Re: [CAD_CAM_EDM_DRO] Re: Ball Screw Options

natchamp_87 wrote:

>Thanks for the info Jon, It isn't a round ram. I asked what the y
>travel was b4 I purchased. You can see it at:
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785720326&rd=1
>
>

Hmm, a high speed model. I think you may find you want a J head upgrade
at some time.
The small, flimsy spindle on the M is a problem with heavier work. but,
the high speed is
an advantage for small work.

>So it looks like I will be installing real ball screws. I took a look
>at Reidtools, as per a previous message by Jim. Why couldn't I use
>the AR-315 ball nut? It is on page 366 here:
>http://www.reidtool.com/Pdf/category/power.pdf
>You can jump right to the page instead of "pgdn". It doesn't say
>what tpi they are. I could use 2 of them to do the preload. They
>are only $45 bucks. The screws are only $88 for a 4' length. They
>arn't double circuit, is that a must?
>

The problem with low accuracy rolled screws is that there may be pitch
variations. This means you
need a spring-like element between the two nuts. (It doesn't need much
spring, you want something
like 1000 Lbs axial load on the nuts.) Obviously, the nuts have to
match the screw pitch.

> Is there any significance to
>right-hand or left-hand thread? I'm assuming it doesn't because the
>motors can be programed to turn either direction.
>

Right, unless you want manual overide, who cares what hand the thread is.

> Also, since the
>screws are hardened, how hard is it going to be to turn the ends for
>the bearings and motor/encoder shafting?
>

You'll need C-6 carbide tools, then you can cut through the hardening
pretty easily. If you still
have a problem, you can torch the ends lightly to soften them. The nuts
won't get all the way
to the end, so it doesn't matter. And, any warpage will be at the ends,
which are then going to
be turned down.

>Is "angular bearing" a type of bearing that means it can take axial
>loading? If not, could splain that a little more? Thanks a bunch.
>
>

Angular contact bearings are designed to take axial loads. Some radial
bearings will take axial
loads, some will come apart.

Jon