Re: [CAD_CAM_EDM_DRO] Re: 5C collet closer drawbar threading problem

I knew this question was going to come up...

The hole through the spindle is 19/16" with an internal 1 5/8" thread
at the end. The base of the collet closer attaches to the outboard end
of the spindle with that thread.

The outside thread on a 5C collet is 1.25" x 20 TPI. If we used that
for the drawbar, there isn't enough size between an external 1.25" x 20
TPI and internal 1.612"x 16 TPI to get 2 tubes in there, ie one for the
base of the closer and another for the drawbar. Using the internal
drawbar we still get a 0.760" through hole. I'm not worried about the
internal thread because the Machinery Handbook shows it as a standard
item on 5C collets and we've got a set that have the internal thread.

We considered mounting the base of the collet closer to the outside of
the spindle, but didn't want some of the hassles associated with that
design.

Kim

On Tue, 2003-07-08 at 15:20, doug98105 wrote:
> Kim,
>
> Just curious.... why are you using the collet's internal threads for
> the drawbar? 5C collets are made to use the external thread for
> closers. Not all 5C collets have the internal thread.
>
> Doug
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Kim Lux <lux@d...> wrote:
> > We just solved this problem.
> >
> > We cut the thread deeper and cleaned up the internal collet
> threads.
> > The collet can now be made to run true on the threads.
> >
> > Kim
> >
> >
> >
> > On Tue, 2003-07-08 at 12:39, Kim Lux wrote:
> > > We are building an air operated 5C collet closer.
> > >
> > > The drawbar we are making is machined from a piece of seamless
> > > mechanical tubing. We've got it adjusted for zero runout.
> > >
> > > We are cutting a 1.044" OD x 24 TPI thread on the outside of a
> 1.250"
> > > piece of tubing turned down to 1.030" This will pull on the
> internal
> > > thread of the collet to close it in the chuck.
> > >
> > > We've threaded two of these drawbars now and both times the
> collet has
> > > significant runout when threaded to the drawbar. Why ? The
> thread
> > > seems to be high quality. The collet seems to be OK. The
> drawbar runs
> > > true. Why does the collet have runout when screwed on ?
> > >
> > > What is the solution to this problem ?
> > >
> > > I'm tempted to cut the thread loose so that the collet can
> center itself
> > > in the chuck irrespective of the drawbar position.
> > >
> > > Any help would be appreciated. Thanks.
> > >
> > >
> > >
> > > Kim Lux <lux@d...>
> > >
> > > Addresses:
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> > --
> > Kim Lux <lux@d...>
>
>
> Addresses:
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>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
--
Kim Lux <lux@...>