Clueless74
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| posted on 13/8/07 at 09:18 PM |
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Rivet confusion
Firstly hello!! My first post, and sorry for the amount of questions below...
Well, I've read lots of threads on this subject and am still confused.
I want to join my galvanised steel panels to my steel frame. I've managed to conclude that using Sikaflex between the chassis and panels is a
good idea, but it's the rivet bit that's getting me confused.
I've read a bit on galvanic corrosion and I'm thinking I definitely want to avoid aluminium rivets and stick with steel.
But then there are lots of different types of rivet. People on here have mentioned that "structural" rivets have greater tensile
strength. Seems reasonable, but when I'm looking for these on the internet, are they always named "structural". I've seen a
few. But then I've seen some rivets described as closed-end which seem to be the same. Are these the same thing?
And then other people have mentioned that a large head for spreading the load is good. Again, seems sensible, but can you get "structural
rivets with large heads"?
And then other people have mentioned dipping the rivets in sealer to be doubly sure of corrosion protection. Once again, seems like good advice. But
to a newbie, "sealer" is too generic. Can someone give me an example of a trade-name that I can look out for? Or can I just use Sikaflex
here again?
And it feels like I'd need to let the sealer dry to form a non-metallic layer, but then I've seen "wet" rivetting mentioned
that presumably means rivetting whilst the sealer is wet?
Anyway, I think I may be suffering from too much information? Maybe I'm just suffering from first-build nerves!! Can anyone help please?
Cheers in advance.
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blakep82
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| posted on 13/8/07 at 09:35 PM |
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i think i'm right in thinking old landrovers (series 1, 2, 3, and maybe even the newer Defenders) are steel chassis with aluminium body
panels...
i woldn't worry too much about a few rivets to be honest. or counteract it with a big lump of zinc somewhere (i think that stops steel
corroding, but don't know what it does to aluminium...)
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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hillbillyracer
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| posted on 13/8/07 at 09:54 PM |
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Yes Landys still use steel bolts throught the aluminium body into the steel chassis & they do corrode the alloy body around the bolts, just look
at the base of the body where it goes onto the rear crossmember on any over a few years old.
If you're using steel rivets to join steel panels to the steel frame then that deals with the disimilar metal corrosion issue, & surely any
steel rivet would be well up to the job. I think the galv sheet would tear before the rivet sheared or snapped.
Just incase you dont know galv sheet isnt as good to paint, probably needs an etch primer. Somebody on here will know!
Keep asking questions though, I've yet to start my build & I see questions asked on here that never crossed my mind!
The above info is from my being an agric mechanic & fabricator.
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James
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| posted on 13/8/07 at 10:02 PM |
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Steel body panels? 
It'll be even heavier than mine!
------------------------------------------------------------------------------------------------------------
"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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RichardK
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| posted on 13/8/07 at 10:20 PM |
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Probably lighter than mine though 
Rich
Gallery updated 11/01/2011
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hillbillyracer
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| posted on 13/8/07 at 10:40 PM |
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As an alternative to rivets if you're going to use steel panels would plug welding be any good? There's obviously an issue with warping
the frame due to the weld shrinking but it'd be strong, no holes in the tube to weaken it & the panel solidly fixed to the frame would
stiffen things up. Mabye you wouldnt need so many diagonals?
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another_dom
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| posted on 14/8/07 at 06:40 AM |
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Blind rivets 101!
A typical blind rivet comprises two parts, the rivet body and a mandrel. The blind rivet is first placed into an acurately drilled hole, and an
installation tool is then used to grip the mandrel. Activating the tool pulls the mandrel, drawing it into the blind-end of the rivet body. This
forms an upset head on the rivet body and securely clamps the application materials together. The mandrel then breaks, leaving part of it in the
rivet body (more on this later).
The rivet body is available in a range of diameters, all imperial originally but now generally sold as metric (eg 3.2, 4.8 etc). They are also
available in a number of lengths, to grip different thicknesses of material. Some blind rivet designs are able to clamp a wider range of material
thicknesses and so this becomes less critical. The body can be manufactured from a variety of materials, this will effect the tensile strength (and
shear less significantly) and the force required to pull the rivet. Finally, bodies are available with a number of finishes - a painted or anodised
rivet should reduce the rate of galvanic corrosion. The mandrels are also available in a range of diameters, and the rivet tool will have a series of
'nose' pieces to accomodate these. If the mandrel is designed to break flush with the top of the surface of the body and to be positively
retained in that position it will add a great deal of shear strength - this is a structural rivet. It will also be significantly more expensive! If
the body is formed as a cup around the mandrel, rather than as a tube, it will seal the hole it is pulled in and help reduce corrosion of the chassis
tubes. These are closed rivets.
Inserting the rivets 'wet' with sealer on them before pulling them up should ensure the holes are fully sealed, but is probably not
necessary as the body will expand to fit the hole. A number of sealants can be used - standard silicone sealant from your local hardware store will
do the job but you can also use more specialised adhesives (Wurth do a good one, as do Car Builder Solutions).
It will all be much less daunting when you get started!
Dom.
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caber
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| posted on 14/8/07 at 07:48 AM |
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Why galvanised panels? Ally panels with sikaflex or simmilar between them and the steel are pretty corrosion resistant. One thing not mentioned about
steel pop rivets. . . .They take a lot more effort to pull! If you are using a plier type hand riveter you will get hand and forearm muscles like
Popeye! Closed end ally rivets are fine for panels, all ally rivets use a steel pin and I have not seen any corrosion problem with them.
LandRovers, Range Rovers and Discoveries all suffer from galvanic corrosion where water can stand for a time, door bottoms being the main problem
followed by panel joints between ally and steel where water can gather and panels that are used as electrical grounds, common with bodged repairs to
lighting.
Galvy steel has a rough surface and needs a specialist primer so will be horrible to get a nice finish on, cars that are built
with"galvanised" body shells are not treated the same way as galvy sheet, they will be hot sprayed rather than dipped, this gives a
smoother finish.
hope this helps1
caber
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MikeRJ
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| posted on 14/8/07 at 08:09 AM |
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quote:
Originally posted by Clueless74
But then there are lots of different types of rivet. People on here have mentioned that "structural" rivets have greater tensile
strength.
I suspect the rivets you have seen refered to are the type that leave part of the mandrel within the rivet body. After fitting, a standard rivet is
efectively just a hollow aluminium tube, so shear strength is quite low. By leaving some of the steel mandrel to fill the center of the rivet, shear
strength (not tensile) can be improved greatly.
For steel to steel applications it would make sense to use stainless rivets to reduce galvanic corrosion issues, though you will need to build up your
muscles if you have many to do!
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Phil.J
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| posted on 14/8/07 at 09:29 AM |
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You could always use monel rivets to avoid corrosion problems. I've used them in the past for attaching aluminium panels to steel frames with no
corrosion problems. Monel is what they used to make diving bottle valve gear from and it is suitable for salt water applications.
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DaveFJ
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| posted on 14/8/07 at 11:11 AM |
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Just to add my 2p worth....
the larger head rivets are usefull for spreading the load on weak materials like GRP. for metal-metal I would stick with normal size dome or
countersunks as you need.
Structural rivets are MUCH more expensive but will last longer and provide far more strength.
I have used a combination of monobolt type rivets (aviation type structural) throughout my build but expect to pay about £100 for a box of 500 !!!!
I coat ALL rivets with a JC5A jointing compound before inserting them, again as per aircraft building. this should minimize corrosion. JC5A is the
military spec, I don't know what the civvy equivalent is or where you can get it - sorry...
finally - the most important thing for good riveting is the holes you drill! ensure they are not elongated by poor drilling or cheap/blunt drills.
Ensure the hole is the correct size for the rivet - if you use 4.8mm rivets then use a 4.8mm drill - don't be tempted to use a 5mm because
it's 'close enough'.. the result will always be that little bit weaker and will lead the rivet starting to fret sooner.
Dave
"In Support of Help the Heroes" - Always
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Clueless74
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| posted on 14/8/07 at 12:36 PM |
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Thanks for all your advice guys.
I should probably say that I'm only using the galvanised steel panels for the floor. I'll go with aluminium for the side panels so
shouldn't be too heavy. I still need to think about which rivets to use there!! Or might try rivnuts.
But anyway, it sounds like:
I don't need large-head rivets.
If I'm worried about galvanic corrosion I can go for anodised, painted or monel rivets.
Also I can also cover the rivet in Sikaflex before fixing. I assume the idea is that most will ooze out but after wiping it off, there will be a
small amount left in any tiny gaps?
Steel rivets are harder to fix. I've got a lazy-tong riveter rather than hand pliers. This should be easier shouldn't it?
And despite another_dom's excellent post, I'm still a bit confused about structural vs closed-end rivets. Both features sound good but
can you get both together?
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DaveFJ
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| posted on 14/8/07 at 01:17 PM |
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Closed end vs structural rivets....
OK.
Generally a closed end rivet is a pop type rivet with little strength in shear. The end is litteraly closed off so that you do not have a
'hole' through the middle into your steel box section - think of it as an upside down top hat..
Structural rivets do not generally have a closed end however the mandrel is designed to break off inside the rivet body and permanently block it, so
you get the same sealed effect. the presence of the peice of mandrel withing the rivet gives it far greater strength in shear.
there is some good info on rivet types here linky
just remeber - there is a world of difference between an Avdel Avex type rivet and the tucker pop type rivet you find in B&Q! (although they use a
similair principle)
Personnally I chose Huck MagnaLok rivets for my floor pan linky
[Edited on 14/8/07 by DaveFJ]
Dave
"In Support of Help the Heroes" - Always
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another_dom
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| posted on 14/8/07 at 01:22 PM |
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Dave,
You work at Wattisham per chance? I'm 2IC 4 AAC Wksp.
Dom.
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DaveFJ
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| posted on 14/8/07 at 01:28 PM |
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Small world!
PS: what you doing with all those MBCs now that they are no longer used.... I know a worthy cause
[Edited on 14/8/07 by DaveFJ]
Dave
"In Support of Help the Heroes" - Always
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another_dom
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| posted on 15/8/07 at 03:42 PM |
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Unfortunately the bulk of the Lynx expense went straight up to Dishforth. I panelled my kit before I started on the aviation side so no gucci rivets
for me either. I did acquire some decent cable after the IPT declared it obsolete!
Dom.
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DaveFJ
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| posted on 15/8/07 at 03:46 PM |
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Out of date POL? 
Dave
"In Support of Help the Heroes" - Always
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