Thanks Graham,
As it so happens, there WAS some of the old bolt left in the hole. I ended
up grinding off the welded-on bolt from the underside because there was
simply no way I was going to get that broken tap out with a hand drill.
I've chalked it up to experience and your useful information is indeed, very
valuable. I'll not make the same mistake again.
Best wishes,
Jeff
----- Original Message -----
From: Graham Stretch <technical@iwnet.screaming.net>
To: Jeff McNeal <jmcneal@ohms.com>
Cc: List Spitfires <spitfires@autox.team.net>
Sent: Tuesday, March 07, 2000 1:53 PM
Subject: Re: screwed... My solution
>
> Hi Jeff
> Whilst we're on the subject of taps here's a tip, and possibly the reason
> your tap broke, always ensure that none of the original bolt is left in
the
> hole you are going to re-tap, if some is left as you tap the thread the
> piece of old bolt will often come loose and act as a wedge, (it gets
pulled
> round rather than have a new thread cut in it!) jamming the tap solid. I
am
> a toolmaker and spend a good proportion of my time repairing steel dies
for
> casting aluminium, these take a pounding and often screws holding the
> handles etc break. I have been where you were several times and have found
> this to be a big cause of broken taps, of course they will also break all
of
> their own accord! I hope this can ease your troubles in future.
>
> Graham.
>
> ----- Original Message -----
> From: Jeff McNeal <jmcneal@ohms.com>
> To: Graham Stretch <technical@iwnet.screaming.net>
> Cc: List Spitfires <spitfires@autox.team.net>
> Sent: Tuesday, March 07, 2000 3:15 AM
> Subject: Re: screwed... My solution
>
>
> >
> > Well, you guys were right. The Cobalt bit didn't even make a dent! But
> my
> > die grinder sure did! Sparks were flying as I ground down the welded-on
> nut
> > into oblivion and with it, that darned broken tap. For now, I just have
a
> > large fender washer doing the honors with a nut and locknut. It'll do
> until
> > I can teach myself how to weld -- or not.
> >
> > Thanks to all who offered suggestions.
> >
> > Got a new problem though... A couple actually. I'll save it for
another
> > thread.
> >
> > Jeff
> > ----- Original Message -----
> > From: Graham Stretch <technical@iwnet.screaming.net>
> > To: Jeff McNeal <jmcneal@ohms.com>
> > Cc: List Spitfires <spitfires@autox.team.net>
> > Sent: Monday, March 06, 2000 12:29 PM
> > Subject: Re: screwed...
> >
> >
> > > Hi Jeff
> > > I doubt that the Cobalt drill will touch it either, for the jig try a
> > piece
> > > of flat steel stock with a hole the right size drilled in it, try the
> back
> > > door of a local machine shop with enough Dollars for a drink! They
will
> > > probably have some scrap around big enough for your needs (1"x1"x6"
> should
> > > do) cramp this to the floor and drill down the hole. Alternatively I
> think
> > > these cars use a nut welded to the floor from underneath why not just
> > remove
> > > it and weld a new one in place.
> > >
> > > Graham.
> > >
> > > ----- Original Message -----
> > > From: Jeff McNeal <jmcneal@ohms.com>
> > > To: Spitfire List <spitfires@autox.team.net>
> > > Sent: Monday, March 06, 2000 4:50 AM
> > > Subject: screwed...
> > >
> > >
> > > >
> > > > Pardon the abrasive header of this message, but it seems like the
most
> > > > concise way to describe my situation. When replacing my seat rails
> > > > yesterday, I noticed that the PO had drilled an alternate hole in
the
> > seat
> > > > track because he busted one of the 1/4" mounting bolts in the
original
> > > hole.
> > > > Up for the challenge, I sawed off the nub sticking up so I would
have
> a
> > > > nice, flat surface to drill through, which I did with a 7/32" bit,
> > > drilling
> > > > through the old bolt. So far, so good.
> > > >
> > > > Next, I borrowed a buddies tap and die set and proceeded to tap a
new
> > 1/4"
> > > x
> > > > 28 thread. Then, SNAP! The tap busted off inside the hole, with no
> way
> > > to
> > > > get it out. I killed two perfectly good drill bits trying. Someone
> > > > suggested a cobalt drill bit to slice through the hardened steel of
> the
> > > tap.
> > > > Now, the thing is a real mess and I'm trying to figure out the best
> way
> > to
> > > > drill back through and retry with a new tap.
> > > >
> > > > I wish there were some kind of jig I could create that gave me the
> > > stability
> > > > and precision of a drill press. Right now, there's no way I can get
> the
> > > bit
> > > > started straight on because of the way the tap broke off. My plan
at
> > the
> > > > moment is to attack the problem from the bottom side this time,
using
> a
> > > die
> > > > grinder to flatten off the bottom, before drilling up and through.
> > Before
> > > I
> > > > attempt this, is the broken tap going to be too much for my grinding
> > > wheel?
> > > > IS there a simple, clever way to rig up a portable drill press so I
> can
> > > > drill straight down without worring about drilling crooked? Or
should
> I
> > > > just say "screw it" and use the alternate hole that the PO drilled,
> even
> > > > though it interferes with the travel of the sliders?
> > > >
> > > > Thanks!
> > > >
> > > > Jeff in San Diego
> > > > 67 RHD Spitfire Mk3 aka Mrs. Jones
> > > > www.ohms.com/spitfire/spitfire.shtml
> > > >
> > > >
> > >
> >
>
>
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