More Profile Mount Information

LAST EDITED ON Nov-16-04 AT 11:08 PM (CST)
 
If you have a profile that already has the cheek added to the motor mount area and you would like to add a tank mount without drilling the cheek. This might be for you.
What I did was cut a couple of 3/8 O.D. dowels about 5/8 in. long. I then drilled a clearance hole thru the center of the dowel for a 4-40 bolt. At one end of the dowel I had to drill 5/32 dia about 3/16 deep so I could install a 4-40 tee nut without spliting the dowel. I added a drop of CA to secure the tee nut. I then drilled a couple of 3/8 holes in the fuse about 3/4 deep in a location to match my tank mounting tabs. I put a little piece of masking tape over the tee nut hole to keep the epoxy out. I put epoxy on the dowel and pressed it into place....... Grins

That'll work just fine. Even simpler is to just install a DuBro or Great Plains 4-40 Brass Insert. Your solution is a buck cheaper . . .

>That'll work just fine. Even simpler is to just install a
>DuBro or Great Plains 4-40 Brass Insert. Your solution is a
>buck cheaper . . .

and a whole lot stronger than installing brass inserts in the balsa. As it is I removed the brass inserts from the motor mounting area as the ones I saw at the field in a ARF Cardinal pulled out rather quickly or should I say spun in place. And they were installed in hardwood mounts at the factory. Oh well, must be lots a ways. Grins

I like it. Nice tip Greg.

>>That'll work just fine. Even simpler is to just install a
>>DuBro or Great Plains 4-40 Brass Insert. Your solution is a
>>buck cheaper . . .
>
>and a whole lot stronger than installing brass inserts in
>the balsa. As it is I removed the brass inserts from the
>motor mounting area as the ones I saw at the field in a ARF
>Cardinal pulled out rather quickly or should I say spun in
>place. And they were installed in hardwood mounts at the
>factory. Oh well, must be lots a ways. Grins

I use the Dubro inserts often and like them better then blind nuts. The problem with the ARF cardinal is that the pilot holes were drilled to large for the inserts and I couldn't see any epoxy or other glue used to secure the inserts into the threaded wood.
As in every technique there is a correct way to do it or your results can be less then satisfying.
Dennis

Greg,

I often use 1/8 OD copper tubing, tapped 4-40, as mini-threaded inserts.

Use a spare, unmounted drill chuck to hold the copper tube. A length of 3/32 wire inside the 1/8 OD tube keeps it from crushing when the chuck is tightened.

The tapping is all done beyond the chuck jaws. The tap swages the tube OD enough larger that it will not fit freely into a 1/8 hole. A usual 4-40 tap can cut about 3/4" thread length. Cut it off and chase the threads at the cut end, if needed.

To put further 'tooth' on the tube's OD, I roll the threaded length between two 60 grit sanding blocks -- not much, just to lay an even speckle on it.

Run a 4-40 bolt into the threaded tube; wipe some (15 to 30 minute) epoxy in the 1/8 hole with a toothpick, and use the inserted bolt to press the tube flush. Remove the bolt. Clean it with acetone or alcohol.

For fuel tanks, this is plenty strong enough. It also does not require a large hole drilled through the (usually profile) body sides. This also works well for hatches of various sorts.

Sounds good Lou, Yes there are lots of ways. Nice for everyone to share.

Greg,
That is a beautiful solution for the tank mounting problem.

Thanks Pat and thanks Don. Just trying to help everyone to know that they have options, thanks again.