Re: Bearing Lock Nuts on 5/8 in ballscrews

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "mmeyers1111"
<mmeyers1111@y...> wrote:

> Hi folks...
>
> I'm going to turn the ends of some Rockford 5/8 inch ballscrews and
> I was wondering if anybody has experience with bearing lock nuts and
> who could comment on a few questions. The lock nut will be used to
> preload an angular contact bearing with a 12mm = 0.4724 inch inside
> diameter that is mounted inside a bearing block. I've never used
> ballscrews or bearing lock nuts so this is very new to me. I'm doing
> this to the ends of 4 ballscrews. I'll be turning them as R-30 Type
> C ends (http://www.rockfordballscrew.com/semchart.htm).
>
> 1) I noticed that McMaster-Carr (http://www.mcmaster.com) has
> bearing lock nuts in 2 different sizes that would be reasonable for
> a 5/8 in screw (.391"-32 and .469"-32 ). The bearing portion (non-
> threaded portion) of the ballscrew shaft will be turned to 0.4724
> inch to accept a 12mm ID angular contact bearing. So I guess I'm
> thinking that the .469 – 32 TPI threads would be the best choice and
> the bearing should slip over the threaded portion without trouble.
> Does the .469 -32 lock nut sound like the most reasonable choice?
> Yes/no?
>
> 2) I noticed that the McMastrer-Carr bearing lock nut indicates that
> it is `self retaining' and I don't see any bearing lock nut washers
> available for it. Other nuts I've seen seem to require special
> washers. Is it true that that all I need is the lock nut itself and
> that a washer would play no role in making sure it stays `locked'
> Yes/no?
>
> 3) Do bearing lock nuts typically have special threads that require
> a special die to cut them, or can I use my lathe to cut 32 TPI
> threads with the compound rest set at 29.5 degrees? I'm assuming
> this isn't a simple yes/no. Sorry.
>
> 4) Does anybody use a simpler less expensive approach to preloading
> angular contact bearings on a shaft so that I don't have to purchase
> special bearing lock nuts?
>
> 5) Can anybody suggest other/better lock nuts from other suppliers?
>
> Sorry for the length of this folks…
>
> Mike

Hi Mike,

I recently took blowtorch to ballscrew and rough turned an end to see
what happens. Great results.

Since I'm leveling and mounting the lathe, I didn't want to do the
finish work as yet. Finished wiring the treadmill motor/controller on
the lathe and set the back of the chip pan last week...

Anyway, I was thinking of putting angular contact bearings into a
single bore with a spacer between them (drawing B) if needed. ( this
would also work for prlain roler bearings for a lightly loaded
machine. ie:low pressure use for axial loads on the bearing.

My concern is that there is little shoulder on the threads to engage
the side of the bearing. Made me think again about welding a section
onto the end of the ballscrew. (3/4 or some such.)

I was also thinking Bellview springs/washers (Kinda like Belleville
but a little more crazy use) to take up the tension. But, I don't
recall the pressure one should maintain for such an application.


Dave