SammyD
Well-Known Member
Anyone ever run into this?:
I scratch built an Executioner recently (LOC tube, LOC nocescone, and scratch cut fins, AT ejection baffle and potscrubber, etc) with a mid-body coupler separation point for ejection - not really sure why, but I think because I built it with a 12", 29mm MMT, the LOC tube might not hold up as well to the shock cord getting racked against the side of it. Anyway...
After attaching the eye-bolt to the bottom of the NC, I used CA to attach it to the upper tube, primed, filled, sanded, primed again, and painted the upper tube with an initial few coats. After about 24 hours of curing, it got an initial wet sanding with 600g. Then, I put it in the sun to get a little more "hard cure" before sanding a second time. This is where I got totally confused.
The nosecone and the tube appeared to begin separating! A distinct paint separation began where the NC shoulder met the tube. I couldn't figure out what was going on for the life of me. Did the tube shrink? Did the NC come apart? Where did my build go wrong and, of course, WTF?!
Then, I remembered all those Physics classes I took... Duh!!! I took the assembly back into the A/C, and voila, the bulge began to disappear. I can't believe I didn't see this coming at assembly, but the air inside the NC was completely sealed off from the outside air; thus, the heat generated by the sun on the black paint caused massive expansion of the NC.
Lesson learned: put a vent hole somewhere on the bottom side of the cone to release trapped air before changing temperatures............ ;-) Yeah, I got a 12" drill bit down the tube to drill a 1/8" hole, but my super-smooth tube is now taking 4 times the amount of time to paint trying to smooth my "repair"...
I scratch built an Executioner recently (LOC tube, LOC nocescone, and scratch cut fins, AT ejection baffle and potscrubber, etc) with a mid-body coupler separation point for ejection - not really sure why, but I think because I built it with a 12", 29mm MMT, the LOC tube might not hold up as well to the shock cord getting racked against the side of it. Anyway...
After attaching the eye-bolt to the bottom of the NC, I used CA to attach it to the upper tube, primed, filled, sanded, primed again, and painted the upper tube with an initial few coats. After about 24 hours of curing, it got an initial wet sanding with 600g. Then, I put it in the sun to get a little more "hard cure" before sanding a second time. This is where I got totally confused.
The nosecone and the tube appeared to begin separating! A distinct paint separation began where the NC shoulder met the tube. I couldn't figure out what was going on for the life of me. Did the tube shrink? Did the NC come apart? Where did my build go wrong and, of course, WTF?!
Then, I remembered all those Physics classes I took... Duh!!! I took the assembly back into the A/C, and voila, the bulge began to disappear. I can't believe I didn't see this coming at assembly, but the air inside the NC was completely sealed off from the outside air; thus, the heat generated by the sun on the black paint caused massive expansion of the NC.
Lesson learned: put a vent hole somewhere on the bottom side of the cone to release trapped air before changing temperatures............ ;-) Yeah, I got a 12" drill bit down the tube to drill a 1/8" hole, but my super-smooth tube is now taking 4 times the amount of time to paint trying to smooth my "repair"...
