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-   -   Designing nose cones (http://www.oldrocketforum.com/showthread.php?t=17975)

Quasar 07-04-2019 10:18 AM

Designing nose cones
 
What thickness would you want to make the nose cone when designing for BT60 and smaller sizes? Thanks.

K'Tesh 07-05-2019 06:48 AM

That totally depends on the material you are using...

Vacuform? Injection mold? Blow mold? Carbon fiber? Fiberglass? 3D printing? Pine? Balsa?

astronwolf 07-05-2019 06:49 AM

Quote:
Originally Posted by K'Tesh
That totally depends on the material you are using...

Vacuform? Injection mold? Blow mold? Carbon fiber? Fiberglass? 3D printing? Balsa?

This is the 3D printing subforum.... :rolleyes:

K'Tesh 07-05-2019 07:05 AM

Quote:
Originally Posted by astronwolf
This is the 3D printing subforum.... :rolleyes:

Sorry my bad... I checked in with "Today's Posts". Didn't see the subforum

Jerry Irvine 07-05-2019 08:17 AM

I would guess over 1/16". On 4" I prefer over 3/32". There is a minimum reasonable for the process itself that doesn't apply, for example, to fiberglass. Blow molding for example would be 1mm to 1.5mm.

teflonrocketry1 07-05-2019 09:07 AM

It depends on the body tube diameter and the relative diameters of the shoulder and nosecone. I like to 3D print with at least 2 layers of overlap between the nosecone body and shoulder. For smaller cones about BT-30 and below that amounts to 3 layers at 0.4mm width; for larger diameters above about BT 30, 4 layers seems to work good. It is best to do a layer by layer view in your slicing software and look for the amount of overlap. A single layer of overlap will be weak at the transition point unless you are doing a post treatment like isopropyl alcohol for PLA and acetone for ABS; but even then the one layer of thickness will still be the weak point. For cones wider than BT-60, I use 5 or more layers as indicated by the amount of overlap shown in the slicing software. This becomes a problem as body tubes get thicker and the difference in cone and shoulder diameter becomes greater. There are some tricks you can use to get sufficient overlap between the cone body and shoulder to get the structural integrity required.

vcp 07-05-2019 11:12 PM

Quote:
Originally Posted by Quasar
What thickness would you want to make the nose cone when designing for BT60 and smaller sizes? Thanks.


That's going to totally depend on what you're trying to do. All of my NARAM-60 models , including the 45mm dia egglofter, https://www.thingiverse.com/thing:3056609 , were printed single-wall vase mode for light weight, and they turned out to be very durable (in ABS). The only finish was sanding out the layer striations completely, which thinned them even more.

So consider single wall a practical minimum, it's hard to go less, and add from there.

Quasar 07-06-2019 06:57 AM

Thanks for the responses, but most of what you guys said went right over my head. I'm a complete NOOB and know almost nothing about 3D printing. I'm using Autodesk Fusion 360 to design the shape I want, but I don't know how thick to make it. It's for a BT-55 tube. If anyone can point me toward some good learning resources, I'd greatly appreciate it. Thanks.

vcp 07-06-2019 09:00 AM

That's ok Mike, we all gotta start somewhere. First question, do you have a 3D printer? Or, are you planning to use one at school or a library or something (where you'll probably be limited to PLA plastic). If you have your own, is it limited to PLA (or PLA types) or can you print in ABS or PETG or something else?

The only reason I could do single-wall (that's just one noodle of extruded plastic, or about 0.5mm thick) is that I was printing in ABS which is much less brittle than PLA. Thin-walled ABS prints become very flexible.

Vase mode, that I mentioned, is a printing method for single wall prints, in which there is no discrete 'step' when transitioning layers as the print progresses upward. The extrusion is a continuous single wrap around the shape you specify.

Do you know how the slicer software prepares your design for printing? In many cases, there is no need to specify wall thickness in your CAD program - you can just do a solid shape, and then specify the wall thickness in the slicer. Do you know what slicer software you'll be using?

Resources, hmmm. For 3D printing in general, or specifically rocketry related? For rocketry, we'd probably need to find some threads on one of the forums.

Quasar 07-07-2019 08:26 PM

Quote:
Originally Posted by vcp
That's ok Mike, we all gotta start somewhere. First question, do you have a 3D printer? Or, are you planning to use one at school or a library or something (where you'll probably be limited to PLA plastic). If you have your own, is it limited to PLA (or PLA types) or can you print in ABS or PETG or something else?

The only reason I could do single-wall (that's just one noodle of extruded plastic, or about 0.5mm thick) is that I was printing in ABS which is much less brittle than PLA. Thin-walled ABS prints become very flexible.

Vase mode, that I mentioned, is a printing method for single wall prints, in which there is no discrete 'step' when transitioning layers as the print progresses upward. The extrusion is a continuous single wrap around the shape you specify.

Do you know how the slicer software prepares your design for printing? In many cases, there is no need to specify wall thickness in your CAD program - you can just do a solid shape, and then specify the wall thickness in the slicer. Do you know what slicer software you'll be using?

Resources, hmmm. For 3D printing in general, or specifically rocketry related? For rocketry, we'd probably need to find some threads on one of the forums.


Thanks for the thoughtful response, vcp. I don't have a printer, yet, but there is one where I work. However, I'm not sure if I can talk the guy that uses it into letting me do a personal project with it. If I remember correctly, it's a MakerBot brand printer. When I do get my own, I'll get one that can use ABS.

If I can use the one at work, I'll find out what software the operator uses. I really don't think he uses it much, as I've been working there for over two years and I've never seen him making anything.

As far as what I'd use a 3D printer for, yes, I would do some rocket parts, but I'd probably use it more for other things.

Thanks again.


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