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Stuck chuck on Atlas lathe
- Thread starter sask3500
- Start date
Chicken lights
Forum Pony Express Driver
I drive heavy truck and try to fix my own junk as much as I can
I seem to break stuff faster than I can fix if though
francist
Super User
Zamak has a pretty good expansion rate (ie:fast) as you probably have already experienced. Many of the v-belt pulleys we think of as aluminum are actually Zamak, and you know that it doesn’t take much to get them on or off a snug shaft. However, a word of caution: Zamak will melt at around 700F, so go gentle.
edit: here’s what will happen if you exceed that magic temperature...
The gear is from a fire salvaged Craftsman I rebuilt. I could tell from which direction the fire came by how the Zamak parts reacted. Some were mint, some not so much, and some were just vaporized. Pretty wild, eh?
Last edited:
historicalarms
Ultra Member
Two ways I can see to tackle this, one is foolproof but you will need to by a new backing plate...the other will work also but has the potential to mar up the spindle or a gear...
The first is to unbolt the chuck body from the backing plate and machine the backing plate off the spindle. B-plates of that nature should be very inexpensive & easily sourced...a forum member might even have on kicking around somewhere.
The second method... Kind of like manualy removing a yolk nut from a pinion shaft on a set of 46,000 lb rears, a 12 foot snipe with 2 grown men jumping on the end of it LOL. I would remove the chuck body also so it isn't being "torqued" with pressure. Bolt a substantial piece of 1/2' thick flat bar to the bolt holes in the b-plate at least 3 ft long. Rig up the same pipe wrench set up you were using before only this time, mesh up the two stoutest gears in the gearbox and lay a piece of dowel into the gear notch where they join ,essentially locking them up. Now put a long pipe snipe on the flat bar and steadily add an increase in pressure (do not "shock load" the pressure") until the b-plate starts to unscrew or the gear train at the lockup spot starts to show excessive flex or strain...if the later shows first return to idea # 1...its your only solution.
The first is to unbolt the chuck body from the backing plate and machine the backing plate off the spindle. B-plates of that nature should be very inexpensive & easily sourced...a forum member might even have on kicking around somewhere.
The second method... Kind of like manualy removing a yolk nut from a pinion shaft on a set of 46,000 lb rears, a 12 foot snipe with 2 grown men jumping on the end of it LOL. I would remove the chuck body also so it isn't being "torqued" with pressure. Bolt a substantial piece of 1/2' thick flat bar to the bolt holes in the b-plate at least 3 ft long. Rig up the same pipe wrench set up you were using before only this time, mesh up the two stoutest gears in the gearbox and lay a piece of dowel into the gear notch where they join ,essentially locking them up. Now put a long pipe snipe on the flat bar and steadily add an increase in pressure (do not "shock load" the pressure") until the b-plate starts to unscrew or the gear train at the lockup spot starts to show excessive flex or strain...if the later shows first return to idea # 1...its your only solution.
If the 4lb microadjuster doesn't work,,,,,,,, get a bigger one
Getting to physical could sheer the lock pin or break the bull gear and/or pulley. I know,,,, stating the obvious.
Another thing I tried was freeze spray in the spindle and the bit of heat on the back plate with no success. I don't think the spray got a deep enough soak on the spindle.
Getting to physical could sheer the lock pin or break the bull gear and/or pulley. I know,,,, stating the obvious.
Another thing I tried was freeze spray in the spindle and the bit of heat on the back plate with no success. I don't think the spray got a deep enough soak on the spindle.
Just a heads up that anti seize works way better than oil on spindle threads. Its used on muzzle loader threaded breech plugs, which is where I got the idea. Never again have I struggled to get my chuck off.
You might try chucking up a piece of hex stock as large as the chuck bore, deeper than the jaws, lock the spindle and use an impact driver. I recently bent a wheel spanner trying to loosen stuck wheel nuts, an impact popped them off effortlessly. I was amazed.
You might try chucking up a piece of hex stock as large as the chuck bore, deeper than the jaws, lock the spindle and use an impact driver. I recently bent a wheel spanner trying to loosen stuck wheel nuts, an impact popped them off effortlessly. I was amazed.
