real old lathe is gonna follow me home

[jcdammeyer]

One of the reasons my South Bend is supposed to be able to do cutting off operations from the front rather than an upside down cutter from behind the work is that the cross slide is pushed/pulled from the back with a telescoping shaft. This means the taper attachment just gets positioned and clamped to the bed and then the cross slide is moved by the guide on the now fixed taper attachment.

This makes tapering really easy.
Here's a link to how to use the taper attachment. However they call it a telescopic cross slide screw that must be fitted at the factory. So the thing to check is to see if your lathe has that sort of mechanism. Otherwise, like the 9" version, the cross slide nut needs to be disconnected.

http://vintagemachinery.org/pubs/1617/25719.pdf

 

[Susquatch]

One of the reasons my South Bend is supposed to be able to do cutting off operations from the front rather than an upside down cutter from behind the work is that the cross slide is pushed/pulled from the back with a telescoping shaft.

There you again! Shaking the solid ground I thought I was safe to walk on.

I always thought that the "normal" way to do parting was at the front with the front surface of the part moving downward (chuck rotating counterclockwise when looking from the tailstock) no matter what kind of lathe you are working on.

When that doesnt work, you have two choices. Upside down in reverse on the front, and upside down on the rear in forward. The choice between these two being driven by whether or not the lathe has a locking chuck attachment. Locking chucks used upside down on the front in reverse, and non-locking chucks upside down on the rear in forward in order to avoid unscrewing the chuck.

Then along you come with a whole new version of what is normal.....

 

[jcdammeyer]

There you again! Shaking the solid ground I thought I was safe to walk on.

I always thought that the "normal" way to do parting was at the front with the front surface of the part moving downward (chuck rotating counterclockwise when looking from the tailstock) no matter what kind of lathe you are working on.

When that doesnt work, you have two choices. Upside down in reverse on the front, and upside down on the rear in forward. The choice between these two being driven by whether or not the lathe has a locking chuck attachment. Locking chucks used upside down on the front in reverse, and non-locking chucks upside down on the rear in forward in order to avoid unscrewing the chuck.

Then along you come with a whole new version of what is normal.....

Did I explain it incorrectly?
On a standard lathe, as you push the parting tool into the work the loading is on the driving edge of the lead screw. But then the cutting force tends to want to pull the tool bit into the work and with backlash there's nothing to prevent it moving the backlash distance. Jamming up against the now much deeper curling chip.

On the South Bend because of the telescoping lead screw I think (and it's a big think) the mechanics are such that it can't be pulled further because of the way the mechanism moves.

But on my older SB I find I still have issues with parting and the back part of the cross slide isn't flat enough to mount a cut off tool back there.

 

[Susquatch]

Did I explain it incorrectly?

More likely my reading skills.....

I was homing in on your use of the word "normal". I always thought normal was on the front right-side up in forward.

On a standard lathe, as you push the parting tool into the work the loading is on the driving edge of the lead screw.

Doesn't matter on a "standard" lathe. The leade screw loaded or unloaded doesn't affect the backlash in the tool pressure. Only the cross-slide screw comes into the equation and on most lathes its a different shaft. Even the ones with a power cross-slide are usually driven off of a separate shaft. But it's true that there are many varients and some may be that way.

But then the cutting force tends to want to pull the tool bit into the work and with backlash there's nothing to prevent it moving the backlash distance. Jamming up against the now much deeper curling chip.

This is a great description. One I've never read elsewhere. I like it. The only hangup I have is "what is normal", and how much backlash are we talking here.

@PeterT did some drawings a while back to show this graphically. I don't recall backlash factoring into his analysis. If it wasn't there, maybe it should have been.

Personally, I'd have to do some measurements and drawings myself before I'd embrace that concept hook line and sinker.

On the South Bend because of the telescoping lead screw I think (and it's a big think) the mechanics are such that it can't be pulled further because of the way the mechanism moves.

But on my older SB I find I still have issues with parting and the back part of the cross slide isn't flat enough to mount a cut off tool back there.

Can't really comment on the South Bend cuz I don't have one and never parted on anyone else's. But what you say sounds plausible.

Again, my only real hiccup was you describing parting on the backside as normal. I totally understand why it works and why you might prefer it.

I MUCH prefer to part on the front in fwrd gear. However, when nothing else works, I part upside down on the front in reverse. It's never failed me yet.

I don't ever remember parting on the backside nor ever seeing anyone else do it. Hence my hickup when you called that normal.

But again, I can see how it might work for you especially if you have a screw on chuck.

 

[jcdammeyer]

I don't ever remember parting on the backside nor ever seeing anyone else do it. Hence my hickup when you called that normal.

But again, I can see how it might work for you especially if you have a screw on chuck.

Yes. There have been lots of articles in Home Shop Machinist and Model Engineers Workshop on putting the parting tool upside down and behind. And likely that's because, as you mentioned, doing it from the front and running the lathe backwards could have some interesting consequences if the chuck unscrews.

 

[historicalarms]

there will be a correction coming up on the 1913 manuf date and will probably clear up the notion that the lathe is a "parted together machine.
it turns out the # I provided wasnt a machine ser # but an internal machine # for some company in its history, I was dirrected where to find the right ser # for the machine.

 

[historicalarms]

Well thats better, the 16 x 6 lathe was built in Dec 1916 and shipped to the Willys company , prob made many parts for the war effort for those little work horses of human transport .

and I did get the taper attachment sorted & working....havent figured out how it works but it does....how can you slide the cross slide freely when taper cutting but yet advance or retract the cross slide with the lead screw when needed???? Ten years ago Ida had that thing apart by now just to satisfy my curiosity ...but not now, I'll just be thankful it works.

 

[Susquatch]

how can you slide the cross slide freely when taper cutting but yet advance or retract the cross slide with the lead screw when needed????

Perhaps it's an A + B mechanism, not A or B?

 

[Rauce]

how can you slide the cross slide freely when taper cutting but yet advance or retract the cross slide with the lead screw when needed????

On my Hendey T&G the end of the cross slide leadscrew is attached to a sliding block that the taper attachment moved.

So when the taper attachment is in use it pulls the end of the leadscrew and moves the whole assembly.

The opposite end of the leadscrew with the handwheel is simply long enough that it can slide in and out a few inches through the feed gear and dial (which are keyed to the leadscrew).

The Churchill Cub lathe I used to have used a similar arrangement with one additional feature. It used a hollow shaft with internal keyway on the handwheel so that it telescoped with the lead screw inside the cross slide assembly.

 

[historicalarms]

Thank you, I sort of understand the mechanism and how it must work now but it was confusing how the hand crank & dial remained stationary when taper cutting but yet still functioned in it's original state....but onwards to the next couple issues to "fix".
I didnt get the pullys lined up perfectly at my first attempt to re-mount the top drive so an "adjustment day " is nigh to make them even from fast to slow speed.

Second issue is that the lathe came with only a big ol' 9 inch 4-jaw ( and it has seen better days, the jaws may need a "grinding" to grip perfect to the axis) and I want a 3-jaw to use on the thing. The problem for me is the headstock is taper threaded and cutting an internal tapered thread is way beyond my "pay grade" and patience at this point ....so my "farmer fix" idea is to acquire a 5 or6" plain back 3-jaw, manuf just a simple back piece with a hollow (same size through hole as the headstock) spud welded to the back of it. I would mount the whole thing in that heavy 9" 4-jaw, centering it's rotation to the headstock whenever it was re-mounted....should work within reasonable limitations.

 

[Bandit]

A friend some years ago had same issue, big old lathe, big chuck, small work, I gave him a somewhat "used" 4inch chuck. He just held it in the jaws of the big chuck. Done the many smaller jobs, and he was happy.

 

[Rauce]

The problem for me is the headstock is taper threaded and cutting an internal tapered thread is way beyond my "pay grade" and patience at this point

I don’t think it would be a tapered thread. At least I’ve never heard of a tapered thread spindle nose.

From what I can find online, old hendey tie bar lathes that size are 2-1/2” 6tpi or 2-3/4” 5tpi.

 

[Bandit]

It might be "tapered" from haveing been worn from many chuck removals over the last 100+ years. Look at the high part of the thread, the "peaks", if they are rounded, somewhat flattened off on the nose end of spindle compared to farther on the spindle, it maybe wear, otherwise ??

 

[historicalarms]

A friend some years ago had same issue, big old lathe, big chuck, small work, I gave him a somewhat "used" 4inch chuck. He just held it in the jaws of the big chuck. Done the many smaller jobs, and he was happy.

I am going to ask the forum if anybody has an old 6 inch 3 -jaw that they have relegated to door stop/boat anchor status that they could part with in the Calgary-Edmonton corridor for quick pickup. Run out isnt a concern as my plan is to "center" using the 4 jaw.....Anybody

 

[Susquatch]

I don’t think it would be a tapered thread. At least I’ve never heard of a tapered thread spindle nose.

My 140 year old girl is definitely tapered....... from usage! LOL!

It snugs up nice and true though.

 

[Susquatch]

I am going to ask the forum if anybody has an old 6 inch 3 -jaw that they have relegated to door stop/boat anchor status that they could part with in the Calgary-Edmonton corridor for quick pickup. Run out isnt a concern as my plan is to "center" using the 4 jaw.....Anybody?

At some point you might need to cast a wider net and pay some shipping.

At that point, you might find a new 3-jaw on Amazon with free shipping for less that the shipping cost for a freebee from a member. I've seen them for $30 through to ridiculous.

 

[historicalarms]

I spun the chuck off and spindle nose threads are definitely tapered, not much but enough to be seen. Looks to be slightly less than 1/8" taper in lenght of threads. It's not from wear neither, the threads ( 6-1") are still very well formed at the crown from front to back.

 

[historicalarms]

At some point you might need to cast a wider net and pay some shipping.

At that point, you might find a new 3-jaw on Amazon with free shipping for less that the shipping cost for a freebee from a member. I've seen them for $30 through to ridiculous.

My only commercial check so far has been BB but I never thought of Amazon so thanks for that.

 

[140mower]

I spun the chuck off and spindle nose threads are definitely tapered, not much but enough to be seen. Looks to be slightly less than 1/8" taper in lenght of threads. It's not from wear neither, the threads ( 6-1") are still very well formed at the crown from front to back.

Are the threads in the backplate tapered as well? I wonder if a little taper on the spindle is for ease of starting the threading on of the chuck..... purely a guess on my part....

 

[historicalarms]

thats a good question...I will investigate that!