New scratch build, "Thump In My Down"

qquake2k

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There is a backstory to the name. When I was a kid, my mom used to tell me a story about when she and my uncle were kids. My grandmother accused Uncle Raymond of farting. He said to her, "I didn't feel a thump in my down, mama!" Well, it sounds like a good name for a rocket to me!
Thump will be 4" diameter, 64" long, have 6 fins, a 38mm motor mount, and be a zipperless design.


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View attachment Thump In My Down 6.ork
 

qquake2k

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I used 1/4" plywood from Michael's for the fins, pinning them together as I usually do, for cutting and match sanding.

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qquake2k

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The design I came up with calls for three centering rings, a bulkhead, and a baffle plate. The bulkhead and two of the centering rings needed to be sized to fit in the body tube. The other centering ring and baffle plate needed to be sized to fit in the coupler.

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qquake2k

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I used a carbide cutter in a homemade handle for cutting the plywood on the lathe. I cut the holes in the centering rings with a 1-9/16" hole saw, and sized them with a Dremel.

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qquake2k

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I drilled the 3/16" holes in the aft centering ring for the tee nuts. I also drilled the holes for the u-bolt in the baffle plate. And finally, epoxied blocks on the centering rings for the tee nuts and rail buttons.

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qquake2k

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I needed to cut one of the body tubes for the aft section. Normally I would use my miter saw, but my son has it buried with his camping stuff.
I really need to get him to clean it up. On my last build, I cut a 3" airframe with my bandsaw, but it didn't cut it straight. So I decided to build a tube cutting jig, which I've wanted to try for a while now. Building it was straight forward, I used 1x4 pine and a few screws. The only problem I had was breaking the razor blade when I put in the top screw. I should have used round head screws instead of flat head.

I ended up putting some bungee cords on it, to help hold the tube against the blade. I also clamped it so I could use both hands to rotate the tube. Cutting it was actually a pain in the butt. It took forever, and there was a LOT of friction against the tube. It was hard to rotate. I'm thinking next time I'll put some felt squares under and behind the tube to make it rotate easier. But in spite of the challenges, it did cut it straight and relatively cleanly. The very last cut is when it tore a little bit, but it tore on the inside, and was easy to fix with an X-acto knife.


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cjp

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I really like your design and fins with their upward trailing edge.Always wanted a tube cutting jig and yours looks like a good design.Decal made me laugh,I' sure your Uncle Ray would approve!lol
 

Gary Byrum

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Your Thumb cartoon reminded me of this. Imagine it with your head on it instead of mine. Could be an interesting candidate.

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qquake2k

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Ha! That's a good one! Never thought about putting my own head on the decal. Not sure how I would accomplish that.
 

qquake2k

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Mundane but necessary stuff. Sanded the rail button blocks. Cut the motor tube to length. I was going to cut it on the bandsaw, but it's too long.Cut out and sized the discs that will be the half moon baffles. Pressed in the tee nuts.

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qquake2k

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Epoxied the tee nuts, epoxied the holes in the half moon baffles, and epoxied the middle centering ring to the motor tube.

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qquake2k

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Flooded the coupler with thin CA and sanded it smooth. Also epoxied the motor mount into the aft section.

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qquake2k

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Got the fin tabs cut. Looks like I need to sand the fin tabs.

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cjp

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Looks great so far Jim,hope you try Gary's idea with the picture.I'm sure you have success!
 

Gary Byrum

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Jim's a man of many talents,a 1st class person as a friend.The rocket will look great no matter what decal you decide on.

Indeed he is! I've seen his work. He even has a better lathe than I do....(grumble, shmumble snicker driffle fliggm frazzle...)
And I feel certain he wouldn't mind a FREE contribution to his class act rocket design. I mean, I got all this time on my hands anyway.
 

qquake2k

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ahem--------------all you gotta do is ask.

I didn't want to be presumptuous. I would love a custom graphic from you. I assume you need a photo of my face?

Indeed he is! I've seen his work. He even has a better lathe than I do....(grumble, shmumble snicker driffle fliggm frazzle...)
And I feel certain he wouldn't mind a FREE contribution to his class act rocket design. I mean, I got all this time on my hands anyway.

I've had plenty of not-so-good lathes. I must say I'm very happy with my Jet. I've seen your builds, too. How is the Blue Baboon coming along?
 

Gary Byrum

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I didn't want to be presumptuous. I would love a custom graphic from you. I assume you need a photo of my face?

I've seen your builds, too. How is the Blue Baboon coming along?

A good size hi res profile and-or face shot. Stay away from shadowy pics. Your choice of cartoons to face bash.
Blue Baboon is someone elses build.
I'll PM you my email addy and you can send your preferred files over.
 

qquake2k

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Damn I'm getting old. I thought Blue Baboon was yours. I got your PM, thanks.
 
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