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1923 SB Lathe Help. Binding

frdtrkguy

Plastic
Joined
Oct 21, 2013
Location
nevada
I have a 15" by 6' that I believe to be 1923 SB based on my research. I just got it running and I have discovered an issue. When I engage the half nut, the spindle/motor binds. Im convinced that it is operator error. I know the power feed on the apron needs to be in neutral for the half nut to control the carriage. The problem is that the knob that controls whether the longitudinal or cross feed is engaged only has 2 positions. It is not like the levers that I have seen on other SB lathes. This one is a knob that you turn to loosen and then select the up or down position.

So, in short, I feel like the lathe is trying to power the feeds and fighting against that when I engage the half nut.

Any help is greatly appreciated!
 
Are you certain there isn't a center position for the clutch nut? Took me a while to understand mine...
 
Series O knob that selects long or cross feed has a neutral.(this is not the feed engage clutch knob)

The drill is you loosen the knob to enable POSITIONING it in one of three selections and then you tighten it up

The sequence is from up to down - not side to side

(from personal experience of owning a '23 13" X 5 foot in the sixties)
 
Series O knob that selects long or cross feed has a neutral.(this is not the feed engage clutch knob)

The drill is you loosen the knob to enable POSITIONING it in one of three selections and then you tighten it up

The sequence is from up to down - not side to side

(from personal experience of owning a '23 13" X 5 foot in the sixties)
That would make sense but this one only has 2 positions. Ill try to take a picture and post it.
 
I have a 1935 15" x 6' SB which I think is probably very similar to yours. When I want to use the half nuts I slide the feed selector shaft on the apron to engage the carriage cross feed. This allows me to engage the half nuts. If I have the longitudinal feed selected the half nuts are locked out and they can not be engaged. There is no center position on my machine... only cross or longitudinal feeds can be selected, one of the other, no off or neutral.

When you select carriage cross feed can you move your saddle up and down the ways manually with the hand wheel? If so, if you engage your half nuts I don't see how anything can interfere with them. Leave the star friction clutch loose so you aren't running the cross feed though.

Good luck,
Ted
 
I have just discovered that it binds when feeding toward the chuck but feeds fine going toward the tail stock.. Maybe it isnt operator error.. Ideas? I had the apron completely disassembled and I didnt see anything wrong in there..

zAYlUx9.jpg

RT60gAb.jpg
 
Nice lookin gap bed....in Ford red too.:)

Thank you! It took me about 2 years to get it to this point. The half nut feeding issue really isnt that big of a deal because I dont foresee needing to cut threads. Its just confusing me. Especially since the carriage moves freely using the hand wheel, then I engage the half nut and it binds up. Releasing the half nut when its bound causes a pop as the half nut threads disengage.
 
I have never seen a South Bend with the detents for the clutch knob machined in like that. I have some 1920's South Bend lathes as well as a 1930 South Bend, and none of them are like that. I have to assume someone modified it.

Here is a post about modifying the apron to make detents:
http://www.practicalmachinist.com/v...-gap-bed-apron-repair-195480/?highlight=apron

Given that your lathe is a gap bed, you may want to add oiling capability like I did. You also need to check your clutch for sticking. Remember, the clutch is not used (IE it is loose) when threading. I ended up regrinding the inner and outer cones of my clutch to make it work right. There was a wear generated ridge that was keeping it from engaging like it should.

Hint for operating cone clutchs on old South Bends: after loosening the clutch, slap it straight in toward the bed with the palm of your hand to make sure it disengages.
 
After seeing your pictures, I was wrong... your lathe is nothing like mine.

The only thing I can guess is something in the lead screw assembly might be binding??? Maybe some misalignment or a bearing or gear on the end of the lead screw???

Just a guess.

Good luck,
Ted
 
I like your mobile frame. I also like the ford red. Same color im painting my 16". I have noticed that a lot of pre 1940 lathe's had T slots on the carriage arms. What are the particular attachments that you would use them for? A follow rest I can see but there must be some other reasons.
My old Cincy has them running the full length of front and rear arms.
 
Your leadscrew appears bone dry?

Admittedly, it is. I’m in the testing phase, not doing any work yet. Everything else to include the bearings at each end of the lead screw are properly oiled.

I have never seen a South Bend with the detents for the clutch knob machined in like that. I have some 1920's South Bend lathes as well as a 1930 South Bend, and none of them are like that. I have to assume someone modified it.

Here is a post about modifying the apron to make detents:
http://www.practicalmachinist.com/v...-gap-bed-apron-repair-195480/?highlight=apron

Given that your lathe is a gap bed, you may want to add oiling capability like I did. You also need to check your clutch for sticking. Remember, the clutch is not used (IE it is loose) when threading. I ended up regrinding the inner and outer cones of my clutch to make it work right. There was a wear generated ridge that was keeping it from engaging like it should.

Hint for operating cone clutchs on old South Bends: after loosening the clutch, slap it straight in toward the bed with the palm of your hand to make sure it disengages.

Good info, thanks! My clutch looked great and functions as it should.

After seeing your pictures, I was wrong... your lathe is nothing like mine.

The only thing I can guess is something in the lead screw assembly might be binding??? Maybe some misalignment or a bearing or gear on the end of the lead screw???

Just a guess.

Good luck,
Ted

I’ll check for binding in the lead screw and gear train tonight. Although, I don’t think it’s binding there. If everything checks out, I’ll probably end up tearing the apron back apart. Thanks!

I like your mobile frame. I also like the ford red. Same color im painting my 16". I have noticed that a lot of pre 1940 lathe's had T slots on the carriage arms. What are the particular attachments that you would use them for? A follow rest I can see but there must be some other reasons.
My old Cincy has them running the full length of front and rear arms.

Thank you! I built the dolly so I can move this heavy sucker for cleaning and such. I still need to buy a machinist level to dial out any bed twist that might be there.
 
The shifter stays in the lower position while threading with the half nuts, the carriage hand wheel will not move (except for some slop in the gears) while the half nuts are engaged and the lathe in not under power. The half nuts have to be disengaged for the rack gear to function. The shifter upper position is for crossfeed. Are you moving the carriage by turning the spindle with the tumbler shifter engaged in fwd or rev, with the half nuts are engaged to feel the binding?

Steve
 
Check the rear saddle gib bolts, leave them loose to check free play and oil them, front saddle lock too.
Check for burs on the lead screw and key way for the worm.

Steve
 
Just fished out my HTRAL # 27. It has a nice picture. of a series O apron with instructions. Up is longitudinal feed,down is cross feed and center is neutral or threading. Actually the same as later lathes but not built the same. Fig 413 page 22. Page 24 has a diagram of the back side showing an interlock that holds the feed lever in the middle when the nuts are closed. Book is from 1928.
 
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You are correct, it is down for cross feed, I had that backasswards. But he describes a non-saftey interlock apron that has 2 positions, up and down. There was not a neutral position on these early O series lathes, prior to the models that were produced for the 1924 introduction of the saftey lock apron.
So you would thread with the clutch disengaged in the upper position.

Steve
 








 
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