[nzben]

I recently replaced my spindle bearings on my Arrow 500 and as any woodbe jack of all trades, master of none would do, I gave the bearings a good caking of NBU15 isoflex grease, I just rubbed it in with my finger. Put it all together - but I find out after the fact, they should only have a tiny amount of grease on them.

What to do? II was thinking abut running the spindle at 200RPM for a couple of days and hopefully the running will spread out the grease?

I've so far only taken the spindle up to 200RPM at this speed the motor is pulling 2% load. How do I know if I've put too much in? Do I keep turning up speed and watch for load to come on, then back it off a bit? I still have yet to do the 'run in' proceedure and am concerned about it due to running at high speed with loads of grease.

Will the grease push itself out running for extended periods at limited speed, or am I just likely to stuff the bearings?

Thx

[mike_Kilroy]

IMO I think it is a bad thing and you need to take it apart and clean them out and start again.... but I dont do the motor repairs here so cannot say for 100%.... I seem to recall that if the grease gets thrown onto the motor windings it will/can cause the varnish to breakdown leading to motor failure, but I am not an expert for sure.

but I would have an idea: call your local motor repair shop and ask them: they should know and probably will give you the free advice.... if they dont then pm me or post again and I will ask our motor repair techs & report back.

[nzben]

I didnt overgrease the motor bearings, just the spindle, I dont want to pull the spindle apart incase I damage bearings doing it. Will the grease get pushed out of the way with a bit of a run in?

[mike_Kilroy]

ooops - thought u meant inside the motor.... I have NO clue in the mechanical spindle itself. sorry. this is a question for Maverick or ....

[RICHARD ZASTROW]

IMHO, you will have to bite the bullet and disassemble the spindle. Usually the spindle bearings are filled less than 20% of available space, with a calibrated hypodermic needle.

Dick Z

[Geof]

While monitoring the temperature of the spindle slowly ramp up the spindle pausing for maybe 10 minutes at every 200 rpm step. Too much grease can cause severe overheating so if the temperature stays low enough that you can hold your hand against the bearing housings it is probably okay.

My guess is that when you start getting up around 1500 to 2000 rpm things will get too warm.

You can damage the bearings by running wih too much grease because the grease gets hot and deteriorates then causes bearing damage.

[underthetire]

IMO you run more of a risk of damaging the bearings trying to get them back out. At this point you need a good thermometer with a thermocouple probe, like a multi meter with one. Get the probe as close to possible of the bearings and slowly run it. When the temp gets to 140 deg and no more than that, back the rpm down till the bearings cool, you may even need to stop the spindle and let it rest. At no point should the temp go over 140. When the spindle is starting to break in, you will see the temp climb, peak, then start to drop back down at every 500 rpm. This is going to take a long time with that much grease. If after fighting it for 2 days and the temp will not break, then tear it down.

[pete from TN]

Having just purchased an arrow 500 I am curious to your whole process. Would you care to elaborate on what you did and how and also if you don't mind where did you get your new bearings and from who for how much? I may be in your shoes at some point so it would be nice to know ahead of time a source and whatever info you can provide. Good luck with this man...peace

Pete

[slowlearner]

Mr Zastrow is telling it like it is. My machine tech told me the Cincinnati spindles must have a certain volume and certain brand of grease. No more or no less. One of the great folks on here will probably chime in with the correct amount before I can find it though. Seems like I recall that there is also a specific tool for installing the bearings as well. That could just be for the TSC heads though. Good luck to you as I do know the approximate value of the bearings are quite expensive.

[RICHARD ZASTROW]

FYI the tech/engineering section of the FAG/Barden machine tool precision bearing catalog has the grease volume for their bearings listed.

The SKF precision bearing catalog engineering lube and maintenance section lists theirs. In that section they specify the amount for A/C sealed bearings. They also state "The quantity of grease fills approximately15% of the free space in the bearing."

The application dictates which grease is used. I tend to use Kluber greases, not cheap stuff.

Hope that helps.

Dick Z

Add: BTW, If space allows I put a lip seal in front of the business end to prevent "stuff" from migrating into the bearings and destroying the integral seals in the bearings. I also put some grease inside the lip seal.

[holbieone]

FYI the tech/engineering section of the FAG/Barden machine tool precision bearing catalog has the grease volume for their bearings listed.

The SKF precision bearing catalog engineering lube and maintenance section lists theirs. In that section they specify the amount for A/C sealed bearings. They also state "The quantity of grease fills approximately15% of the free space in the bearing."

The application dictates which grease is used. I tend to use Kluber greases, not cheap stuff.

Hope that helps.

Dick Z

Add: BTW, If space allows I put a lip seal in front of the business end to prevent "stuff" from migrating into the bearings and destroying the integral seals in the bearings. I also put some grease inside the lip seal.

people get in trouble when they start thinking it's like replacing axle bearings

[sudip]

This link can help you to solve the problem of spindle noise

Abnormal Sound In VMC 400 Spindle And Chattering Mark On Job & Spindle Assembly Of VMC 400 Machine.

[nzben]

Hi Pete, It was an easy job to do, just a few things you have to watch out for.
Basically to ensure it is the spindle being making that racket I pulled the belt off (take top cover off, loosen motor hold down bolts and open access port on bottom side of Z axis then flip belt off. I spun the spindle by hand and there was a really audible rumble. To take the thing apart I pulled off the tool changer ram, then wound off the big lump of steel ontop of the springs, this can be a bit awkward, you have to put something inside the slot of the inner shaft to hold it still. Once thats off, remove all the spring discs, then the platten that they all sit on. Under that there is a nut you'll have to get off, I got a piece of tube and welded four 6mm rods to it sticking out the end - this locates into the nut. On the top of the tube I welded a plate with an M20 nut on it (this is to torque it up on later). Undo the nut. Undo the alan screws beneath the spindle holding the ali cover on and with a soft hammer tap the spindle down making sure you have a catcher below.


Once out pull the bearings off with any method you have available. Open all the boxes of the new bearings and look at the pattern on the side of them. The bearings I used were RHP precision $$$ I believe FAG make some equivalents about 30% cheaper. Make sure the pattern lines up - they are made to go on in a specific order and in a specific direction, the little arrow in the middle on the markings point to the direction of load that bearing will take, the outer marks should all line up to form a pattern. All these marks must line up when you put spindle back in machine.

Putting spindle bearings on I used a tube that fitted on the inner race and tapped the bearings on - note the bearings are pre lubricated DO NOT ADD EXTRA GREASE!!!! To put the spindle back inside I packed up with pieces of wood and used a car jack make sure you do not apply undue load to the bearings when sliding in, jiggle back and forth if needs be to get the spindle sliding up. Easiest to line spindle keyway and all markings on bearings to front of machine. Once jacked up put together in reverse order. Tighten nut on top to 100Nm. And presto all done. Should only take 2-3 hours if nothing gets stuck.

Lets hope you have better luck with yr machine than I've had. Mine is down again spindle drive jst blew up for the second time in as many months - after all it's hunting issues. Am hoping I can get it going soon, the pressure is starting to hurt.

[pete from TN]

Thank you for that thoughtful response. I am curious as to how you indicated the postition of the spindle for toolchange alignment, knowing it has a cogged or timing belt for the drive belt it would seem that you need to make sure it all lines up again once you reinstall it or did you realign it once you are finished? My belts are not the same length and when I looked inside there when I bought the machine one of the belts is much slacker than the other one. The previous owner did say that he thought the spindle was getting a bit louder as time went on but could not say exactly what the cause was. I am HOPING it is the fact that these belts are whining due to improper tightening between the odd sized belts but it could possibly be the bearings but I sure hope not. I have put bearings in several machines before but this being my first VMC I am hoping to stave off that challenge at least for awhile. Looking at it tho it does appear pretty straight forward. You mentioned how you removed the belts but it seemed like you were able to take them off the spindle end without having to remove the power drawbar assembly? Maybe I misread it but when I looked at mine it was not that simple unless I was missing something. I honestly have not had it apart tho....

I have not looked into bearings just yet but It would be nice to get an idea of price if you do not care to tell it here perhaps you could PM me the price you paid and I understand you are apparently outside of the US.... Again thanks for the detailed and informative response..Good luck with your machine and peace.....


Pete

[nzben]

It would be possible to change the bearings without messing up the timing, but I dont think it's a big deal to reset the timing. We get ripped off in NZ for everything s o likely you will be able to find cheaper, I got RHP super precision for around $1000USD motor bearings again were RHP sp and around $400USD.

I havent gone to the effort of setting up timing yet, cos my machine still isnt working, the manual states a method for setting a value to adjust the datum point of the spindle - however I was never able to find my way to the part of the menu system that was stated in the manual, so I'll likely just keep making the belt skip teeth till it lines up again.