hole in the middle?

Home| Search | About
User Password
Register Now! Lost Password?

Model Engineering in UK - Model engineering, metal crafts in UK 

Bookmark this page:  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
hole in the middle? bugbear 01-07-2008
Posted by bugbear on January 10, 2008, 4:52 am
Please log in for more thread options
 Allan Waterfall wrote:
> 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

Posted by the wizard on January 8, 2008, 10:56 am
Please log in for more thread options
> 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
>
> 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?
>
> =A0 =A0BugBear

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.

Posted by Peter Fairbrother on January 16, 2008, 9:09 pm
Please log in for more thread options
bugbear wrote:
> 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

Similar ThreadsPosted
Moving a hole in a casting, by half a hole March 18, 2008, 5:22 am
Canard with middle-motor, outrunner, contrarotating & coaxial April 30, 2008, 2:20 pm
Cutting narrow deep rectangular hole..... May 21, 2008, 2:50 pm

Contact Us | Privacy Policy

XML SitemapXML Sitemap