stainless steel screw

[bragee]

hi,
i need to know the code for a peculiar type of protruded head stainless steel screw. the one i've seen has the hexagonal head socket that goes through the entire length (i.e. there is an hexagonal cavity inside the threaded shank).
thanks a lot

 

[CorBlimeyLimey]

Never seen or heard of those. What style of head? Or is it a threaded rod with a through hex.

 

[bragee]

something like pictures attached (i've omitted thread and the half sphere head shape).
understood more or less? (i've briefly designed it using sketchup)
thanks for helping

 

[CorBlimeyLimey]

So like a regular Socket Head Cap Screw, but with the hex drive throughout. Strange!

Do you have one of these? Does it have any markings on it?

 

[bragee]

nope.. i don't.
i've seen it past week in a nautical store and was unmarked.
it's a strange piece, yes.. but perfect for my purpose.
thanks again

 

[CorBlimeyLimey]

Suggest you ask someone at the store.

 

[berkshire]

In the 1970's A company I worked for used a screw like this as a tamper-proof screw on a coin collection device. It was inserted from underneath the part, and screwed into place with an Allen wrench so the only thing visible was the small end of the bolt. The average person looking at the part would assume it was a standard Allen screw, and upon trying to loosen it, would tighten it even more.
we made the things entirely in house with a Hardinge screw machine and broached the hex. I have never seen another until I saw your sketch.Unfortunately that machine shop was bought out and closed in the early 1980's.
B.E.

 

[evolvingape]

Well I have never seen one of those. Puzzling!

My gut reaction was its a security screw. You drop it into a cavity onto a hex type "key" and then you can turn the key easily. No allen sockets are that thin and long that I know of. Best guess is its the key to Fort Knox but only for those in the know lol

 

[bragee]

i've tried almost everywhere here in venice but looks like this type of screw is somewhat not findable..
i think i'll have to review my ideas..
thanks again for helping.
best regards

 

[mcgyvr]

yes thats a custom screw for sure... How many do you need? Anyone that makes fasteners will make them for you..for a price/min qty obviously.

 

[CorBlimeyLimey]

I've seen it past week in a nautical store

Why not ask the management of the store, where they bought them?

 

[racookpe1978]

1) What part of the screw do you really need to clamp your assembly? That is, do you need the external threads on a cap-screw type head, with the internal hex not needed to go all the way through?
Do you need the internal hex opening all the way through the shaft and head, or only in the cap-screw head part, or only in the shaft part?
Can you live with a round hole at one end or the other? If so, would that round hole need to be larger than the hex opening (tip-to-tip), or internal to the hex openingflat-to-flat?
Do you need external threads at all, just on the end of the bolted shaft, or all the way up the external bolt shaft to the bottom of the head? Can the cap-screw head be square or hex itself? Knurled?

 

[kacarrol]

I think I've seen one of these before. Pretty sure it was on an Eagle Talon (car). I think it was to allow oil or something to get through while holding the two pieces together.

 

[KENAT]

Never seen one with a hex all the way through.

I have seen vented screws which had a round hole all the way through.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[kacarrol]

It's almost like a banjo bolt, but I'm pretty sure the one I was originally thinking of had a different name. Sorry I can't think of it right now.

http://www.schofieldcomputer.com/myCoupe/modules/wordpress/?p=160

 

[asimpson]

Looks like a special.

Misumi do through hole screws:

http://uk.misumi-ec.com/pdf/fa/p1359.pdf

They also do specials

 

[bragee]

hey thanks for all these answers..

i can't ask to nautical store where they bought them since the nautical store itself is attempting to sell me them for 10 euros the pair.. i won't receive any good indication for sure.
what i need is having the metric thread outside and an internal hole to fit a 5mm dia shaft (a circular hole would be perfect as well).
nautical store parts are always expensive and unfindable (that's why they can sell them to 5 euros each).
the fastest solution could be reaming a 5mm dia hole on each stainless screw one by one or, better, review my design using a drilled plate with two screws to grab it to fiberglass (i.e. something like a nutplate without thread).
i'll go on searching for now..
thanks you all again guys for precious attention
cheers

 

[KENAT]

Just plain vented screws aren't that special, you should be able to find something. As asimpson says places like misumi should be able to supply them.

Not sure which eurozone country you're in but if you have an equivalent to Mcmaster-Carr or the like then they may even be able to help.

A google search of 'metric vented screw' will turn up plenty of results.

Now if you need the vent holes to be precision, then it might be trickier.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[DAVIDSTECKER]

Are you trying to tighten the screw by the tip instead of the head?
If so you might think about cutting a flat blade screw driver slot in the tip.