Is this lathe worth buying for constructing small engines.

[samc88]

I find twist drills in the tail stock tend to wander, even when centered correctly. I do know about carriage drilling but i was wondering if using an annular cutter would give better results since it has the hole in the middle to avoid the low speed area.

Tailstock alignment can cause drills to wander. You can check it with 2 dead centres (one in the headstock and one in the tailstock) with something thin like a razor blade between them

[gipetto]

I've found that i can destroy a twist drill in seconds by drilling in reverse accidentally.
does the same happen with carbide cutters in a lathe. i.e. if i make a cut and do not retract the crossslide on the return before the next cut, will it destroy it, assuming there is sufficient coolant.

[crueby]

If I understand correctly,  just cranking back the tool on the same path you just cut, that will not wreck the cutter since the lathe is still turning forward. I do that a lot to smooth the cut, at the same depth setting it would just take off a tiny amount.

[uuu]

I find inserted-tip threading cutters are very fragile.  Threading into a nice open groove makes stopping in the right place easier.  But reversing the spindle while the tool is engaged will take the tip off.

Wilf

[Jasonb]

That is why you should back the tool out when threading as backlash in the leadscrew drive means the tool does not follow the exact part on return.

As Chris says no need to back the tool out for general turning as that won't hurt a insert. But running an insert into a workpiece rotating the wrong way is a fast way to waste inserts

[gipetto]

thanks all. i was of course referring to turning. there's a lot of friction with single point threading so i certainly wouldn't chance it.

[crueby]

Ah - for single point threading, if you reverse the spindle to rewind, definitely retract the cutter or you can easily break an insert, especially the sintered metal ones. I thought you were talking about normal turning.

[gipetto]

I know on a 240v supply that the house has, the max size of a motor is about 3hp. I have read that inrush current is 4 to 5 times larger than the working current of a motor and that one way for air compressors to get more power is to use two motors and two compressors on a single tank, staggering the turn on times.
Though i've never seen it, if i was to get a large lathe and didn't want to use a generator or pay for 3 phase hookup, could i use two motors to lower the inrush current and what would the max draw be, 6 hp perhaps? would one motor need to be clutched.