tapered roller bearings

[henryr]

I’ve spent hours over the last three days looking for tapered roller bearings with tighter than normal tolerances and didn’t find any. Timken and SKF sites list tapered roller bearings with standard and tighter tolerances but I couldn’t find any. So I spoke with their technical support people and was told that, while they list them with tighter tolerances they don’t make them but if someone ordered 1000 they might make them. I’ve also searched many bearing distributor sites, in the US, UK and Japan and even sent emails to a few and got replies that they only have standard class K or class 0 tolerances. Does anyone know where to get tapered roller bearings with tighter tolerances?
Thanks,
henryr

[Bented]

Why tapered rollers?
Look at angular contact sets with high precision such as are often used as spindle bearings.

[henryr]

My Prazi SD300 uses tapered roller bearings. If another type of bearing would work I would consider it.

[henryr]

I looked on Timken and SKF site and angular contact bearing are not made in the sizes I need.

[Rich Carlstedt]

Your out of luck. had that situation many years ago. and we waited 6 months before they ran that speck .
One thing you can try is not the web, but calling bearing "Distributors " in large cities or manufacturing areas.
I have no idea of where you live, so I am talking about Chicago or Detroit for example.
We did that and asked them who bought the particular bearing from them and maybe they have them on the shelf and we would pay extra.
In our case, they found the bearings at a company, but the company did not want to part with their stock

If you know the machine they go into, try used machinery dealers who handle that machine.. they sometimes stock parts.
Lots and lots of phone calls...good luck
Rich

[MattiJ]

Honestly I think it won't be worth a trouble. STD bearing from one of the reputable manufacturers is probably "good enough"
SKF, INA, NTN, FAG..

Beware, lots of counterfeit bearings "out there" so whatever you buy I'd look for official distributor or at least reputable looking shop.

[Sparky_NY]

My Prazi SD300 uses tapered roller bearings. If another type of bearing would work I would consider it.

The original bearings were more than likely not a precision grade. Manufacturers throw around terms like "precision bearings" all the time, one could argue that off the shelf standard bearings are "precision". Years ago, I replaced the tapered roller bearings on a Jet lathe spindle, there were no markings on the bearings to signify a precision grade. I could see no difference in performance with the standard grade bearings I used.

A good name brand bearing is probably as good as you will find and should be quite suitable for a lathe of that class.

[Sparky_NY]

Why tapered rollers?
Look at angular contact sets with high precision such as are often used as spindle bearings.

The tapered roller bearing are much more rigid and have much higher load ratings. Many lathes use tapered rollers in their spindles and they work quite well. A very common upgrade on the 7X lathes is to replace the ball bearings with tapered roller bearings for MUCH better performance, its probably the most common upgrade.

Most table top type import mills also use tapered roller bearings and have good performance.

[David Powell]

The tapered roller bearings fitted to Atlas milling machines are also used in Fiat 500 car back axlesof the 1950s. Regards David Powell,

[old mart]

I fitted SKF to the lower and Timken to the upper spindle positions of the R8 modification for the Tom Senior light vertical. They are just standard off the shelf and the spindle runs 0.0001"tir which is good enough for me. Actually, I was very pleased. The top bearing runs on the splined half.

[chipmaker4130]

. . .there were no markings on the bearings to signify a precision grade. . .

Sometimes the only mark on a precision tapered roller brg is a tiny dot on the edge of the race.

[Sparky_NY]

Sometimes the only mark on a precision tapered roller brg is a tiny dot on the edge of the race.

Yes but precision grade tapered roller bearings are e extremely rare breed as the OP is finding out. My bet is that people are assuming they are precision grades when in fact they are standard ones. Its worth noting that with modern cnc equipment precision tolerances/fits/finishes have gotten pretty routine, a common grade bearing today may well be as precise as a precision of yesterday. Look at Old Mart's post, .0001 TIR with standard bearings.

[old mart]

You would expect good results with high quality bearings, the big names have very good inspection standards. Buy from a proper bearing stockist for peace of mind. I would have found 0.005" tir to be acceptable for the mill spindle. That lower half of the spindle is a spare for one of the Seig Chinese mills, and I was very pleased to find that the bore and od had no measurable eccentricity.

[MattiJ]

Yes but precision grade tapered roller bearings are e extremely rare breed as the OP is finding out. My bet is that people are assuming they are precision grades when in fact they are standard ones. Its worth noting that with modern cnc equipment precision tolerances/fits/finishes have gotten pretty routine, a common grade bearing today may well be as precise as a precision of yesterday. Look at Old Mart's post, .0001 TIR with standard bearings.

As an example older Weiler (highly regarded German lathe brand) was calling for precision spindle bearings. After digging some old references it turns out that the designation is same as ABEC-5 today.
All SKF ball bearings have been manufactured to ABEC-5 runout for something like last 30 years so sourcing replacement was rather easy.

[Ringo]

I recently put new bearings in my Millrite, it called for higher class bearings and I found them. Timken had them listed, and of course the price goes up by cubic dollars every step class.