[Frogblender]

I have a spare spindle collecting dust which fits my NM135. It had previously been removed from service (via hammer) since it had horrible runout (I've since found out the top cap was loose, so this was probably the cause of the runout).

My goal is to turn my 6kRPM machine into 9k or 10kRPM by changing the pulley sizes. Most of my milling involves 1/8" bits on 6061, so RPMs are important since I don't want to wait all month for a job to finish. And this spare spindle is a good guinea pig.

Anyhoo, there seems to be alot of "stuff" rattling around inside the spindle, I want to check the state of the hammered bearings, and also check the lube. So a teardown of the spindle is in order.

In the picture below, I've removed the top cap, and the top threaded cap, which has exposed the top bearings. Now I'm stumped. Any ideas how to get this apart?

[JoeBean_NEW]

My guess would be it's pressed out in stages, like a wheel bearing, but I haven't seen one so I can't say for sure. But that is typical of some other spindles I've seen.

[diyengineer]

I have a spare spindle collecting dust which fits my NM135. It had previously been removed from service (via hammer) since it had horrible runout (I've since found out the top cap was loose, so this was probably the cause of the runout).

My goal is to turn my 6kRPM machine into 9k or 10kRPM by changing the pulley sizes. Most of my milling involves 1/8" bits on 6061, so RPMs are important since I don't want to wait all month for a job to finish. And this spare spindle is a good guinea pig.

Anyhoo, there seems to be alot of "stuff" rattling around inside the spindle, I want to check the state of the hammered bearings, and also check the lube. So a teardown of the spindle is in order.

In the picture below, I've removed the top cap, and the top threaded cap, which has exposed the top bearings. Now I'm stumped. Any ideas how to get this apart?

Mount the quill in a vise or holder of some sort and use the hammer to bang the spindle downward to the floor. It should pop right out with some force. If it is a press fit, then your gonna need a small press to push it out. Simple as that.

[JoeBean_NEW]

Banging on bearings like that is a sure way of destroying them, though. Use a press as God intended.

[diyengineer]

Banging on bearings like that is a sure way of destroying them, though. Use a press as God intended.

"It had previously been removed from service (via hammer)"

Already destroyed haha ^

I need a press in my shop bad.

[JoeBean_NEW]

"It had previously been removed from service (via hammer)"

Already destroyed haha ^

I need a press in my shop bad.

I never noticed that, you're right. Might as well have some fun with a BFH now!

Speaking of presses I made myself up a press a number of years ago out of 8" channel, a one-way cylinder from a forklift, and a control valve from a stair truck that you used to see at airports. The pump was originally a modified power steering pump from a VW that had the bypass disabled, and it was driven by a salvaged 3hp motor from a jet pump, using a v-belt and pulleys from anothet VW. I later replaced it with a store-bought unit (he only store-bought item on the thing) because I couldn't get it over 1500PSI anymore and the volume was low anyway, meaning the speed was low. I put a pressure gauge in-line with a new scale showing the calculated tonnage (by multiplying the cylinder bore area by the gauge's stock PSI rating at that point and dividing by 2000). It will comfortably do 50 tons. It originally was going to have a monster 2 way cylinder that I have hanging around, but the seals were bad and it leaked and they cost a small fortune to replace, so I went with the one way. It's retracted by a winch that's mounted on top of the frame with the steel cable ran through an already-present hole in the piston nose with a brass bushing and connected to a fixed point on the frame.

If I were in the US, though, I would just pick one up from Harbour Freight. I've heard good things about one of their models, after the cheap bolts are replaced. It's one of those things that once you have it you wonder how you lived without it.

[gleas]

I just want to adjust my spindle bearings. How do I get to the ring or is there one?

Thanks, -Greg

[Frogblender]

Well I finally got around to buying one o' them cheap 20 ton presses - and the spindle came apart just fine. I removed the dust cap and nuts on the top, then uneventfully pressed the spindle shaft out the bottom.

Then, I found out why the spindle sounded a bit like a maraca when shaken: a homeless M3 screw fell out of the spindle's belly. No idea why it was in there, as there are no screws in the spindle.

And the top ballbearing, despite protection from the dustcover, was very gritty (grit could easily be felt when turning the spindle by hand). I'm pretty sure it was like that from the factory.

A quick inspection of the angled outer race of the bottom roller bearing showed no marks from the precision hammer-bashing removal process. So that's good.

Getting it back together is still an unknown. But at least now I have a hope of dealing with ornery spindles.

[Frogblender]

I just want to adjust my spindle bearings. How do I get to the ring or is there one?

Thanks, -Greg

The two novakon spindles I've messed with each had differing spindle nuts:
One had two c-nuts, which requires two spanner wrenches (like this) to tighten/loosen the nuts against each other.
The other had one "split-nut" kind of thing, which only needs an allen wrench.

Both of the spindles did not have enough preload; one was downright loose (must've loosened off), and caused massive runout (and endplay).

[gleas]

I can't even get the timing pulley off at this point. Any tricks for that?

-Greg

[Frogblender]

I can't even get the timing pulley off at this point. Any tricks for that?

-Greg

That is the ugly part. Here's how I (rodney from novakon, actually) got it out: Load up the spindle-pulley interface with penetrating oil and leave it for a day or two. Remove the four screws from the top of the spindle, and the four screws from the bottom. Bash the top of the spindle with a rubber mallet - with any luck, the spindle should start moving through the pulley, and a gap should open up at the bottom between the spindlebody and the machine's head, as the spindle and body move down and out. Continue pounding. Eventually you'll need a proper-diameter slug (I think I used a long socket from a socket set) once the top of the spindle descends into the pulley.
Other hints:
- move the Z axis to it's highest point - I was paranoid about leaving marks on the Z dovetails from all the pounding, so at least the marks would be way up in a part of the travel rarely used.
- before you start, clean the exposed top part of the spindle of any surface rust with sandpaper, as rust will be difficult to force through the pulley.
- the area was too confined for a gear puller - I doubt a puller would've worked anyway.
- if the rubber mallet doesn't work, place a 3/8" aluminum flat on the spindle, and hit the aluminum with a steel hammer. You want to avoid steel hammer on steel spindle.... although you may have no choice.

Part of the problem was the silly woodruff key was too tight - subsequently fixed in a few seconds on the belt sander. And when you re-assemble, be sure to use anti-seize to prevent the same problem a year from now.

I'm not sure if the pulley was intended to be an interference fit; IIRC, once it was apart and cleaned up and the woodruff key sanded, everything slid back together nice and easy.

If I had to do the same again, I might try to get my hands on liquid nitrogen and fill up the hollow spindle. Or take the entire 100+lb head off and put it on my new 20 ton press. Or both. It wasn't pretty, I can assure you of that.