Date: Fri, 17 Aug 2012 19:44:55 -0500
Reply-To: mcneely4@COX.NET
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dave Mcneely <mcneely4@COX.NET>
Subject: Re: windshield wiper repair redux
In-Reply-To: <502ecdd3.5284cd0a.7719.594c@mx.google.com>
Content-Type: text/plain; charset=utf-8
Well, all this is sensible. David, and though the advice comes too late for this time, I am always seeking edification, and am glad to have the information.
For what it is worth, I tried to salvage the botched job anyway. After examining the shaft, I thought I might be able to file it off flat again, redrill starting with a tiny drill and working up, and tap it. It would be shorter, and the splines therefore shorter, but it might work. Those things all worked well, and I now have a nice shaft, with a nice hole, and a 6 mm bolt threads right in properly.
However, I was unable to get the splines that remain to bite into the metal of the wiper arm axle adequately to hold the wiper arm. At first I thought I had done so, as the wiper arm seemed to anchor solidly on the shaft. But upon trying the wiper, it ran for three minutes by my watch, with water on the windshield, then worked loose and flopped around again.
I also tried the fix with steel wool that someone suggested, but that didn't give any anchor at all, seemed to act more like a lubricant (and yes, I used plain steel wool, not a soap pad).
I will try a new wiper arm with this fix before I go the extreme of digging into the insides of the dash, but I think that's where we are headed. I tried to examine the inside of the wiper arm axle with bright light, and I do see grooves, but I can't feel them with a tool, and they don't seem to run all the way around the inside of the axle.
BTW, only one of the online vendors claims to have wiper arms in stock -- the most expensive one. But I am going to try NAPA as I've had good luck with them on some parts in the past.
mcneely
---- David Beierl <dbeierl@attglobal.net> wrote:
> At 04:18 PM 8/17/2012, Dave Mcneely wrote:
> >Well, I worked on the "simple" fix for the broken windshield wiper
> >shaft stud. Despite punching a good, centered dimple on the tip of
> >the stud after filing it flat, I was unable to keep the drill bit
> >from slipping sideways and so removed too much metal on one side.
>
> That's too bad. If I'd known you were going right ahead with it I'd
> have said some more.
>
> Things that can help keep your point from walking:
>
> Triangular point on the center punch, nice deep punch. Light punch
> first so you can walk it sideways if need be; then a good deep one
> when it's definitely in the right place. The three triangular faces
> should be reasonably even.
>
> First drill bit used should be very small. A 1/8" pilot-point drill
> (1/8" is as small as is practical to put the much smaller pilot point
> on) is probably ideal for hand use on this size hole; otherwise start
> with a 1/16". You could probably start with the correct size of
> pilot-point bit, but not nearly so likely that you could find one the
> correct size for tapping an M6x1 hole (which without doing the
> calculations I've seen listed as 5.2 mm (or #5 in the US numbered
> series of drills) or a 5 mm or #5, incidentally. Pilot-point drills
> around here come in the US fractional-inch series, by 64ths. So I'm
> wrong, a 13/64" is about right.
>
> Alternatively you can start the hole with a small (Nos 0-2, say)
> center drill of the type used with lathes, which have a very short
> straight-flute pilot point followed by a sixty-degree cone which
> makes a good starting hole for a drill bit. This is the conventional
> method, so to say, but they tend not to sell center drills in
> hardware stores, more's the pity.
>
> Second (and possible subsequent) drill bits, the chisel point of a
> standard bit (the flat line across the end of the point) must be
> shorter than the width of the existing hole. Conversely with a
> pilot-point bit the pilot must be large enough to be drilling into
> metal and not air, as with that type of bit the outer edges cut first
> rather than the inner, and they'll simply fling the bit away if the
> point isn't solidly anchored.
>
> Pull the bit frequently to clear chips, more frequently as the hole
> is deeper; use cutting fluid of some sort, slow speed and heavy
> pressure relative to the bit diameter.
>
> A jig can help immensely to keep the hole direction along the shaft
> axis. I have one where a second drill chuck slides up and down in a
> frame. A jig is also the best way to keep the tap from choosing its
> own direction of travel which it will very readily, being in effect a
> tunneling machine on its own. There are more angled holes tapped in
> this world than straight ones.
>
> Yours,
> David
>
>
>
--
David McNeely
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