Parcel Shelf Bolts?

[MrBurns]

Hey guys, I've got limited/no knowledge of nuts n bolts so, was wondering if anyone knows what these bolts might be called and where I can find them (see pic below)? I've been to bunnings, mitre 10, etc... but none of them have them (or at least I couldn't find them after searching forever). I've searched google for days n days, but still cant find anything even close to these. If I knew what they were called it might help i suppose cos then i'd know what to ask/search for.

I'm intending on using a few of them to secure my rear parcel shelf (which i'm re-building using MDF), to the car body. Before you ask, the reason I cant using normal bolts is they'll be covered with black carpeting so I then wouldn't have access to the bolt heads to allow me to tighten them and also, the bolt heads would stick up into the carpetting leaving little lumps everywhere that the bolts are.

I've thought about using the pronged tee nuts instead, but all of the ones i've found allow the bolt to go all the way thru the top of the nut which could allow the bolt to go all the way thru the nut and thru the carpet sitting on top it.

If anyone knows what these are called, where I can get them or perhaps can think of a better way of solving my problem (i'm sure i'm missing something stupidly obvious ), that'd be great cos i'm stumped here.

Cheers

Edited March 18, 2010 by MrBurns

[Duncan]

um can you take another shot at explaining what you are trying to do :|

no doubt there is a solution!

are you just trying to fit an mdf sheet to metal parcel shelf - then cover with carpet?

[Rekin]

Buy regular bolts and use them. You wont see any bumps in the carpet.

Jump in the boot and find the bolts sticking out. Grab a spring washer and a wing-nut and tighten them.

Simple

[Rekin]

Refer to this;

http://www.skylinesaustralia.com/forums/in...t&p=2756718

[The Bogan]

I just used the plastic press in jobbies from a 100 Series Land Cruisers rear trim which was 5mm ply covered in sub box carpet stuff , fitted like they were made for it, could glue them under the carpet or just paint them black.

[Craved]

you want a lag stud - wood screw on one end, metric threaded stud on the other

unfortunately i do not know if :

A) you can get them small enough to suit your requirements - eg M6

B) you will be able to manouver the tray into place with studs fixed to the bottom of the tray if mounted close to the window

there are other option such as a allen key counter sunk bolt, with a nut holding it in place under the tray (drilled out to have nut flush with the underside of the tray to hold the bolt captive) then run another nut under the metal tray

your flush plate idea would work but is over thinking the solution - and could be fabricated easily by a metal fab shop or home welder

[MrBurns]

Thanks for the tips guys, they've put me back on track... i hope.

Yeah, I figured I was over-thinking it. I've decided to just go the simple hex-bolt option, going through flat washers on the top of the MDF, locked with Nyloc Nuts on the underside of the MDF:

I used the Nyloc nuts instead of just using spring washers due to this site advising against spring washers (whether its rubbish or not, i dont know but seemed pretty logical). I figured that over time the speaker vibration might cause the spring washer to spin loose.

Anyway, i've put a few of them on and there's no chance of it spinning loose (the nyloc nuts make it very tight) and the bolt heads dont stick up as much as I thought they might, so it shouldnt leave any bumps in the carpet. I'll put a sheet of sponge between the MDF and the metal parcel shelf to help prevent them from vibrating against each other.

Hopefully this info can help out other rookies stuck on the same problem.

Edited March 19, 2010 by MrBurns

[warps]

instead of just using spring washers due to this site advising against spring washers (whether its rubbish or not, i dont know but seemed pretty logical). I figured that over time the speaker vibration might cause the spring washer to spin loose.

Spring washers are still specified and used commonly on mining equipment, so they aren't as bad as that article says. Bolts that are close to their limit will be likely to loosen even with spring washers, specially if the joint is under massive shear forces. If that were the case, I'd argue the bolts aren't offering enough clamping force so you need more of them, or bigger bolts.

There are a couple of errors on that website. Their assumption that bolts fatigue when they are subjected to bending from loosening is incorrect. It's the fluctuating tensile stress in the bolt (due to insufficient clampig ) that usually causes them to break. I've seen big structures located in fitted spigots (so there's absolutely no possibility of bending on the bolts) break due to fatigue loading. Longer bolts / correct bolt tensioning (not torquing) fixed the problem. If bolts were subject to enough bending to break them, you would most likely get fretting around the bolt hole and possibly in the mated surface.

What this article failed to mention is that you don't need any movement between the bolted components to start breaking bolts in fatigue.

Sorry - just a bit of bolt nerd talk, but yes, very few people understand the science of bolts.