Dumb question on R8 (i think) spindle

The nut on the grizzly had a set screw to retain it. The nut in the Bridgeport video has a bent tablock washer to retain it. The grizzly has neither. I have seen some spanner nuts sold with a self locking design. The grizzly genuine replacement part is seriously back ordered and I do not know if it is self locking or not. Would you all expect there to be some means of locking this nut? Thoughts that come to mind Are a second thin lock nut or a drop of low strength thread locker

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128 and 129 look like spacers for the inner and outer bearing rings? No? If they are spacers, they may be ground to establish preload when the nut is tight.
 
Interesting - my Enco spindle had only one larger spacer which is loose on the spindle shaft and comes into alignment as the bearings are preloaded. I transferred this to the replacement Grizzley spindle. You are right that the Grizzley spindle shows a "large" and "small" spacer which based on the photos, have different ID and OD. Not positive what to make of that.

Part 128 https://www.grizzly.com/parts/grizzly-bearing-spacer-small/p0730129
Part 129 https://www.grizzly.com/parts/grizzly-bearing-spacer-small/p0730129
 
It looks like the nut seats on the inner race? If you tighten this nut with the spacers in place that could be a way to set preload if the spacers are correctly ground.
See post 206 by Ischgl99
"The way these mills are designed, the bearings are spaced apart to increase the rigidity of the spindle, it also helps with heat dissipation. The spacer provides the spacing between the bearings on the outer ring, as well as keeping them parallel. You can adjust how much preload you want by how tight you make the nut against the top bearing inner ring. If there was a spacer on the inner ring as well, it would either have to be precision ground to the amount of preload you wanted for the bearing set, and then you would just tighten it down until it stops and not worry about adjustment, or you would have both spacers the same height but use bearings with the appropriate preload ground into the rings. It’s a lot cheaper to do it with a single spacer and manually adjust the correct preload."

Grizzly seems to have 2 spacers. You may want to go with one spacer and try to set the preload but I think you will need some way to fix the nut in place.
 
r-mm said:
Thanks. I suppose I should have ordered a locking nut from McMaster such as: https://www.mcmaster.com/6343K39/
Instead of the all metal one I purchased which is called a lock nut but I don't see any provisions for it to lock - https://www.amazon.com/Winco-Bearin...km-7+km+bearing+lock+nut,industrial,93&sr=1-1
Click to expand...
The Amazon and McMaster linked ones relies on a lock washer link in the following link to keep it from unscrewing. Those are considered industrial locknuts. There will be a keyway slot through the threads for the lock washer to prevent rotation relative to the spindle, and then one of the tabs gets bent up into a slot in the lock washer. That method requires access to it bend it, which is usually not available in a spindle.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com

For a milling machine, you will want a precision locknut, the face that presses against the bearing will have a tighter tolerance to the threads for perpendicularity, and there will be a set screw that presses against the threads, or has some sort of provision for something to press against the threads to make it difficult to unscrew. These often also have shallow holes that allow you to stick a pin in it to help adjusting the preload while installed in the machine. If you have a locknut with a through threaded hole, make sure your set screw is either brass tipped, or there is a soft metal slug between the spindle threads and set screw so you don’t damage the spindle threads. Here is an example of what SKF offers.

SKF

www.skf.com www.skf.com
 
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