# SB - Threaded Spindle Chuck Removal



## Canuck75 (Nov 4, 2021)

Read a post about removing chucks and faceplates from a SB lathe threaded spindle but cannot find it again, so I’ll just post this separately.

By 2008 I had owned my SB 10” for 33 years and never had a problem removing chucks by the common way of engaging the back gear. Along came the fateful day that for whatever reason the bull gear drive pin snapped at the groove where the detent spring rests. A new pin cost CDN $142 by the time it arrived at my door!
I never ever ”snapped” the chuck on but now am even more careful to just “bump” it on.
To avoid this catastrophe entirely I also made an “arm” to utilize the keyway in the back of the spindle and brace it against the chip tray to have something solid to work against as opposed to the back-gear teeth, and, I also “pull” the drive pin to "disengage" just because I’m anal about this now.
Might be overkill but what price peace of mind?

Thanks for looking.


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## SLK001 (Nov 4, 2021)

That keyway is part of a gear at the end of your spindle, which is only cast iron.  It also is part of a hand lever collet closer set and is almost impossible to source if it is broken.  

An alternate method of locking the spindle is with a spindle crank, construction of some is detailed here.

Another way to prevent stuck chucks, is to get some parchment paper and cut out a washer to fit between your chucks and the spindle shoulder.


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## Canuck75 (Nov 4, 2021)

Good point. The boss on the arm locates inside of the end of the actual spindle too.


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## Weldingrod1 (Nov 4, 2021)

Dont use parchment, use sheet plastic! Pick something that dissolves in acetone, not polyethylene.
That way you get the function of even contact AND the ability to dissolve it in an emergency. 

Sent from my SM-G892A using Tapatalk


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## SLK001 (Nov 4, 2021)

Canuck75 said:


> Good point. The boss on the arm locates inside of the end of the actual spindle too.



But the boss inside the spindle doesn't grab onto anything - all the force is placed on the cast iron gear.


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## Canuck75 (Nov 5, 2021)

SLK001 said:


> But the boss inside the spindle doesn't grab onto anything - all the force is placed on the cast iron gear.


Good point again but the gear is absorbing only the rotational force, any radial pressure is taken up by the actual spindle. Will look into putting a thin steel sleeve on the outer end of the gear just in case.

Thanks.


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## RJSakowski (Nov 5, 2021)

For the those with threaded on chiucks, a tool like this would be useful.  The multiple teeth will ditribute the load, greatly reducing the possibility of breaking a gear tooth.  The teeth on the tool don't need to follow the geometry of the gear tooth.  A trapezoidal profile will work just as well.  The contact point should be near the root of the gear teeth for greatest strength.  The tool  would be designed to match the gear on your lathe and could rither be 3D printed or milled using a rotary table for indexing.  If I were printing the tool, I would allow for embedding a steel spine  for strength.  Here is a concept model.


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## woodchucker (Nov 5, 2021)

RJSakowski said:


> For the those with threaded on chiucks, a tool like this would be useful.  The multiple teeth will ditribute the load, greatly reducing the possibility of breaking a gear tooth.  The teeth on the tool don't need to follow the geometry of the gear tooth.  A trapezoidal profile will work just as well.  The contact point should be near the root of the gear teeth for greatest strength.  The tool  would be designed to match the gear on your lathe and could rither be 3D printed or milled using a rotary table for indexing.  If I were printing the tool, I would allow for embedding a steel spine  for strength.  Here is a concept model.
> View attachment 384418


you think a 3d printed one would have the strength to hold the spindle?  I'm more than a little skeptical.


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## Canuck75 (Nov 5, 2021)

RJSakowski said:


> For the those with threaded on chiucks, a tool like this would be useful.  The multiple teeth will ditribute the load, greatly reducing the possibility of breaking a gear tooth.  The teeth on the tool don't need to follow the geometry of the gear tooth.  A trapezoidal profile will work just as well.  The contact point should be near the root of the gear teeth for greatest strength.  The tool  would be designed to match the gear on your lathe and could rither be 3D printed or milled using a rotary table for indexing.  If I were printing the tool, I would allow for embedding a steel spine  for strength.  Here is a concept model.
> View attachment 384418


Are you talking about fitting such a tool on the bull gear or the small gear on the back end of the spindle?, in either case you would have to remove a cover to get at the gear which would be a bother.


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## ericc (Nov 5, 2021)

woodchucker said:


> you think a 3d printed one would have the strength to hold the spindle?  I'm more than a little skeptical.


It just needs to touch on a few more teeth than the back gear usually engages on.  Due to the geometry, this is assured.

When I was a kid, the science teacher showed us a steel tube and taped a piece of tissue paper on the end.  She then poured a small amount of salt in the tube and asked the biggest kid to try to push the mass out with a steel rod.  The salt interlocks and neutralizes most of the force along the contacts with the side of the tube.  You will buckle the steel rod before you can break that little piece of tissue paper.


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## woodchucker (Nov 5, 2021)

ericc said:


> It just needs to touch on a few more teeth than the back gear usually engages on.  Due to the geometry, this is assured.
> 
> When I was a kid, the science teacher showed us a steel tube and taped a piece of tissue paper on the end.  She then poured a small amount of salt in the tube and asked the biggest kid to try to push the mass out with a steel rod.  The salt interlocks and neutralizes most of the force along the contacts with the side of the tube.  You will buckle the steel rod before you can break that little piece of tissue paper.


I get that.

I'm just not sure that the printed part will do it. if the teeth disengage enough to move the force to the edge of the teeth I don't think it will hold, I am also doubtful of the strength of the lever arm.  Honestly I'm just guessing. I don't have a 3d printer, anything I need I ask my son to print for me.
I don't know how much force the prints can take. I believe they are hard to crush because of the way they are printed, but I do believe that the layers would separate much easier (as in teeth layers)  So I guess it depends on how the layers are laid down . if the tooth is added to, less abilty, if the shape is printed from the outer shape then probably it is strong enough.


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## RJSakowski (Nov 5, 2021)

Canuck75 said:


> Are you talking about fitting such a tool on the bull gear or the small gear on the back end of the spindle?, in either case you would have to remove a cover to get at the gear which would be a bother.


 Whichever one would work best. The larger the gear, the better.  It won't necessarily work for every make and model lathe.  It would be preferable to busting a tooth on a lathe gear though.   Maybe only used for stubborn cases.

I have always used the engagement of the low gear countershaft on my Atlas/Craftsman.  So far, I haven't broken a gear but it is scary.  My Grizzly lathe has provisions for a bucking bar and I made a spanner for it which makes chuck changes less worrisome.


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## RJSakowski (Nov 5, 2021)

woodchucker said:


> you think a 3d printed one would have the strength to hold the spindle?  I'm more than a little skeptical.


With a reenforcing spine and the right material, I think it would.  At any rate, if it failed , it wouldn't be the lathe's gear.  It would be worth a try.


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## woodchucker (Nov 5, 2021)

RJSakowski said:


> Whichever one would work best. The larger the gear, the better.  It won't necessarily work for every make and model lathe.  It would be preferable to busting a tooth on a lathe gear though.   Maybe only used for stubborn cases.
> 
> I have always used the engagement of the low gear countershaft on my Atlas/Craftsman.  So far, I haven't broken a gear but it is scary.  My Grizzly lathe has provisions for a bucking bar and I made a spanner for it which makes chuck changes less worrisome.


I have had a tough time on a couple of occasions. I keep a strap wrench and wrap the cone pulley.
But I worry I might break the pin for the bull gear.
When it does get stuck on, I use a piece of hex in the 3 jaw, and a square in the 4 jaw so that all jaws are involved, rather than stressing the casting of the chuck on one jaw.

I guess it's worth a try. Can't hurt...


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## Canuck75 (Nov 8, 2021)

Took SLK001's advice and made a steel .100" thick collar to strengthen the outer end of the spindle gear. Heat shrunk on with .0025" interference. Clears the guard no problem and doesn't cause issues with the hand-lever or hand-wheel collet attachments.

Thanks for looking.


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## Grendel (Nov 17, 2021)

better breaking the teeth on a 3d printed tool than a backgear tooth, and a lot cheaper to replace, I tend to throw a wedge into the cone pulley between it and the headstock body (usually where the belt is positioned, then I can chuck up some hex bar and use an impact gun if needed.
one of my chucks and a backplate had solid rust in the threads and had to be chased out with a 1 3/4 x8tpi UNC tap before i even stood a chance of threading them on, so I am wary about overtightening.


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## porthos (Nov 25, 2021)

*i've had luck with a Rigid  #5 strap wrench around the cone pully. but, the first time that it got REALLY...... stuck; it was a nightmare. ended up removing the chuck from the backplate . bought a 1/2 in. piece of aluminum a little bigger than the back plate. drilled holes in it and bolted it to the backplate. and a a cobbled piece of hardwood  clamped around the back of the spindle. with that and the strap wrench (both were  locked in place). i had drilled 2 holes in the 1/2 in aluminum and screwed in large bolts. then i used a breaker bar between the bolts and  wacked the bar with a hammer. after all the previous grief; it came off pretty easy. haven't had any stuck chucks since. i would NEVER lock the back gear!*


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