PDR Gemini Titan fin can

[snuggles]

What cement are we supposed to use on the plastic fin can????
I used butyrate dope like the instructions say to, but it didn't work.
Mark T

[ghrocketman]

I used butyrate clear and it worked fine for me....were you using CLEAR ?
You have to hold it a long time, and make sure the dope is thinned with 1 part thinner to 2 parts dope...the thinner (MEK, Xylene, Toluene, MIBK) is actually doing the bonding.
You could try plasti-weld or Tenax7R...those would work better.

[snuggles]

I did use thinned clear dope, it wasn't water thin though. I taped the seam as tight as I could and used rubber bands to hold it overnight. When I removed the bands and tape it just fell apart. I then tried Tenax 7, it didn't work either.
I'm at a loss to explain this.
Mark

[snuggles]

Would MEK by itself work???
I can get that at the hardware store.
Mark

[dwmzmm]

I would like to know as I'm expecting to get the PDR Gemini-Titan kit too. I recall when I
built the original Estes Saturn - V, I used clear butyrate dope to "cement" the clear halves
of the slip on fins together...it held extremely well. The instructions to the Estes GT3 kit that
you can view online also mention using the same technique on the GT3's clear fin can.

[snuggles]

I used butyrate dope on my Estes Saturn V years ago and yes, it did work well on the flat fin pieces. the problem is that you are forcing the flat plastic into a circular pattern.
My GT is dead in the water till I can figure this out.
Mark T NAR27793L1

[dwmzmm]

I used butyrate dope on my Estes Saturn V years ago and yes, it did work well on the flat fin pieces. the problem is that you are forcing the flat plastic into a circular pattern.
My GT is dead in the water till I can figure this out.
Mark T NAR27793L1

Maybe the next time I have a chat with John Pursley, I'll ask him for his advice. Yeah, I know
if he really wanted to, he'd build his own scratch built Gemini-Titan scale model finless, in that the model's stability would use gimballing motor mounts (just like his 1/12 scaled Mercury Redstone and Vanguard models). Pursley doesn't want to mess with any kit
models...

[kurtschachner]

Maybe the next time I have a chat with John Pursley, I'll ask him for his advice. Yeah, I know
if he really wanted to, he'd build his own scratch built Gemini-Titan scale model finless, in that the model's stability would use gimballing motor mounts (just like his 1/12 scaled Mercury Redstone and Vanguard models). Pursley doesn't want to mess with any kit
models...

I can't recall if I posted this before or not, but when I built my GT I made the fin can out of polycarbonate. I also had the machinist at work make a mandrel for me and I heated the body tube portion of the fin unit on the mandrel. If you heat polycarbonate above its glass transition temperature then it retains the shape very well. You end up with a nice, stress free ring.

I then solvent bonded the two edges of the ring together and then bonded on the fins. IIRC I used a solution of about 15% polycarbonate in methylene chloride for the bonding agent.

I still have the mandrel (and some plastic but not too much). If anyone wants to borrow the mandrel and some plastic, I can loan it to you. It really makes a nice fin unit.

[A Fish Named Wallyum]

I still have the mandrel (and some plastic but not too much). If anyone wants to borrow the mandrel and some plastic, I can loan it to you. It really makes a nice fin unit.

Where do you find Mandrel Chow? :eek: :rolleyes: