Pop Rivet vs Screw..Which is stronger?

Discussion in 'Materials' started by rebar, May 9, 2012.

  1. Petros
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    Petros Senior Member

    If tensile loading is critical you need an expansion anchor that will be enlarge after it is inserted though the wall. A blind fastener is not that strong, it is soft ductile material and it is hollow, so there is not that much strength.

    IF the wall is thin, than self tapping screws will not have enough threads in contact with bast material to give you much strength. The "riv-nut" that PAR suggests is a good solution, but I do not think they have that high of a tensile rating.

    There are high strength blind fasteners made for aerospace application, but I am not sure where you would get just a few for your application. Try Aircraft Spruce and Specialty perhaps (they sell small quantities of aircraft parts to home builders).

    Is there any way to redesign the mount so it puts the fasteners in shear rather than tension? How about through bolts?

    If you can post pictures of the problem, or better, detailed drawings someone might think of something that might be useful to you.

    Good luck.
     
  2. Frosty

    Frosty Previous Member

    Rivets come in different lengths, you can get longer ones to use a back plate or 2. you can even hammer a pop rivet like a ships rivet.

    You can rivet a back plate that holds an encapsulated nut and bolt it.

    All this is providing you can get the the back of it.
     
  3. SamSam
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    SamSam Senior Member

    Is 200 lbs a guess or was some formula followed?
     
  4. Frosty

    Frosty Previous Member

    Mike in your situation where you cant install a washer or nut I would suggest a

    ( sorry not been invented)
     
  5. jehardiman
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    jehardiman Senior Member

    You might be able to use a single piece blind rivnut like PAR shows, but you need the RIGHT rivnut, of the RIGHT material, for the RIGHT grip. So far I have only found rivnuts of 10-32 UNF up to a grip of 0.080 in aluminium, which means that they do not expand enough to develop full strength for 0.125 sheet. FWIW, I never recommend down-rating fittings, because you never know who will come in behind you and just check the rating stamped on the fitting..
     
  6. PAR
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    PAR Yacht Designer/Builder

    I'm not sure what grip range he needs, nor much else about his situation with the given information, but I'm looking at a catalog with over 3 times the grip range you've seen John, in aluminum, mild steel, stainless and brass.
     
  7. rwatson
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    rwatson Senior Member

    Don't forget, you don't have to be restricted by the diameter of the hole.

    You can drill a hole big enough for the washer and nut to go through, as long as the vertical slot underneath is only the width of the bolts diameter.

    Its rare that the ability of the wall panel to slide up is crucial.
     
  8. rebar
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    rebar Junior Member

    Thanks PAR. The Thick-wall maximum strength design on the Hansonrivet.com site look like what I need.
     
  9. rasorinc
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    rasorinc Senior Member

    Last edited: May 11, 2012
  10. Saildude
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    Saildude Junior Member

    The issue is they don't have access to the back side -

    the "sex bolt" I have seen called "Barrel Bolt" at my local stores - I have used them a lot to get rid of the nuts and such hanging down into the cabin (no liner) - looks nicer than regular nuts and safer from bumps and such.
     
  11. SheetWise
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    SheetWise All Beach -- No Water.

    If what you're mounting will cover the wall material, just cut a keyhole slot and put a washer behind it. I'm also surprised nobody mentioned Molly bolts.
     
  12. SheetWise
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    SheetWise All Beach -- No Water.

    You didn't mention how much space there is behind the wall, or if the mounting hole has to be flush with the wall -- but here's another idea.
     
  13. P Flados
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    P Flados Senior Member

    I did a quick search for hanging stuff to metal stud walls and noted that some molly bolts and toggle bolts seem interesting.

    Even though designed primarily for sheetrock, a 3/16 molly is rated at over 200 lb in 3/4" wallboard. For thinner walls, the sheetrock would be limiting, not the molly. The molly expands big on the backside. You could probably get a pack for a few bucks at your hardware store and give them a test on some scrap material to see how they work. I am a little concerned that you may not find any that will work without more thickness than you have available.

    Still, just look over the display for wall hanging supplies. This stuff is made to hold up big heavy TVs and such.
     
  14. PAR
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    PAR Yacht Designer/Builder

    If you stick with the parameters of the original poster's requirements, then most of these go out the window folks.

    He needs something that works well in tension, not so much in shear. He can't get at the back side, so washers are out. The material is relatively thin walled aluminum.

    Mollys are good in shear, but will point load on thin walled aluminum badly. Ditto for toggles of the various types.

    I'm not sure what you're doing yet, so more advise is difficult, but it sounds like you might be attaching a sail track? If this is the case, the close centers along the track will permit regular pop rivets (stainless). A threaded insert can also be used, but is a little over kill on a small boat sail track, unless you need to remove it a lot.

    Again, if you told use what the use is and the actual situation, it would be easier to adapt a solution.
     

  15. rebar
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    rebar Junior Member

    I don't know what more information I can add PAR. The aluminum wall studs Im attaching to are 1 x 2 1/2 x 1/8" 6061 so the depth I can insert something is limited to 7/8" max.

    I found this and these.. But I cant decide if I want SS or steel in this dry environment.
     
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