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. your answers might well lie in an article by Dick Stephen
in issue 103 of Model Engineers workshop. Basically what you put on
the end of a ball screw has to be absolutely concentric with the
shaft, or it will not run!. Ball screw shafts are as as hard as
hades to machine as they are case hardened, firms supplying them
will anneal the end for you, but at a cost, and ball screws cost too
much for me to dare take a blowlamp to them. What Dick advocates is
drilling out the centre of the shaft(which is soft), and gluing in a
spigot of user friendly EN1A leaded steel. The shaft of that steel
then being machined / threaded, and whatever else you want to do.
I have done this on my conversion of an X3 mill and it works. What
is more, if I can do it anyone can.
John