I recently replaced a 70kw electrical motor with a new one, due to the worn out axle of the old one. The old motors' fan broke, for some unknown reason and it overheated substantially. I replaced the fan and bearings, but ever since, it had a slight vibration, which got worse over time, to such an extent that the motor would draw too much current and trip the O/L.
The problem is that the rear bearings' inner does not fit tight enough over the motors' axle after the over heating event and that's where the vibration takes place. The bearing can actually be moved slightly by hand! I fitted a new bearing and I tried to fix the problem by adding shim stock, but it only worked for a day or so.
Seeing that the motor doesn't really have anything else wrong with it, I'd like to fix it. A friend of mine suggested that I turn the axle down on my lathe and then turn a sleeve, which is pressed onto the axle and then machined down to the exact required diameter to ensure the proper fitment of the bearing.
My questions are:
1. Will my Graziano SAG180 be able to handle the load? I haven't weighed the armature, but it is extremely heavy, with a 70mm axle.
2. If the lathe can handle the load, should I opt to use my 300mm 4 jaw chuck, instead of the smaller 3 jaw?
3. What size live center should I use at the tail end?
4. What should the recommended wall thickness of the sleeve be and what material should I use for the sleeve?
5. What is the recommended tolerance between the bearing inner and the outer diameter of the sleeve, to ensure the proper fit of the bearing?
6. What is the recommended tolerance between the sleeve and the axle, to ensure that the sleeve stays put and not start moving around the axle? Should I opt to add some sort of grub screw to prevent any movement of the sleeve?
7. Should I rather have a qualified shop do this job, because I can just imagine the chaos that would erupt if this job is not completed extremely precisely?
Thanks in advance for your feedback.
The problem is that the rear bearings' inner does not fit tight enough over the motors' axle after the over heating event and that's where the vibration takes place. The bearing can actually be moved slightly by hand! I fitted a new bearing and I tried to fix the problem by adding shim stock, but it only worked for a day or so.
Seeing that the motor doesn't really have anything else wrong with it, I'd like to fix it. A friend of mine suggested that I turn the axle down on my lathe and then turn a sleeve, which is pressed onto the axle and then machined down to the exact required diameter to ensure the proper fitment of the bearing.
My questions are:
1. Will my Graziano SAG180 be able to handle the load? I haven't weighed the armature, but it is extremely heavy, with a 70mm axle.
2. If the lathe can handle the load, should I opt to use my 300mm 4 jaw chuck, instead of the smaller 3 jaw?
3. What size live center should I use at the tail end?
4. What should the recommended wall thickness of the sleeve be and what material should I use for the sleeve?
5. What is the recommended tolerance between the bearing inner and the outer diameter of the sleeve, to ensure the proper fit of the bearing?
6. What is the recommended tolerance between the sleeve and the axle, to ensure that the sleeve stays put and not start moving around the axle? Should I opt to add some sort of grub screw to prevent any movement of the sleeve?
7. Should I rather have a qualified shop do this job, because I can just imagine the chaos that would erupt if this job is not completed extremely precisely?
Thanks in advance for your feedback.