It's so lonely out here on the left coast of the USA. I do hope that the
list forum
comes back up soon...all I'm getting in my in-box now is spam for marital
aids
and home loans.
After the discussion on bending hinge pins, and not liking the way the hinge
began
binding slightly after bending the second end,
I took it upon myself to try drilling the hinge pins instead of bending
them.
Bottom line - there's a better way.
I used a #58 drill, which is large for 0.031 safety wire, but is more
resistant
to bending than the #62 which is the better match to the wire diameter.
A drilling block and drill press must be used to keep the drill straight.
This block consists
of a mild steel plate about 3/16" thick and 3/4" wide with a 3/32" hole for
the pin
across the width, and a #58 hole in the end of the plate about 1/16" in from
the edge.
The length is about 3", but will shorten as you drill the holes ( more on
this later )
Since you are drilling high strength steel, a 135 degree split point cobalt
steel drill
must be used. These are about $1.50 each. You will need 10.
The main problem with this method is that the drill is too flexible to
withstand the
pressure needed to drill the hinge pin. The cobalt steel drill will easily
drill mild
steel, and as the drill flexes, the shank flutes will widen the hole
rapidly. The drill
won't remain on center. A further problem is that cobalt steel lasts about
3-4 holes.
Thus, you'll consume 1 drill (at least) for every 2 pins, at which time
you'll also need
to build another drilling block.
The result is nice, but Tony Bingelis in "The Sportplane Builder" offers a
better
method - cut the hinges about 3/16" overlength, the pins to the specified
length,
drill through the hinge loops about 3/64" in from the ends, and safety wire
through the
hinge. You're drilling aluminum, not steel. You'll need cut the hinges
---From the stuff
the factory gives you and buy some more hinge stock (from either Europa or
Wicks),
but the cost of the additional hinge plates would have been far less than
the $20 I spent
on drills and hinge pin.
Shaun
A207
----- Original Message -----
From: "Rowland & Wilma Carson" <rowil@clara.net>
Subject: Re: Bending hinge pins
>
> >Has anyone out there got a neat trick for bending the hinge pins? They're
so
> >stiff I'm rather nervous of bending or damaging the hinge
>
> Jeremy - this is probably too late, but I, too, am at the stage of
> assembling some hinges and have this day constructed a hinge-pin
> bending tool (HPBT) which works fine for me.
>
> I took a length (I had a piece about 200mm lying around spare) of
> .25" mild steel rod, popped it in the lathe, drilled the end 2.4mm
> (sliding fit on hinge wire) then swung the topslide and chamfered it
> 45 degrees (like sharpening a pencil with no lead).
>
> To use, slide the tool onto the protruding end of hinge wire and
> bend, (preferably in the plane of the hinge to give minimum
> likelihood of bending the hinge), until the chamfer touches the end
> face of the hinge. Repeat at opposite end while ensuring the first
> end doesn't migrate out. The hinges are actually remarkably resistant
> to bending (and to drilling as well if you don't use a sharp drill
> bit!). I actually fitted and bent my hinge pins for the trim tabs
> _after_ clamping the first halves of the hinges to the straight-edge
> for line-up. (I found it useful to be able to "sight" through the
> hinge holes from both ends to ensure line-up before inserting the
> pins.)
>
> You can have my HPBT after I've finished with it (not sure when that
> will be, though), or if you don't have the resources to make your
> own, you might try the local model engineering club - or there might
> be someone at your local PFA Strut with a lathe. If all else fails,
> I'll make another one & pop it in a Jiffy-bag, but I don't want to
> become known as a source for such things!
>
> >the only
> >tool I've found that makes any impact on the pins is a large hammer
>
> I've tried to limit my use of hammers so far in this project, but I'm
> sure that once we get past the cookery & dressmaking stuff and onto
> real engineering ....
>
> regards
>
> Rowland
>
>
> | PFA 16532 EAA 168386 Young Eagles Flight Leader 017623
> | Europa builder #435 G-ROWI e-mail <rowil@clara.net>
>
>
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