hole in the middle?
bugbear
1" diameter, 1/4" thick, 1/4 whit hole in the middle.
Simple enough job, but I only had some 1" x 1/4" Alu flatstock
(actually an old shelf bracket!!).
I cut off a slice, centre popped, marked a circle,
and attempted to drill the tap hole for 1/4"
I was off the mark by 1.5mm
As a "proof of concept" I then hacksawed the square
piece octagonal (remove corners) and filed to a good
circle. The hole (of course) was still off centre.
At this point I should point out that I am a woodworker
with a few files and a hacksaw. I don't have a lathe,
or even a drill press.
It's all hand work.
What techniques could I use to get an accurately placed
hole?
BugBear
Norman Billingham
"bugbear" <bugbear@trim_papermule.co.uk_trim> wrote in message
news:13o4iuu...@corp.supernews.com...
Give yourself a chance by not trying to drill the tapping size hole in one
go. Either buy a 1/8" stub drill or (better) a BS3 centre drill. Either
gives you a short stiff drill which will locate much better in your centre
pop and give a start for the bigger drill.
You can drill aluminium with wood drills - if you had a brad point wood
drill of the right size (1/4 BSW = 5.3mm) that would work too - what you
need is a positive centre location.
Austin Shackles
<bugbear@trim_papermule.co.uk_trim> enlightened us thusly:
>over the holiday I had cause to make a 1/4" whitworth knob.
>1" diameter, 1/4" thick, 1/4 whit hole in the middle.
>
>Simple enough job, but I only had some 1" x 1/4" Alu flatstock
>(actually an old shelf bracket!!).
>
>I cut off a slice, centre popped, marked a circle,
>and attempted to drill the tap hole for 1/4"
>
I assume you got your centre punch in the middle, by the expedient of
drawing diagonals on the square bit first?
--
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Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!
bugbear
> On or around Mon, 07 Jan 2008 15:57:18 +0000, bugbear
> <bugbear@trim_papermule.co.uk_trim> enlightened us thusly:
>
>> over the holiday I had cause to make a 1/4" whitworth knob.
>> 1" diameter, 1/4" thick, 1/4 whit hole in the middle.
>>
>> Simple enough job, but I only had some 1" x 1/4" Alu flatstock
>> (actually an old shelf bracket!!).
>>
>> I cut off a slice, centre popped, marked a circle,
>> and attempted to drill the tap hole for 1/4"
>>
>
> I assume you got your centre punch in the middle, by the expedient of
> drawing diagonals on the square bit first?
Yes, and I even marked a 7mm circle (as well as the outer 25mm circle
for the final shape of the knob) from the centre "dot".
So I can see and measure my error quite well :-(
BugBear
MikeH_QB
As Norman B suggested, if you 'center popped' first it will only be
quite a shallow indentation, use a small drill first (like 1/8") as
that will locate in the mark. Then use the 1/4" tapping drill.
Alu is obviously quite soft, so a 'big' drill will tend to grab into
the metal only approximately where u first place it - hence (probably)
your 1.5mm error.
Mike
Austin Shackles
<bugbear@trim_papermule.co.uk_trim> enlightened us thusly:
did you give the centre punch a good smack? sometimes people are too
circumspect with the hammer. nice deep centrepunch hole (once you're sure
it's in the right place) helps to locate the drill bit better.
the wizard
Hi BugBear,
When centre punching Alloy a pronounced burr is raised, it is all to
easy for a drill to slip down the outside of this burr, leading to a
misplaced hole. You could try filing the alloy flat, this would leave
just a dimple for the drill to start in, ideally this drill should be
a centre drill, which "does what it say on the can". Centre drill till
the hole is wide enough for the chisel point to fit in. Better still
is to completely drill through with a drill about the size of the
chisel point, then follow up with the final size. I understand that
Cherry Hill uses an archimedian drill, to open up a centre popped
location,before drilling to size. If it is good enough for her, it
certainly good enough for anyone in this group..
T.W.
Suzy
"MikeH_QB" <MikeHu...@yahoo.co.uk> wrote in message
news:b71ed2a3-57b0-45e7...@e6g2000prf.googlegroups.com...
Plus, I would add, as they are so cheap buy yourself a drill-press. It will
revolutionise (ouch!) all your work. And if you've got away without before
ALWAYS wear safety spectacles especially now that drilling is nearer eye
level.
bugbear
Actually, I am desperately short of workshop space, the issue
with a drill press is not cost, but space. I also strongly prefer
(just as a personal quirk) not using electric tools.
http://i48.photobucket.com/albums/f234/bugbear33/workshop.jpg
I may try and buy something like this:
http://homepage.mac.com/galoot_9/gpimages/post_drill.jpg
BugBear
Trevor Jones
>
> Actually, I am desperately short of workshop space, the issue
> with a drill press is not cost, but space. I also strongly prefer
> (just as a personal quirk) not using electric tools.
>
> http://i48.photobucket.com/albums/f234/bugbear33/workshop.jpg
>
> I may try and buy something like this:
>
> http://homepage.mac.com/galoot_9/gpimages/post_drill.jpg
>
> BugBear
Take a look at the Cole Drill, as well, then. At least, know what one
looks like, so as to recognise it as the bargain it is, if you see one
at a car boot sale.
They take up little space, and will drill holes that would make many
other drills give up. Portable, too! :-)
Lesse.... http://www.dogpatch.com/bobp/shop/cole_drill.jpg
Cheers
Trevor Jones
bugbear
>
> Take a look at the Cole Drill, as well, then. At least, know what one
> looks like, so as to recognise it as the bargain it is, if you see one
> at a car boot sale.
>
> They take up little space, and will drill holes that would make many
> other drills give up. Portable, too! :-)
>
> Lesse.... http://www.dogpatch.com/bobp/shop/cole_drill.jpg
Duly Noted ;-)
BugBear
Allan Waterfall
Just drill the hole first and mark the outer circle afterwards using a
paper template if you're only making a knob.
Allan
--
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bugbear
> Just drill the hole first and mark the outer circle afterwards using a
> paper template if you're only making a knob.
Aah, but I wanted the largest possible knob from limited stock...
BugBear
Peter Fairbrother
> over the holiday I had cause to make a 1/4" whitworth knob.
> 1" diameter, 1/4" thick, 1/4 whit hole in the middle.
>
> Simple enough job, but I only had some 1" x 1/4" Alu flatstock
> (actually an old shelf bracket!!).
>
> I cut off a slice, centre popped, marked a circle,
> and attempted to drill the tap hole for 1/4"
>
> I was off the mark by 1.5mm
That's where you went wrong
>
> As a "proof of concept" I then hacksawed the square
> piece octagonal (remove corners) and filed to a good
> circle. The hole (of course) was still off centre.
>
> At this point I should point out that I am a woodworker
> with a few files and a hacksaw. I don't have a lathe,
> or even a drill press.
>
> It's all hand work.
>
> What techniques could I use to get an accurately placed
> hole?
Drill into the pop correctly - keep the drill vertical (assuming it
isn't in a drill stand) - start with a small drill then enlarge - or use
center drills, or better, spot drills to start off with.
A zillion RPM also helps sometimes, if under control.
-- Peter Fairbrother