Tiger II didn't come with enough 6-32 Socket screws. Went to Home depot for four 6-32 socket screws. They're for motor mount. Are they of lesser quality than Hobby Store screws?

They are all generally the same cept for price...which is more at your LHS.

Oyay.

Tahnx

Use hardware store screws all the time. Work just fine. They are pretty much the same.

Mark Shuman

And I'd guess, if there's a difference in quality the ARF will come with cheaper hardware than you'll normally find at Home Depot.
Dennis-

Can't be any worse than what comes with most ARF's.

Bolts do come in various harnesses, but I've never seen anyone worry about that. And like other folks here, my experience has been that the stuff at the hardware store is higher quality and less expensive than most "hobby" hardware, and pretty much all the hardware that comes in ARF kits and with many engines.

Did a couple of quick and dirty calculations on the shear and tensile strength of #6 screws made from the weakest steel I could locate online (30000 psi tensile, 50000 psi shear).

The bottom line is that with a factor of safety of three, a set of four of the cheapest #6 screws known to the hobby world will safely handle 423 lb in tension and 704 lb in shear....

If your engine weighs 1 lb, this means the screws can withstand more than 400 g's in tension, 700 g's in shear.... reckon the airplane will have become rekitted somewhere before that... That also explains why the engine is usually found firmly attached to the engine mount, often some distance from ground zero...[:-]

If you're really bored, this means that you and a friend can grab the prop and hang from it and not pull the engine off the mounts if you each weigh less than 200 lb... Keeping the firewall attached to the airplane during the "pilot hang" will present the largest problem Will leave that calculation to someone else!

Got to thinking (always a dangerous undertaking) that breakaway engine bolts might save some engine damage during lawn dart operations, and did some even quicker and dirtier calculations for nylon 66 screws (unsure if nylon 66 is even used in hobby applications) Used midrange values of 6000 psi tensile, 8500 psi shear.... With a safety factor of two, the max loads are 127 lb in tension and 180 lb in shear... hmm... Any materials gurus on the forum who can confirm what type of nylon is used in hobby screws? Specific mechanical properties would be even better! Has anyone tried this? Any concerns about fatigue or fuel exposure? Think that used nylon insert locknuts and steel washers would work well enough to keep the engine tight to the mount....[&:]

Just realized - I have way too much time on my hands --- Off to break in an engine!!


Calculation recap:

............DIA.....AREA...... PER SCREW......No of..........TOTAL LOAD......Safety.........Max Load
Size.......in.......sq in......Tension..Shear....Screws....Tension...Shea r.....Factor.....Tension...Shear

#6 St...0.116....0.0106.....316.9...528.1........4... .......1267.6....2112.6.....3.0.........423....... .704

#6 Ny...0.116...0.0106.......63.4.....89.8........4.. ..........253.5.....359.1.....2.0.........127..... ...180


my $.02

Jim