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  #1  
Old 01-18-2021, 10:56 PM
shuyge shuyge is offline
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Default First attempt at turning a nose cone

I decided to try the old technique of mounting a dowel in a block of balsa and chucking that into a drill press.

I've got a long ways to go, but I did create a nose cone that could be used in a pinch. The shoulder is a bit mangled and short. I could dress it up if I wanted.

I managed to create an very close copy to a BNC-20AM as shown in the picture. The cone was turned entirely by eye without any measurement at all. I was just working the balsa in an attempt to end up with a cone.

Pretty cool. I'll definitely be working on my technique.

Stan
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  #2  
Old 01-19-2021, 05:51 AM
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Not bad for a first try. Look about like the nose cones we made in Jr. High shop class.
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Old 01-19-2021, 04:33 PM
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I had to smile at this. Back in the late '60s, I put my Dad's drill in the workbench vise and turned a nose cone. Little did I realize that the bearings in the drill would not handle the pressure that I was exerting on the balsa. Somewhere there is a nose cone with an oblong cross-section. I got better after that.

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Old 01-19-2021, 07:09 PM
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A thing I learned the hard way was a dowel can be "crunched" in the chuck, and promote wobbling. So I began to use a short piece of music wire, about 3/16" to 1/4" (or 1/8" for a really small nose), depending on the cone size.

Of course afterwards, a process of using a grinding bit or series of runs with a small drill bit to drill away the balsa along the sides of the metal rod to be able to remove it.

Often though I turned cone shapes as master molds for vac-forming, so I leave the music wire in and have a big hole in the center of the vac-forming platform to let the rod go down into.
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Old 01-19-2021, 10:53 PM
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I started turning nose cones when I was about 13. I used my dad’s electric drill, clamped to my mom’s metal foldout kitchen stool. I wish I had pictures. They were pretty decent looking. In my 20s, I turned a few on a drill press. I had some good turnings, but I hated turning a nose cone that was pointed down. I much preferred them horizontal, like that clamped drill. It was more like a lathe.

I now have a lathe. The only way to reliably turn a nose cone on a dowel, is to hold the dowel in a collet chuck. It grips round shapes uniformly. So you do not get crushing of the dowel. And you can take the turning out of the collet, put it back in, and have good registration when you start turning it again. I have a range of collets that snap into my collet chuck, but I typically use a 1/2” collet, so flex is minimal using a short piece of dowel. For this upscale of a Saros noseon, I used a 3/4” dowel, it was totally wobble-free!] I also support the end of the block (the tip of nose cone) with a live (spinning) center point. That helps prevent inducing wobble. Since balsa can easily tear or deform, I usually glue a disc of thin plywood onto the end of the block to keep the live center well registered.

Pictures show the collet chuck, and the end of cone with live center retracted and tip almost done, so the block at tip can be cut off. (I cut off support block with razor saw, then sand tip while running lathe at moderate speed, and pressing very lightly. Although, the 1/2” dowel supports the block very well, and it would take a lot of pressure to snap it off.). I also keep a short piece of body tube on the dowel, which can be used to check for a good fit over the shoulder. On this nose cone, I did not have body tube on the dowel end to start, but removed nose one from collet and added it before final sanding.
If you love the idea of making your own balsa (or basswood, or other wood) nose cones, I highly recommend getting a lathe. Fun to use, and so many other things can be made using one.
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  #6  
Old 01-20-2021, 02:54 PM
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Quote:
Originally Posted by shuyge
I decided to try the old technique of mounting a dowel in a block of balsa and chucking that into a drill press.

I've got a long ways to go, but I did create a nose cone that could be used in a pinch. The shoulder is a bit mangled and short. I could dress it up if I wanted.

I managed to create an very close copy to a BNC-20AM as shown in the picture. The cone was turned entirely by eye without any measurement at all. I was just working the balsa in an attempt to end up with a cone.

Pretty cool. I'll definitely be working on my technique.

Stan


That'll work. I found that gluing various grits of sandpaper to paint sticks is about the easiest way to do it, and the most precise. You have to "sneak up" on the actual sizes you want. Another thing I find immensely helpful is to have some cardboard templates of the cone shape you want, and to hold it up to the work in progress occasionally as you work, so you know where to take more off and where not to. I turned a capsule for my Ares I-X and a transition for it on a cheap Harbor Freight power drill mounted sideways on a block of wood for a base. Much easier to work horizontally than vertically IMHO. Course some drill presses can do both.

Once you get the block cylindrical, for a stepped cone like the Orion, it helps to be able to mark each "step" or change in conical shape (change in the angles) with a pen as the part turns using the templates, then you can work up to the line, gradually turning down the shape until it matches the outer mold line templates you've made beforehand...

I also used the trick you used on the shoulder-- hard to turn a shoulder and get it the precise size you want for the tube in terms of fit and finish, and still have a nice square shoulder to butt up against the end of the tube when inserted into the tube. I turned it down undersize and used a tube coupler glued over the shoulder to assure a proper fit. That allows you to focus on making a nice shoulder to butt up against the tube rather than trying to get the diameter just right...

I turned a transition for my BT-80 Saturn V out of pink house foam insulation glued together into blocks... worked really well. Get the thickest sheets of foam you can get, I think mine are like 1-2 inch thick. Cut a block epoxy in a thick dowel and turn it like balsa.

Later! OL J R
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