Stuck Lathe Chuck

My American was an old timer, I think made in 1919, and was a sturdy and accurate lathe, it cut perfectly straight in chucking work and ran smoothly and quietly. An old friend bought it back east in the mid 1950s from a dealer who had 24 of them all alike and nearly that many 36" swing; this was when the railroads were dropping steam for diesel, it must have been form the shop of a major locomotive manufacturer.
Interestingly, the chuck was held on by a coarse acme thread. The lathe is still in use at my shop, which I sold when I retired.
 
I was looking at it again this afternoon. I'm not sure if this is a good idea, so give me your opinions. The bull gear is about 24 inches across and the teeth are massive. I measured 5/16 at the tip and 5/8 at the root. I'm wondering if putting a piece of flat bar that fits the gap between the teeth snugly and bottoming it out on the headstock housing, which is over 1 inch thick cast iron, would hurt anything? Like I said, right now I don't have power for it, I'm trying to loosen it up with hand tools.

Apparently it's been stuck on there a long time. There's evidence on the backside of the chuck that somebody tried to 'convince' it with a hammer at one time. I don't see any damage, but you can see the marks they left.
 
Hammering is how teeth get broken; wait for power up, and bump power repeatedly, not all power until something breaks.
 
As a last resort, the chuck can be removed from the backplate, then the backplate made into chips, then a new one made after the spindle threads are cleaned up.
 
If the gears are massive,then using a reverse force on the drive is likely safe.I have used a large shifter 36" on one of the chuck jaws to move threaded chucks.,but lacking a big shifter,a piece of 4x1/2" flat across the face of the chuck should be ok.....Dry ice in the spindle bore,and heat the backplate,if there is one,or the chuck around the outer edge with the strongest oxy flame you have.......no use fiddling with a small torch,as heat will equalize,and what you want is to expand the rim before the rest of the metal expands.Then give it your best shot.
 
This discussion makes me really appreciate my 13" lathe with a D1-4 spindle. Never an issue with chucks after refitting them properly to the spindle nose taper, and the chucks are not too heavy to carry (so far.)
 
Really prehistoric to make a lathe that big with a threaded spindle, but there you go
I like the split wedge in the spindle bore idea, even if it slips as you whack on the chuck no harm is done
 
I guess I'll put this on the back burner until the shop is finished (hopefully about 2 months) and I can power it. Then I'll try a combination of all the suggestions. I'll have to find a source for dry ice. It's not available around here.

The chuck is apparently bolted to some sort of back plate, but the only fasteners visible are four bolt heads in the front of the chuck. There isn't enough clearance around them to put a socket on them. I'm not really sure how it all goes together. I can look behind the chuck and see a couple of threads on the spindle, so I'm sure it screws on. I'd post pics but I've never figured out how on this site. Can't seem to find instructions anywhere. I quit using Photobucket when they started wanting to charge for links.

Thanks for the help fellas. I'll let you know how it goes. I'm seriously thinking about videoing the restoration. There are tons of videos for Southbends, Monarchs, and other more popular lathes, but very little on L&S to be found anywhere.
 
A thin walled socket for the removal of the bolts for the chuck, Removal of the chuck from the back plate will allow you to better heat the back plate. With the Chuck in place you ware wasting your heat on the chuck and not getting enough to the back plate where it will do the most good.

Also look on here for home made penetrating fluid, There are several and some often work better than the commercial stuff at times.
wish you luck But keep putting penetrating fluid on things.
 
Thin walled socket is the way to go. You can make one easy enough. The best place I have found to get dry ice is Continental Carbonic, they have locations all over. But if you can't get that the next best thing is liquid CO2 which you can get in a lot more places since it can be contained in a cylinder under pressure. It isn't as easy to work with though and you have to be careful with it as it will give you freezer burn. But anywhere that has a soda fountain or beer on tap will have it.

Being in that area of the country you probably have a better option though. You for sure have cattle in the area and most ranches brand with liquid nitrogen. If they don't have anything like that around look for a place that does bull semen. Again you have to be careful with it but it is an order of magnitude colder than dry ice. Get a stainless vacuum thermos bottle to put it in. Don't seal the top, it creates a lot of gas as it evaporates, think balloon with too much air. Again be careful with it, stuff is seriously dangerous, but they let cowboys play with it so just requires common sense. And it will pour where you want it to go. Build a dam to contain it where you need it to cool the part and it will cause serious shrinkage. If you can get to the spindle bore from the chuck side and pour it inside that will give you the most bang for your buck.
 
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