Books are great but they don't make really basic things clear

J

jbmauser

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From the get go I turn with moving the carriage by hand. I have never used the the leadscrew to make cuts and I always get a rough finish. I am working on tool shape. I know about carriage stops, don't have one for my SB 9C lathe but what is the point? by hand you can hit a hard stop but turning with the leadscrew moving the carriage would be a disaster? Do the half nuts pop open when they hit a stop? I don't know and am not prepared to try it.
 
For lathes without a clutch on the carriage drive (like my import 10x22), you are right that you do not want to power feed into a hard stop. Doing so will break something (generally the shear pins on the lead screw but possibly gears, etc.). But you can stop just short of the hard stop and feed the last bit by hand. You can mount a dial indicator so that you can see the end of travel approaching with more accuracy than just a narrowing gap, if you prefer.
 
jbmauser said:
From the get go I turn with moving the carriage by hand. I have never used the the leadscrew to make cuts and I always get a rough finish. I am working on tool shape. I know about carriage stops, don't have one for my SB 9C lathe but what is the point? by hand you can hit a hard stop but turning with the leadscrew moving the carriage would be a disaster? Do the half nuts pop open when they hit a stop? I don't know and am not prepared to try it.
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Hello,

You would stop the power feed before the hard stop and move to the hard stop by hand. Some lathes do have clutches for emergency situations and some have auto disengage for the power feed using adjustable stops of some sort.

You might use a hard stop if you were doing repeat parts for example, plus many other uses too :)

A soft stop implies some sort of dial indicator that you use to see where you are.

Stu
 
Kinda primitive, isn't it jb? Actually requires some input and attention from the operator, imagine that :big grin:
 
You will gain confidence by using your lathe as intended. Take your time, pay attention.
That's my experience anyway. I use my auto feed all the time on my 13" SB., release the clutch when I hit my spot.
Threading, release the half nuts, in your relief area. Pull the carriage back one turn and rinse and repeat.
You will get it.
 
If you're really worried about crashing the carriage while power feeding you could turn a run-out groove in your work, similar to what is often done while threading. Just make it a bit deeper than the final diameter you want in the piece. Of course, this will only work if you have some extra material to work with. If you are turning a piece on both ends, or need to turn it around to finish it, you can't use this method. But see below.

I have a lathe I modified by adding a hand crank to the lead screw. Engaging the half-nuts and slowly turning the crank produces a pretty decent finish, and I can feel when the carriage hits the carriage stop. And there is no danger of breaking a gear.
 
Can you cut threads at very slow speed using the back gears? Enough torque?
 
Of course, one of their main usages, to give slow speeds with good torque
 
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