Halifax614
23rd Sep 2020, 06:58 PM
Tailstock rebuild:
Before, as below.....
388869
Found a bent lead-screw, damaged/cracked hand-wheel & finger piece, damaged eye-bolt & all gummed-up inside, upon dismantling. Some corrosion too. The unit must have been off the end of the bed & bounced off the floor at least once in the past..
Now; all fixed...
388866
I straightened the lead-screw & repaired the hand-wheel with Devcon epoxy. I wasn't game to try brazing or welding it; fine now. The eye of said bolt was stretched into an ellipse; it had gone out of round by well over a mm., which surely can only happen because of excess force on the over-centre locking cam arrangement. It was a bugger to get that cross shaft out because the diameters now clashed. Anyway I later put the eye bit in the hydraulic press & squashed it back the other way so it is now out of round a little across-wise. I thought it would be made of a harder steel than that. MT2 taper inside the sleeve was OK condition. No other major dramas. A good clean, remove crappy finish & repaint to finish up.
Installed back on to the bed....
388868
Here is the simple stop that I made to prevent the tailstock making another bid for freedom off the r/h end of the bed. Just a piece of 25mm galv. steel strip bent to suit, secured with a 6mm winged bolt into a nut-sert in the end of the strip & through the edge of the drip tray. It bounces back the other way now.
388867
Here below with a view from the back, we have all the major parts re-fitted back together... The tail & headstock centres [MT2 & 3 respectively] were used to check that the heights match, which they do thankfully, & the cross-wise alignment was set too.
388865
So now on to the motor & step-down drive system; as you can see in the r/h side of the pic., that area is empty at the moment. The drive motor as originally fitted was a big older single phase 1.5 hp. unit, i.e. three times larger than required. I have checked & rebuilt it with new bearings & start cap & it runs fine. However, I'm considering fitting a new VFD & three phase smaller 0.5hp/0.75Kw kit to it. Or maybe just a standard small single-phase motor. Dunno yet. Seeking advice on VFD's etc. elsewhere on this forum.
Subsequent to all of the above, I've started an alignment check using the trusty ground alignment bar that plugs into the MT3 socket in the headstock, using a magnetic base & DTI on the carriage & have found a bit of an issue with longitudinal run-out; due I believe to the suspect condition of the inside surface of the headstock taper, with some light corrosion pocketing I think.
I earlier stripped & rebuilt the TOS chuck, which seemed in reasonable condition after all the swarf was removed, except that the jaws need a serious grind to straighten the bell-mouthing out on the inside faces. Obviously I can't do that until I refit a drive system, whatever that may be. There is wear on the jaw scroll teeth too; because they are dual inside/outside jaws I need to compare them to a newer example for acceptable wear. It might be preferable to buy a new 125mm chuck.
388870
Before, as below.....
388869
Found a bent lead-screw, damaged/cracked hand-wheel & finger piece, damaged eye-bolt & all gummed-up inside, upon dismantling. Some corrosion too. The unit must have been off the end of the bed & bounced off the floor at least once in the past..
Now; all fixed...
388866
I straightened the lead-screw & repaired the hand-wheel with Devcon epoxy. I wasn't game to try brazing or welding it; fine now. The eye of said bolt was stretched into an ellipse; it had gone out of round by well over a mm., which surely can only happen because of excess force on the over-centre locking cam arrangement. It was a bugger to get that cross shaft out because the diameters now clashed. Anyway I later put the eye bit in the hydraulic press & squashed it back the other way so it is now out of round a little across-wise. I thought it would be made of a harder steel than that. MT2 taper inside the sleeve was OK condition. No other major dramas. A good clean, remove crappy finish & repaint to finish up.
Installed back on to the bed....
388868
Here is the simple stop that I made to prevent the tailstock making another bid for freedom off the r/h end of the bed. Just a piece of 25mm galv. steel strip bent to suit, secured with a 6mm winged bolt into a nut-sert in the end of the strip & through the edge of the drip tray. It bounces back the other way now.
388867
Here below with a view from the back, we have all the major parts re-fitted back together... The tail & headstock centres [MT2 & 3 respectively] were used to check that the heights match, which they do thankfully, & the cross-wise alignment was set too.
388865
So now on to the motor & step-down drive system; as you can see in the r/h side of the pic., that area is empty at the moment. The drive motor as originally fitted was a big older single phase 1.5 hp. unit, i.e. three times larger than required. I have checked & rebuilt it with new bearings & start cap & it runs fine. However, I'm considering fitting a new VFD & three phase smaller 0.5hp/0.75Kw kit to it. Or maybe just a standard small single-phase motor. Dunno yet. Seeking advice on VFD's etc. elsewhere on this forum.
Subsequent to all of the above, I've started an alignment check using the trusty ground alignment bar that plugs into the MT3 socket in the headstock, using a magnetic base & DTI on the carriage & have found a bit of an issue with longitudinal run-out; due I believe to the suspect condition of the inside surface of the headstock taper, with some light corrosion pocketing I think.
I earlier stripped & rebuilt the TOS chuck, which seemed in reasonable condition after all the swarf was removed, except that the jaws need a serious grind to straighten the bell-mouthing out on the inside faces. Obviously I can't do that until I refit a drive system, whatever that may be. There is wear on the jaw scroll teeth too; because they are dual inside/outside jaws I need to compare them to a newer example for acceptable wear. It might be preferable to buy a new 125mm chuck.
388870