B/S vs. acme was Re: What makes a machine CNC ready?

Lester,

I'm not sure I get your point?

But here's a link for "small" acme screws. (ballscrews as well. Like
I said, the mfrs. seem to understand that each has its place, and
carry/provide both...)

http://www.nookindustries.com/acme/AcmeCatalog.cfm

Hope this helps,

Ballendo

P.S. Simple physics favors acme screws, load wise. For a given size,
the full-contact mating surface area is MUCH larger with Acme than
the ball contact points(ovals actually) in a B/S assy.

FWIW, the same is true for linear bearings used in CNC axes. That's
why the heaviest duty VMC's have box ways, not the linear bearings
now often seen on lower-end models.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Lester Caine <lester@...>
wrote:

>
> ballendo wrote:
>
> >>In CCED, R Rogers <rogersmach@> wrote:
> >>/// What are the advantages of acme or 60 degree screws over
> >>ballscrews in a CNC application?
> >
> > First, let me ask you a few questions:
> > If all cnc machines would be better using ballscrews, why aren't
> > they all using ballscrews???
> > Why do screw manufactureres sell both types?
> > Why do CNC machines come with both types?
> >
> > Let's list a few reasons:
> > 1) Acme screws have better load capability for their size.
>
> I think there needs to be a little expansion on the starting

point,

> since I think one would not expect to see 'small' Acme screws?
> So perhaps we need to expand the original question and ask "What

size".

> At say 6mm OD ISO Metric Trapezoidal threads are a bit small but

a V

> screw or ball screw are more practical? Move to 10mm and all parts

start

> appearing on the catalogue pages. Or am I barning up the wrong

tree?

>
> Certainly looking for off the shelf products 10mm seems to be a

switch

> point over here.
>
> --
> Lester Caine - G8HFL
> -----------------------------
> L.S.Caine Electronic Services - http://home.lsces.co.uk
> Model Engineers Digital Workshop -
> http://home.lsces.co.uk/ModelEngineersDigitalWorkshop/
> Treasurer - Firebird Foundation Inc. -

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>