[k9slayer]

the three jaw chuck was firstly running out of true by about 0.008'. I realized that the bushes inside the spindle ( these are applied so long bars can be machined ) was keeping one of the jaws out of align, reason not enough clearance. meaning that when the jaws closed the bar in the chuck and running through inside the spindle was being pushed onto the bushes and this caused the bright bar to run out of true by 0.008'. On removing the bar and bushes then inserting a machined bar back into the 3 jaw. I clocked up the bar and this was running out of true to 0.003.
can i adjust anything to bring the chuck back in to align? Is this a simple operation or is it going to be a major job? Or does one have to replace any parts?
the machine is a TM8 Hurco lathe.

Thank you for reading

[Brock_r]

If I were you, I'd first remove the 3 jaw chuck. Indicate both the Radial and Axial run out of the Spindle nose taper, and the Spindle Face. If this is out, then the head stock may need re-alignment. Ideal would be no run out of the spindle. .0002" may be acceptable depending on the machine age. If all checks well, then re install the three jaw chuck, and tighten the 6 mounting bolts in a crisscross pattern (such as when changing a wheel on a car).

Re-Check the chuck run out is 0.0008" (0.02mm) or less.

[underthetire]

Almost sounds like your seeing run out it the jaws, not the chuck. Check the od of the chuck and see if that's true first. You may need to re bore your jaws if that's the case.

[k9slayer]

thanks for the reply. Can i say i don't think the spindle is the problem, but i will check this first? i have a feeling its the draw-bar levers,they are not moving the jaws simultaneously,( i am just guessing that there are levers moving the jaws) one of the levers may be buckled. Can i ask? Is removing the chuck simple; for hurco don't issue a maintenance manual with the machine. As i understand the procedure, turn the hydraulics down is there something about a key? and just remove the 6 bolts that you have mentioned. it will be a while before i carry out this repair, but hopefully i will return to comment on this task.

[bloke]

You'll have the manual on a DVD that came with the machine.

[k9slayer]

solved the problem.
need to say a big thank you to the Hurco Service Engineer Andrew (UK)
The problem was that the chuck was fitted without the covering plate, so obviously the working mechanisms within the chuck were getting clogged up with debris. Andrew removed the draw bolt and chuck and cleaned everything, put back together, all is now fine.