3D Printing 29mm Von Karman nosecone

[manixFan]

Here's a 29mm nose cone I printed on my Prusa MK3. It's in PETG printed at .16mm layer height. The bottom 2/3rds looks very good but I started getting some blobs at it got towards the top. The tip printed very well and kept almost all its detail. I set the seam to random and increased the retract amount to 1.2mm but I think I may need to increase it a bit more. In person it looks really very good and will only take a little bit of work to get it nice and smooth. I'm going to experiment with some fillers to see if I can get something to fill the surface rather than having to sand it all down.

Any comments or suggestions are welcome.

Tony

full nose cone:


smooth base:


blobby tip:

 

[cwbullet]

Does it need a coupler?

 

[manixFan]

I printed the coupler separately. It will hold the battery for a featherweight tracker. The tracker itself will ride in the nose come. The diameter is pretty close. Here it is on the body tube - you can see the coupler through the G10:

 

[Nacho]

Looks good! Which infill did you use?

 

[manixFan]

It's solid all the way through except for a small portion of the nose. I used the Slic3r cubic infill for that. It's about 1.75mm thick and seems quite sturdy. I'll eventually try a 38mm version but figured I'd get the 29mm one dialed in first. I made the model in OpenSCAD by simply subtracting a slightly smaller cone from the size I wanted to create the hollow interior. Of course with OpenSCAD by just changing a few variables I can alter both the size of the cone and the thickness of the wall. The coupler simply slides up into the nosecone and has a nice friction fit for now. Eventually it will be glued into place. It will also have two bosses(?) for screws so the bottom bulkhead can be easily removed.

 

[Ben Martin]

Slowing down the print speed around halfway through the print would would improve the quality. I personally set my seam so that it is aligned which makes it easy to sand and creates a smooth consistent finish.

 

[manixFan]

Actually I figured out what happened. The Prusa Editing of Slic3r allows you to adjust the line 'detail' vertically along the model when you slice it. I dialed up the detail at the tip of the nose cone to try and get a smoother surface and sure enough, that's where the blobs started. So next time I'll leave that alone.

I found I got much better results using a Radom seam. When it was set to aligned it created a very noticeable pattern. When set to random it was pretty much impossible to see. But that was for the nose cone. For other parts I'm sure the results vary.

Tony

 

[Andrew_ASC]

I did one VK in 29mm in 2017 for university rocket project with custom interior geometry and had it SLS printed for a superior surface finish. I since made my own 24mm MD version for the x1.4 thread. Unfortantely after graduating I don’t have access to Solidworks anymore. I’ve tried FreeCAD but Solidworks literally ruined me. Trouble was they run about $50-60 each when SLS print by a contractor.

Both have been flight tested.

 

[Ben Martin]

View attachment 372424

I did one VK in 29mm in 2017 for university rocket project with custom interior geometry and had it SLS printed for a superior surface finish. I since made my own 24mm MD version for the x1.4 thread. Unfortantely after graduating I don’t have access to Solidworks anymore. I’ve tried FreeCAD but Solidworks literally ruined me. Trouble was they run about $50-60 each when SLS print by a contractor.

Both have been flight tested.

Try out Fusion 360, it is very similar to Inventor/Solidworks. FDM printing is normally sufficient and it is MUCH cheaper. However, you can get some more reasonable pricing using nylon printers such as Shapeways.