milling shaft problem on HF 5980

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mikeamick
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milling shaft problem on HF 5980

Post by mikeamick » Sat Nov 05, 2011 10:58 pm

Working on a old HF 5980 and the shaft of the mill/drill feels like it is turning
in molasses. Its real slow to turn and the motor can't get it going.

Im thinking the grease has hardin'd.

I got the pulley off and don't know how to continue taking it apart ...

heres a pic for clarification ..
Attachments
mill_shaft.jpg
how to get this out or .. what to do.

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mikeamick
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Re: milling shaft problem on HF 5980

Post by mikeamick » Sun Nov 06, 2011 2:55 pm

wow .. stumped ya huh .. ?

what do you guys think about maybe .. slowly pouring acetone or some other
grease dissolver slowly down around the bearings ... while working the
shaft around. Maybe I can get rid of the solidified grease .. then repack it.

Torch
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Re: milling shaft problem on HF 5980

Post by Torch » Sun Nov 06, 2011 6:34 pm

If it's like my machine, the spindle is a press fit in the bearings. I had to pound mine out when I changed it. Then I installed sealed bearings.

Reassembly was interesting. The nut drew the spindle into the bearings - slowly - but the question was how much preload to apply? Couldn't find the answer anywhere. Basically, lathes and mills should have a bit of preload on the spindle bearings. Too much and the bearings won't last long. Not enough and the bearings will be sloppy as the machine warms up through running. As a rule of thumb, the inside of the spindle should feel warm but not hot after running with no load for 10 minutes.

What I did was to find the 0 preload point by using a DTI and wiggling the spindle while slowly tightening the nut. Then I tightened the nut just enough to engage the first available tab on the tab washer.

Testing showed a 30°F temperature rise of the lower bearing after 5 minutes at the highest speed, and it didn't heat up much more by the 10 minute mark. So I left it there and folded the tab into the nut.

In the end, I retorqued it several times as it tended to lighten up a touch with use.

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mikeamick
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Re: milling shaft problem on HF 5980

Post by mikeamick » Sun Nov 06, 2011 7:47 pm

wow .. sounds like you did a nice job ...

as it turns out I didn't have to take mine apart ... I poured acetone down
around the bearings .. and kept turning it .. and it loosened right up.

now all I have to do is figure out how to force some new grease down
there.

Torch
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Re: milling shaft problem on HF 5980

Post by Torch » Sun Nov 06, 2011 9:43 pm

I lied. I installed tapered roller bearings.

spro
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Re: milling shaft problem on HF 5980

Post by spro » Sun Nov 06, 2011 10:00 pm

There's those needle-like attachments with a grease nipple to go into bearings. The problem is of course the pressure required tends to blow the nipple right out. An actual Zerk fitting is a Half Twist,locking affair and then doesn't require pressure against a needle, in a bearing.

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mikeamick
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Re: milling shaft problem on HF 5980

Post by mikeamick » Sun Nov 06, 2011 10:59 pm

Hey torch ...

Tell me if I am thinking right ...

Is it basically a tube ... with a bearing at the bottom and a bearing at the top ..
with the mill/drill shaft shoved up(or down) into the two bearings ... ?

And Spro .. I really wish they did have Zerks .. it would make it easier ..

Torch
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Re: milling shaft problem on HF 5980

Post by Torch » Mon Nov 07, 2011 12:17 am

Yeah, that's about it. The bearings mount the spindle inside the quill, which is also a hollow tube. The quill has an external rack and the spindle has a set of splines on top. The splines run inside the pulley, which has it's own bearing (that's the ball bearing I replaced with sealed!)

From my notes:

Lower: tapered roller 32007X 35mm bore 62mm OD 18mm thick
Upper: tapered roller 32006x 30mm bore 55mm OD 17mm thick

The spindle has about 4 external diameters below the threads. The lowest is the largest, and serves to stop the lower bearing. Moving up, the next is the press fit for the lower bearing. Then there is a long section of still smaller diameter, the top of which serves as the stop for the upper bearing. Finally the uppermost is the press fit for the upper bearing. That one was real tight! I broke a thick chunk of maple driving that one out, and I believe it is the reason I had to go back and re-torque things several times -- I don't think the upper bearing was seating against the stop, it was just gripping the press fit. But there's no way to see what is going on without driving things out! I couldn't get a torque spec even from the factory. Here is the direct quote from the e-mail they sent in response to my 3rd query:

1)Pls preloading the item #532 amd #533.
2)Take the feed wheel at the end of place.
3)Pls preloading the #581 and #582 and knock it .
4)Preloading the item #578,now it's ok.

Ummm, yeah. Great. That explains everything. :?

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Davo J
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Re: milling shaft problem on HF 5980

Post by Davo J » Mon Nov 07, 2011 12:27 am

I would recommend you at least take it apart, wash the bearings properly and repack them. Who knows what rubbish is in those bearing if they where that tight. To repack them, the grease should fill about 1/3 of the free space in the bearing, not like a wheel bearing where you pack it full.
Take the quill out, and after the top nut is off, a dead blow hammer or a normal hammer and a block of wood should get the spindle out of the quill. Bearings are that cheap these days is often easier to just replace them.
VBX has a full range that are not expensive and will post them to your door.
http://www.vxb.com/

Dave

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mikeamick
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Re: milling shaft problem on HF 5980

Post by mikeamick » Mon Nov 07, 2011 2:22 am

Ok .. I am brand new at this ... so the vocabulary is foreign to me.

I do have a shop with welders and drill presses and grinders etc .. and do
a lot of fabrication work .. as a hobby .. but I have never touched a lathe or mill ..

( I can't wait to start though )

So bear with me when I ask .. how do I get the quill out .. i'm sure I can handle
it from there .. just need that other inch ...

Torch
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Re: milling shaft problem on HF 5980

Post by Torch » Mon Nov 07, 2011 7:04 am

Ok, the spindle is the part that rotates. It is installed in the quill. The quill is the part that goes up and down when you pull the handle.

Removing the quill involves messing with the return spring. I don't want to give specific directions because your machine differs from mine. However, the spring tension must be safely released and then the handle, with it's axle and gear, extracted from the casting to release the quill. When I changed my spindle, I did it in place after supporting the quill with a 4x4 block of wood between the lathe bed and the mill head (off centre to clear the spindle, of course!)

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mikeamick
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Re: milling shaft problem on HF 5980

Post by mikeamick » Mon Nov 07, 2011 1:41 pm

ok .. that's what I needed ..

Thanks Torch

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