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3" Semi-Scale Bullpup Build

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qquake2k

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I'm back!

Three years ago when I got my Jet lathe, I turned a tailcone for a 3" Bullpup that I really didn't plan on building. I only turned it because I had a short piece of basswood left over, and thought it would be simple and fun. It was, and I successfully turned it. Fast forward three years, and my Secret Santa gift at work was an Estes Bullpup 12D kit. That got me thinking about the tailcone, and I dug it out. I thought about a 3" upscale for several days, and even played around with the Open Rocket file I had made then. I rooted around and found a length of LOC 3.1" tubing, along with a 29mm motor tube. I thought about ordering a LOC nose cone, but then I found a 16" piece of basswood I had. So to make a long story short, I decided to go for it.

https://www.rocketryforum.com/showthread.php?60359-A-thing-of-beauty!&p=627474#post627474


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qquake2k

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I have a nice 3" faceplate for my lathe, which is threaded in the center for a 1/4-20 hanger bolt. That allows it to be used as a screw chuck. I put a #8 screw through the hole and attached it to the basswood to center the faceplate. I marked the four mounting hole positions with a transfer punch, then drilled pilot holes and attached the faceplate with #10 woodscrews.

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qquake2k

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The nose cone doesn't require any weight, but I decided to embed the eyebolt in resin, as I've done in the past. I trust it more than using a screweye. So I removed the faceplate, and started to drill a 1" hole in it with a spade bit. Well, that didn't work. The spade bit I used is threaded on the tip, to help "pull" the bit into the wood. Since I didn't have the basswood mounted in a vise, the bit immediately grabbed it and drilled at an angle. Bummer. I decided to try drilling out the hole with an S&D 1" bit. That didn't work either. Bummer.

The block is 16" long, and the finished nose cone will be 12-1/2" with a 2" shoulder. I think I can trim off the damaged section, and start over. I think.


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qquake2k

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As it turns out, I have a drill press vise that the basswood block fits into. I should have used it the first time, but I will definitely use it the second time.

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cjp

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The best build threads ever!!!!!!!!Glad you decided to build it Jim.Now I might get off my rear end and work on my V2.
 

Cl(VII)

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The Captain in Back!!!!!!!! This year is already better than last because we have a Jim build thread.
 

o1d_dude

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I've had much better luck using Forstner bits. Spade bits tend to grab as you've illustrated in your nose cone.
 

AlfaBrewer

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A new build thread from Captain Low 'n' Slow!! This is most awesome!!
 

bill2654

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Alright Jim! Show em what a real build thread looks like.. Great to see you getting around once again.
 

qquake2k

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I got the 29mm motor tube and body tube cut to length. I also cut a 1" piece of body tube to use for sizing the nose cone.

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qquake2k

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I cut an inch off the basswood block before re-drilling it. This time I mounted it solidly in a vise. Using a new stubby spade bit without a threaded tip, I successfully drilled the new hole.

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qquake2k

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As I said, the hole in the nose cone will be for attaching the forged eyebolt, by embedding it in resin. The faceplate I'm using was just a tiny bit tight. Normally, I would file something like this, but the faceplate is chrome plated, and is too hard for a file. So with it spinning on the lathe, I ground it a little bit with an angle grinder. That did the trick. I also remounted the basswood block to the faceplate.

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qquake2k

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I mounted the block on the lathe, and with it spinning very slowly, I advanced the cupped live center into the opposite end. Apparently my bandsaw didn't cut it square, because the tip end was wobbling quite a bit. I'm pretty sure I have enough material to cut it to shape. I started the long process of roughing it round.

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rocketgeek101

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Great to see you back at it Captain :)! The build is coming along nicely. Excellent job on the wood turning!
 

cjp

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Just like turning a fine pen,great looking nose cone Jim.That will be a great looking Bull Pup!
 

qquake2k

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I marked the blank for the 2" shoulder, then cut it with a variety of chisels, and finished it with 60 and 120 grit sandpaper. One of the better shoulders I've cut. Lots of nice curly shavings from this project.

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qquake2k

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Now the process of shaping the nose cone begins. I marked it at 12" from the shoulder, but that probably wasn't necessary. A trick that Sandman told me about, and that I've used in the past, is to hold the small nose cone up to the big one, to use as a shaping guide. But the shape of the Estes nose cone that came in the Bullpup kit I have doesn't look right to me. It looks more tapered that ogive.

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rharshberger

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Now the process of shaping the nose cone begins. I marked it at 12" from the shoulder, but that probably wasn't necessary. A trick that Sandman told me about, and that I've used in the past, is to hold the small nose cone up to the big one, to use as a shaping guide. But the shape of the Estes nose cone that came in the Bullpup kit I have doesn't look right to me. It looks more tapered that ogive.
A trick for shaping NC's that has worked for me is using a profile drawing and cutting a pattern I can hold up to the blank as I turn it. The profiles can be gotten via pictures that have been blown up to the right scale or from line drawings done the same way. I cut the patterns on either foam board or picture mat board.
 

qquake2k

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A trick for shaping NC's that has worked for me is using a profile drawing and cutting a pattern I can hold up to the blank as I turn it. The profiles can be gotten via pictures that have been blown up to the right scale or from line drawings done the same way. I cut the patterns on either foam board or picture mat board.
Funny you should mention that...
 

qquake2k

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One of the features of Open Rocket, is the ability to print the nose cone profile. As it turns out, the Estes cone is closer than I thought. I printed it on card stock, then used it as a guide as I slowly shaped the cone. As with cones I've turned before before, final shaping was done with 60 and 120 grit sandpaper. Then finally, I cut the tip off.

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qquake2k

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I chiseled the tip a bit, then went to sandpaper. I'm very, very happy with how this turned out! I still need to do final sanding with finer grits to get it paint ready. I got to thinking about it, and this is the first true ogive cone I've turned, and also the longest.

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qquake2k

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Sanding basswood on the lathe is a messy business. And yes, Kit, I wore a mask!

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