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Posted by Nigel Eaton on October 1, 2006, 7:25 pm
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>
>D-bit?
http://www.geocities.com/Paris/5701/smallpipes/tools.htm
FWIW, I think his description's OTT. I wouldn't bother with the
"swarf-lock" slot, for example - certainly not for a one-off in a
through hole.
--
Nigel
When the only tools you have are a Bridgeport, a CNC Taig Mill, a Colchester
and assorted other stuff, every problem looks like a steam engine.
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Posted by Gary Wooding on October 2, 2006, 4:48 am
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anotherid wrote:
> D-bit?
>
> Brendan
>
>
Its called a D-bit 'cos the cross-section of the cutter is something
like a D. For a through hole, don't bother going to the trouble of
making one by cutting an axial flat as shown on the website; a much
simpler, though just as effective, one can be made by cutting a flat at
an angle. Imagine sawing the end off of a rod of silver steel, but
instead of holding the saw at right-angles to the axis, hold it at a
rather sharp angle so as to cut a thin wedge. The shape of the tool is
then something like...
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Make the angle about 20 degrees - its not critical at all. For aluminium
its not even required to harden the silver steel. After cutting the
wedge off, file the flat so as to make nice sharp edges - that's the
only important part: its the sharp edge that does the work.
In use, treat it like a drill - first drill your undersized hole, then
use the new D-bit.
--
Regards, Gary Wooding
(To reply by email, change feet to foot in my address)
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Posted by anotherid on October 1, 2006, 6:06 pm
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Would a hand reamer hold in a drill chuck? I could then drill the hole
on my
mill and enlarge it with the reamer immediately afterwards. Could
I do this
under power or should I turn the drill chuck by hand for
reaming?
Brendan
--
anotherid
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anotherid's Profile: http://www.rcgroups.com/forums/member.php?u=80362
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Posted by mark on October 1, 2006, 4:04 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
sound like you have a burr on the silver steel
all the best.mark
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Posted by anotherid on October 1, 2006, 6:08 pm
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I did check for that and I also chamfered the end slightly. Still
wouldn't go into the 5mm drill hole!
Brendan
--
anotherid
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View this thread: http://www.rcgroups.com/forums/showthread.php?t=577122
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>D-bit?