toss up. If you can only get one chuck I'd be tempted to get a 4 jaw chuck but you'll have to have a dial indicator on hand to indicate every time you want to spin a part. The reason I say that I would be tempted is because although slower and at first more cumbersome a 4 jaw can do just about anything where as a typical self centering 3 jaw can only chuck "round" parts and with that being said it can only chuck them as well (aka centered) as the chuck is manufactured.
A 4 jaw can get any part dead nuts center with the right operator.
I'll put it this way, if you already had a 3 jaw I wouldn't say go out and spend money on a 4 jaw. If you can find a decent quality self centering 3 jaw I'd go that route since it's a home "hobby" type setup that won't see production work. If you think you're up to the task of learning to indicate parts it'll eventually become a very quick process and won't be too much of a headache in which case go with a 4 jaw.
Sorry for the novel but it's not all that common that I get to talk conventional machine work.
