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MuellerNick
11-27-2010, 08:41 AM
Hi!

Got my mill's spindle parts back from re-grinding a week ago. Had to wait for the grease I forgot to order in time. Got that two days ago. 400 g just 70 . OMG!
Yesterday, I preassembled it and let it sit over the night for the temperatures to equal out. The shaft was in the freezer, the bearing in the oven and the quill's house at room temperature.

Temperature difference between shaft and bearing was 90C, so it slipped over with no force at all, all the way down.

Here's a picture how I measured the axial play. 5 m was the call. Indicator is a Mahr with 0.5 m per division. The hammer was needed to set the bearing against the nut. By just adjusting with the nut, the bearing jumped about 1/100 mm and then the play was out of specs again:
http://img842.imageshack.us/img842/2159/sp1a.jpg

Yes, that puppy is about 450 mm long! Has an type 40 cone.

The taper was quite abused, so I asked to remove as little as possible and leave some spots unground. Otherwise, the hydraulic clamp would shift too much:
http://img14.imageshack.us/img14/6861/sp3q.jpg

As the mill has two absolutely identical spindles (horizontal and vertical) but I only got one new pair of tapered roller bearings, I had to rescue one pair of bearings. The second not-so-good-spindle will be the horizontal one. Two bearings (out of the 4) were ruined. One had a severe pitting in a single spot of a single roller. The other one started microscopic pitting at all cones.
Here is one of the good ones disassembled and after cleaning:
http://img522.imageshack.us/img522/5829/sp4d.jpg

As this bearing has no outer ring, the rollers directly roll in the quill's housing. Due to the pitting that ocured, that race way had to be reground too.

The second spindle is out for re-grinding and will be assembled with the spare parts.
I was told, that a new spindle costs 10000 . Clearly NOT an option!

Will let run it through the RPM and temperature cycles today and enjoy a like-new-spindle with a beer or two. :D


Nick

wierdscience
11-27-2010, 09:24 AM
Nick what mill has a quill with no outer bearing race?I want to know so I can avoid buying one;)

MuellerNick
11-27-2010, 09:32 AM
Nick what mill has a quill with no outer bearing race?I want to know so I can avoid buying one


The bearing itself has no outer ring. Instead, it runs directly on the quill's tapered bore. They wanted to make it slim I think.
I have no picture, but if I don't forget it, I can make one as soon as the second spindle comes back from grinding.
After 4000 hours, it needs a service. Disassemble, clean, regrease and adjustment.
The tapered rollers are bored and you have to put the grease in there. Works as a reservoir.


Nick

JoeLee
11-27-2010, 09:34 AM
Nick, I take it you made note as to any markings on the bearing races as opposed to markings on the spindle for proper run out.
A race ground into the spindle scares me also.........

JL.................

MuellerNick
11-27-2010, 09:47 AM
Nick, I take it you made note as to any markings on the bearing races as opposed to markings on the spindle for proper run out.


No. The inner ring has no high spot marking. The shaft was reground with a steady rest running on the bearing's seat (bearing removed). So the shaft should have zero runout. Only runout remaining is from the bearing, a "Garmet High Precision".


A race ground into the spindle scares me also.........


That's for better earings through service. :D
Disregarding for that, it is OK. But even more expensive.


Nick

vpt
11-27-2010, 09:57 AM
That reground spindle end looks great! Are you sure there isn't a race hidden in the quill? It may look like one piece but is really a pressed in race.

JoeLee
11-27-2010, 10:49 AM
That reground spindle end looks great! Are you sure there isn't a race hidden in the quill? It may look like one piece but is really a pressed in race.

If there were a (hidden race) I think there would be some kind of dead giv away such as a slight difference in the color of the steel or an inner edge with a slight radius or break, markings on the edge of the race, etc. I've run across stuff like that in the past.

JL................

JoeLee
11-27-2010, 10:55 AM
Nick, just wondering........... are you mixing and matching rollers from other bearings????????? That could lead to premature wear.
I never heard of that brand bearing.......... it resembles a Timkin roller bearing which my Clausing 5900 uses for the spindle, but they have outer races.

JL....................

lazlo
11-27-2010, 11:03 AM
I never heard of that brand bearing.......... it resembles a Timkin roller bearing which my Clausing 5900 uses for the spindle, but they have outer races.

Gamet is a proprietary English tapered roller bearing. Their schtick is hollow rollers. They're now made to order, and thousands of dollars/set.

But the Gamet bearings I've seen have cups and cones, just like a conventional tapered roller bearing.

A.K. Boomer
11-27-2010, 11:05 AM
The taper was quite abused,
http://img14.imageshack.us/img14/6861/sp3q.jpg





Boy I'll say ---- do you own any tool holders without drive flanges?
It's like something spun in that dawg....:eek:

JoeLee
11-27-2010, 11:23 AM
Looking at the damage that was too deep to clean up, I think your lucky it came out as well as it did. Too much removal on a taper could result in the mating piece seating too far in. I've seen it before in Bridgeport R8's.

JL...........................

MuellerNick
11-27-2010, 11:32 AM
Boy I'll say ---- do you own any tool holders without drive flanges?


That wasn't me. I removed the stones for assembly. They shure will come back in. :)
It looks like someone "repaired" it with a die-grinder. Freehand! You can see an extra cone right at the end that doesn't belong there. At the very end, directly at the face, there is a chamfer the grinder made. Just maybe 2mm wide to remove the sharp corner.
Also, the cone's seat is split. Means the middle has a recess. You see that at the lower end of the reground surface.

On one spindle, I had a runout of 0.02 mm, on the other 0.025 mm.


Nick, just wondering........... are you mixing and matching rollers from other bearings????????? That could lead to premature wear.


No. Rollers and inner ring are NOT mixed. The outer ring doesn't exist. All bearings were disassembled, cleaned and re-assembled separately. So no chance to mix any parts.

Also, if just one single roller had a pitting, the ring is ruined. -> bin! There is no use in trying to rescue it.

If you have doubts about recycling the used but good (or undamaged) bearings, you are right. But they will go into the horizontal spindle that I will use very seldom.


could result in the mating piece seating too far in.

Right. So that's what I asked for. He also faced it off to get the right distance back. I'm very happy with what he did.
I'm also happy that it was too big for my cylindrical grinder. I'm not at all as good as the one who made it.
It took him 5 hours. Most of that was setting things up (as always).

Edit:
I also got the original drawing, so he/we knew how deep the hardness went. He didn't have to grind through the hard layer.


Nick

lazlo
11-27-2010, 11:33 AM
Nick, what machine is this from? Have you posted pictures of it before?

MuellerNick
11-27-2010, 12:01 PM
It is a MAHO type MH 700 C.
I doubt I have posted pictures, and I don't have good ones at hand.
I bought that mill almost two years ago with a broken CNC. I replaced that with EMC2 and a bunch of custom-made boards. The control is running and works, but it ain't finished. That conversion took me longer than I imagined in my worst nightmares. :mad:

The mill was built '82. Weights something like 3.3 tons, has 700 mm in X, 500 mm in Y and 450 mm in Z. The DC(!) motor for the spindle has 8 kW. The biggest servo for Z weights 84 kg. :eek:
Spindle RPM is 20 .. 3100 with 4 gears. But I think I'll change the max speed to 4000 RPM when I see that it is running nice and doesn't get too hot.


Nick

MuellerNick
11-27-2010, 04:33 PM
Can't complain! :D
Spindle run in. Temperature at 2000 RPM is 35 C. Maximum allowed would be 50 C. Gonna remove the whole spindle again tomorrow and add the hydraulics and recheck the play.
Runout is 2..3 m. Not to shabby. ;)

But now, I do have a puzzle for you!
There is a seal in front of the lower bearing. It is contact-less, because a contact seal generates a lot of heat. One was ruined, so I cut it apart, because I don't know how it is made. That didn't help.
http://img404.imageshack.us/img404/5496/sp501.jpg
There is an inner and an outer ring. You can't disassemble them without cutting at least one ring. The outer ring seems to be out of aluminium, the inner ring is steel. They do have a little axial play to avoid contact. The play is maybe 0.3 mm. There is no seam whatsoever.

How are they made?
Al cast over the steel ring and then rolled to increase the Al rings diameter?

Prost!
Nick

lazlo
11-27-2010, 05:02 PM
It is a MAHO type MH 700 C.

Wow, good pedigree! If they used a cup-less roller bearing design, they must have known what they were doing!

MuellerNick
11-27-2010, 05:21 PM
they must have known what they were doing!

Well, ... er ... the design isn't that much state of the art. Just two tapered bearings in O-arrangement. This really isn't stable over a temperature range. The outside is force cooled, the shaft gets warm -> play increases.

I talked with a friend who is construction engineer at Spinner (http://www.spinner-wzm.de/index2.php?lang=en) (lathes and mills). He said, that their high precision lathe spindle (8000 RPM) expands 0.5 mm when getting warm. They do have a brilliant design to compensate that. I think I can't tell, sounded very patentable to me.


Nick

John Stevenson
11-27-2010, 05:31 PM
I'd have bought a new spindle and not messed about with that crapped up one.

MuellerNick
11-27-2010, 05:35 PM
I'd have bought a new spindle and not messed about with that crapped up one.


I know. You can get new Bridgport spindles at the scrap yard paid per kilo. :D


Nick

John Stevenson
11-27-2010, 05:38 PM
Don't need a Bridgeport one but if I did I'd just but a new one and sod messing about, lifes too short. I can't afford crap.

JoeLee
11-27-2010, 07:35 PM
Nick, I have to guess that the outer ring was either cast babbit or alum. around the inner steel ring or it was rolled down to the appropriate fit. I had some confusion way back when I was rebuilding my lathe. The collet closer that came with it was in need of a new bearing. The bearing had a special housing over it as you can see in the picture. At the time I couldn't figure out how they did that because there was no seam, but then came to realize that the bearing was put into the housing first and then the thin flange was rolled closed over the end enclosing the whole bearing in the housing. It was way too expensive to buy from the mfg. so I improvised, I started to make a housing as you can see in the second picture, since I have no real way to roll form the end I designed it to have a screw on end cap. It was just a $20 Fafnir ball bearing in the original housing. I later ran across a near perfect collet closer with a good bearing and never finished the project. I always love a good mystry.
My shop is full of unfinished projects.

JL......................


http://i911.photobucket.com/albums/ac317/JoeLee09/Royal%20Collet%20Closer/Image001.jpg
http://i911.photobucket.com/albums/ac317/JoeLee09/Royal%20Collet%20Closer/Image002.jpg

MuellerNick
11-28-2010, 06:58 PM
Don't need a Bridgeport one but if I did I'd just but a new one and sod messing about, lifes too short. I can't afford crap.


Maybe you just missed the part where I said that a new spindle costs 10000 . I need two of them. A spindle repair costs 2000 ... 4000 .
I won't tell how much I paid, but it was way less.


Nick

John Stevenson
11-28-2010, 07:22 PM
Think of all the money you have saved NOT buying crap :D

recoilless
11-28-2010, 08:42 PM
Think of all the money you have saved NOT buying crap :D

Made me laugh, in spite of my busted hand(haven't smiled much for last couple of days)