Re: [CAD_CAM_EDM_DRO] Dumb question on the drilling of holes

If you end mill is not ground for center cutting you will need a pilot hole.


At 11:15 PM 10/22/02 -0700, you wrote:

>Jon,
> Thanks for your input. My spindle is tight, so are the bearings, and
>the 1/4" end mill is held in a pretty new collet. When I tried plunging the
>end mill through an 1/8" wall aluminum extrusion, I could feel resistance on
>the quill. Then I realized that, as the cut started, the chips built up
>between the end flutes, and caused some galling and hole distortion, since
>the chips, unlike a fluted drill which gets rid of it's own chips, had no
>place to go. I'll try to do some testing, and document my findings, to
>arrive at the best solution.
>
>Marv Frankel
>Los Angeles
>
>----- Original Message -----
>From: "Jon Elson" <elson@...>
>To: <CAD_CAM_EDM_DRO@yahoogroups.com>
>Sent: Tuesday, October 22, 2002 10:25 PM
>Subject: Re: [CAD_CAM_EDM_DRO] Dumb question on the drilling of holes
>
>
> >
> >
> > Marv Frankel wrote:
> >
> > >Tim,
> > > I'm pretty familiar with reaming holes for proper fit, but the
>holes
> > >I'm talking about, are sometimes so misshapen, they almost look
>triangular.
> > >They're 1/4" holes, and I've even tried cutting them through with an end
> > >mill, and that wasn't great either.
> > >
> > >
> > A properly sharpened drill bit will not do this except on very thin
> > sheet. A dull drill bit can
> > sure do things like this. End mills generally make VERY round and
> > smooth holes, even when
> > plunged. If you are trying to plunge an HSS end mill into tool steel,
> > however, that could cause
> > deflection. Are you sure your spindle is solid? A bad spindle bearing
> > or loose quill could
> > do this. I hope you aren't holding a 1/4" end mill in a Jacob's chuck.
> > That really won't work,
> > and isn't safe, either!
> >
> > Jon
> >
> >
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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
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>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
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>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/