Re: re:Final leadscrew design - thanks to all (not yet?!?!)

Hugh:

Thanks for attempting to set me straight. I inadvertently uploaded
the wrong drawing for my final design, and therefore had to suffer
some corrections offered by helpful folks. The corret dwg is now in
place in the Files section.

I decided to follow the advice given earlier by Ballendo to simplify
the design to a FIXED mount instead of the previously detailed RIGID
mount. The comments on the preload and the grinding of the bearing
pair to a matched set was a little beyond me. The final FIXED mount
will require simple shimming under the lead nut, at most, to remove
any play, per the Ballendo directions early on, and no step in the
bore. This seems like a good way for me to proceed since my screw
does not operate near the critical speed, and my production skills
for this first machine are not sophistocated.

I have deleted all preliminary layouts from the Files section.

Thanks all,

Ron

--- In CAD_CAM_EDM_DRO@egroups.com, Hugh Currin <currinh@O...> wrote:
> Ron & Ballendo:
>
> >I'm going to repeat the "talk-through" of my earlier post. Pretend
> >you are making this "fixed style" mount as you read. To avoid
> >confusion, I will leave out the description of any mounting holes
for
> >the finished assembly. I am also going to "assume" that a 1.25
> >bearing will fit in a 1.25 bore.(In other words, std.clearances
will
> >be ASSUMED)
>
> (snip)
>
> >If the bearings are "face ground angular contact matched pair",
> >you're done!
> >
> >If you are using the plain radial bearings to save money, you have
> >another step. measure the "end play" in the shaft(while the mount
is
> >assembled) disassemble, and put this "discovered" thickness
of "shim"
> >washers between the bearings. If you have worked carefully, you now
> >have a fixed mount with a thrust capacity equal to ONE bearings
> >RADIAL capacity.(see previous posts)
>
> I just up-loaded a drawing "leadscrew.jpg" that I think depicts this
> mounting. Ballendo, please let me know if this is not what you had
> in mind. If it is OK I hope it clears up some of the confusion.
>
> So, if the bearings are "face ground angular contact pair" they are
> made to be correctly pre-loaded when forced face to face? i.e. no
> slop. How about the "double row ball bearings" or "double row
angular
> contact bearings". Are these built with a pre-load so there is no
slop
> or simply to take more load than a single row? I looked at the SKF
site
> a little but couldn't determine if this were the case. (Well, I
didn't spend
> a lot of time looking. :-) ).
>
> Thanks.
>
> Hugh
> --------------------------------
> Hugh & Denise Currin
> currin@c...
> Klamath Falls, Oregon USA
> 541/884-3023
> --------------------------------