Chinese 2.2kw Spindle Bearings

[jimskeet]

I have no backlash on my cnc router. This is how those spindles work. They produce their torque at high rpm. A good quality spindle will probably have a more balanced torque curve but those chinese spindles I guess don't.
Also it is not ideal to low speed mill with those spindles because you are rubbing the tool then. Better lower the depth and width of cut but maintain the feed it needs to have the appropriate chip load for the current rpm.

[handlewanker]

No backlash???.....you must have the only CNC router in the World that does not have ANY backlash.

BTW....the double ballnut application to CNC does not guarantee no backlash, it's purely for hard driving hence the heavier preloading.

It's purely academic as the topic is the bearings in the spindle and the getting them out and back in again without damaging the innards.

Purely my opinion but if you are making parts for a living with this machine you'd be well off having a spare spindle for the just in case scenario......at the moment you have all your eggs in one basket and that basket is starting to fall apart.

Are you working on the theory that any VFD will drive any high speed spindle?
Ian.

[jimskeet]

No backlash???.....you must have the only CNC router in the World that does not have ANY backlash.

BTW....the double ballnut application to CNC does not guarantee no backlash, it's purely for hard driving hence the heavier preloading.

It's purely academic as the topic is the bearings in the spindle and the getting them out and back in again without damaging the innards.

Purely my opinion but if you are making parts for a living with this machine you'd be well off having a spare spindle for the just in case scenario......at the moment you have all your eggs in one basket and that basket is starting to fall apart.

Are you working on the theory that any VFD will drive any high speed spindle?
Ian.

My ballscrews are held with angular contact bearings so I do not have backlash on my axis.
The replacement of the bearings will be done with tools for removing bearings and for pressing them back in. My brother is working for a machine shop (working on a haas vf2 mainly) with a lot of tools and machines and he will take the spindle with him the to replace them with the appropriate tools.
Also about the vfd theory I have no clue :P
I don't know much about electronics but I am trying to get as much knowledge as I can.

[jimskeet]

While I am waiting for my bearings I am looking into the disassembly procedure.
First I will disconnect the connector and the liquid tubing and drain the spindle.
Then is there a specific order on how I remove its parts?
First top and bottom caps, then top left handed bolt and then I push the axle out of the housing?
The lower 4pin nut is what holds the bearings in place and will be removed after the axle is out of the housing?
Did I get this right?

[jimskeet]

Also how tight is the 4pin lower nut? I plan to machine an aluminum wrench with matching pins. Will it be able to do the job? Or os the nut so tight that aluminum won't hold?

[mactec54]

While I am waiting for my bearings I am looking into the disassembly procedure.
First I will disconnect the connector and the liquid tubing and drain the spindle.
Then is there a specific order on how I remove its parts?
First top and bottom caps, then top left handed bolt and then I push the axle out of the housing?
The lower 4pin nut is what holds the bearings in place and will be removed after the axle is out of the housing?
Did I get this right?

Use air to blow through the water lines in the Spindle, to make sure no water is left inside before you disassemble

There is nothing to press out, if it Rotor does not just slide out of the housing, you are doing something wrong, the Rotor only comes out the front of the spindle, you have to take very careful note of the Belleville spring washer assembly at the top Bearing, you won't see this until you slide it out, this is the preload for the Bearings

The top nut / bolt you need a special wrench as well, your brother will not have the correct tools to take it apart, but he could make them

If your Spindle has AC Bearings, you will have to note how the Bearings are mounted, correct orientation of the Bearings are the most important part of the assembly, and being shielded this make it harder to determine the correct assembly

Some of the cheaper spindles do not have AC Bearings, they have regular Deep Grove Ball Bearings

[jimskeet]

Cool. Do we know the dimensions of the top nut so we can have the tool machined before we open the spindle?

[mactec54]

Also how tight is the 4pin lower nut? I plan to machine an aluminum wrench with matching pins. Will it be able to do the job? Or os the nut so tight that aluminum won't hold?

Yes a Aluminum wrench will do the job, the Pins want to be steel, Dowel pins work well, they must be a good fit in the holes, or the soft aluminum nut will get damaged

[jimskeet]

Hmm I was thinking to machine the wrench with the pins on the wrench as one piece. Instead of doing wholes and inserting dowel pins.

[mactec54]

Are you working on the theory that any VFD will drive any high speed spindle?
Ian.

There is no theory to it

Any VFD will drive one of these high speed spindles, the requirement the VFD has to have it the Hp rating of the Spindle or higher Hp rating is better, for single phase use

The only other requirement is that the VFD is 400Hz which most are, and above, nothing more to it

[mactec54]

Hmm I was thinking to machine the wrench with the pins on the wrench as one piece. Instead of doing wholes and inserting dowel pins.

Most likely the small aluminum pins would just shear off, aluminum pins are not what you want, the nut will be at least 60 Ft lbs. and some have Loctite on them, the top nut does as well

[jimskeet]

Good so it will be with dowel pins. Now that you mentioned about the torque. Should I use my torque wrench to re tighten those 2 (top and bottom nuts?) and if so what torque should I use?

[mactec54]

Good so it will be with dowel pins. Now that you mentioned about the torque. Should I use my torque wrench to re tighten those 2 (top and bottom nuts?) and if so what torque should I use?

I don't think there is any numbers that have been posted, I have always used 40Ft lbs. on the top nut and small dab of ( one spot ) Loctite, the bottom nut 40 to 60Ft lbs. this depends on the threads in the nut, some have good threads, some are just plain bad threads, the bottom nut is something you can check to see if it is tight after running it, so start low and add a higher torque if it need to be retightened after some use, here is a photo of one of my Pin wrenches, I could not find a photo of the top nut wrench

[jimskeet]

Great. Thanks!

[handlewanker]

There is no theory to it

Any VFD will drive one of these high speed spindles, the requirement the VFD has to have it the Hp rating of the Spindle or higher Hp rating is better, for single phase use

The only other requirement is that the VFD is 400Hz which most are, and above, nothing more to it

Thank you for the info.....I'm wiser as well as older in the process.

[handlewanker]

I don't think there is any numbers that have been posted, I have always used 40Ft lbs. on the top nut and small dab of ( one spot ) Loctite, the bottom nut 40 to 60Ft lbs. this depends on the threads in the nut, some have good threads, some are just plain bad threads, the bottom nut is something you can check to see if it is tight after running it, so start low and add a higher torque if it need to be retightened after some use, here is a photo of one of my Pin wrenches, I could not find a photo of the top nut wrench

Hi, I've made a few pin wrenches over the years.......always with high tensile steel, commonly known as silver steel or just high carbon steel, and then hardened and tempered etc.

The pins were cut in situ by cutting across the end with a saw to leave two square pins and then finished by offsetting in a 4 jaw chuck in the lathe.......a mill with a boring head could also be used.

The main body was finished with a square on top for a spanner.

If you don't spend some time to make the pin wrench properly you could have the pins shearing off and jamming in the holes in the nut......once made it's a valuable tool for any future spindle work.

One wrench I made had 2 sets of holes at 180 deg and hardened dowel pins for two nuts with different pitch centres.......whatever it takes etc.
Ian.