X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 29 Apr 2009 21:45:50 -0400 Message-ID: X-Original-Return-Path: Received: from snt0-omc3-s23.snt0.hotmail.com ([65.55.90.162] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3611244 for lml@lancaironline.net; Wed, 29 Apr 2009 21:14:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.55.90.162; envelope-from=gary21sn@hotmail.com Received: from SNT112-DS2 ([65.55.90.135]) by snt0-omc3-s23.snt0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Wed, 29 Apr 2009 18:13:55 -0700 X-Originating-IP: [68.186.114.52] X-Originating-Email: [gary21sn@hotmail.com] X-Original-Message-ID: X-Original-Return-Path: gary21sn@hotmail.com From: "Gary Edwards" X-Original-To: "Lancair Mailing List" References: Subject: Re: Tridair fasteners X-Original-Date: Wed, 29 Apr 2009 18:13:52 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005A_01C9C8F6.410311C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.60.0053.2200 In-Reply-To: Seal-Send-Time: Wed, 29 Apr 2009 18:13:52 -0700 X-OriginalArrivalTime: 30 Apr 2009 01:13:55.0732 (UTC) FILETIME=[EEB67D40:01C9C930] This is a multi-part message in MIME format. ------=_NextPart_000_005A_01C9C8F6.410311C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Well said Brent. =20 I have had my eye on these fasteners for 20 years, and have mentioned = several times on this forum through the years that when I build my next = Lancair (Legacy), I will be using them. Gary Edwards LNC2 =20 Most kids like to take things apart. The ones that learned to reliably = reverse the process usually go on to become engineers. I first learned about these fasteners over 30 years ago when I was=20 designing and building IMSA race cars. I was visiting another car=20 builder, Dave Kent, in Los Angeles and he took me to an aerospace=20 fastener surplus store where you could buy "sweepings" from the = various=20 aerospace facilities. You could get every kind of cool high = performance=20 fastener and pay by the pound! If I knew then what I know now I would=20 have mortgaged the farm and bought the entire store. A couple of years = later there was a scandal where where people were buying up these=20 surplus parts, repackaging them and selling them back to the market as = new. The FAA cracked down and my "Fastener Heaven" store vaporized and = is now a tattoo parlor. BTW, it was Dave that introduced me to WLS=20 coatings. Dave also had a penchant for topless bars and double Dewer's = up, but that is way off topic. Tridair fasteners are positive retention fasteners, originally = designed=20 for supersonic aircraft. Dzus and Camlock fasteners are "fixed force"=20 spring type. When you use a spring fastener you produce a fixed = clamping=20 force at the fastening interface. This is bad news in high vibration=20 environments as the vibration can momentarily separate the two clamped = parts, allowing them to move laterally and cause fretting and wear. If = you examine most spring fastener installations that have been in = service=20 for a while you will see indicia of wear proximal to the fastener. The Tridair fasteners are different because there is no mushy spring = in=20 the clamping system. Also the OD of the female "screw" is a close=20 tolerance fit to the ID of the receiver. This provides positive=20 clamping without the wiggle. HOW THEY WORK There is a reason these things are expensive. Refer to the pictures below. All the magic is in the receptacle. The=20 housing is capped by a stud that has a multi start male thread. Inside = the housing is a coaxial barrel that contains a spring that prelaods = an=20 axial sliding plate. On the bottom of the barrel and the top of the = stud=20 heads are radial teeth that engage each other. During assembly, slots on the end of the screw engage tabs on the=20 sliding plate. Other tabs on the perimeter of the sliding plate engage = slots in the barrel so that as the screw turns the sliding plate the=20 plate turns the barrel, causing the teeth to on the barrel to rotate=20 against the teeth on the stud. This produces a clicking noise during=20 assembly and removal. It also prevents the fastener from loosening in=20 service. Installation and use tips: Try to only use one grip length. I used -2s. This eliminates the=20 possibility of using a wrong length. You can grind down or bid up the=20 receiver mounting area to make the grip distance within the fastener's = range. The retainer clip is not a requirement. Having the screws come off of = the cowling eliminated the possibility of having them scratch the=20 paint during reassemble. Use a reamer (0.251") to size the holes with the cowling mated to the=20 fuselage. Repeat after painting and then install the receivers. Periodically wash out the screws and receivers and relubricate with=20 something better than WD40 (e.g. LPS #2 spray lubricant). Remember, paying for quality is a tough decision to make but an easy=20 decision to live with. Regards Brent Regan ------=_NextPart_000_005A_01C9C8F6.410311C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Well said Brent. 
 
I have had my eye on these fasteners for 20 years, and have = mentioned=20 several times on this forum through the years that when I build my next = Lancair=20 (Legacy), I will be using them.
 
Gary Edwards
LNC2  
Most kids like to take things apart. = The ones=20 that learned to reliably
reverse the process usually go on to = become=20 engineers.

I first learned about these fasteners over 30 years = ago when=20 I was
designing and building IMSA race cars. I was visiting = another car=20
builder, Dave Kent, in Los Angeles and he took me to an aerospace=20
fastener surplus store where you could buy "sweepings" from the = various=20
aerospace facilities. You could get every kind of cool high = performance=20
fastener and pay by the pound! If I knew then what I know now I = would=20
have mortgaged the farm and bought the entire store. A couple of = years=20
later there was a scandal where where people were buying up these=20
surplus parts, repackaging them and selling them back to the = market as=20
new. The FAA cracked down and my "Fastener Heaven" store vaporized = and=20
is now a tattoo parlor.  BTW, it was Dave that introduced me = to WLS=20
coatings. Dave also had a penchant for topless bars and double = Dewer's=20
up, but that is way off topic.

Tridair fasteners are = positive=20 retention fasteners, originally designed
for supersonic aircraft. = Dzus and=20 Camlock fasteners are "fixed force"
spring type. When you use a = spring=20 fastener you produce a fixed clamping
force at the fastening = interface.=20 This is bad news in high vibration
environments as the vibration = can=20 momentarily separate the two clamped
parts, allowing them to move=20 laterally and cause fretting and wear. If
you examine most spring = fastener=20 installations that have been in service
for a while you will see = indicia=20 of wear proximal to the fastener.

The Tridair fasteners are = different=20 because there is no mushy spring in
the clamping system. Also the = OD of=20 the female "screw" is a close
tolerance fit to the ID of the = receiver.=20 This provides  positive
clamping without the = wiggle.

HOW THEY=20 WORK

There is a reason these things are expensive.

Refer = to the=20 pictures below. All the magic is in the receptacle. The
housing is = capped=20 by a stud that has a multi start male thread. Inside
the housing = is a=20 coaxial barrel that contains a spring that prelaods an
axial = sliding=20 plate. On the bottom of the barrel and the top of the stud
heads = are=20 radial teeth that engage each other.

During assembly, slots on = the end=20 of  the screw engage tabs on the
sliding plate. Other tabs on = the=20 perimeter of the sliding plate engage
slots in the barrel so that = as the=20 screw turns the sliding plate the
plate turns the barrel, causing = the=20 teeth to on the barrel to rotate
against the teeth on the stud. = This=20 produces a clicking noise during
assembly and removal. It also = prevents=20 the fastener from loosening in
service.

Installation and = use=20 tips:

Try to only use one grip length. I used -2s. This = eliminates the=20
possibility of using a wrong length. You can grind down or bid up = the=20
receiver mounting area to make the grip distance within the = fastener's=20
range.

The retainer clip is not a requirement.  Having = the=20 screws come off of
the  cowling  eliminated the = possibility of=20 having them scratch  the
paint during reassemble.

Use = a reamer=20 (0.251") to size the holes with the cowling mated to the
fuselage. = Repeat=20 after painting and then install the receivers.

Periodically = wash out=20 the screws and receivers and relubricate with
something better = than WD40=20 (e.g. LPS #2 spray lubricant).

Remember, paying for quality is = a tough=20 decision to make but an easy
decision to live=20 with.

Regards
Brent Regan

 
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