Slotted Lead Screw Question

[ShagDog]

I have an older (1979?) Taiwan 8x16 lathe. It has one screw that drives the carriage. The screw is slotted. The cross feed is powered as you will see in the 2 levers in a photo. The other lever on right engages the half nuts.

I thought that the slot in the lead screw was to allow the carriage to feed without engaging the half nut. Yet, for the life of me, I cannot figure out how to engage the carriage travel without engaging the half nuts. Is it just that despite the slotted carriage, this lathe just does not have that capability? Help would be greatly appreciated.

PS, the carriage looks similar to a South Bend 9 carriage.

 

[682bear]

The slot in the lead screw is what drives the carriage feed.

Can you provide a picture of the full front of the apron? There may be another lever or knob that changes the feed from the cross slide to the carriage...

Or it may be like the Leblond we have at work... the feed engagement lever has 2 positions... will it move to either side?

The Leblond has one lever... push it to the left and lift to engage the crossfeed... push it to the right and down to engage the carriage feed. Or vise-versa... I don't remember exactly...

-Bear

 

[MyLilMule]

The slot in the lead screw should be for a key that is inside a worm screw, inside the apron. The worm screw engages with a corresponding worm gear that ultimately drives the pinion on the rack. Generally, there is a clutch on the apron that you need to engage that will link the worm gear with the pinion gear on the rack. I have simplified this. There are other gears between the worm gear and the rack pinion gear. There would also be a lever that will switch the power coming from the worm gear to either the carriage or the cross slide (unless you do not have power feed on the cross slide). That lever would also lock out the half nut. That's how my South Bend works.

Without a better picture of the apron, it's hard to tell what controls you have. I hope this helps.

 

[682bear]

What is this 'boss' for?





Also, in your first pic, it looks like there are 2 handwheels? In the other pic, I only see one?

-Bear

 

[RJSakowski]

Your lathe looks similar in operation to the Grizzly G4000. The lever to the left in your first photo should be the one that engages the power feed. The manual for the G4000 warns against engaging both the power feed and the half nuts.

NOTICE
NEVER attempt to engage the feed lever (up)
and half-nut lever (down) at the same time,
and NEVER force these levers. Otherwise,
severe damage to the lathe could occur.

 

[jcp]

Shagdog, I would think the left lever (pic 1) would have 3 positions....crossfeed, neutral, carriage feed.

 

[SLK001]

It looks to me that pulling the lever (NOT the half nuts) DOWN engages the carriage feed. Either that , or your lathe is missing some important parts (like what goes in that boss hole that you didn't provide a picture of).

 

[ShagDog]

Thank you for all the responses so far. As I thought, the consensus is that the slot is for auto feed of the carriage. There are only 2 levers. I have attached more photos.

Bear, what you point to in the photo is just a part of the shape of the casting. It is sealed. Also, there is only one handwheel. The other may be the cross slide dial.

JCP, I may have to take the automatic cross feed lever off and see if I can get 3 positions out of it. Right now, "up" is neutral and middle and bottom are cross feed engaged.

 

[jcp]

I would think up is cross feed, pointing at the operator would be neutral, and down would be carriage feed.

 

[682bear]

Ok, I see now that I was seeing the cross slide wheel...

Just to verify, this lever will not move to the right?



Otherwise, I don't know... but I would think there is a carriage feed...

-Bear