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?
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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.
