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Thread: SKF-nut thread specifications
08-31-2005, 10:52 PM #1
I'm working on a new shaft, one end of which requires a No. 5 SKF nut. Measuring the original shaft, the thread OD is 0.966 with 32 tpi.
I'm not familar with the SKF thread series. Are they commonly called something else?
Can anyone provide information or a link about SKF threads?
08-31-2005, 11:21 PM #2
That is an N 05 locknut. You can find the list on the SKF or FAG website in the interactive engineering catalog in the bearing section under bearing accessories. It opens as a separate window without a URL so I can't give a link to the page.
08-31-2005, 11:23 PM #3
09-01-2005, 12:03 AM #4
Thanks for your help. I figured it must be associated with the SKF bearing company, but I never knew they had proprietary thread systems. Well, maybe not proprietary, but certainly unique.
09-01-2005, 03:55 AM #5
Nuts and lockwashers for bearings is not an SKF proprietary product. These locknuts are called American National Specials (unified special or UN.)For everything you ever need to know about bearing locknuts, including the entire series from the small 32 thread per inch to really large nuts go to www.whittet-higgins.com/thrddim.asp?id=1 Their chart gives every bit of information you could dream of for these threads.I program for cutting these threads on machine tool spindles, and their page is posted right on my lathe.
A few companies make this series of nuts, including some companies in China. Avoid the chinese nuts. I buy direct from Whittet-Higgins. They even make all the wrenches needed to install the nuts. Any bearing house will have these and the associated lockwashers.
09-01-2005, 04:18 AM #6
"(Unified special or UN.)"
Not sure about you’re post reply. Are you are referring to "UN" or "UNS"? UNS (A special) is basically a "build your own" thread based on existing specification elements. It's primarily used to create a single source for replacement parts, i.e. the OEM. The thread, when properly specified, ends up being unique, but not recreateable. It is not a specific standard, but more of a license or avenue to create your own, universally recognizable, thread.
09-01-2005, 06:45 AM #7
The lock nut series is not a special to Skf or any other bearing company, Look in Machinery's Hand book under "Lock Nuts for Ball and Roller Bearings. The "N" series is a metric diameter but with an in pitch, the metric series are also metric diameter but with metric pitch.
09-07-2005, 12:18 AM #8
I posted an expired link to the Whittet-Higgins website, in my earlier post. The current address is- www.whittet-higgins.com/thrddim.php?id=1
Still the best chart to have right next to your lathe if making threads for bearing nuts! If you read their informative page on specs for threads, the series used for the bearing lock nuts are identified as UNS. They certainly are repeatable, as all the dimensions are specified.