Machine screw drives

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timotb
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Machine screw drives

Post by timotb »

Vans supplied lots of Phillips head machine screws for the short 1/2", 8-32 and 6-32 used commonly on my RV7. Phillips, in my opinion, is a poor drive choice because you have to be so careful not to cam-out and damage the screw drive when using a power tool. Same thing for Allen/Hex drive heads.

I'm considering a change from the Phillips to Square (Robertson) drive using 18-8 stainless steel. Has anyone had any experience with this or have a comment?

Tim
N12ZP

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bullojm1
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Re: Machine screw drives

Post by bullojm1 »

Tim,

I discovered this same issue the hard way when I was doing my first annual. A lot of the phillips heads pan head and countersunk #8 and #6 screws had their heads strip out on me. For all non-structural screws that needed to be removed for the annual (seat pans, baggage bulkhead, wing inspection panels, etc..) I replaced them with Stainless Steel 6-lobe (Also called Torx) screws.

I found that Albany County Fasteners (http://www.AlbanyCountyFasteners.com) had the best deal on the pan-head screws (http://www.albanycountyfasteners.com/To ... 100000.htm). I used their Ebay store, and found them to be extremely quick to ship. Finding 100 degree flat/countersunk head Torx screws was a little more challenging, however http://www.MicroFasteners.com has them here http://www.microfasteners.com/home.php?cat=620.

I have been very happy with both of these products since I swapped out some of my screws to them in 2012.
Mike Bullock
http://www.rvplane.com
RV-7 | Superior IO-360 | Whirlwind 200RV
Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!

timotb
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Re: Machine screw drives

Post by timotb »

Thanks Mike...

I found the same results looking around ......no one vendor has it all. Do you think Torx is better than square (Robertson) drive. I hope to use one drive tool for all screws

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bullojm1
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Re: Machine screw drives

Post by bullojm1 »

Tim,

I like the Torx because I can get to it at up to a 20-30 degree angle. This is a nice feature in places like the end rib on the floor pan, the bottom of the rear baggage bulkhead, and the PITA screws that hold in the fuel pump. Plus, I think you might be able to find a torx driver easier than a square driver if you were ever in a bind. Additionally, many other RV'ers seem to use the Torx's. I haven't heard of anyone using a square drive.
Mike Bullock
http://www.rvplane.com
RV-7 | Superior IO-360 | Whirlwind 200RV
Garmin GTN650 | GRT Dual Sport SX EFIS
Status: FLYING!

timotb
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Re: Machine screw drives

Post by timotb »

looks like Albany and Micro are the way to go......Have to use T10, T15, T20 not just one drive.

Thanks again.

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captain_john
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Re: Machine screw drives

Post by captain_john »

bullojm1 wrote:Tim,

I discovered this same issue the hard way when I was doing my first annual. A lot of the phillips heads pan head and countersunk #8 and #6 screws had their heads strip out on me. For all non-structural screws that needed to be removed for the annual (seat pans, baggage bulkhead, wing inspection panels, etc..) I replaced them with Stainless Steel 6-lobe (Also called Torx) screws.

I found that Albany County Fasteners (http://www.AlbanyCountyFasteners.com) had the best deal on the pan-head screws (http://www.albanycountyfasteners.com/To ... 100000.htm). I used their Ebay store, and found them to be extremely quick to ship. Finding 100 degree flat/countersunk head Torx screws was a little more challenging, however http://www.MicroFasteners.com has them here http://www.microfasteners.com/home.php?cat=620.

I have been very happy with both of these products since I swapped out some of my screws to them in 2012.
FWIW

I believe those seat pan screws to be structural. That being said, putting any kind of screw in that location would likely be fine, regardless of type.

I have substituted several specified fasteners on my plane in lieu of better functioning or more aesthetically pleasing designs. Case in point... panel screws. Those are probably structural also, but I didn't want to stare at ugly screws for hours on end. I installed some black Allen head ones in their stead.

:) CJ
RV-7
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It's all over but the flying! 800+ hours in only 3 years!

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Thermos
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Re: Machine screw drives

Post by Thermos »

Aren't screws specifically called out as being structural or non-structural? Some screws like AN509 are specifically called out as "structural machine screws" while the AN515s that hold the RV-7 seat pans in place aren't labeled "structural". Same goes for the AN507s that hold inspection plates in place - not labeled as structural.

So if a callout isn't for a "structural" screw, does it make a difference what kind of non-structural screw you use?

:?

Dave
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