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HelicopterMain Discussion › titanium or stainless steel?
10-25-2012 10:41 PM  5 years agoPost 21
honda411

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Surprise, AZ USA

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Thanks a ton for all of the replies guys! It really helped out!

So if i go with the black oxide screw (first one on the link provided), how do i know which one to get? I need all M3 screws of an assortment.

Can someone provide me exact link of item needed. I need button head, flat head, and socket head.
Id like to have silver colored screws to match the washers being used. But again i want strongest as well. These are mainly all frame screws, thanks

HeliDirect Field Rep, Synergy N7 w/ OS 105, Torq Servos, Cyclone/ Rail blades

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10-25-2012 11:35 PM  5 years agoPost 22
Ace Dude

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Did you try looking using the links and/or vendors mentioned?

  

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10-25-2012 11:41 PM  5 years agoPost 23
BobOD

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The button and flat head screws are grade 10.9. Highest grade available for these.
http://www1.mscdirect.com/cgi/NNPDF...59124&PMCTLG=00

http://www1.mscdirect.com/cgi/NNPDF...57603&PMCTLG=00

The Socket head cap screws are grade 12.9
http://www1.mscdirect.com/cgi/NNPDF...17657&PMCTLG=00

The import are probably sufficient for the frame screws...better than a lot of the ones in kits but not great.

The Made in USA ones are better.

Holo-Krome are very good but if you're going to spend that, might as well go for the Unbrako (the best IMO).

Team POP Secret

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10-25-2012 11:59 PM  5 years agoPost 24
Ace Dude

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USA

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Example 3mm x 12mm 100 pieces for $5.26
The ones I have bought were made in USA.
I highly doubt those are made in the USA. Just look at the price difference here:

http://www1.mscdirect.com/cgi/NNPDF...17657&PMCTLG=00

3x12 100:

Import $5.35
USA $19.19
Holo-Krome $15.66
Unbrako $19.28

The USA made are 3.6 times more than the imported ones.

  

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10-26-2012 12:14 AM  5 years agoPost 25
MartyH

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I'm not familiar with Unbrako but Holo-Krome is very very high quality.

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10-26-2012 12:24 AM  5 years agoPost 26
BobOD

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They are indeed...but I've found that Unbrako forms a deeper, higher precision socket and better finish overall.

Both are better than the Made in USA ones for sure...a lot better. Kinda crazy that the Made in USA are often more expensive. It didn't used to be.

Team POP Secret

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10-26-2012 01:50 AM  5 years agoPost 27
honda411

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BobOD: thanks for adding the additional links. I appreciate it. Now i just need to take my pick. Thanks for every reply guys!

HeliDirect Field Rep, Synergy N7 w/ OS 105, Torq Servos, Cyclone/ Rail blades

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10-26-2012 11:11 AM  5 years agoPost 28
MartyH

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Don't buy the cheapest, please! We've given you a number of higher quality choices.

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10-26-2012 11:43 AM  5 years agoPost 29
Richardmid1

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There are all different grades of Titanuim. You can't just say Titanium is too brittle.

60% of the time, it works every time!

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10-26-2012 07:44 PM  5 years agoPost 30
BobOD

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That's true but the same statement can be made for steel.

Team POP Secret

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10-26-2012 08:21 PM  5 years agoPost 31
MartyH

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did someone say titanium is brittle?

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10-26-2012 11:01 PM  5 years agoPost 32
Ace Dude

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There is such thing as high tensile stainless steel you know.
Is it available in 2, 2.5, 3, and 4mm SHCS? What's the tensile strength?

  

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10-26-2012 11:32 PM  5 years agoPost 33
rexxigpilot

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Florida

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did someone say titanium is brittle?
I laughed at that one too! Titanuium is much less brittle than steel, even in every alloy available. Ti64 has approximately half the stiffness (Young's modulus) of typical steel and almost 4 times less than high strength steels like that used in DIN 12.9 screws.

Titanium is just too costly to refine and machine compared to steel. Otherwise it would be used much more.

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10-27-2012 12:09 AM  5 years agoPost 34
BobOD

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Well, TI64 has a lower elongation at break then the material of a common cap screw. Isn't that more a measure of brittleness?

Anyway, find me a titanium M2 cap screw that would be available to the hobbiest and lets take a look at its properties before we get too giddy.

Team POP Secret

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10-27-2012 03:54 AM  5 years agoPost 35
honda411

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MartyH: no I won't go cheap. I can't stand cheap stuff and are very picky about my stuff. I have taken all screws into consideration and are deciding right now. I'm pretty set on the 12.9 bolts. Looks aren't everything. And when I have blades from a 700 zooming in my face I can't and don't want failure. Thanks for all inputs guys and will continue to read on with comments.

HeliDirect Field Rep, Synergy N7 w/ OS 105, Torq Servos, Cyclone/ Rail blades

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10-27-2012 04:16 AM  5 years agoPost 36
Justin Stuart (RIP)

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Plano, Texas

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Is titanium the only "alternative" or "space aged" metal used for screws?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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10-27-2012 03:06 PM  5 years agoPost 37
icanfly

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ontario

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get the psi/stress rating for every application where possible and work backward from there. Your heli will never see high stress forces in operation than in a crash.

Carbon steel is cheep, ti is expensive, cobalt steel expensive, aluminum in the middle but soft, stainless heavy. All these materials are used in the largest of full size aircraft you sit your a$$ in up there.

those in the know choose ti, giggle tee hee,

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10-27-2012 06:11 PM  5 years agoPost 38
rexxigpilot

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Florida

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Well, TI64 has a lower elongation at break then the material of a common cap screw. Isn't that more a measure of brittleness?
Perhaps you are thinking of tungsten instead of titanium?

The measure of a material's brittleness is its stiffness or elastic deformation property. This is known as it's Young's modulus (E) when discussing tensile stress. It is a measure of the force over area (pressure) needed to deform the material elastically twice its original length. In other words, the lower the Young's value the MORE elastic it is and the LESS brittle it is. The Young's modulus of titanium (~16x10^6 psi) is almost half that of structural steel (~30x10^6 psi).

Total elongation includes plastic deformation. This is a measure of ductility and/or malleability. These properties have to do with "formability" such and turning sheet metal into a car body. They have nothing to do with brittleness.

Screw and bolt type fasteners are designed to operate in the elastic phase of the stress-strain curve. They act like loaded springs when tightened to hold parts together. This is why overtightening a screw or bolt/nut is so bad. Once you exceed the Yield strength of the material (such as an overtightened screw) it deforms plastically and losses its "spring" force which keeps the fastener tight (under tension) and the parts together.

Titanium has a much higher yield strength than steel without being so brittle. All the processes used to increase steel's yield strength make it more brittle. Titanium is a superior material to steel when comparing brittleness, strength and weight. It just costs more. If you don't need to use it why spend the money?

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10-27-2012 06:30 PM  5 years agoPost 39
BobOD

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Ductility and brittleness are related.

Anyway, find me an M2 TI screw available to the hobbiest and let's look at it's properties because I was basing my comment on experience. I got some rather expensive TI screws and found them to be rather brittle. And my judgement of that was that they did not yield much before sudden failure. That is, they were not very ductile...they were brittle.
Others I've gotten were indeed very ductile...but they were soft and the hex would strip.
Does this mean all Ti is this way. No. It means a Ti screw that a hobbiest would buy is, per my experience, as I stated. I am actually hoping that you are able to prove me wrong....I could save 15 or 20 grams on my helis.

Team POP Secret

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10-27-2012 06:38 PM  5 years agoPost 40
BobOD

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Oh...and by the way, some of the parts that I machine out of Ti is quite strong, and light, and very ductile.

Team POP Secret

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HelicopterMain Discussion › titanium or stainless steel?
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