---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 03/20/13: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:57 AM - Vacuum vise (Robert L. Nuckolls, III) 2. 08:35 AM - Re: vhf transponder interference (jappie) 3. 09:10 AM - Cessna Switch Bulletin CE-09-42 (Jeff Page) 4. 10:10 AM - Re: Vacuum vise (Y! edpav8r) 5. 12:53 PM - Re: Work bench cord clutter solution (eschlanser) 6. 02:31 PM - Re: Cessna Switch Bulletin CE-09-42 (Vern Little) 7. 07:59 PM - Re: Vacuum vise (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 07:57:03 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Vacuum vise On several occasions I've thought it would be nice if a vacuum vise I inherited from my dad would 'stay put' better on the workbench. Seems it's difficult to pull a lasting vacuum on a wooden surface. A solution occurred to me a couple of days ago. I used some E6000 to bond a 7 x 7 inch piece of copper clad to the bench thusly. Emacs! I weighted it down well and gave it 48 hours+ to get bonded. E6000 is a solvent based adhesive and I wanted to give the solvents plenty of time to escape from under the sheet. This produced a smooth, vacuum friendly surface . . . Emacs! . . . yet thin enough not to be in the way when the vise was not in service. You could do the same thing with a piece of aluminum or perhaps some plastic that was impervious to the effects of the E6000's solvents. A thin steel sheet might be even better. Time tell how well the copper clad stands up to the rigors of bench surface before it too becomes 'leaky' . . . By the way, the surface under the copper clad is tempered Masonite. I use this to surface many of my benches attaching it with flat head screws. When it gets too beaten to clean up I can easily replace it for a whole new work surface. Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:35:37 AM PST US Subject: AeroElectric-List: Re: vhf transponder interference From: "jappie" what is the importance of the Impedance bushing inside this connector TED 9-30-10 ? I've been told to use use it only with a certain type of cable ... My old one had none, maybe one of the many reasons I have interference... JP Read this topic online here: http://forums.matronics.com/viewtopic.php?p=396657#396657 ________________________________ Message 3 _____________________________________ Time: 09:10:20 AM PST US From: Jeff Page Subject: AeroElectric-List: Cessna Switch Bulletin CE-09-42 The FAA released a Special Airworthiness Information Bulletin CE-09-42 advising that the landing, beacon and taxi light switches have been overheating in the field resulting in smoke or fire in the cockpit. This apparently occurs after approximately 4000 operations. The design of the switches is less than ideal, since it is just a slider with no over-center snap action. Since the landing light switch in my Cessna 172 has been in operation for 43 years and 6500 flight hours, it could have as many as 10000 operations. So I decided that I would replace the switch and tear apart the old one to investigate its condition. It was in better shape than I expected. The contacts are large rivets of copper, still firmly attached to the chassis. The slider plate has very thick paths of copper - it is not just an etched circuit board. As the plate slides, the paths make contact with the rivets and that is where arcing occurred. However, the sliding action of the switch cleans the contact points, so during use the current is passing between the contacts and the plates in a different location than where the arcing occurred. The contact operation of the switch is very dependent on the strength of the spring that pushes the plate against the contacts. If the spring weakened or broke, switch operation would be dangerously degraded. The spring in my switch was stronger than I would have expected. Conveniently, the spring also functions for the detent positions of the switch. So if one of these switches seems loose and doesn't click into position, it is time to replace the switch. The switch I replaced is Cessna 0713035-1 and cost me $45 Canadian. Jeff Page Dream Aircraft Tundra #10 ________________________________ Message 4 _____________________________________ Time: 10:10:02 AM PST US Subject: Re: AeroElectric-List: Vacuum vise From: Y! edpav8r Bob, Great idea! Very nice to be able to have a vise front and center when you n eed it and get it out of the way when you don't. Re workbenches. I've made a couple of benches using a plain-front solid cor e interior door as the top. They're rigid, flat and stable, and come with a nicely finished surface. It's easy to fab and attach a simple support fram ework and legs with a few dollars worth of lumber and hardware. Unfortunately, the nicely finished surface doesn't hold up very well to gara ge bench use. I'll try your idea and screw down a sheet of Masonite next ti me my bench needs a refinish. Thanks for the tip. Eric On Mar 20, 2013, at 7:55 AM, "Robert L. Nuckolls, III" wrote: > By the way, the surface under the copper clad is tempered > Masonite. I use this to surface many of my benches attaching > it with flat head screws. When it gets too beaten to > clean up I can easily replace it for a whole new work > surface. > > Bob . . . ________________________________ Message 5 _____________________________________ Time: 12:53:02 PM PST US Subject: AeroElectric-List: Re: Work bench cord clutter solution From: "eschlanser" holger-d(at)shadowbrush.c wrote: > 12 plug strip now on sale (until tomorrow) at Newegg: http://tinyurl.com/ckdgpnq . $36 shipped with promo code EMCXTWL228. That's $3/plug. > > Holger SOLD OUT! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=396681#396681 ________________________________ Message 6 _____________________________________ Time: 02:31:06 PM PST US From: "Vern Little" Subject: Re: AeroElectric-List: Cessna Switch Bulletin CE-09-42 These are the same circuit functions that failed using Carling switches after less than 100 operations in my RV-9A. These failures were well documented on this list several years ago and are in the archives. I've eliminated switches carrying loads in my Harmon Rocket and I am using relays controlled by low-current switches. The relays can be replaced when (not if) they fail in less than 30 seconds, even in flight. The Vertical Power products do this with automotive-style electronic switches. Any electromechanical device, including switches, relays, breakers and contactors have a lifetime and plans should be made to provide service access for replacement. The promise of electronic (solid state) breaker/relays is that there is no practical wear-out mechanism. When a failure does occur, however, it's quite a bit more complicated to repair. There are two philosophies at play here: Design so that it never breaks, and don't worry about serviceability; or assume that it will break and allow easy service access and low cost maintenance. Sometimes, however, in our amateur-builts, we get it backwards... sigh. V -----Original Message----- From: Jeff Page Sent: Wednesday, March 20, 2013 9:08 AM Subject: AeroElectric-List: Cessna Switch Bulletin CE-09-42 The FAA released a Special Airworthiness Information Bulletin CE-09-42 advising that the landing, beacon and taxi light switches have been overheating in the field resulting in smoke or fire in the cockpit. This apparently occurs after approximately 4000 operations. The design of the switches is less than ideal, since it is just a slider with no over-center snap action. Since the landing light switch in my Cessna 172 has been in operation for 43 years and 6500 flight hours, it could have as many as 10000 operations. So I decided that I would replace the switch and tear apart the old one to investigate its condition. It was in better shape than I expected. The contacts are large rivets of copper, still firmly attached to the chassis. The slider plate has very thick paths of copper - it is not just an etched circuit board. As the plate slides, the paths make contact with the rivets and that is where arcing occurred. However, the sliding action of the switch cleans the contact points, so during use the current is passing between the contacts and the plates in a different location than where the arcing occurred. The contact operation of the switch is very dependent on the strength of the spring that pushes the plate against the contacts. If the spring weakened or broke, switch operation would be dangerously degraded. The spring in my switch was stronger than I would have expected. Conveniently, the spring also functions for the detent positions of the switch. So if one of these switches seems loose and doesn't click into position, it is time to replace the switch. The switch I replaced is Cessna 0713035-1 and cost me $45 Canadian. Jeff Page Dream Aircraft Tundra #10 ----- No virus found in this message. Checked by AVG - www.avg.com ________________________________ Message 7 _____________________________________ Time: 07:59:08 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Vacuum vise At 12:07 PM 3/20/2013, you wrote: >Bob, > >Great idea! Very nice to be able to have a vise front and center >when you need it and get it out of the way when you don't. > >Re workbenches. I've made a couple of benches using a plain-front >solid core interior door as the top.\ Hmmm . . . I've used doors for drafting tables. That was back in the days when the Bruning broken-arm drafting machine was king. Bought one used at Cessna and built a drafting table from a door. Used it a lot of years until the first time I loaded AutoCAD 1.17 onto a PC-XT with a monster 20 Meg hard drive. The Bruning, table and all those tools went into the next garage sale! That was 30 years ago! >Unfortunately, the nicely finished surface doesn't hold up very well >to garage bench use. I'll try your idea and screw down a sheet of >Masonite next time my bench needs a refinish. Thanks for the tip. Yeah, beat-n-bash benches need some mass. The last one I built was when we were operating the Benton Airport (1K1). I used a two-layer 3/4" MDF top covered with Masonite. You can plunk a V8 block down on it . . . 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