Re: [CR]Question about drilling and countersinking

(Example: Component Manufacturers:Avocet)

Date: Thu, 31 Aug 2006 22:13:32 -0700
From: "nicholas harteau" <nrh@ikami.com>
To: "Raymond Dobbins" <raydobbins2003@yahoo.com>, classicrendezvous@bikelist.org
Subject: Re: [CR]Question about drilling and countersinking
In-Reply-To: <20060901045418.42232.qmail@web60422.mail.yahoo.com>
References: <20060901045418.42232.qmail@web60422.mail.yahoo.com>


Indeed there are special bits for countersinking. you should not attempt to use a larger bit. the face of a drill bit is designed to take away large chunks of material and move the bit towards the opposite side of the material. a countersink bit is designed to do just that, countersink.

I think that if you're going to spend the time to drill that, you would be better off spending the time to make a proper drawing of the hole patterns (referenced from either the center of the piece or the center of one of the mounting holes) and taking the drawing to a CNC shop to drill and/or countersink. It's not a challenging or time-consuming operation to line that up and mill, and the outcome will be spot-on. I would be happy to draw it up in solidworks if you can supply a chainring to take dimensions from, or have a good quality drawing of a chainring to work from.

I'm would imagine that when drillium components were originally made, they were made not with a drill, but on a mill, along with most of the rest of the parts.

Not trying to bash your work, but I think you would be happier with the outcome from the mill.

nicholas "brief respite from lurking" harteau san francisco, ca

On 8/31/06, Raymond Dobbins <raydobbins2003@yahoo.com> wrote:
> For my Molteni replica project, I decided to try my hand at reproducing the Nuovo Record ring seen on this exteme close-up:
>
> http://www.raydobbins.com/merckxmolteni/drilled_ring.jpg
>
> That is Eddy by the way, or at least his feet. If anyone has a better pic of this ring, PLEASE let me know.
>
> And here is the result of my newbie drilling effort:
>
> http://www.raydobbins.com/merckxmolteni/my_first_drilled_ring.jpg
>
> Far from perfect, but still satisfying for a first effort, at least for me.
>
> Anyway, as far as I can tell from the first photo, it looks like Eddy's ring had countersunk holes. Unfortunately, my attempts at countersinking have failed pretty miserably. My questions are:
>
> - Is there a special drill bit for countersinking?
>
> - Or do I simply use a larger drill bit? If so, how much larger? The holes in my ring were made with a 5/32 bit.
>
> - Am I right to think that I absolutely need to use a drill press to achieve uniform countersinking? (I don't have one nor do I have access to one without buying one.)
>
> Any advise will be greatly appreciated.
>
> Thanks,
>
> Ray Dobbins
> Miami Florida
>
>
> _______________________________________________
>

--
nicholas harteau
nrh@ikami.com