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Mystery Flathead Screw

Mystery Flathead Screw

Mystery Flathead Screw

(OP)
I would appreciate it if someone could give me the technical term for this flathead screw. http://www.vegasamusement.com/eng/Mystery_Flathead_Screw.jpg I have searched high and low for this fastener with no success. The screw I measured was one that I found on a computer case. I am in need of them for my current project I am working on, thanks in advance.

RE: Mystery Flathead Screw

Are you sure it's really a metric thread?

TTFN



RE: Mystery Flathead Screw

It appears to be a standard countersunk screw with a 120 degree bevel instead of the standard 90 degree.
You use to find these everywhere when it was fashionable to build you own box. All the component suppliers had little bags of them, in fact I'm looking at a half bag of them a the present time. Unfortunately it has no label.

How many are you looking for?

I would check.

www.mdmetric.com

RE: Mystery Flathead Screw

(OP)
I am looking for 1000 or so, we are making our own proprietary computer case, and I am also hoping to use them on a monitor enclosure.

RE: Mystery Flathead Screw

(OP)
I just checked it with an M4 x .7 thread gage, so yes I am certain that it is metric.

RE: Mystery Flathead Screw

If you had 1/2 a bag of the finish washers, I would swear that they were finishing screws.  I too use them, on computer rack cabinets to hold the panels in place.

Lee

RE: Mystery Flathead Screw

(OP)
I thought it was a fan screw as well but come to find out fans screws use a bastard thread size. mainly used to tap am existing diameter.

RE: Mystery Flathead Screw

I conferred with my fastener buddy about your fastener and here are some of the conclusions reached.

He has seen fasteners with your approximate dimensions but they had thread forming threads.

The bevel at 120 degrees is unusual in respect that the normal bevels are 82, 90, and 100 degrees. The 120 degree bevel is common on flush rivets for thin skin applications.

We tried to use the backdoor approach by contacting manufacturers of 120 degree countersinks. No luck, they professed no idea of the end use and didn't part with any names of purchasers.

A local box builder, no longer builds, couldn't tell him any of their suppliers even though they were sure they used this size. They were no old hands around.

His suppliers only offered the 82, 90, and 100 degree head as standard. Both had a a quantity 1000 for non-stock items. This might be of help if you find someone who makes them.

Don't give up, strange things have happened on the way to the Forum.

RE: Mystery Flathead Screw

120° ???   The image shows approx 58° angle. (180-2*64)

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: Mystery Flathead Screw

Have you tried the 8-36 thread to see if it
also fits.  This would be equivalent to a
M4.165 x .706mm pitch.  Very close to the
M4 x .7mm pitch.

RE: Mystery Flathead Screw

Doh ... that should be 52° ... I need some sleep!

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: Mystery Flathead Screw

CBL's excuse was lack of sleep. Right now I don't know what mine was except senility.

GamEng,
Will you please verify the angle of the conical section and help an old man out.

RE: Mystery Flathead Screw

(OP)
unclesyd, I do not know the exact angle of the head, and i have no way of checking it other than doing the math. The bottom line is this screw will actually screw in flat to a .072 (14 Ga) piece of sheet metal. This is due to the fact that you cannot countersink sheet metal over 1/2 the depth of the thickness of your material, due to fatigue performance issues. Your standard 82 deg and 100 deg screws will not set flat when you have countersunk the sheet metal to it max diameter.  

RE: Mystery Flathead Screw

Clean up the drawing and send it out for bids.

There will probably be a minimum order of 25,000 pieces or so for a total custom screw, with any features you want.

You will be amazed how small a container that quantity will need.

You will probably be pleasantly surprised at the cost.

Mike Halloran
Pembroke Pines, FL, USA

RE: Mystery Flathead Screw

(OP)
lumenharold ,

You are right that is the closest I have seen, if it only had a phillips head instead of the slotted head I would kiss you, lucky for me and you it isnt the exact screw. Tempted to try them but the old fashion slotted head proves to be worthless in many application. Thanks lumenharold .

RE: Mystery Flathead Screw

This screw reminds me of the stang attach fasteners on Grumman manufactured thrust reversers, such as those used on the AMD-BA Falcon 10, or the IAI 1124 Westwind Corporate jet aircraft. I don't have the p/n in front of me, but I'll check tommorrow. Betcha they're too expensive for your application, tho.

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