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Posted by mark on October 1, 2006, 7:54 pm
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anotherid wrote:
> I need to drill a (fairly) accurate 5mm hole in aluminium to hold a 5mm
> silver steel rod, which will be acting as a pivot. I thought silver
> steel was fairly accurately cut to diameter, so I first drilled a 4.9
> mm hole in the aluminium as I read that drill bits tend to cut
> oversize. The s.s. wouldn't fit, wouldn't even enter the hole. So I
> opened the hole out to 5mm. Still wouldn't enter (and a micrometer
> check on the s.s. showed it as about 4.97 mm). A tiny touch of filing,
> still no fit. In the end I had to use a 5.1mm drill before I could get
> the s.s. through. What gives? Should I invest in a 5mm reamer?
>
> Brendan
>
>
> --
> anotherid
> ------------------------------------------------------------------------
> anotherid's Profile: http://www.rcgroups.com/forums/member.php?u=80362
> View this thread: http://www.rcgroups.com/forums/showthread.php?t=577122
it's possible if you drill the hole too quickly and to drill a spiral
sided helter-skelter hole.
i would say drill it at over 1000 rpm also
you should maybe push the "undersized" 4.8- 4.9 drill bit in and out
of the hole two or three times to clear this up.
All the best.mark
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>Got chance to check my (three) 5.0mm drills tonight. All will enter the
>jaws of a micrometer set to 4.99mm. The silver steel won't. Perhaps
>drills are made to cut undersize these days?
>
>I'll have a go at making a drill bit out of the silver steel. Hey,
>suddenly I'm a toolmaker! :)