New mill, what's considered normal vibration?

[Bob Korves]

The standard bearings are as you say 'of a class' Z or ZZ for the gearbox so decent -2RS ones are worth the money just for peace of mind.

Z is single shielded, ZZ is double shielded (metal shields), -2RS is double sealed (rubber seals). That nomenclature says nothing about accuracy class.

 

[coffmajt]

Until you get your new machine fastened down to some mass, you will have difficulties knowing where vibration is coming from and it can cause a number of problems. A heavy base with cross braces will help if you can do it. Also unless your quill is locked down, even hand pressure can cause movements a test indicator will easily register but may be meaningless to achieving a satisfactory finish on your parts == Jack

 

[NortonDommi]

That nomenclature says nothing about accuracy class.

Yep! As Mikey mentioned the bearings are of a class but what class is doubtful and debateable. They work but when the time comes there are much higher quality with closer tolerances that can be fitted and which will make a noticeable improvement to the machine. I also don't think shielded bearings at the top of the gearbox are a good idea as they do not get much in the way of splash lubrication and the stock grease is meager and again of unknown quality.
If something works and does the job I believe in running it until it needs work and by then hopefully the notebook has a list of modifications to do at the same time and most of the parts are sitting ready to go. I can't find the safe place where I put the piece of paper with the bearing numbers on it so I can't say what class they are meant to be.
This is on another site but has one of the best write-ups on these that I have found: http://www.metalworkingfun.com/showthread.php?tid=405
denkenz, I hope you got it at a good price and I'm sure you will be happy. They are noisier than belt drive and some people convert them.
CNC Cookbook has some good info too: https://www.cnccookbook.com/cnc-projects/ Scroll down to the CNC retrofit page there is articles on Epoxy Granite fill etc.

 

[mikey]

I can't find the safe place where I put the piece of paper with the bearing numbers on it so I can't say what class they are meant to be.

Cracked me up! I put so many lists in "safe" places that I cannot find. I even took to putting my lists on the computer but I can't find the file they're in when I need them. I usually find them when I'm looking for something else and it is long past the time when they were needed. Getting old ain't for sissies!

By the way, I suggest at least a class P5/ABEC 5 for a spindle. There are more accurate classes but the spindle on an Asian machine is just barely capable of the accuracy a P5 bearing provides so I would stop there.

 

[Mark Needham]

Yep, bet your spindle bearings just need a nip up. RF30, mine was the same.

 

[BaronJ]

Hi Guys,

I mentioned in another thread that from new my mill had a rhythmic noise that varied with speed. It also had a plastic gear in the train. It was some time later that I found out that the gear was slightly off center and presumably causing the noise.

I made and replaced it with a steel gear and the noise went away.

 

[magicniner]

I have a Rong Fu 400 DVM Mill Drill, it's like a giant drill press on steroids, and it runs as smooth as silk from 150rpm right through to 3000rpm.
None of my mills have noticeable vibration when running, bolted down or not.