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Help with machine screw source needed

Larry DeCamp

Well Known Member
My project wings came with tanks mounted. The 10-32 flat head screws have a smaller head diameter .270" than standard.370". They also have a strange drive cross that is not Phillips but not full Posidriv.

What kind of screw is it ? Where can I buy them?

If they cannot be sourced today, where can I buy any style of .270" head dia flat head machine screw ? Thanks for any help :)
 
A picture or two will help us to see the screws you are talking about. Click on the "Manage Attachment" and add your pictures.

My RV8 tank has the AN #8 screws so it's strange to see the 10-32 screws at the tank
 
Flat head, or flush head countersunk?

Larry,
if your referring to "reduced head" flush countersunk screws they are the norm in much of the heavy jet industry.The head diameter is smaller than standard AN screws. I built my -4 using many of them, mostly titanium. It sounds like you are describing an offset Philips head which are used on Airbus in some places. There re also Tri-wings which have 3 slots. Spruce sells some reduced heads..check with them. https://www.aircraftspruce.com/cata...ihIJZ8_4Gzoo80TOKrcPZFPb5rrFc_BkaAkaBEALw_wcB .
 
If so, that is a torq set drive. Do not use a four point (Phillips) bit. The sides of the recess are flat not to mention the offset. Used a lot on the space shuttle way back when. No idea why I still have one in my desk from >25 years ago.
 

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Thanks for the help

Yes, it appears they are a torq-set cruciform screw. The part number on the screw is NAS1581 A3 R. ACS and Gen aircraft parts are potential sources. Apex and Mc Master are the two driver sources I have found. The screw is 10-32. I assume it uses a #3 bit ??

Any advice on dimple die ? 3/16 appears appropriate.
Countersink options on spruce are.1890" for screws and .1875" for rivets ????

All advice appreciated...Larry
 
torq screws

Used on North American RA5C skins. Wished i had a penny for every one i took out and put back.

Used to have a few bits around.

Keith Rhea
RV7
2022 donation
 
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