Attaching Items to Walls ??? - Event Date: 29 Mar 2020 - 29 Jun 2020 |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Calendar Event: Attaching Items to Walls ??? Posted: 31 Mar 2020 at 8:39am |
lostagain, cold flow (aka creep) is a phenomenon that occurs with some materials when they are subject to mechanical stress at elevated temperatures. That is what the problem has been with Al household wiring from the 70's. Poorly designed and installed electrical terminations get hot from the current flow and then the Al creeps, getting looser and looser until the terminations wind up catching fire. That shouldn't be a problem with mechanical fasteners at normal temps. Another property of Al can be a problem with those. Steel has a fatigue limit, meaning that stresses imposed below that level don't cause fracture (crack) propagation. Aluminum has no fatigue limit, so even low stress levels can cause crack propagation, just more slowly. That's why Al aircraft parts often have life limits, but they're usually in the range of tens of thousands of hours. In reality, neither of these is likely to be a concern with hanging stuff on the aluminum structure of your rPod. The parts aren't under a lot of stress to being with and the over the road stresses don't go on for a long time. If I wanted to hang something heavy to the outer walls I would attach it to the Al tubes, and I'd use multiple self tapping fasteners as suggested. There are specs for fastener shear and pullout strength depending on material type and thickness, or you could do a couple of pullout tests on your fastener of choice in the same material and use that information to decide how many to use. Typical good practice would be to use a 2 or 3x safety factor on top of the 2 to 2.5x bump load increase, so around 6-8x as much fastener strength as the weight of the thing you're hanging. As for 3M tapes, these like the Command ones use adhesives that are in the family of pressure sensitive adhesives (PSA's). They can work well if you are careful to control application conditions, but they can also fail really badly if not applied right, if temperatures are out of range, or if surfaces you are attaching are not compatible or properly prepared. Take a look at the wikipedia article on them for example. Personally I don't trust the adhesive tapes for anything important, especially in one off or field applications where you're not sure you're getting things perfect. I once had a whole 250 kilowatt solar array that someone had the bright idea to attach with VHB tape come apart in a windstorm. Broken glass everywhere. Give me nice properly engineered mechanical fasteners anytime, they are much more tolerant of imperfect application conditions than the PSA tapes are. Our use both, can't hurt. The other thing you can do is attach your stuff to a closet wall where you have access to the other side so you can add backing material and reinforcement that will end up concealed. Then you can attach whatever you want. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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rPodCamping
Newbie Joined: 28 Mar 2020 Location: Michigan Online Status: Offline Posts: 21 |
Posted: 31 Mar 2020 at 8:01am |
It sounds like there are some very strong tapes that will do the job - but we better be sure where we want things attached !!!
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geewizard
Senior Member Joined: 16 Apr 2017 Location: Spokane Online Status: Offline Posts: 347 |
Posted: 31 Mar 2020 at 7:49am |
I've used this product on a number of applications and it's VERY strong. Don't expect it to ever come off and plan accordingly. I haven't used it yet in my Pod. I got mine from Amazon. |
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2021 Winnebago Micro Minnie 1708FB
2017 R-Pod 177 (Blue) HRE SOLD 2004 Outfitter Apex 8 camper 2014 Toyota Tundra DC |
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JR
Senior Member Joined: 31 Aug 2018 Location: Manistee, MI Online Status: Offline Posts: 345 |
Posted: 30 Mar 2020 at 6:30pm |
On a cool night and a warm camper the studs will show off on the outside of the walls and humidity helps (I think that is what is needed) and that Cribbage board has stayed on the wall for about 13,000 miles or until my wife want to play a game but I have used 4 - 16 lb strips, little over kill
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Jay
179/2019 |
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mcarter
podders Helping podders - pHp Joined: 07 Apr 2016 Location: Greenbrier, TN Online Status: Offline Posts: 3419 |
Posted: 30 Mar 2020 at 5:21pm |
+1 to Lostagain. Stud finders are unreliable, and I have some good ones. The frame is not a standard frame as one would think. It basically follows windows and door in sidewalls.
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Mike Carter
2015 178 " I had the right to remain silent, I just didn't have the ability." |
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rPodCamping
Newbie Joined: 28 Mar 2020 Location: Michigan Online Status: Offline Posts: 21 |
Posted: 30 Mar 2020 at 4:54pm |
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lostagain
Senior Member Joined: 06 Sep 2016 Location: Quaker Hill, CT Online Status: Offline Posts: 2587 |
Posted: 30 Mar 2020 at 3:02pm |
We have successfully combined a mechanical fastener, such as a short coarsely threaded screw, with 3M super double sided foam tape. <https://www.uline.com/Product/Detail/S-23154/3M-Double-Sided-Tape/3M-414-Scotch-Extreme-Mounting-Tape-1-x-60?pricode=WB9107&gadtype=pla&id=S-23154&gclid=EAIaIQobChMIxarGt_rC6AIVguNkCh06wg7cEAYYByABEgI30_D_BwE&gclsrc=aw.ds> The tape is inserted between the wall and the thing you are attaching to the wall, but there has to be enough surface area on the item being attached or you won't get strong adhesion. We never had anything come off. But, 10 lbs. attached to the wall is really heavy and, speaking for myself, I'd want multiple fasteners, with all being attached to a structural member for something like that.
Just for fun, before posting this, I weighed our 10" Lodge cast iron skillet. It weighed 5 lbs. I'd never hang something like that on a trailer wall, even with a fastener going into the aluminum frame. Aluminum is famous for giving way to constant pressure, I think they call it cold flow, and eventually the fastener would likely pull out. For things of that weight and up, I'd want it through bolted with washers or multiple fasteners all attached to a structural element.
I tried two different electronic stud finders, one with a metal setting, and got erratic results. I can't speak for others, but the ones I have are too unreliable, even though they find metal studs in my house just fine. |
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Never leave footprints behind.
Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 30 Mar 2020 at 1:21pm |
Good question. I haven't tried a stud finder. The side walls have aluminum square tubing so I'm not sure a magnetometer based detector will find that. The old school stud finders with the magnets in them wouldn't. The new imaging ones ought to work.
You might not need that though, you can know pretty close where to look if you review the construction videos, mostly the aluminum frames the doors and windows. Use a tiny drill bit to make a pilot hole, worst thing that happens is you seal up the little hole with a bit caulk. Don't drill all the way through the wall though, its only an inch.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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rPodCamping
Newbie Joined: 28 Mar 2020 Location: Michigan Online Status: Offline Posts: 21 |
Posted: 30 Mar 2020 at 12:23pm |
Ok, thanks.
Forgot about the ride down the road potentially making items heavier and knocking them off the wall. Maybe we take everything done before we go down the rood...... Have you ever tried to use a standard stud finder to locate wood or metal 'studs' (or whatever the correct term used for trailers is...........)? Guess I'll give it a go when we finally get the trailer to our home. Appreciate your thoughts..............
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 30 Mar 2020 at 11:23am |
I've had Command stuff fall off walls before. Seems like it adheres well initially but once its there for few months it often seems to fail. I suspect humidity causes it but don't know for sure. One good thing is that the hangers came off clean and didn't mar the wall finish. Can't say the same for the stuff that fell down though.
Also note that something that weighs 10 lbs will effectively weigh 20-25 in a trailer going down a bumpy road, so plan accordingly.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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