Milling machine motor bearing

[RRMBKParticipant @rrmbk]

I have a BBMTCO vertical mill – virtually identical to a Warco ZX16. The motor drive end bearing is running in the alloy housing. I have previously stripped it, centre popped the inside of the housing and re fitted with loctite bearing retainer fluid. noise gone all lovely and quiet. This lasted quite a while but after a recent session of heavy milling the motor got warm – not excessively so, and the bearing started running again presumably due to expansion in the alloy end casing. I doubt I will have any success with loctite a second time around . The motor has a specific spacing 4 bolt mounting to fit the eccentric that tensions the belt. Anybody got any thoughts how to solve this one please? Or if I do have to get a new motor where is the best deal to be had. Motor plate says Type JY 7134 – 370W -220V – 1400 rpm.

PS – wont be able to respond for a while as I will be out of e. mail contact for the next week or so.

Many thanks

BK.

[RRMBKParticipant @rrmbk]

Loose bearing housing.

[Neil WyattModerator @neilwyatt]

Why not replace with a high-temperature Loctite?

Ideally an internal knurl is what you want, but unlikely to be practical.

Roughing the internal surface of the bearing house would help, or you could wrap the bearing in a shim.

Neil

[Tim StevensParticipant @timstevens64731]

One answer might be to fit a steel shell to hold the bearing – but there might not be enough 'spare' metal to permit this. (And of course it is difficult to machine a part for a mill if the mill itself is out of order). Or perhaps a top-hat bush so that the flange (brim) can be held down by a ring of small screws, trapping the bearing so it cannot fidget. Just don't block the ventilation slots.

There are lots of alternative ideas for drive systems, better, cleverer motors, etc, so I will leave it to thers to explain, and perhaps offer links to previous comments.

Regards, Tim

[Max ToleranceParticipant @maxtolerance69251]

You don't state which end bearing you fitted. Normally on a motor the shaft end bearing if fixed and locked in place usually with an end cap, or on some cheaper versions a circlip. The other end of the armature is allowed end clearance to allow expansion in the armature shaft during running and is normally fitted with a wavy type spring washer.

If the front bearing housing has worn then you need to make a better repair than centre punched dots and lock tight especially given that the housing will likely be some type of die cast aluminium / zinc type metal. The best way is to bore out the housing true to the flange and fit a bush to give total support to the bearing outer ring. There are available ready made bearing shims made to suit popular sizes of metric bearings. These are made of steel and are a top hat section complete ring (not split or joined) normally about .25mm thick. maybe one of these would work for you. I don't know where they are sold but your local bearing supplier should be able to point you in the right direction.

[JasonBModerator @jasonb]

As these are hobby machines they benifit from a rest every so often to let them cool, that combined with some high temp 648 Loctite would be a simple solution.

[David JuppParticipant @davidjupp51506]

Stainless steel Tolerance Ring – one possible supplier

[HopperParticipant @hopper]

And while you are there, replace the cheapo Chinese motor bearings (plural) with good quality brand name bearings such as SKF etc. The root cause of the problem may well be a bearing that is getting sticky when under load or heated up. No point in just fixing the symptoms and having the same happen again if the old bearing locks up.

[Nick_GParticipant @nick_g]

Posted by Hopper on 26/06/2017 10:46:27:

And while you are there, replace the cheapo Chinese motor bearings (plural) with good quality brand name bearings such as SKF etc. The root cause of the problem may well be a bearing that is getting sticky when under load or heated up. No point in just fixing the symptoms and having the same happen again if the old bearing locks up.

.

What that man said.

Nick

[Ian S CParticipant @iansc]

The Loctite bearing grade will fill a fairly large gap, can't remember how much, but it suprised me. If the gap is too big, a strip of shim metal in the gap, and the Loctite to hold every thing together. The retainer grades need a smaller gap to get the strength. Yes get a good grade bearing.

Ian S C

[Russell EberhardtParticipant @russelleberhardt48058]

Loctite 641 is usually recommended for fitting bearings and will cope with gaps up to 0.25 mm although with such gaps it should be left to cure for two or three days. Yes, replace the bearings. They probably became loose in the first place due to stiffness.

Russell

[Ian S CParticipant @iansc]

I found out about Loctite bearing retainer when the top beearing on my Rexon vertical mill spun in it's housing, i measured it up and found it was .015 over size, I refitted with a new bearing.

ian S C

[mark costello 1Participant @markcostello1]

If You wonder about the durability of Loctite, I used some to hold a wobbly fly wheel on a chain saw. It worked for about 20 years until the saw wore out around it and was scrapped.

[RRMBKParticipant @rrmbk]

Just back in digital contact so a big thank you to everyone for your help and responses.

Once I stripped the motor, I found out that the noise, which I thought was the same drive end bearing come loose for a second time; was actually coming from the other ( fan end) bearing and the one I had repaired was nice and tight in its housing without any movement at all. I decided not to disturb this one but took your advice and replaced the loose fan bearing with a kosher new one with loctite 641. All gone back together and quiet as a mouse so far! I think the long term solution is to look at a 3 ph motor and inverter drive setup. Not straightforward on these due to the 4 bolt face mounting and the pulley being held on the shaft by a central bolt in the output shaft. But should be doable.

Once again thanks for the help and advice.

Keep well all.

BK.

[John ReeseParticipant @johnreese12848]

Posted by David Jupp on 26/06/2017 08:39:12:

Stainless steel Tolerance Ring – one possible supplier

Darn. Beat me to it. If you have enough metal in the bearing housing to allow for the larger diameter needed this would be a great way to go.

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