On Thu, 19 Sep 2013 14:11:36 -0500, Tim Wescott
wrote:

On Thu, 19 Sep 2013 13:07:56 -0400, Ed Huntress wrote:

On Thu, 19 Sep 2013 08:49:21 -0700 (PDT), PCS
wrote:

On Thursday, September 19, 2013 9:00:34 AM UTC-4, Karl Townsend wrote:

Thanks for the carbide lead. A push button was in my (super cheapo)

price range.





I'm going to modify a turret plate with a 1.375 square by real long

gundrill tool holder. Drill 12", back up and stop. Loosen holder,

slide ahead, restart drilling. I'd use a manual lathe but the hardinge

has a nice flood coolant setup and complete enclosure.



Karl

Ahhh, very clever that.

I would think your push bar problem is less about compression and more
about bowing.

It's so constrained by the bore that there would be no significant
bowing.

Certainly once it's well in -- but if those things work the way I think
they do, getting it started would be critical.

Of course, I'm just extrapolating from the term -- I haven't even hunted
up a YouTube video of the process.

That's a good point. Maybe a guide wold be needed. Also, maybe that's
a good reason for pulling rather than pushing. That's the case with
very long (often over 12 feet), thin broaches. Beyond a certain length
and minimum diameter, they're usually pulled.

But they have guide bushings if they're pushed. With the skinny push
rod talked about here, you'd certainly need some kind of help at the
beginning of the push.

--
Ed Huntress