Airframe Rail Button attachment

This is how I made the rail button attachment on a minimum diameter rocket airframe. I used 8-32 bolts for attaching the rail buttons.

I start with an 8-32 T-nut.  I drilled a hole in a scrap piece of wood and cut both sides of the t-nut as shown. I used a Dremel tool with a cutoff wheel. You can see that the t-nut got pretty hot during the cutting process.

Next I drilled a hole the size of the 8-32 bolt (I think it was a #18 drill) in the airframe, inserted a bolt from the inside, screwed the t-nut in position and trace the shape of the trimmed t-nut onto the airframe.  Then removed the t-nut and bolt. I used a Dremel tool to cut out the shape.  The result is the following.

I inserted a section of coupler with a piece of polypropylene plastic (I think about 4-5 mil) as seen in the above photo to set the t-nut on.  I used JB Weld to attach the modified t-nut to the airframe. This will be covered by the fin tip-to-tip carbon fiber. More on that later.

After the JB Weld cured, I used some microspheres in epoxy to smooth out the JB Weld and fill in any indentations so it's level with the airframe.  I cut the threaded portion of the t-nut to a length of about 1/8". Now it's ready for the fin tip-to-tip carbon fiber lay-up.

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Copyright 2021  Paul Hopkins. All rights reserved.
Revised: 10/10/21.