Gramparocket
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K.i.s.s.
Jig for cutting nose cones into tail cones
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BDB
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Where’s the fun in that?
rocketguy101
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Not sure what CAD program you are using, but here are the steps I use to draw ogive nose cones in SolidWorks...sometime back there was discussion of this topic on the forum and I posted this. Seems some CAD program out there already had preset buttons to create some nose cone shapes...searching "drawing ogive" may turn it up.
EDIT: found it right here
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When I cut my tail cones, I simply take a short length of body tube and put the nosecone in it, then I take the motor tube, and put a series of centering rings inside it, and slide it over the point of the nose cone (the centering rings inside the motor tube hold it straight on the nosecone). Then I scribe the area where the motor tube meets the nosecone until I cut through, and sand down from there (if needed).
+1. I’ve always used a mitre box.
Part 2
Once you cut the tip you can take a router and about $100 make this slotting jig. You either need a LONG flute router bit or just raise the tail in the jig to make perfect slots.
Once you cut the tip you can take a router and about $100 make this slotting jig. You either need a LONG flute router bit or just raise the tail in the jig to make perfect slots.
I'd just draw the cut line, cut it with a hacksaw and finish it with a sander.
My redneck might be showing.
My redneck might be showing.
I would do something similar. I’d put the nosecone into a piece of body tube and stand it up to make it plumb. Then I would use a plumb piece of tubing that matches the size I want the aft opening to be to mark the cut line on the outside of the nosecone. I’d probably use a razor saw or fine tooth hacksaw and make light cuts working around the circumference. Then I’d use a sanding block to dress it.
lakeroadster
When in doubt... build hell-for-stout!
Here, hold my beer.
I've got a tabletop style Ryobi belt sander.
Put an 80 grit belt on that sucker, push the nose cone down on it and you'd be done in about 30 seconds.
As my old boss would say "Let the big hog root!"
Cutting cones is great fun (when you get used to it) and opens up some real scratch-build possibilities.
Did this with a LOC. 4 inch nose cone. I wrapped tape around the shoulder of the cone until it was super tight inside the tube then did one wrap of blue tape around the outside where the cone met the tube.
From there I used a regular old miter saw and chopped it off. Little bit of sanding to clean up the edges and I was good to go
From there I used a regular old miter saw and chopped it off. Little bit of sanding to clean up the edges and I was good to go
I do not do high-powered stuff but if someone has access to a 3D printer why not 3D print a boat tail instead of printing a jig to cut a nosecone into a boat tail? I can appreciate the issues for printing nosecones for high-speed launches but I did not think there were as many issues with using a 3D printed boat tails.
BDB
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I thought about it. This tail cone is 6” dia x ~ 18”, so it’s bigger that I can print in one piece. If this was a smaller project, I definitely would have printed it.
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Lathe: Using a wood lathe, chuck the base and support the tip in a ball-bearing cup center. Tighten chuck slowly to allow good centered alignment. Run lathe to check centration and adjust as necessary. Turn at relatively low speed, especially if it’s a plastic cone. Use a thin parting tool or skew perpendicular to the axis. Be prepared to make final parting cut by hand as wall thickness may not be uniform.
Band saw: Use fine tooth blade, about 6 tpi or greater. Set miter gauge to 90 degrees and cut several pieces of melamine, MDF, baltic birch, or particle board for practice, adjusting as necessary for exact 90 degree cut. Using similar uniform flat material (I prefer baltic birch) and table saw, cut two identical squares about 1” larger per side than the major diameter of your cone. Mark centers precisely. Drill hole in one piece a diameter that will allow NC tip to protrude out the back side the distance of the amount you want to cut off plus maybe 1/8”. Drill hole in second piece a diameter close to but slightly less than the diameter of the base of the cone ( the outside part, not the part that fits inside the BT). Cut a base out of your flat material the exact same width as the two cone supports and a bit longer than your NC. Screw and glue the upright with the smaller hole on top of but flush to the end of the base. Measure to confirm squareness in all directions. Insert cone (after marking your intended cut line on the tip) through the upright with the bigger hole until it sits tight against the edges of the hole. Place on base and slide cone/upright assembly through the upright with the smaller hole until the tip of the cone is supported firmly and screw and glue rear upright to base. Once dried, slide your cone through the openings. If you measured and cut precisely, the cone should now be supported on-center and front and rear. Put base against miter gauge, set blade support height, and cut off your tip. I recommend clamping your jig to the miter gauge. You can get fancy with the protruding rear end of the cone, but whatever you do needs to keep the cone firmly registered against the upright supports, even if it’s just your hand. You also want enough grip here to keep the cone from spinning in response to the saw cut. Go slow, with the understanding that the blade speed may melt the cone material. It’s a judgement call.
Wear safety glasses with all cuts.
i know its a lot of work for cutting just one cone. But if you have a whole bunch of the same cones you want cut the same way, it may be worth the effort. If you want to get really fancy you can put a piece of T-track down the middle of your base and make a drawer-full of uprights with different diameters to handle a wide range of cones.
Band saw: Use fine tooth blade, about 6 tpi or greater. Set miter gauge to 90 degrees and cut several pieces of melamine, MDF, baltic birch, or particle board for practice, adjusting as necessary for exact 90 degree cut. Using similar uniform flat material (I prefer baltic birch) and table saw, cut two identical squares about 1” larger per side than the major diameter of your cone. Mark centers precisely. Drill hole in one piece a diameter that will allow NC tip to protrude out the back side the distance of the amount you want to cut off plus maybe 1/8”. Drill hole in second piece a diameter close to but slightly less than the diameter of the base of the cone ( the outside part, not the part that fits inside the BT). Cut a base out of your flat material the exact same width as the two cone supports and a bit longer than your NC. Screw and glue the upright with the smaller hole on top of but flush to the end of the base. Measure to confirm squareness in all directions. Insert cone (after marking your intended cut line on the tip) through the upright with the bigger hole until it sits tight against the edges of the hole. Place on base and slide cone/upright assembly through the upright with the smaller hole until the tip of the cone is supported firmly and screw and glue rear upright to base. Once dried, slide your cone through the openings. If you measured and cut precisely, the cone should now be supported on-center and front and rear. Put base against miter gauge, set blade support height, and cut off your tip. I recommend clamping your jig to the miter gauge. You can get fancy with the protruding rear end of the cone, but whatever you do needs to keep the cone firmly registered against the upright supports, even if it’s just your hand. You also want enough grip here to keep the cone from spinning in response to the saw cut. Go slow, with the understanding that the blade speed may melt the cone material. It’s a judgement call.
Wear safety glasses with all cuts.
i know its a lot of work for cutting just one cone. But if you have a whole bunch of the same cones you want cut the same way, it may be worth the effort. If you want to get really fancy you can put a piece of T-track down the middle of your base and make a drawer-full of uprights with different diameters to handle a wide range of cones.
Do you think it is worth it, even if you do not have a lathe, to use a drill w/ an adapter to spin nose cones and cut with a blade mounted in an external jig of some type?
I would consider using a lathe or drill to spin the NC and cut it using an angle grinder with a thin 1mm cutoff disc. The angle grinder can be hand held (both hands please) with wrists resting on the tool rest or compound slide. I have used this method and found it to work well. A Dremel with a cutoff wheel would work well also.
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I’ve thought about this for years but the challenge is to get the NC chucked into the drill press straight because if it is even the least bit out of alignment the NC will wobble and you will get a sloppy cut. Presumably here we are talking about hollow blow molded or fiberglass NCs. The fat end is too big for a drill press or cordless chuck. You would have to figure out a way to attach a smaller diameter (5/8” or less depending on drill chuck capacity) spindle into the fat end of a NC and have it be precisely axial. I’ve never figured out how to do that.
as for the folks recommending a sanding disc or belt sander, again, you have to figure out a way yo hold the NC firmly and exactly tangential to the plane of the sander. This is hard to do with a curved NC Because you have no reference straight edge. If you had a section of BT you could insert the NC into, that would help one axis, but the attachment would have to be rock solid.
Further, these techniques might work with a fiberglass NC but the linear speed of a belt or disc sander will pretty much melt a blow molded poly propylene or polystyrene NC. I suppose you could cut the tip a bit shy with a razor saw and use the belt or disc sander yo lightly touch up the cut edge, but again, alignment is critical.
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