Advice on Seat Hardware

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#1

Hello and thanks in advance for those who reply.

I’m working on a very small project for really kicks and they’re bucket seats. The materials I’m using are the MTI hose and also the duratec sunshield IMC.

Details are that it’s a single piece seat with mounting hardware on the side, basically 2 bolts on each side with 4 total securing the seat to the seat rail.

This is a mold that needs to be double bagged as well so I’ll be envelope bagging everything.

The issue I’m coming across is that the mold is already done. I made it with just slight indentations where the bolt mounting holes are on the side. I originally thought it would be fine to just use some some epoxy adhesive, then put carbon around the base of the “weld nut”.

If you are unsure about a weld nut here’s a link to what they look like.
http://www.mcmaster.com/#weld-nuts/=y2x3lo

Let’s say above is option 1, drill the hole and then add the mounting hardware later.

Option 2 would be this:
Drill holes in the mold all the way threw, since it’s being envelope bagged it’s fine.
Take a bolt that the weld nut will attach too and put the base of the weld nut in between inner layers of the carbon. The bolt will secure and hold the weld nut from moving since it will be on the outside of the mold and the weld nut will be on the inside of the mold.

If anyone has any suggestions or tips please let me know. I’ll probably use plastic bolts and coat with release agent for easier release than metal as well.

#2

If the mould is not made for inserts I would not drill holes in a mould. So mount them after the part is finished. I have done that a other seats too but I used different nuts.

#3

DDcompound. Thank you for the advice.

Can you maybe send me the link to your boots used? I looked at bighead and a few others but I don’t think anyone had a m6 thread that I was looking for.

Would you say though epoxy and layers of carbon afterwards is enough strength in a crash? I guess as long as the seats are thick enough in those areas all the standoff bolt surface has to do is keep it from pulling threw the seat itself encase of an accident.

I’m just trying to be as safe as possible

#4

Sounds like best to glue them in after.

I have done this using T nuts where I set the nuts on the backside of the part using a nylon bolt ( or waxed bolt) with epoxy glue and then add a few layers of carbon cloth over/around the nut also.

T nuts http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCQQ9QEwAGoVChMI5c7SlY_ixgIVYdimCh0yWwBh&url=http%3A%2F%2Fwww.google.com.au%2Fimgres%3Fimgurl%3Dhttp%3A%2F%2Fwww.theboltbin.com%2Fimg%2Fp%2F8%2F9%2F89-home_default.jpg%26imgrefurl%3Dhttp%3A%2F%2Fwww.theboltbin.com%2Findex.php%3Fid_product%253D29586%2526controller%253Dproduct%26h%3D200%26w%3D200%26tbnid%3DnZdt6Ektd9LPgM%3A%26tbnh%3D160%26tbnw%3D160%26usg%3D__P4Xbkyo2cm16SQ69uFlPJL-G3M0%3D%26docid%3D-ShKwh3E8f9e0M%26itg%3D1&ei=mO6oVeWiN-GwmwWytoGIBg&usg=AFQjCNEG3SLmbDnUPPWRvpD3VdIQGFerIA&sig2=lbYbafAKZBZFpx9duQbkiw&bvm=bv.98197061,d.dGY

The spikes kind of poke through the carbon layers you place over the back. Also available in SS.

#5

Sorry, take a look here

http://shop1.r-g.de/art/305156

http://shop1.r-g.de/kat/Werkzeuge---Zubehoer

#6

I agree with DDC. I have mounted nuts after part was made in several parts. I use ROTOLOC. I’m in Houston if you’d like to check them out. They are like the ones that DDC showed.

#7

What can I say but thanks! You guys are awesome. Ro Yale I’ll shoot you a pm and maybe swing by sometime!

#8

Just got some m8 open stainless steel items from rotoloc.

Any tips on what to use to bond? I also think I’ve heard you should put a layer of fiberglass to not have any reaction with the stainless and carbon down the road.

I have a 1.5 inch base plate so it gives me plenty of surface area, but how much further should I extend past that with my carbon? Maybe 4 inch diameter?

Just trying to be as safe as possible. Again these are seats I’m using and a friend so the last thing I want to do is something to fail.

Or would I use some type of thick 3m bonding adhesive with the expensive two part mixing dispenser and after that cures add the carbon afterwards?

I’d like to avoid buying the 3m bonding adhesive and stick to the adtech 820 epoxy or other methods if possible…

#9

The glue should just hold it in place, it should not take any loads. So you can use also otger glues. If it will take loads you have to calulate that.

#10

Well that’s the main reason why I’m asking for advice.

I guess following this and doing some quick research. If I’m using this adhesive which has a peel strength of 50lbs per and a shear strength of 4500 per square inch then assuming a crash that creates for the driver 20g’s that equals 4,000lbs of force for a 200lb driver.

Am I looking at this correctly? Where this would be a good product to use since the shear strength is decent and the peel strength is ok? I’d like to though use something with a higher peel strength, although there are two bolts on each side spreading the load.

http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~/3M-Scotch-Weld-Epoxy-Adhesive-DP420-Black-200-mL-12-per-case?N=5754+4294871752&rt=rud

#11

I prefer to manufacture parts so that the fasteners would have to “pull through” the laminate in a failure scenario This lets you rely on the material failure as a baseline, not adhesion limits which are specific to the angle of the applied force and hard to predict

#12

Yeah I know… I wish at this point I would’ve done that but the molds already done at this point. However I do plan on adding a few lawyers of carbon over the base

Anyone have any comments on the theory I had above with the 3m bonding agent?

#13

In theory your bondi g calculation is correct, but only in a perfect world. There are a lot more thongs to take care in your calculation.
But even if the mould exists it should be possible to infuse the insert between or under the layers.