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 Post subject: Basic body question
PostPosted: May 12, 2021, 12:34 am 
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Joined: August 14, 2006, 1:15 pm
Posts: 47
Location: Burbs of Detroit
Looking at the sevens on this site, have a question about the body skins, particularly the side skins. I see they are riveted along the top and bottom, but it looks like the skin is not riveted to the frame vertical members. Seems that securing the skins to the verticles would improve rigidity. What am I missing?


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 Post subject: Re: Basic body question
PostPosted: May 12, 2021, 2:33 am 
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Joined: December 24, 2007, 5:11 am
Posts: 1237
Location: Seattle area
You made me look! I went over the photos of my Locost at various stages and the rivets on the vertical members just don't show up. But where the alloy and steel meet there are rivets. Spaced 4" apart.

Good luck and happy building!

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 Post subject: Re: Basic body question
PostPosted: May 12, 2021, 8:24 am 
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Joined: December 22, 2006, 2:05 pm
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Ease or repair or modification, cleaner looking, and fewer holes to allow water in. You could bond with epoxy or urethane but removal for future work could result in ruining an expensive panel. It is a good idea to apply silicone to the tubes before final skin installation for leaks at the rivetted areas and potential rattles where the skin and tube touch. Silicone is easy to remove later without skin damage.

Originals had a support brkt for the long wings that sandwiched the skin at the middle vertical.
Build books don't suggest rivets at the mid verticals.

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 Post subject: Re: Basic body question
PostPosted: May 12, 2021, 8:38 am 
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Joined: July 17, 2008, 9:11 am
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Location: West Chicago,IL
The aluminum panels are not considered structural. Sure, one could rivet them to the verticals and/or diagonals. It might add a small improvement. These space frame chassis' are pretty rigid without the added rivets. I didn't add the silicone that MV8 suggested and didn't hear any rattles. OF course in a Locost, you won't hear a passenger talking unless they are yelling at the top of their voice. I did eventually add a bead of house caulk on the upper edge of the horizontal and diagonal members. That was to keep the road pebbles from working their way BETWEEN the frame and the skin. Once in there, they will never come out and their presence will telegraph to the outside surface.

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 Post subject: Re: Basic body question
PostPosted: May 12, 2021, 1:30 pm 
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Joined: January 7, 2011, 10:47 am
Posts: 131
Location: Bethlehem PA
I used 3m panel bond adhesive in place of rivets. Much cleaner look and no issue 10 years later.

Attachment:
blended edge.jpg
blended edge.jpg [ 46.48 KiB | Viewed 705 times ]

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Chris White
Locost 7 type 1 power and a rear transaxle
Lotus Elise Sold
ND Club Miata
Nissan Titan Sold
Rubi Wrangler
http://www.locostusa.com/forums/viewtopic.php?f=35&t=13200


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 Post subject: Re: Basic body question
PostPosted: May 13, 2021, 10:33 am 
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Joined: August 14, 2006, 1:15 pm
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Location: Burbs of Detroit
I was thinking that riveting it to the verticals and diagonals would act like the shear wall in a building. Although is true triangulation will make make the frame a structure


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 Post subject: Re: Basic body question
PostPosted: May 13, 2021, 11:25 am 
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Joined: October 24, 2008, 2:13 pm
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Location: Carlsbad, California, USA
cwhite wrote:
I used 3m panel bond adhesive in place of rivets. Much cleaner look and no issue 10 years later.

. . . image deleted . . .


That's interesting. I'm taking it from the photo the bond is from the bare aluminum to the paint on the chassis. Have there been any issues with the paint coming free from the steel?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 9:31 am 
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Joined: January 28, 2021, 3:32 pm
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twentyover wrote:
I was thinking that riveting it to the verticals and diagonals would act like the shear wall in a building. Although is true triangulation will make make the frame a structure


It can, it's called "stressed skin" construction. Doesn't happen using ordinary pop rivets though.


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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 10:57 am 
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Location: Carlsbad, California, USA
Well, there are pop rivets, and then there are pop rivets. I would agree that hardware store pop rivets are marginal for our builds. However there are many race cars and airplanes doing perfectly well with aerospace quality pop rivets.
Attachment:
File comment: Lotus Elise Chassis
Lotus-Elise-Chassis.jpg
Lotus-Elise-Chassis.jpg [ 11.5 KiB | Viewed 606 times ]

Attachment:
File comment: Pop rivet detail - Lotus Elise chassis
Lotus Pop Rivets.jpg
Lotus Pop Rivets.jpg [ 79.07 KiB | Viewed 606 times ]

The above used pop rivets and epoxy, but I could have found examples with pop rivets only. There are some nice builds on this site using pop rivets for attachment of aluminum body panels. There have been long discussions of this here on LocostUSA. Try searching for "FEA Analysis" and "Chassis Rigidity" on this site.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 11:19 am 
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Joined: February 8, 2014, 10:47 pm
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Location: Cornholio OR "Where the magic happens"
I don't see aluminum side panels significantly increasing the rigidity of your chassis if you have used the recommended materials and frame member placement...

:^)

I do like the panel adhesive trick but, like the other poster observed the connection is limited by the paint applied to the steel. POR15 with the prep may stick the best?

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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 1:13 pm 
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Joined: January 28, 2021, 3:32 pm
Posts: 98
Bent Wrench wrote:
I don't see aluminum side panels significantly increasing the rigidity of your chassis if you have used the recommended materials and frame member placement...

:^)

I do like the panel adhesive trick but, like the other poster observed the connection is limited by the paint applied to the steel. POR15 with the prep may stick the best?


Any number of race car designers from the 60's and 70's would disagree. Worked on and restored a bunch of them.


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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 1:15 pm 
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Joined: January 28, 2021, 3:32 pm
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Lonnie-S wrote:
Well, there are pop rivets, and then there are pop rivets. I would agree that hardware store pop rivets are marginal for our builds.


I was talking about the usual generic hardware store variety most folks know about. Actual structural "pop" rivets are an entirely different animal and used extensively in aircraft and race cars.


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 Post subject: Re: Basic body question
PostPosted: May 14, 2021, 1:37 pm 
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Joined: January 7, 2011, 10:47 am
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Location: Bethlehem PA
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That's interesting. I'm taking it from the photo the bond is from the bare aluminum to the paint on the chassis. Have there been any issues with the paint coming free from the steel?


There is no paint between the chassis and the aluminum panels. I sanded both surfaces with an angle grinder with 80 grit disk on it so the epoxy would have something to bite into.

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Chris White
Locost 7 type 1 power and a rear transaxle
Lotus Elise Sold
ND Club Miata
Nissan Titan Sold
Rubi Wrangler
http://www.locostusa.com/forums/viewtopic.php?f=35&t=13200


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 Post subject: Re: Basic body question
PostPosted: May 15, 2021, 1:43 am 
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Joined: January 18, 2015, 2:34 am
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Location: Los Angeles
I would love to find the rivet gun that installed the rivets inside the boxed sections. Aerospace rivets with steel pins take a degree of hand strength that these old paws struggle to produce anymore.


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