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Removing Chuck
- Thread starter porthos
- Start date
- Joined
- Jan 2, 2014
- Messages
- 8,853
Porthos, it comes down what exactly you are measuring........
1) the first measurement should be either on the spindle nose un-threaded shoulder or on the internal tapered face. This will give spindle run-out and show any lathe bearing or bent spindle issues. This will add to other measurements taken with a chuck or bar in the chuck. This is easier with a dial test indicator than a dial indicator as it's easier to adjust the holder so that the DTI goes into the spindle and the measuring arm rides on the spindle ID.
2) the measurement of a chuck body will included 1) above plus any error due to chuck body itself and the backing plate
3) finally measurement of a bar held in the chuck will include 1) and 2) above, plus the additional error of the chuck jaws and bar itself.
The 4 tenths that chevydyl mentions above seems amazingly accurate to me. Also, it sounds like he is measuring on the body of an end mill held in the chuck....so that should include all the errors above. Wow! My equipment would not hold that tolerance, however, it still meets my expectations and my needs.
-brino
1) the first measurement should be either on the spindle nose un-threaded shoulder or on the internal tapered face. This will give spindle run-out and show any lathe bearing or bent spindle issues. This will add to other measurements taken with a chuck or bar in the chuck. This is easier with a dial test indicator than a dial indicator as it's easier to adjust the holder so that the DTI goes into the spindle and the measuring arm rides on the spindle ID.
2) the measurement of a chuck body will included 1) above plus any error due to chuck body itself and the backing plate
3) finally measurement of a bar held in the chuck will include 1) and 2) above, plus the additional error of the chuck jaws and bar itself.
The 4 tenths that chevydyl mentions above seems amazingly accurate to me. Also, it sounds like he is measuring on the body of an end mill held in the chuck....so that should include all the errors above. Wow! My equipment would not hold that tolerance, however, it still meets my expectations and my needs.
-brino
- Joined
- Jun 15, 2013
- Messages
- 1,199
My 8" universal Bison 3jaw, has .003 maximum allowable runout, universal is keyword for more runout than a precision chuck. The bigger the chuck the more runout that's allowed in the spec before the factory considers it to need fixing. According to my Bison work holding catalog a 6 1/4" chuck has a max runout of .0016, this is holding a bar. I suggest you download that catalog. I consider the 4 tenths to be allowable, my Bison collet chuck (5c) has about .0006-.001 runout. To me, that's so terrible for a collet chuck that I don't use it, won't use it until I fix that, which means maybe grind the taper.
- Joined
- Jun 12, 2014
- Messages
- 4,819
Agree with Brino and Chevydyl , even the best chucks from say Bison or PB, a 6" will spec at around 0.002" maximum TIR, others are up to 0.004", set-tru type usually are 0.0004" or better. Problem with 5C is that even though the chuck may hold tolerance, 5C collets have a much greater TIR than say ER types and the collet clamping range is very limited.
So specific to your discussion on the binding of the chuck when removing them, I think the use of some hard wax may be helpful. When I did woodworking, wee would use beeswax on the screw threads when tapping them into hard wood. I also use it in other threading situations where I want something to stick and not get messy. You could also have a mounting issue that something is binding because of the interface not being a 1 to 1 fit. You could use some Dykem to see if there is a specific problem spot.
So specific to your discussion on the binding of the chuck when removing them, I think the use of some hard wax may be helpful. When I did woodworking, wee would use beeswax on the screw threads when tapping them into hard wood. I also use it in other threading situations where I want something to stick and not get messy. You could also have a mounting issue that something is binding because of the interface not being a 1 to 1 fit. You could use some Dykem to see if there is a specific problem spot.
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Firestopper
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For this type of application, I have had pretty good luck with Engineers blue or Prussian blue. Much easier to work with over Dykem when it comes to mating surfaces.