Any riveting experts here? Moto trailer bed upgrade

[Mario]

Hi all, looking to upgrade the beds in my 6x10 moto trailer. Currently I have two foldable coleman cots dimensions 75" x 25" that I fold and stack against a wall. They work but they are not the most comfortable.

I am looking to replace with my own design and build the whole frame of aluminum angle, aluminum sheets and lots of rivets. Planning on using pop rivets for now (easy). If this goes well, I would like to venture into solid rivets in the future.

The plan: maintain same dimensions of 75" x 25", create an aluminum frame with 2" angle 1/8" thick, rivet the ends together with 12-14 gauge aluminum sheets. Bolt on some door hinges to the frame to fold to the wall (one frame will be fixed and hinged to wall), use more door hinges to connect the other frame to either other frame or wall (door hinges pins are easy to remove). Add IKEA slats, get a full IKEA mattress and cut in half, sew the cover and done.

I would like to do this riveted because I don't have access to welding equipment and riveting allows to make modifications anytime. I have never created riveted structures. Questions:

- Anyone with experience that can tell me if this is a terrible idea? I read riveted structures can be as strong, if not stronger than welded structures
- Any idea on ratio between sheet metal gauge and aluminum thickness that I need to join? I would like to keep gauge as small as possible to use bench shears. I don't know if I can even calculate this without CAD software.
- For number of rivets, I am planning on eyeballing it or try to calculate shear stress
- Does the joint drafted below look OK?

I am sure I can come up with more questions but this will likely get me started, or stopped if idea is terrible :teeth

 

[littlebeast]

am not an expert by any means, but in a former life overseeing aerospace manufacturing - welding was stronger, but rigid. we used rivets for structures where flex was required, and welding where strength was the primary issue (required). but these applications were at the extreme end of the stress spectrum.

my SO is an ME and used to design that shit - will ask him if he has any advice.

 

[JesasaurusRex]

Hmmm
I wouldn't trust the sheet metal interior skin, especially as thin as it is in most trailers. Course that's just a hunch, my dad's not an engineer so i could be wrong.

Have you looked into e tracks on the walls? Can atleast tie into the wall studs and then you can fab up some brackets for your bed pretty easy. And removable too.

 

[Maddevill]

Pop rivets are hollow. Not very strong unless you use steel.

Mad

 

[DannoXYZ]

How about riv-nuts and bolts? Or just old-fashioned nuts and bolts? With power-tools, it's same speed as rivets for more strength.

 

[Mario]

Thanks for replies

in a former life overseeing aerospace manufacturing...my SO is an ME and used to design that shit - will ask him if he has any advice

I was hoping to see someone that works in the field to reply I know nothing about the topic but seen aircrafts built with rivets, so I know it can be done

I wouldn't trust the sheet metal interior skin...Have you looked into e tracks on the walls?

I have e-tracks installed to the framing of the trailer. This is an aluminum trailer that I removed the interior paneling and secured everything to the frame. In places where I needed to add extra load, I bolted 2"x2" angles to the frame to make it stronger. Nothing hangs from the skin

Pop rivets are hollow. Not very strong unless you use steel

They are hollow but there should be no issue if I have enough rivets to withstand the shear load. Best would be that I use solid type rivets but don't want to make the jump to that (yet)

How about riv-nuts and bolts? Or just old-fashioned nuts and bolts?

Because I wanted to get into riveting, it lies in between old-fashioned fastening and welding. Ultimately I want to get into solid riveting, I think that is just pure mechanical porn :teeth

Pretty sure what I am looking it is not farfetched. Here is an aircraft frame build on pop rivets:

https://jameswiebe.wordpress.com/20...ture-rear-fuselage-on-an-ultralight-aircraft/

 

[Killroy1999]

Hmmm
I wouldn't trust the sheet metal interior skin, especially as thin as it is in most trailers. Course that's just a hunch, my dad's not an engineer so i could be wrong.

Have you looked into e tracks on the walls? Can atleast tie into the wall studs and then you can fab up some brackets for your bed pretty easy. And removable too.

My dads a engineer, so I asked him what he would do:

We sat down and he asked me a lot of details about the riveting problem, but we could not get anywhere because from the OP, I dont know if a ending pulling the trailer is a triple.

 

[auntiebling]

Questions:

- Anyone with experience that can tell me if this is a terrible idea? I read riveted structures can be as strong, if not stronger than welded structures
- Any idea on ratio between sheet metal gauge and aluminum thickness that I need to join? I would like to keep gauge as small as possible to use bench shears. I don't know if I can even calculate this without CAD software.
- For number of rivets, I am planning on eyeballing it or try to calculate shear stress
- Does the joint drafted below look OK?

i didnt' really read EVERYTHING but read through this
https://www.engineersedge.com/calcu...ength Design,plate, expressed as a percentage.

rivets and glue joints share many design criteria. above all, you need to keep the joint in SHEAR. as soon as it enters a PEEL scenario things start separating. think of a piece of tape attached to a desk with a loose end hanging free. pull that piece of tape parallel to the desk surface and it's pretty hard to remove. pull that piece of tape straight up off the desk and it's easy to remove. the first scenario is SHEAR, the second PEEL. Shear good, peel bad.

riveted joints can be really freaking strong, absolutely. keeping the pieces joined of similar thickness is desirable.

this setup is probably fine. i would match drill every hole and make it fit as tight as possible to the pop rivet. they're strong-ish untill there is a little bit of clearance that lets them waller out the hole and things get messy in a hurry.

this is a good excuse to get some cleco pliers and a mess of clamps to hold stuff in place while you're riveting. if the joint isn't tight together before you pop rivet it, it won't be after either.

 

[Mario]

Forgot I had the Machinery Handbook in my shelf. Same formulas there. Haven't thought about the "peel" issue, thanks for pointing that out.

if the joint isn't tight together before you pop rivet it, it won't be after either.

This is something I was not expecting. Clecos and clamps ordered!

Thanks!

 

[auntiebling]

lemme temper that statement a little: if the joint isn't together before riveting it's not going to be as tight as it could be afterwards. they'll draw together a little.

you have a machinery handbook what are you asking us yahoos for?!

putting a doubler bracket on the inside of your joint would help tremendously so the rivet is in double shear. each of the plates could be half as thick also

 

[dravnx]

Use Cherrylock rivets, buy a Harbor Freight pneumatic puller and invest in Clecos and a Cleco plier.

 

[Johndicezx9]

This is a very riveting thread. :teeth




Somebody had to... carry on.

 

[Mario]

you have a machinery handbook what are you asking us yahoos for

It wasn't till you sent that link that reminded me I had it sitting in the shelf :teeth old school solid rivet stuff but theory still applies, so I'll give it a good read

Good point on the inside bracket for double shear.

Use Cherrylock rivets

Didn't know these existed... I'll read more about these. Thanks!

This is a very riveting thread.

:laughing

 

[littlebeast]

Thanks for replies



I was hoping to see someone that works in the field to reply I know nothing about the topic but seen aircrafts built with rivets, so I know it can be done

so following up on my prior post - i showed my SO your design. he looked at it and said ‘this thing is going to be fucking bomb-proof - holy shit, how much does this guy weigh?’ lol. he added that he’s done a shit-ton of research on riveted structures (which i knew based on the aerospace design work he’s done). he gave it a :thumbup

 

[Mario]

he looked at it and said ‘this thing is going to be fucking bomb-proof - holy shit, how much does this guy weigh?’ lol.

Goes to show I know nothing about eyeballing riveted joints! :teeth

Thanks all, I am getting the supplies and building some shit :thumbup

 

[CDONA]

Aircraft & Airstreams, same riveting tech.
http://www.airforums.com
Get back into the service section, lots on rivets.

 

[afm199]

Rivet and epoxy and it's not going to come apart. I've had structural failures where the epoxy join ripped apart the aluminum skin it was bonded to.

 

[Mario]

Rivet and epoxy and it's not going to come apart. I've had structural failures where the epoxy join ripped apart the aluminum skin it was bonded to.

I talked to the trailer manufacturer about their new trailers, all of the skin (inside and outside) is now glued to the frame and not screwed. I asked about removing the inside panels to do insulation, wiring, repairs, and he told me it was impossible without destroying the skin and possibly the frame. Unbelievable how far adhesives have gone. I will miss the reparability of screws and rivets...

Aircraft & Airstreams, same riveting tech.
http://www.airforums.com
Get back into the service section, lots on rivets.

Thank you, this is a good tip! Already DuckDuckGo'ed the site and found a bunch of info. Didn't know they are heavy into rivets. :thumbup

 

[Mario]

So here goes first attempt. Had some scrap 1.5"x1.5"x1/8" aluminum angle, then went to home depot to get an aluminum sheet, got the only thing they had, a 0.019" sheet. It was not ideal but it would work to do the first try and learn some lessons. And I learned a lot of lessons!

- The sheet was too thin, the inner side would get bent and destroy by the drill once it goes through the 1/8" angle
- The L shape thing does not work (don't know what I was thinking), it concentrates the stress in the corner creating a very weak point
- I didn't pay attention to the position of the rivets, some were so bad placed that a slight force would rip the rivet from the sheet (peeling)

I ended up with this POS work

 

[Mario]

Second attempt I put a bit more effort. Got a thicker aluminum sheet, 0.063" (half of the thickness of the aluminum angle) and planned to do the double shear thing by having a plate on the inside and outside. This time I printed a template and positioned the rivets with some logic: as spread apart as possible, and as close to the 90deg corner as possible to avoid any "peeling". I also replaced the L shape with a triangle shape (I am sure all of this shit has a technical name, sorry I don't know them). Took my time to clamp the crap out of everything, clecos everywhere. Even with the clecos this thing would not move a bit. Once riveted, this thing feels stronger than a weld! This took me about 2hrs. Way slower than a weld but I really like the look of it :teeth

Next I will try the rivets suggested in this thread and at some point I will invest in solid riveting equipment.

Thanks all! :thumbup