South Bend 9/10 Feeding with Thread Handle

[Dan1900]

Hello,

I moved from a 9c to a 10k recently. I really liked on the 9c that when power feeding longitudinally, I could disengage the half nuts instantly to stop the carriage from feeding. Now that I have the 10k with power long/cross feeds, I need to screw/unscrew the small knob to disengage the power feed and it's a lot slower than just disengaging the half nuts. How many of you just end up just using the handle linked to the half nuts when power feeding?

Apologize if this is an obvious question but I am far from an expert. Thanks

 

[lazz]

The south bend lathes I have operated use a knob to control the clutch.... and a 3 position lever to switch between longitude and cross feed.

Im sure an expert will speak up...


both examples are in neutral

 

[Dan1900]

Thanks, I am not sure I am wording the question right. So on my carriage, I have the clutch which engages the power feeds (long/cross depending on which position the lever is in), but then you also have the handle on the right hand side used for threading, which is tied to your half nuts. I find that disengaging the clutch takes a few seconds whereas disengaging the half nuts is almost instant. So for power long. feed, I am wondering how many people use the clutch vs. using the half nuts?

 

[Tony Quiring]

They are for different functions and are interlocked to prevent both.

The 1/2 nuts are for threading only.

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[promacjoe]

Yes it is quicker to disengage the half nuts, instead of using the clutch. but the problem with using them for everything, is it will eventually wear out. Making them useless for threading. This is the biggest problem with the model C, lathe. Using the clutch will help prolong the threading accuracy of your machine. the Clutch does not have to be extremely tight. Just tight enough to move properly. It should only take about 1/4 to 1/2 of a turn to stop the feed.

Stay safe and have fun.

Joe.

 

[hsracer201]

You can cheat and use your half nuts but sometimes you may need to feed a more precise speed only achieved by using the correct feed. Not to mention you are uselessly wearing your half nuts out.

South Bend later moved to a cam lever clutch that was more "instant" than turning the star knob.

Maybe your clutch isn't adjusted correctly or installed properly? It shouldn't take Many turns to engage/disengage. Maybe a half turn or so and it can be done quickly.

ETA: Joe typed out and submitted while I was typing.

 

[johansen]

i replaced the worm gear in my 9" with a 3d printed one.

thus i don't really care if i break it.

i never did have a chance to use the cast iron one because the tooth form was reduced to knife edges and i think they would sheer off if i stopped the carriage with a hard stop while power feeding, depending on how tight the clutch knob was turned.


anyhow, if you're doing something sensitive i'm fairly confident you can safely clamp a hard stop to your carriage and just powerfeed right into it. just pay close attention to how tight you turn the knob and tighten it only a tad more than what is required to reliably keep the tool in the cut.

i've taken cuts that nearly take two hands to turn the carriage handwheel and i'm wondering what the 20dp cast iron? teeth can handle in that lathe.. so i'm fairly confident the worm gear is not going to break. something else might.. if the teeth are good.


the cast iron clutch/worm gear should disengage with hardly half a turn of the knob. a plastic one will take a bit more until its worn in.. depending of course on some other details which are specfic to the geometry of the clutch.

not to mention the potential of crashing your lathe with the half nuts engaged. does it have a sheer pin in the leadscrew or is the keyway the weak point?

 

[Monarchist]

Thanks, I am not sure I am wording the question right. So on my carriage, I have the clutch which engages the power feeds (long/cross depending on which position the lever is in), but then you also have the handle on the right hand side used for threading, which is tied to your half nuts. I find that disengaging the clutch takes a few seconds whereas disengaging the half nuts is almost instant. So for power long. feed, I am wondering how many people use the clutch vs. using the half nuts?

If.. you search around .. you MAY find a how-to on converting the Starwheel AKA Pain in the ASS if not also the hand, clutch knobs to lever & cam handles as newer (design) lathes utilize.

Last time I had to deal with those damned starwheels, they were on a War ONE Niles. SB made their bones on being a living fossil, so...

 

[gadget73]

If you don't reef down on the knob it will disengage pretty easily. Usually I just keep my hand on it near where the point I need to drop it out and simply hold it. The knob turns as it runs, so holding it still will drop it out for you. The lever system would be a nice upgrade but the parts aren't exactly falling from trees and costing pennies these days.

Maybe whenever I get myself a mill I'll make myself the parts to convert it.

 

[steve-l]

I have a 10k that I bought new. The star wheel works just fine when properly adjusted, half turn in and a half turn out. It is easy to get used to. My other lathes have cam levers. For me there is never any element of confusion jumping from one to the other. I see no issue with either method nor do I have a preference.

 

[johnoder]

Move three position lever to neutral - instant feed stop

Then you can leisurely undo the clutch knob

 

[Monarchist]

I have a 10k that I bought new. The star wheel works just fine when properly adjusted, half turn in and a half turn out. It is easy to get used to. My other lathes have cam levers. For me there is never any element of confusion jumping from one to the other. I see no issue with either method nor do I have a preference.

See JO's note. Some old HEAVY lathes, the starwheels could self-tighten.

 

[steve-l]

See JO's note. Some old HEAVY lathes, the starwheels could self-tighten.

Yes, I have read that as well, but never experienced it in the 37 yrs. I have owned the 10k or with the 9 I had owned before.....jus sayin.......

 

[PmGRacer]

I documented in another thread the making and use of a knurled knob in place of the star wheel for carriage feeding. I also posted a dimensioned drawing to make the knob.

The knob came about after going to look at a Heavy 10 that uses a lever to engage the clutch. It is too difficult to adapt a lever to a 10k. I have gotten used to using the revised knob vs a lever. The clutch also provides much finer feeds which produce very fine finishes vs using the half nut. I only use the half nut for cutting threads.


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[Monarchist]

Yes, I have read that as well, but never experienced it in the 37 yrs. I have owned the 10k or with the 9 I had owned before.....jus sayin.......

Umh.. old "HEAVY" were 30-to 50 inch swing, 12-foot or better bed, Niles-Niles with MASS not Niles-P&W with CLASS, and surely not SB, so.. may not even have been the identical mechanism inside.

But yes, one CAN adapt a lever. Use the broad ash shovel shape early L&S used so the cam action rests against the apron wall to either side of the clutch.

 

[tobnpr]

I use my 9A exclusively on rifle barrels- turning to diameter, threading to shoulders. I can disengage the clutch when turning almost (not as quite) as precisely as the half nuts when threading. I just keep the feed rate (and spindle speed when threading) manageable. I'll disengage the clutch 5-10 thou ahead of my stop point when turning- and turn the handwheel on the carriage for the last few thou.With practice and "touch", you'd be surprised how precisely you can slide it along the rack.

Use a dial indicator set .100 (one full rev) from the stop point as a "kickout" indicator, makes it easier to time exactly. I have DRO's, but it's much easier to time to a dial, than flickering numbers!

As mentioned, SB designed this to minimize wear on the half-nuts and I think they got it right.

 

[Dan1900]

Thank you everyone for your input, I am going to practise some without actually cutting anything. There was one comment that said you could feed directly to a hard stop with the clutch engaged, but I'm not sure I'm up for that. On my 9c I know I would mess up the half nuts; with the clutch I feel something would break if I fed into a hard stop. But if anyone has done it before with no issues, I may be willing to give it a try.

 

[johansen]

Thank you everyone for your input, I am going to practise some without actually cutting anything. There was one comment that said you could feed directly to a hard stop with the clutch engaged, but I'm not sure I'm up for that. On my 9c I know I would mess up the half nuts; with the clutch I feel something would break if I fed into a hard stop.

try restraining the carriage with the handwheel while tensioning the clutch to understand what it feels like, the friction should be predictable and linear with how tight you turn the knob.. but mine is plastic and the coefficient of friction is probably half of what it was with the cast iron worm gear.