Lead screw question.

[Exuptoy]

After recently purchasing my 10F TV36 I’m not really au fait with what should or shouldn’t happen when in use.

I’ve noticed even without the drive selected on the left hand lever, my lead screw is still turning and sometimes moving the carriage if it’s locked with the half nuts. I’m thinking it may be due to the banjo/gear meshing? What’s wrong with my set up? I’m sure it didn’t do this when it was collected and after removing a few of the gears I never set the mesh with paper. Could this be my problem?

 

[brino]

My advice:

1) Pick a version of the Atlas "Manual of Machine Operation" (aka "MoLO") and/or Southbend "How to Run a Lathe" and get to know them intimately.
There are several version in our downloads section.
Southbend, How to Run a Lathe
Atlas, Manual of Machine Operation (MOLO)

2) With the manual go over your machine carefully to understand _ALL_ the knobs and levers. It's also a great time to become familiar with all lubrication points.

3) Start small and slow. With my 1916 Cincinnati Mill I had NO manuals. Once cleaned-up, I started learning it without the motor by turning the flywheel by hand. That let me engage spindle and feeds without any worry of "crashes". Once I knew how to disengage everything and it was all lubed I carefully tried it with the motor. Things like how to switch between the built-in X/Y/Z power feed were NOT initially obvious.

Be careful and have fun!

-brino

 

[brino]

Is it possible that while you were exploring the gearing that it didn't quite get put back together properly?
Is it perhaps in the reverse position not off position?

On my 1937 9-inch Southbend, the power-feed level has three positions; forward reverse and centre-off.
(see manual page below)

-brino

 

[T Bredehoft]

sometimes moving the carriage if it’s locked with the half nuts.

Its normal for the lead screw to be turning all the time. If the half nuts are closed, the carriage will move. Yes, the lead screw may be put in neutral, but most of us don't do that. We just let it turn so when we want it it will be there.

 

[pontiac428]

If your carriage moves with the half nuts disengaged, it might be worth your time to remove the skirt and clean/inspect the half nut assembly. Also, if your carriage is creeping on a disengaged half nut, your gibs might be a little on the loose side in addition to whatever is causing the lead screw to drag.
Edit: Also check your reversing gear assembly. Something may be loose/dirty in there.

 

[wa5cab]

First off, the Atlas 9" and all of the 10" except the QC and Pic-O-Matic have a FWD-OFF-REV gearbox on the front of the bed below the head stock. And do not have a tumbler. So studying the left end drawing of the South Bend lathe above will only confuse the issue. And most people probably disengage the gear box when the lead screw is not being used. But I guess that's just personal preference. However, if your lead screw continues to turn with the gearbox in OFF, and especially if the carriage moves when you engage the half-nuts, the problem is in the gearbox. Something is dragging or the drive dogs are not disengaging,

 

[Exuptoy]

Cheers Robert. I’ll look into it. Even without the half nuts engaged and the Fwd-Rev in neutral it’s turning. If I lock the carriage with it in N it still tries to drive and there is a noticeable change in sound like it’s under load. Once my bench is finished and the lathe is in position I’ll start looking at it.
Thanks for the other info guys.

 

[Exuptoy]

Whilst I’m at it I think I’ll set up the gears for metric threading (1.5mm pitch) as I probably will never use it for imperial.
I notice from the threading chart that the spindle stud gear needs to be 16 tooth.
I have a number of spare 16/32 compound gears, is this 16t stud gear the same gear? I assume it’s the 32/16 compound thats the under the gear at the end of the spindle which starts the gear train down the end to the lead screw? Do I turn the compound gear around or just use the 16t to drive gear A?

Sorry for the basic questions? This really is new to me.

 

[wa5cab]

If you spend some time studying the threading chart, it would answer your question, but the 16T/32T compound spindle stud gear always goes on the machine the same way, with the 32T gear closest to the headstock. The 32T spindle gear is so wide for historical reasons. The Atlas 9 and the 10 through 10E did not have the stud gear.

But 0.5 mm pitch is going to give you a pretty rough looking finish if you always set up the lathe for threading it. 0.5 mm is almost 20 thousandths in real numbers. It is more than twice the coarsest feed shown on the chart, which is 8.7 thou. Which would generally only be used for roughing cuts.

 

[timmeh]

Check fwd/rev gear box. Mine also turned the leadscrew when in neutral, not enough to drive the carriage. The gear box housing had been damaged in a crash. Will try to find the thread I posted the info to.
"Atlas 10F V42" is thread title, bottom of first page.
Pics not very clear, can take more. Need more info? By all means, ask.