Re: Re: Re: New Acme or similar--recommendations?

On 23 Aug 2008 17:02:35 GMT, D Murphy
<spamto154@xxxxxxxxxxx> wrote:

Gerald Abrahamson <jerryab@xxxxxxxx> wrote in
news:q1pua45s0jd17245s9hiirgfa12sq9hq18@xxxxxxx:

None of the screw machine shops mentioned a rotary broach
anywhere, nor did they say they could do it (make the spline
on the machine). They stated they could *not* make the
spline on the machine. Possibly, they did not want to do the
job--so they effectively "no bid" it.

It depends on the spline. If it is an involute spline with any kind of
tolerance then rotary broaching is out of the question.

On a CNC Lathe or Swiss you might be able to hob it right in the machine.

Another option is to use this "shaving" cutter from Schwanog. You take five
passes on the first tooth, then one pass on each subsequent tooth. This
system works very well.

<http://www.schwanog.com/produkte/produkt.php?id=75
&PHPSESSID=e5479a18dd077b76156c52504b336ba7>

or <http://tinyurl.com/5dyv4o>

If your parts are high volume you would be better off to design the spline
in such a way that it can be rolled as a secondary operation. Rolling is by
far the least expensive way to manufacture a spline.

We are talking about 60 splines in a 360 degree circle, each
6-degree spline identical (center-to-center or
valley-to-valley). The front of the spline is open (no
material blocks access). The problem is the spline is .030"
in front of a feature that is a "wall" that can't be moved.

The Schwanog looks good (as long as it does not require more
than say .025" clearance behind the cut area), but is it a
time hog? Adding seconds to the total cycle time is no big
deal, but adding a minute (or more) would be a killer.
Initially, the idea was to broach in the CNC. Then it was
changed to rotary broach (while still in the CNC).

I think getting a complete part out of an initial--but more
complex--setup on one machine will be cheaper (overall) than
doing a finishing secondary operation on a second machine. I
am thinking runs of 5k to 10k at at time, for now.
.