Date:         Tue, 26 Jun 2001 22:52:22 -0700
Reply-To:     Austin <austins@IX.NETCOM.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Austin <austins@IX.NETCOM.COM>
Subject:      Re: Heli-Coil tap and drill size needed as soon as poss
Comments: To: John.Clemens.jbclem@EARTHLINK.NET
In-Reply-To:  <002501c0fec5$8fd83ea0$bf1ff4d8@doo>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 09:56 PM 6/26/2001, you wrote:
>Hi all.
>
>  It's 9:30 PM California time and I am trying to finish  resealing an oil
>cooler on  a 1971 Bus......

>I've tried the heli-coil web site which is totally worthless, unless someone
>knows what drill size "Q" means, or tap size "2087-8".
>
>If there are any night owls with this kind of information handy, I would
>greatly appreciate  receiving it.
>
>Thanks,  John


John - 'Q' is a legitimate drill size, 0.332 inches diameter (ie, just a
bit bigger than a 5/16" drill, which is a decimal 0.3125 inches
diameter).  Heli-Coils use size specific taps which are *not* standard
(thus the weird part #) - you don't have to purchase HC brand taps, but
they must be listed for 'helical inserts'.

BTW & FWIW, the really hot set up for helical inserts in soft
metals/plastics is to use a 'roll tap' instead of a standard cutting tap -
roll taps start with a still larger drill, & reform / flow the metal into
the thread form; you end up with much stronger threads in the parent
material - slightly polished if you use the correct lubricant, making for
easier HC installation.  You'll have to go to a professional tool supplier
to get roll taps (Shop Tools, Advanced, Western Tool, etc), but they're the
only way to go, HC's or standard threads.

Austin