Discussion in '3-D Printing and Related topics' started by DRAGON64, Jan 21, 2019.
Pretty cool design. You should help or participate with the 3D design challenge.
I needed a 3" 5.5:1 nosecone with Aluminum tip... Voila! FG baseplate total weight 12.2Oz.
What did you need the aluminum tip for????
It was given to me, with an 18" threaded rod.
Is that a Der Red Max cone that is 3d printed?
No, This is one for the BAR-None rocket sold by Bay area rocketry a few years back. The plastic nose cone just isn't heavy enough to balance bigger motors and I don't want to add 8Oz of weight! By lengthening the nosecone out another 4" I can now get those beer can 43/852' in there without needing serious ballast.
The aluminium tip gives you strength where it is needed too.
Probably not needed unless you come in balsitic and that is not gonna save the cone in that case.
The pointy bit digs in on impact and there can be a large bending moment which snaps the tip off. That happens even at the lower descent rates, and 3D printed part can be more prone to snapping due to z-axis weakness which is typical on FDM parts.
Rounding the tip would mitigate this issue somewhat.
Is the small overhang at the shoulder of a nose cone a problem to print? The overhang below is only about .040".
I have not haDthat problem. It must be due to the fact that I print thick WALLS with 15 - 15 % infill.
I was thinking about .115"/3mm walls for a 4" diameter cone. Does that sound crazy thick? (just like I or J motors, nuthin' crazy)
Well one of them finished today. Starting on Saturday I printed the original size (Not my design, credit to STTrife, Thingiverse link below) stand alone box (perfect for resistors) and then started larger drawers which were finished in the morning and I started the next set of drawers, and finally started the box yesterday afternoon which finished around 8 this morning. Please excuse the messy desk.
This is a better design and system:
I would add a little chamfer or do it in 2 parts like I did.
View attachment 397933
Slice with Cura, there is a setting to make overhang printable. Puts in a 45 deg angle chamfer automatically without having to redraw. Although I have discovered that the area around that diameter change is a weak spot, especially form openscad nose cones. The two piece idea mentioned above is better due to square edge of nose cone shoulder and much stronger, glue with 3dGloop. (They just came out with their latest one for PETG, it works great!) Don't use epoxy or CA to glue 3d parts, it does not work well. 3DGloop is available for PLA and ABS too.
Made this in stand in openSCAD last night, and finished printing today. My requirement was that everything fit on the bed, it went together using M3 heat set threaded inserts (because I experimenting with them), and M3 pan head screws (because I have a bunch).
payload bay for Mach 1 BT55 Saberhawk. The files are at https://www.thingiverse.com/thing:3960145
Posted my rail jaw adapter to Thingiverse.
Sometimes yes, sometimes no. I like a sharp edge to the shoulder, so I just don't take chances. Slicer support never seems to work well there, so I always do it programmatically, i.e., I build the support into the CAD model. A single-wall ring, slightly larger than the diameter of the nose cone
base (so that it does not touch the shoulder), and a height 1-2 layers less than the shoulder edge. Then I poke some holes in it so it takes less time and material to print.
The above is not a good example; just the first I came across - gives the idea. The ring works better if it's the same smoothness as the NC, and I have a better method of adding holes to it (~8 large, semi-elliptical arcs so it looks like the support of a bridge). A small brim helps the support ring footing too. I've usually got it adjusted so that the support ring zips right off leaving a perfect shoulder edge.
Print it in two parts so the coupler section slips inside the upper cone. That way, it prints on the printer bed for a nice smooth, sharp edge. Glue together with epoxy so you have some time to check and adjust it for alignment by inserting it into a body tube.
Of course, this means the nose must be hollow, and its wall must only be as thick as the body tube wall, unless you design the coupler to have two sections with different diameters.
To re-iterate, don't use epoxy or superglue for 3d print parts, neither will stick well. Use the "Right Stuff" ... https://www.3dgloop.com/
I've always used MEK or acetone (on ABS), but this stuff looks interesting. Expensive, but I'll give it a try.
That is not entirely true. You have to use the right CA glue and an activator. I use professional grade CA and a professional activator and it is still stuck 12 months later after multiple launches.
ABS will dissolve in acetone or mek, so they will work just fine for ABS, but PLA and PETG are not. The 3DGloop is a proprietary blend that also contains some of the respective filament in it so it will gap fill pretty well too. A little goes a long way. I bought the little tube at first because it is expensive, I wish I got the bottle then. The PETG stuff just came out 6 weeks ago. It works great! YOu could approximate the ABS glue by dissolving some waste filament in MEK, mix till consistency of pancake syrup. Store small amounts in a twist lock pill bottle from pharmacy. The polyethylene seal wont get attacked by the MEK.
LV-haack nose cone( 150mm long, 42mm diameter, ~35g, PLA).
For those curious, I created a tool that, given the parameters, would create a 3D mesh that can be imported into Fusion360 or directly to your slicer! I would like to polish that tool and make it available to everyone.
Most people don't have or can't get that, But I have had ca pop off with very little force. (Used the Bob Smith stuff) 3DGloop dissolves the parts together. Note: gluing 3d printed part to something else is a different problem. I am working on some fin ideas, needed to design the fin halves with a cavity that will be a mechanical lock to a fiberglass thru the wall tab glued in with epoxy. Will post photos of that when I get to it. Other things in the queue first...
I am stuck in a rut. No printing today. I need inspiration.
That is true when gluing plastic to plastic, but when gluing other materials, consider CA.
I you cannot find a professional CA glue and activator, you are not looking. It is all over the internet.
I use Loctite 401 or 406 and apply it to ABS parts when I need them to be filled and sanded. No accelerator needed, and I have never had any separate.
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