I'm in trouble- stuck backplate on threaded spindle

itsme_Bernie

itsme_Bernie

Active User
H-M Lifetime Diamond Member
Well I'm back to machining for the first time in a while, and machining a backplate for a chuck.

I have a Heavy Ten with 2-1/4 - 8 spindle.
The backplate is now threaded onto the spindle with no holes for the chuck yet.

There was a void in the backplate casting, so while cutting the relief for the chuck, the back gears were banging at that void. I had to put pressure, via grabbing the spindle with my hand with a rag, to keep from wrecking the banging back gears.

I let the chuck backplate sit on the spindle overnight (I don't know if this should matter), but now the backplate is JAMMED on there.

I have already put a heavy leather strap around the spindle and a 3-foot steel bar, while running the lathe in back gear until my lathe belt SLIPPED. UUGH!!!

I can't imagine what to do, but I thought I would write you guys before I do anything drastic.

I am afraid to use a torch so close to the spindle! But I don't know what else to do to release it!!

Bernie
 
Get you a hair dryer and apply heat by that method. Yep, you should have "popped" it loose while it was warm, may have had a better chance of it loosening.
 
Thanks 4gsr!

I put a heat gun on it instead of the hair dryer you suggested, and put the leather strap (actually an old weight belt), and did one more thing I'm NOT supposed to do:

I engaged the back gear without releasing the pulley pin- effectively locking the spindle, using the teeth of the back gear.

I just didn't put any impact force on the spindle, but a slow 4 feet of leverage.

WHEW!!!


Bernie
 
you might want to give this a try....
put a 50/50 mix of acetone/automatic transmission fluid on the connection of the chuck and spindle.
give the chuck a few raps with a soft mallet to start the capillary action of the mixture to get into the threads.
unplug the power cord.
engage the back gears.
hold the spindle beltway with a strap wrench, put a heavy piece of metal or wood 3-4 ft long in the chuck at 90* to the axis.
hold the strap wrench on the beltway to prevent rotation of the spindle,(it souldn't move much if at all)
then give a light pull on the metal/wood lever.
it should loosen, if not apply more mix for another 24 hrs, once in the morning and night. and try again.

i hope this method helps out!

- - - Updated - - -

looks like you just got er'
good!
 
Thanks guys!

It was more challenging because it is not a full chuck yet, but just a featureless faceplate.

I did use, what was effectively, a strap wrench. I then engaged the back gear without disengaging the pulley. I know it's a no-no, but I was desperate!


Hopefully I won't need it, but I will try the acetone ATF trick next time!


Bernie
 
It's always a pita to get a bare face plate loose when your machining it. I like to start by putting it on the mill and cutting slots in the perimeter of them so I can grab the plate with a spanner wrench. I've done the same thing to my chucks that already had faceplates on them. It's a simple thing but it makes life a whole lot easier especially after the chuck gets hammered on from doing interrupted cuts.

Chuck
 
You aren't kidding there Chuck!! Not only hammered on, but I had to drag the faceplate with all my might to "load" the back gear to not bang the teeth to death.

I am just getting back into the groove of making chips, and didn't even THINK about the plate sticking UGH.

I don't want to think of the slurs that would have come out of me if I had bustle the back gear teeth!

Bernie



Chuck K said:
It's always a pita to get a bare face plate loose when your machining it. I like to start by putting it on the mill and cutting slots in the perimeter of them so I can grab the plate with a spanner wrench. I've done the same thing to my chucks that already had faceplates on them. It's a simple thing but it makes life a whole lot easier especially after the chuck gets hammered on from doing interrupted cuts.

Chuck
Click to expand...
 
I don't like the idea of putting acetone/automatic transmission fluid anywhere near the spindle bearings of any lathe. I realize acetone will evaporate but at the same time will starve lubricant from the bearings.

My personal suggestion when you mount a back plate or chuck, especially one made of steel, is to apply anti-seize to the threads. Never put a back plate or chuck on the spindle threads dry! At least put oil on the threads. And make sure both the spindle and chuck are at the same temperature. And when shouldering out, just let the chuck or back plate make-up snug. Don't snap it tight! That's when you have troubles getting them loosen. Just a few pointers being offered. Ken
 
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