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General control line discussion => Open Forum => Topic started by: Glenn (Gravitywell) Reach on March 21, 2009, 10:19:23 PM
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Hi everyone. I was wondering, what type (hardness?) of aluminum do you use to make motor mount pads? I've never used them before, but I want to do this Vector right, so I want to order some aluminum, but don't know what type to buy. Thanks in advance for any help. H^^
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Give Tom Morris A call at(256)820 -1983 he will have what you need
Tom Weedman
AMA63672
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Hi everyone. I was wondering, what type (hardness?) of aluminum do you use to make motor mount pads? I've never used them before, but I want to do this Vector right, so I want to order some aluminum, but don't know what type to buy. Thanks in advance for any help. H^^
3/32 6061 T6 will do.
Brett
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Thanks much for the info. Much appreciated. H^^
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'wish I'd thought of Tom myself. Last month I ran around looking for 2024-T3 or other aircraft grade stuff and finally ended up locating some 50-series at a scrap place that sorted well. The LHS - for what that's worth - had 6061, a viable material, but in too thin sheets. Look under scrap in the yellow pages and expect a lot of ignorance, when you ask for aircraft grade. If you have a large airport nearby, maybe you can find some free scrap in aircraft maintenance facilities. We used to go out to the airport and pick up scrap off the ground and pay for it by weight - lots of good aircraft hardware too. Just don't buy the soft hardware stuff; I cannot see it being worth much in our MM applications.
SK
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Have used the hardware stuff forever without any issues. Bought a 2 inch X 1/8 strip and cut 3/8 slices off the end. Most of my engines (including 60's) are mounted with counter-sunk 4-40 screws through the back of an aluminum strip with the aluminum mounted using 4-40 cap screws in blind nuts. Makes switching engines fairly easy.
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Don't forget Control Line Central www.clcentral.com Jim Snelson carries all of Tom Morris products.
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Thanks to everyone that replied. I prefer making my own stuff whenever possible as it is so much more cheaper (er....I guess I should say inexpensive! LL~) that way and a whole lot more fun! So in that vein......Bob, your method intrigued me. If I read it right, this (looks at attached photo) is what you are doing? What thickness aluminum do you buy? I have only ever seen 1/8th or slightly less in our hardware stores. I can order a different thickness though and if I am going to order it, I may as well get the 6061 T6 as Brett mentioned. The picture is just a quick and dirty free-hand in Paint, so don't criticize it too much! LL~
Thank everyone for the help and suggestions. As always....answers had at an amazing speed! %^
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Your illustration is correct except that the screws used to secure the aluminum pads to the hardwood engine mount beams should go through the wood and into either blind nuts (some times called T-nuts), or self locking nuts if yiu can access the bottom of the beams to hold the nuts while tightening.
Wood screws into the hardwood beams will almost always come loose under vibration / engine loads, usually discovered at the worst possible time- like when the sun finally comes out and the wind stops blowing, the lines are rolled out and hooked up, and you are ready to fly!.
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OK....I changed the drawing and I think I have it now. I would have used bolts and blind nuts anyway....LOL Thanks so much for the help. Really appreciate it fellas. H^^
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You got it.. The aluminum I bought is just run of the mill 1/8", short leverage points and most stress being shear, any old aluminum is plenty strong. I use flat head 4-40's and countersink like the wood screws you are showing in your first drawing not recessed as the aluminum would have to be much thicker. This photo might give you a better idea of how I mount an engine, basically do the same thing on a built up fuselage.
You can easily cut aluminum with almost any saw made for wood, I have a cheap Sears band saw I use strictly for aluminum with regular wood blades. Use Pam for a lubricant...
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6061T6-used to make aircraft garbage cans.
2024T3-standard structural grade aluminum
7075T6-very hard aluminum, hard to bend, hard to drill. Used on Lockheed Electra.
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We have aluminum motor mount pads at UHP for $4.00/pair. That's
pretty cheap. They are 2" x 3/8" x 3/16". I mount them to the
motor bearers and then tap and drill them for the particular motor
being used. Cheap, simple, and effective.
Steve
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I have some scrap 1/8" aluminum sheet, pretty soft, which I cut my NMUEMPs
from, using my jigsaw with a fine blade, and patience. Since they are 1/8" thick,
I don't have confidence in them for threaded engine mount holes, and I use
flathead brass screws, nuts and washers to secure the motor to the plate.
Also, I have some harder 1/8" aluminum, an old front panel for electronic equipment,
which works.
Ah but to have a machine shop; all the UHP accessories are definitely first rate..
L.
"Choose the life that is most useful, and habit will make it the most agreeable." -Francis Bacon
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I have some scrap 1/8" aluminum sheet, pretty soft, which I cut my NMUEMPs
from, using my jigsaw with a fine blade, and patience. Since they are 1/8" thick,
I don't have confidence in them for threaded engine mount holes, and I use
flathead brass screws, nuts and washers to secure the motor to the plate.
I would have been leery of using brass screws for engine mount, from my experience of twisting the heads off when drive brass wood screws into hardwood if you don't get the pilot hole just right. Are you using 4-40's or 6-32's ? Have you ever had any break or come loose from stretching ?
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We have aluminum motor mount pads at UHP for $4.00/pair. That's
pretty cheap. They are 2" x 3/8" x 3/16". I mount them to the
motor bearers and then tap and drill them for the particular motor
being used. Cheap, simple, and effective.
Steve
What alloy aluminum are you using for your motor pads ? Tapping threads in the pads, you are only going to have about 4~5 threads. Seems kind of marginal, but if its working OK on that big ol 4-stroker, must be OK..