---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 02/02/11: 19 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:27 AM - Re: Inst GND Bus and 18 AWG wire (Robert L. Nuckolls, III) 2. 05:31 AM - Wrong pins shipped in 37-Pin Panel Ground Bus (Robert L. Nuckolls, III) 3. 07:02 AM - wire squash connections (Bob Marshall) 4. 07:42 AM - Re: wire squash connections (Robert Borger) 5. 02:26 PM - Re: wire squash connections (Robert L. Nuckolls, III) 6. 03:37 PM - Re: wire squash connections (rayj) 7. 05:12 PM - Re: wire squash connections (Robert L. Nuckolls, III) 8. 05:44 PM - Re: wire squash connections (Robert Borger) 9. 06:15 PM - When is a 'ground' not a 'ground' (Robert L. Nuckolls, III) 10. 06:24 PM - Re: wire squash connections (Robert L. Nuckolls, III) 11. 06:27 PM - Re: wire squash connections (Robert L. Nuckolls, III) 12. 07:56 PM - Re: wire squash connections (Don) 13. 08:09 PM - Re: wire squash connections (Don) 14. 08:26 PM - Re: wire squash connections (Robert Borger) 15. 09:27 PM - Re: wire squash connections (Robert L. Nuckolls, III) 16. 09:34 PM - Re: wire squash connections (Bob Marshall) 17. 09:46 PM - Re: wire squash connections (MikeRV6-A) 18. 09:56 PM - Re: Re: wire squash connections (Don) 19. 10:23 PM - Re: Re: OT-potting with RTV silicone (rayj) ________________________________ Message 1 _____________________________________ Time: 05:27:22 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Inst GND Bus and 18 AWG wire At 11:31 PM 2/1/2011, you wrote: > >I bought the AEC Instrument ground bus, which is a Dsub 37 pin >connector. In looking at my instrument panel items the radios have >18 AWG wires for the power and grounds. >The Dsub standard density pins only take up to a 20 AWG wires, so >how to deal with the 18 AWG wires. should I solder a Y of 20AWG to >the 18 AWG wire to go into the ground bus or should I just run the >wires all the way to the forest of tabs on the firewall. One fella >on another site said this would work but you can't guarantee the >flow of power would evenly split down the "Y". The radio is on a 10 >amp breaker to protect the 18 AWG wire but how does this work if you >slit to smaller wires, to share the load so to speak. Peel out enough strands from the end of the 18AWG wire to allow remaining strands to fit into the 20AWG pin. >I assume it would be bad grounding practice to just bolt these 18 >AWG wires to the cross beam behind the panel? No, but neither is is bat practice to trim the wire down until it fits the pin. Bob . . . ________________________________ Message 2 _____________________________________ Time: 05:31:44 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Wrong pins shipped in 37-Pin Panel Ground Bus It has come to my attention that a number of 37-pin ground bus kits were shipped with female as opposed to male d-sub pins. I had a note from one builder . . . I also found some kits in inventory that were incorrectly pinned If anyone finds that they have the wrong pins, drop me a note. I'll forward a correct set of pin along with a pre-addressed and stamped envelope for returning the incorrect pins. I guess that's what I get for playing around in the shop when I probably should be in bed! Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:02:38 AM PST US Subject: AeroElectric-List: wire squash connections From: "Bob Marshall" I plan to use p-mags and the installation instructions show the connections made to the controller are simply striped wire leads placed under screws. Since this is under the cowl, I was hoping that there was a better way. Is there a crimped terminal that could be used along with some heat shrink tubing? My first post here though I have been reading for a while. Thanks, Bob I would post a photo but I cannot figure how to do it. -------- RV-6A construction resumed. Planning electrical and building wing. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=329292#329292 ________________________________ Message 4 _____________________________________ Time: 07:42:25 AM PST US Subject: Re: AeroElectric-List: wire squash connections From: Robert Borger Bob, Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot. Rather than bare wires under a screw, I'd think about crimping a suitably sized ring terminal onto the wire with proper shrink tube and placing the ring under the screw along with a lock washer. Others, please chime in if there's an error in my thinking as it's info I'll eventually need. Thanks, Bob Borger Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232 http://www.biplaneforumgallery.com/index.php?cat=10046 Europa Flying! 3705 Lynchburg Dr. Corinth, TX 76208 Home: 940-497-2123 Cel: 817-992-1117 On Feb 2, 2011, at 8:58, Bob Marshall wrote: > > I plan to use p-mags and the installation instructions show the connections made to the controller are simply striped wire leads placed under screws. Since this is under the cowl, I was hoping that there was a better way. Is there a crimped terminal that could be used along with some heat shrink tubing? > My first post here though I have been reading for a while. Thanks, > Bob > I would post a photo but I cannot figure how to do it. > > -------- > RV-6A construction resumed. Planning electrical and building wing. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=329292#329292 > > > > > > > > > > ________________________________ Message 5 _____________________________________ Time: 02:26:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire squash connections At 09:58 AM 2/2/2011, you wrote: > > >I plan to use p-mags and the installation instructions show the >connections made to the controller are simply striped wire leads >placed under screws. Since this is under the cowl, I was hoping >that there was a better way. Is there a crimped terminal that could >be used along with some heat shrink tubing? Yeah, my biggest disappointment with that product. Their service experience with that configuration must be okay . . . that's what they've used since day one. Crimping the appendage of some sort of terminal in those connections might be a bit better than just crimping the wire . . . but not much. My best suggestion is to strip leads (20AWG) to proper length and then 'comb' them such that they all lay parallel to each other. Then connect with as much torque on the screws as you dare. Try to support the bundles within a few inches of where they connect with the ignition modules. Bob . . . ________________________________ Message 6 _____________________________________ Time: 03:37:42 PM PST US From: rayj Subject: Re: AeroElectric-List: wire squash connections do not archive General question on wires under screws. Is there any benefit in using an antioxidant similar to what is used on Al wire in electrical panels. Perhaps not best but better than without? Raymond Julian Kettle River, MN On 02/02/2011 03:22 PM, Robert L. Nuckolls, III wrote: > > > At 09:58 AM 2/2/2011, you wrote: >> >> >> I plan to use p-mags and the installation instructions show the >> connections made to the controller are simply striped wire leads >> placed under screws. Since this is under the cowl, I was hoping that >> there was a better way. Is there a crimped terminal that could be used >> along with some heat shrink tubing? > > Yeah, my biggest disappointment with that product. > Their service experience with that configuration must > be okay . . . that's what they've used since day one. > Crimping the appendage of some sort of terminal in > those connections might be a bit better than just > crimping the wire . . . but not much. > > My best suggestion is to strip leads (20AWG) > to proper length and then 'comb' them such > that they all lay parallel to each other. Then > connect with as much torque on the screws as > you dare. > > Try to support the bundles within a few inches > of where they connect with the ignition modules. > > > Bob . . . > > ________________________________ Message 7 _____________________________________ Time: 05:12:26 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire squash connections At 10:26 AM 2/2/2011, you wrote: > >Bob, > >Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot. > >Rather than bare wires under a screw, I'd think about crimping a >suitably sized ring terminal onto the wire with proper shrink tube >and placing the ring under the screw along with a lock washer. > >Others, please chime in if there's an error in my thinking as it's >info I'll eventually need. Just so we're all on the same page . . . The twist-n-squash terminal strips featured in this thread are probably the best there is for taking wires to etched circuit boards with convenience, minimum cost and reliability . . . UNDER CERTAIN CONDITIONS. Here's one example of the technology: Emacs! Here's one of my favorite $100 data acquisition modules that uses the same terminal strip. Emacs! Note that the bared end of a wire is NOT captured by a head of the mash-screw . . . Emacs! But by the END of the mash-screw. Further, there is a buffer strip between the wire strands and the end of the screw. If one REALLY needs to use a twist-n-squash technology, this is one of the best. Legacy design goals for aviation (and other disciplines) have adopted processes that offer gas-tightness in the metallic joints of the current carrying pathway along with wire support immediately adjacent to the gas-tight joint that prevents failure of the wire under vibration. Without getting in too much of a dither about new design goals, I think the best application of this process calls for parallel strands of wire pressed into the lower concave surface of the cavity with force from above offered by the screw. Then supply bundle support within a couple inches of the squash-joints. Note that is NOT what I did on this particular example . . . but then this DAM isn't expected to be in place and functioning after what we hope is decades of otherwise unattended service. Bob . . . ________________________________ Message 8 _____________________________________ Time: 05:44:55 PM PST US Subject: Re: AeroElectric-List: wire squash connections From: Robert Borger Bob, Oh, OK. Now I see (literally) what was being talked about. Not the "wrap the wire around the screw and tighten" kind of under screw. Would crimping a D-Sub female connector pin onto the end of the wire and adding a couple layers of shrink tube over the junction for some stress relief provide a better item to be pressed under the screw? Again assuming you would provide some wire support close to the box. Thanks, Bob On Feb 2, 2011, at 17:25, Robert L. Nuckolls, III wrote: > At 10:26 AM 2/2/2011, you wrote: >> >> Bob, >> >> Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot. >> >> Rather than bare wires under a screw, I'd think about crimping a suitably sized ring terminal onto the wire with proper shrink tube and placing the ring under the screw along with a lock washer. >> >> Others, please chime in if there's an error in my thinking as it's info I'll eventually need. > > Just so we're all on the same page . . . > > The twist-n-squash terminal strips featured in this > thread are probably the best there is for taking > wires to etched circuit boards with convenience, > minimum cost and reliability . . . UNDER CERTAIN > CONDITIONS. Here's one example of the technology: > > <1e81a25b.jpg> > > Here's one of my favorite $100 data acquisition modules that > uses the same terminal strip. > > <1e81a2d8.jpg> > > Note that the bared end of a wire is NOT captured by > a head of the mash-screw . . . > > <1e81a345.jpg> > > But by the END of the mash-screw. Further, there is a buffer > strip between the wire strands and the end of the screw. If one > REALLY needs to use a twist-n-squash technology, this is one of > the best. > > Legacy design goals for aviation (and other disciplines) > have adopted processes that offer gas-tightness in the > metallic joints of the current carrying pathway along > with wire support immediately adjacent to the gas-tight > joint that prevents failure of the wire under vibration. > > Without getting in too much of a dither about new design > goals, I think the best application of this process calls > for parallel strands of wire pressed into the lower > concave surface of the cavity with force from above > offered by the screw. Then supply bundle support within > a couple inches of the squash-joints. > > Note that is NOT what I did on this particular example . . . > but then this DAM isn't expected to be in place and > functioning after what we hope is decades of otherwise > unattended service. > > Bob . . . > ________________________________ Message 9 _____________________________________ Time: 06:15:00 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: When is a 'ground' not a 'ground' At 09:58 PM 1/30/2011, you wrote: Bob N., et al, I have run a bunch of additional tests of my antennas in various configurations to see what effect they had on VSWR readings. The raw data and VSWR results are pretty variable (to my eyes) and not very encouraging. But my immediate issue is the one that Bob N. focused on shortly after my original post -- the quality of the ground between my antenna base and my ground plane. At the time I did the original tests, it tested out at ~0.1 Ohms on my digital VOM. But I dug out the four-wire ohmmeter that I build years ago based on Bob N's directions in the AeroElectric Connection and soldered in a fresh "D Cell" battery. The meters (especially the voltmeter) fluctuated quite rapidly and over quite a range so I'm not sure my data are accurate (although it did come close to the calculated resistance of a hunk of 18 AWG wire that I used to check the four-wire ohmmeter for accuracy). While based on solid physics, THAT test tool was a hurry-up jury-rig that helped me make some good measurements in the field with locally acquired materials. It had no constant current generator and therefore taxed the operator to visually integrate voltage/current readings to deuce resistance value with something like 10% accuracy. The test current was not REAL stable. Further, using 'shorted' Adapter I'm offering from the website. I mention this because one should approach low-ohms measurements with some degree of caution. Be aware that SOME devices may not tolerate so high a test current. While exploring 'hardware' it's not a concern but be cautious with the measurement of electro-whizzies. As best I can tell, the resistance between my antenna mounting screws and the ground plane are in the 250 milli-Ohm range. This seems to be way too high. Is it? I believe you said that resistance should be in the very low milli-Ohm or even micro-Ohm range. Yes . . . and forgive me, I need to interject another simple but significant idea into this discussion. Using the DC ohmmeter to evaluate the metallic connection between two components is a legacy standard examination of the joints between ground straps and the airframe. These investigations are concerned with predicting performance of a high current ground like a cranking battery or a bond- strap for lightning protection. The DC measurement offers SOME insight for grounding antennas when the base of the antenna is brought into forceful proximity with the belly skins and structure of an airplane. But as soon as we insert a gap between the base and ground plane, the reliability of a DC resistance begins to fail for predicting performance of the joint at very high radio frequencies. For example, We could set the comm antenna up on a 22" tall pedestal of copper tube. The DC resistance of that tube may still be in the low milliohms but because its LENGTH is exactly 1/4-wave at 126 Mhz, the ground IMPEDANCE at the top of pedestal would be THOUSANDS of ohms. This is why I made the statement earlier this week that the "quality" of your antenna grounding was more of an "art" borne of experience and command of simple-ideas than a matter of measuring milliohms from one point to another. I've got one of your newer low resistance testers on order and as soon as I get it, I'll measure the resistance again. I'll probably just have to pull the ground plane and re-do the mechanical mounting again and hope I get a lower resistance. As stated above, a HIGH DC resistance reading in a stack up of metallic components is reason for further investigation, a LOW reading is not necessarily golden at radio frequencies. Would it make sense to get some conductive epoxy and bond a ground strap from the antenna base to the ground plane? I know soldering copper to aluminum doesn't work and corrodes almost immediately. I've seen some silver-filled epoxies rated as low as 0.001 Ohm-cm but that stuff is expensive. Could I solder a small ground strap to the antenna's metal base without damaging the antenna? I've got room in the hole for the BNC connector to run a small ground strap up from the antenna base to a ring terminal that I could clamp under one of the mounting screws. Would conductive gel under the hardware help? Yeaaahhh . . . maybe . . . but . . . As a a practical matter, the TC aircraft industry has learned to minimize process sensitive materials that involve pastes, goops, glues, goos and extraordinary technician's skills. In addition to the demands of skill and process to maximize performance, these materials tend to have a poor service life. They're not even close to both performance and longevity of a (1) a single piece of metal or (2) multiple pieces welded together or (3) pieces bolted together with enough force to achieve and maintain gas-tightness between the pieces in spite the variables of temperature, moisture, flexure and time. Since I've got a glass skin between the antenna base and the washer stack that leads to the ground plane, I didn't "brighten" the underside of the ground plane -- just the top under each of the four machine screws. I'm thinking if I brightened up both sides of the ground plane, there might be some improvement because of the additional contact between the hardware stack, the machine screws and the underside of the ground plane. Okay, if it were my airplane . . . I'd ditch the aluminum ground plane. Get a piece of brass sheet, .032 to .040 thick and 1" larger than extremes of antenna base on all four sides. Drill #10 close clearance holes and BNC clearance holes to match antenna base and exactly centered on the sheet. Cut 4 spacers from brass. 3/8 to 1/2-inch diameter and drilled for #10 close clearance. Cut and drill these on a lathe. By definition, the end of a cylinder faced in a lathe is perfectly perpendicular to the axis. Also, the thru holes will be exactly centered. Make them 1/32" longer than the distance it takes to come through the thickness of the composite belly material. Use 63/37 solder to 'tin' both ends of the spacers and the area around the bottom side of the brass plate. Wipe the 'tinning' off with a dry rag while still hot . . . you don't want any visible 'thickness' of solder. Bolt the spacers to the plate and solder to the plate. Tighten the bolts while the solder is molten to make sure spacers are flat to the plate. You need just enough solder to form a small fillet around the spacer. When you're done, you'll have a one-piece of metal that can be installed in the airplane. The four spacer holes need to be enlarged to about 1/8" larger radius than the spacer diameter. Put some 10-32 screws in the holes, nuts against the plate. Tape over the bottoms of the four spacer holes in the belly skin. Fill the holes about 1/2 with catalyzed resin. Paint the underside of the plate with catalyzed resin. Press the assembly into the final resting place and fixture with sand bags, shot bags, etc. When the resin has set up, remove tape and temporary screws. Clean up any resin that would interfere with seating the antenna on the ends of the spacers. Make sure the tinned ends of the spacers are clean. Fabricate at least 4 but no more than 8 'radials' from copper foil. 3/4" to 1-1/2" wide and 21" long. these can be multiple strips spliced together by soldering to get desired total length. Lay these out in as uniformly circular pattern around antenna. Length can curve up the sides and 'hop' over ribs, stringers, stiffeners, etc. Solder end of radials to the brass sheet using 63/37 electronic solder. Heavy duty iron will flow these joints one at a time and with minutes between joints to keep from heating the whole thing up and putting resin at risk. Put strips of glas and resin over the radials to keep them in place and protect from damage. Brighten under-surface of antenna base before installing antenna using 10-32 grade 8 or stainless cap head screws. Screw heads against antenna base; MS20365 or equal metallic lock nuts over washers against the plate. Caulk around base of antenna with RTV. There are no doubt other ways to get an RF-SOLID installation but this one is based on materials and tools I have. I know too that the processes and configuration would produce an installation with robustness and performance difficult to improve upon. A DC ohmmeter test of this installation would be superfluous. Bob . . . ________________________________ Message 10 ____________________________________ Time: 06:24:35 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire squash connections > >Would crimping a D-Sub female connector pin onto the end of the wire >and adding a couple layers of shrink tube over the junction for some >stress relief provide a better item to be pressed under the >screw? Again assuming you would provide some wire support close to the box. That might 'protect' the wire but now you have a single, solid, small diameter being captured between two surfaces having a larger radius. I.e., potentially less contact surface area than one could get with a compressed stack of wire strands (19 of them when it comes to legacy standard wire). The guys who designed this terminal strip were no dummies. It's really a pretty well thought out product. But I'd bet that they would not recommend that it be used under the cowl on any vehicle. Not recommending doesn't make it automatically "bad" . . . just not the best we know how to do. I think the risks are low. One could use PIDG 'pins' . . . http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND Bob . . . ________________________________ Message 11 ____________________________________ Time: 06:27:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire squash connections At 06:12 PM 2/2/2011, you wrote: > >do not archive > >General question on wires under screws. Is there any benefit in >using an antioxidant similar to what is used on Al wire in >electrical panels. Perhaps not best but better than without? Probably wouldn't hurt . . . but unless we're talking about a really bad@#$@ environment (salt air on sea-going boat?) I can't imagine that it would help. Bob . . . ________________________________ Message 12 ____________________________________ Time: 07:56:25 PM PST US From: "Don" Subject: RE: AeroElectric-List: wire squash connections Or you could use ferrules. When they are crimper down the contact is flat. See http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr els -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Wednesday, February 02, 2011 5:21 PM Subject: Re: AeroElectric-List: wire squash connections > >Would crimping a D-Sub female connector pin onto the end of the wire >and adding a couple layers of shrink tube over the junction for some >stress relief provide a better item to be pressed under the >screw? Again assuming you would provide some wire support close to the box. That might 'protect' the wire but now you have a single, solid, small diameter being captured between two surfaces having a larger radius. I.e., potentially less contact surface area than one could get with a compressed stack of wire strands (19 of them when it comes to legacy standard wire). The guys who designed this terminal strip were no dummies. It's really a pretty well thought out product. But I'd bet that they would not recommend that it be used under the cowl on any vehicle. Not recommending doesn't make it automatically "bad" . . . just not the best we know how to do. I think the risks are low. One could use PIDG 'pins' . . . http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND Bob . . . ________________________________ Message 13 ____________________________________ Time: 08:09:12 PM PST US From: "Don" Subject: RE: AeroElectric-List: wire squash connections You will need to reattach the "els" to the link on the allied web site -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Don Sent: Wednesday, February 02, 2011 7:50 PM Subject: RE: AeroElectric-List: wire squash connections Or you could use ferrules. When they are crimper down the contact is flat. See http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr els -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Wednesday, February 02, 2011 5:21 PM Subject: Re: AeroElectric-List: wire squash connections > >Would crimping a D-Sub female connector pin onto the end of the wire >and adding a couple layers of shrink tube over the junction for some >stress relief provide a better item to be pressed under the >screw? Again assuming you would provide some wire support close to the box. That might 'protect' the wire but now you have a single, solid, small diameter being captured between two surfaces having a larger radius. I.e., potentially less contact surface area than one could get with a compressed stack of wire strands (19 of them when it comes to legacy standard wire). The guys who designed this terminal strip were no dummies. It's really a pretty well thought out product. But I'd bet that they would not recommend that it be used under the cowl on any vehicle. Not recommending doesn't make it automatically "bad" . . . just not the best we know how to do. I think the risks are low. One could use PIDG 'pins' . . . http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND Bob . . . ________________________________ Message 14 ____________________________________ Time: 08:26:59 PM PST US From: Robert Borger Subject: Re: AeroElectric-List: wire squash connections Bob, Yes, I can see the PIGD pin working. If contact area is the issue, how about crimp on male spade? Lots of contact area for the screw to mash into. It has a crimp onto the wire and a crimp onto the insulation. Add some heat shrink tubing for strain relief and support the wire. Bob On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote: > > >> >> Would crimping a D-Sub female connector pin onto the end of the wire and adding a couple layers of shrink tube over the junction for some stress relief provide a better item to be pressed under the screw? Again assuming you would provide some wire support close to the box. > > That might 'protect' the wire but now you > have a single, solid, small diameter being > captured between two surfaces having a larger > radius. I.e., potentially less contact surface > area than one could get with a compressed > stack of wire strands (19 of them when it > comes to legacy standard wire). > > The guys who designed this terminal strip > were no dummies. It's really a pretty well > thought out product. But I'd bet that they > would not recommend that it be used under > the cowl on any vehicle. Not recommending > doesn't make it automatically "bad" . . . > just not the best we know how to do. I > think the risks are low. > > One could use PIDG 'pins' . . . > > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND > > > > Bob . . . ________________________________ Message 15 ____________________________________ Time: 09:27:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire squash connections At 11:22 PM 2/2/2011, you wrote: > >Bob, > >Yes, I can see the PIGD pin working. > >If contact area is the issue, how about crimp on male spade? Lots >of contact area for the screw to mash into. It has a crimp onto the >wire and a crimp onto the insulation. Add some heat shrink tubing >for strain relief and support the wire. I like the pins better . . . or simply the combed strands. Bob . . . ________________________________ Message 16 ____________________________________ Time: 09:34:28 PM PST US Subject: AeroElectric-List: Re: wire squash connections From: "Bob Marshall" Great suggestions, thanks everyone!! I think I will order the ferrules from Altech though they come in packs of 100. If I do order, does anyone want a few? My thinking is that the ferrules will do as advertised and prevent strand breaks and maybe a bit of oxidation, too. Just seems like a better connection. -------- RV-6A construction resumed. Planning electrical and building wing. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=329418#329418 ________________________________ Message 17 ____________________________________ Time: 09:46:10 PM PST US From: "MikeRV6-A" Subject: Re: AeroElectric-List: wire squash connections Wire termination ferrules are designed for use in connectors of the type used in P-Mags. See digikey.com, part number 298-10044-ND for an example. These ferrules are tin-plated copper, and they provide an insulated segment that keeps the wire bend away from the stripped part of the wire- this helps to prevent flexing that can break individual wire strands. The ferrule crimper (yes, another tool...) leaves flat sides on the ferrule that align with the clamp action of the terminal into which the ferrule is inserted. Ferrules are sized for various wire gauges, the part number that I gave above is for #18. Ferrules are available to receive two conductors, having a double- width insulation sleeve. Catalogs often contain part numbers that offer various ferrule tube lengths, but the small connectors that are used on P-Mags would probably lead to trimming the longer ferrules to fit, which is OK. I think that this approach is more desirable than the PIDG pins, because the ferrule can be trimmed to length so that the ferrule fits quite neatly into the receiving area of the connector body, leaving the ferrule's insulator supported within the box-shaped entry to the connector. PIDG pins have enough bulk that, in some of these kinds of connectors, the pin projects outside the confines of the connector body: This means that the pin is essentially a miniature cantilevered beam carrying whatever bending load that might exist in the wire's installation. In the long run this might result in flexing and breakage of the PIDG pin. Mike Linse Corvallis, OR > > Bob, > > Yes, I can see the PIGD pin working. > > If contact area is the issue, how about crimp on male spade? Lots of > contact area for the screw to mash into. It has a crimp onto the wire and > a crimp onto the insulation. Add some heat shrink tubing for strain > relief and support the wire. > > Bob > > On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote: > >> >> >> >>> >>> Would crimping a D-Sub female connector pin onto the end of the wire >>> and adding a couple layers of shrink tube over the junction for some >>> stress relief provide a better item to be pressed under the screw? >>> Again assuming you would provide some wire support close to the box. >> >> That might 'protect' the wire but now you >> have a single, solid, small diameter being >> captured between two surfaces having a larger >> radius. I.e., potentially less contact surface >> area than one could get with a compressed >> stack of wire strands (19 of them when it >> comes to legacy standard wire). >> >> The guys who designed this terminal strip >> were no dummies. It's really a pretty well >> thought out product. But I'd bet that they >> would not recommend that it be used under >> the cowl on any vehicle. Not recommending >> doesn't make it automatically "bad" . . . >> just not the best we know how to do. I >> think the risks are low. >> >> One could use PIDG 'pins' . . . >> >> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND >> >> >> >> Bob . . . > ________________________________ Message 18 ____________________________________ Time: 09:56:22 PM PST US From: "Don" Subject: RE: AeroElectric-List: Re: wire squash connections Bob I use them on my P-MAGS. Like Bob N says these will not form gas tight connections in screw down devices, but they do provide a fairly lagre contact area and they keep the wire from being stressed. I check mine every condition inspection. So far I have not needed to replace any wires but it will be easy when the time comes. I wish that the P_MAGS came with D-SUB connectors, but I am not holding my breath. Don -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob Marshall Sent: Wednesday, February 02, 2011 9:32 PM Subject: AeroElectric-List: Re: wire squash connections Great suggestions, thanks everyone!! I think I will order the ferrules from Altech though they come in packs of 100. If I do order, does anyone want a few? My thinking is that the ferrules will do as advertised and prevent strand breaks and maybe a bit of oxidation, too. Just seems like a better connection. -------- RV-6A construction resumed. Planning electrical and building wing. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=329418#329418 ________________________________ Message 19 ____________________________________ Time: 10:23:52 PM PST US From: rayj Subject: Re: AeroElectric-List: Re: OT-potting with RTV silicone do not archive Thanks to all for the info. I'm going to go with a coating of E 6000 and I'll add additional layers of RTV, if necessary. Raymond Julian Kettle River, MN On 01/30/2011 01:15 PM, Robert L. Nuckolls, III wrote: > > > At 10:30 AM 1/30/2011, you wrote: >> >> You can buy silicone without acetic acid at the pet store - used for >> sealing aquariums. I haven't tried it for potting though. > > Thank you! I'd forgotten about that. I think the > same grade of RTV is approved for situations that > come into contact with food. > > I'm pretty sure this stuff would do the job if applied > in several layers of 1/4" or less and allowed to cure > before more is added. > > > Bob . . . > //// > (o o) > ===========o00o=(_)=o00o======== > < Go ahead, make my day . . . > > < show me where I'm wrong. > > ================================ > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.