Thread: Mini-HowTo VTOL-Trainer Build Thread
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Old Jan 29, 2013, 07:38 PM
Ran D. St. Clair is offline
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United States, CA, Sunnyvale
Joined Dec 2006
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Waiting for parts

I am still mostly just waiting for parts. The Bixler I ordered hasn't arrived yet, and the CarbonBird motors are still out of stock, so I can't even order them. It doesn't bode well for something I want to be readily available for anyone to build.

I did get my order from Mcmaster Carr. These will be used for the tilting motor mounts. The 1/8" long by 1/4" dia. stainless steel standoff has a 4-40 internal thread, McMaster Carr part number 91125A339. They are $1.14 each and we need 8 of them for 4 motor mounts.

The 90062A015 are the nylon short barrel sholder washers that will act as bushings. They have an I.D. of about 0.26" and the standoff has an O.D. of about 0.25" so there is about 0.01" of slop, which is a bit more than I would like, but I don't seem to have a lot of choice in the matter. At a 3/4" lever arm that 0.01" of slop calculates to 0.76 degrees of angular slop so it is not horrible, but I had still hoped for better. The flange is .060" or about 1/16", and will form the spacer between the inner motor mount and the outer yoke. They are $5.82 for a package of 100 so not expensive.

Also shown is the 91145A162 which is a long barrel nylon bushing. I bought 100 of them for $6.02 hoping that they would be a tighter fit on the standoff, but they have an I.D. of 0.26" the same as the sholder washer, so I might as well use the sholder washers and not need to modify the barrel length.

The plan is to press the sholder washers into the motor mount yokes from the inside out. The inner part of the motor mount, which rotates, will have the standoff's mounted on the outside acting as stub shafts that fit into the sholder washers. One small 4-40 screw on each side, and some loctite should finish the assembly. The outer yoke will "pinch in" slightly on the inner motor mount, so I don't think there will be any need to capture the assembly, but if there is, I can always use a small washer and a nut on the outside.

Now if I can just get the motors so I can measure them and layout the sheet metal. It is probably the same as what I already have, but I don't want to share the design until I am sure it is correct.
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