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View Full Version : How do I tell if a tapered roller bearing is good?



Spookydad
01-31-2012, 02:01 PM
I am replacing the bearings in the headstock of my Grizzly G0602 lathe. Grizzly sent me replacement bearings since the lathe is only 6 weeks old.

I have some concerns with the replacement bearings. I should have checked them before I tore apart the headstock. If I hold the bearing with my fingers inside the inner ring and spin the bearing with my other hand from the top, (with the outer ring put on top), the one bearing spins freely and quietly. The other one has a distinct vibration, is noisy, and won't spin after I let go.

The bearing might have a differing amount of oil in it so the rollers might be sticking before they move.

Should I clean out the bearings and compare them clean? If so, what should I clean it with?

It seems to me that if it vibrates at 10 rpm, it is going to be noisy at machine speed. Will the load on the bearing quiet it down?

Any help would be appreciated.

Neil

Spookydad
01-31-2012, 05:38 PM
After speaking to Grizzly, they agreed to replace the "replaced" bearing.

I decided to try cleaning the bearing in mineral spirits, as per the tech's approval. The cleaned bearing now spins freely but in cleaning it up, I discovered the two bearings have two different manufacturers. One is marked "HL" and the other is marked "ZWZ". The ZWZ is the one that was running rough. It is clear that there are 2 different tolerances and finish levels. The ZWZ has a rough edge on the inner race and counter-intuitively, a much looser fit. The vibration is gone but the ZWZ is still noisier.

For me, Grizzly's reputation for having a higher quality level among the importers is not really deserved. I found grit and metal shavings in the original bearings when I pulled it apart. My mill is currently down due to a blown circuit board. Both machines were delivered in early December.

Neil

KiddZimaHater
01-31-2012, 06:13 PM
Grizzly's reputation for having a higher quality level among the importers is not really deserved
That's true, they are importers from Tiawan.
However, they DO have actual customer support. And you can talk to an honest-to-goodness human being that's not from the great nation of India.
When I bought my surface grinder the cable was frayed, and they replaced it. And when I called asking about modifying the mag chuck, they were helpful.

Ryobiguy
01-31-2012, 07:01 PM
For me, Grizzly's reputation for having a higher quality level among the importers is not really deserved. I found grit and metal shavings in the original bearings when I pulled it apart.

You should see how bad the other importers are! Maybe Grizzly is better.

But yeah I have to agree that having a non-negative opinion of them is hard when there's grit in the bearings.

PeteM
01-31-2012, 09:16 PM
Grizzly earns faint praise for being a bit better than some other importers of cheap Chinese tools. However, they also charge more for the privilege of ordering from them. And, FWIW, Harbor Freight is almost as good (meaning hit or miss) at having Chinglish manuals, parts lists, and the availability of some parts.

In the past I've had both decent buys (usually simpler stuff, or proven designs made in Taiwan) and poor buys (usually newer machines made in China). Among some problems with a Chinese wood shaper:

- A 120/240 volt motor, but with a power cord with only enough ampacity for 240 volt operation.

- A parts list that called out a part that didn't fit.

- Bad bearings.

- An adjustment screw with seriously buggered threads.

Willy
01-31-2012, 09:42 PM
Well, while the quality of some of the components seem to be an issue, you certainly can't fault Grizzly's customer service. Two sets of bearings sent sight unseen is about as good as one can expect.
Most would probably want you to send back the old bearings in order to for them to be properly inspected before replacement.

However I do agree, you should not have to endure any issues, but then hey, it's a brand new $1000-$1200 lathe, you have to accept the fact that there are going to be some compromises.
At least it's not at the customer service level.;)

Getting back to the bearings. Since you will be doing the spindle bearing replacement yourself, do yourself and the lathe a favor by reading the link to the pdf file I've linked to below to Timken's bearing maintenance manual.
Here is part of the index just give you a bit of a teaser.



Index

Timken - Where You Turn.................................. 5
General bearing handling and inspection................ 9
Internal clearances ......................................... 19
Shaft and housing requirements ........................ 31
Shaft and housing tolerances abma standard 7..... 37
Tapered roller bearings..................................... 55
Spherical roller bearings.................................... 89
Cylindrical roller bearings.................................. 101
Thrust bearings ............................................. 109
.......

http://www.timken.com/en-us/products/Documents/Industrial-Bearing-Maintenance-Manual.pdf


Nothing wrong with not knowing all the facets of bearing maintenance, but you will feel more confident about the results of the spindle bearing replacement procedure when equipped with a little extra knowledge.
Some good info in here that will last you a lifetime.
Have fun.:)

Spookydad
01-31-2012, 11:59 PM
I only commented on the initial quality of the equipment, not the customer service. Customer service has been excellent so far. They have been more than reasonable. The only real complaint is they wanted to send the replacement of the replacement bearing via 3-5 business days shipping. They did decide to send it via second day air after I asked to speak to a manager.

I was annoyed because I foolishly assumed that someone would have taken 30 seconds to spin the first set of replacement bearings before shipping them out. Since the lathe was less than 60 days old, I was well within my rights to ship the entire lathe back for repair.

When I purchased the lathe and mill, I fully expected some rework and a lot of tuning up. I think I have had more grief than most, but within the normal range. It was the fact that I was already fixing a defect and the replacement parts were defective.

On the plus side, customer service shipped me a set of single readout DRO's to offset the amount of work that I had to do on the mill.