Motor Mounting Question

[xCrashNBurnx]

Just wanted to get other suggestions on how others mount their motors on 3DHS planes that aren't pre-drilled. The reason I ask is because of a few snags that I ran into on my 58" Edge build that wasn't pre-drilled with blind nuts already installed. I drilled out the holes, no big deal there. Then, I inserted the blind nuts into the back of the motor box and then started cranking down the screws. However, the barbs on the blind nuts were too long and protruded through the firewall and hit the motor mount, preventing me from being able to fully secure the mount to the firewall. So I removed the blind nuts and cut a peice of balsa that I glued to the back of the firewall, essentially making it twice as thick. After drilling out the new balsa, I was able to re-insert the blind nuts and fully tighten the motor to the firewall.

I heard that some guys don't use the blind nuts at all and just us lock nuts instead. How do you guys install your motors?

 

[xCrashNBurnx]

All four of my other 3DHS airframes, including my 51" Slick, came pre-drilled and with blind nuts already installed .

 

[SnowDog]

The only thing I can suggest is to use a small round piece of plywood instead of balsa as the spacer/filler between the blind nut and the firewall.
Strange that the tabs on your blind nut went all the way through the firewall; I've not seen that before...?

 

[gyro]

The only thing I can suggest is to use a small round piece of plywood instead of balsa as the spacer/filler between the blind nut and the firewall.
Strange that the tabs on your blind nut went all the way through the firewall; I've not seen that before...?

I've seen it once before... I don't remember which of my planes it was though.

On e-power setups I use a large metal washer and lock nut on each bolt behind the firewall.

 

[xCrashNBurnx]

Cool, thanks guys, I'll try that.

 

[Joe's Dad]

Just wanted to get other suggestions on how others mount their motors on 3DHS planes that aren't pre-drilled. The reason I ask is because of a few snags that I ran into on my 58" Edge build that wasn't pre-drilled with blind nuts already installed. I drilled out the holes, no big deal there. Then, I inserted the blind nuts into the back of the motor box and then started cranking down the screws. However, the barbs on the blind nuts were too long and protruded through the firewall and hit the motor mount, preventing me from being able to fully secure the mount to the firewall. So I removed the blind nuts and cut a peice of balsa that I glued to the back of the firewall, essentially making it twice as thick. After drilling out the new balsa, I was able to re-insert the blind nuts and fully tighten the motor to the firewall.

I heard that some guys don't use the blind nuts at all and just us lock nuts instead. How do you guys install your motors?

usually a good washer and locknut