HELP! Can anyone modify and STL for me

I have an STL for the perfect duct, but I need to modify it to fit a larger prop (7.5") while keeping the base that connects to the motor the same. Can anyone help me? I am still new to fusion360. Thanks in advance!

Send a link to me and I can take a look after the weekend

Thanks so much…

Nice design, what are you going to print it in?


I printed one out on the ender3 and it came out perfect. just need to resize a few things

What filament?


used PLA for the first one, thinking petg on the second. You think they will be strong enough?

This is a really detailed model. Nice. What’s the origin of the file?

Not sure, I fount it online somewhere. Its fits my motor perfectly and all the bolt holes line up nicely. BTW its ok if you cant make it work. I know that modifying STL after the fact can be difficult, and I have a few other options I can explore.

Nah I am already well under way reverse engineering it. I am pretty good at it. Just need to find the time, that’s all. Sometimes work gets in the way of hobbies :slight_smile:

edit: Status update: Just finished the reverse modeling. This is now fully parametric and easy to modify in SolidWorks. I’ll proceed to adapt it to a larger prop soon.


Nice work, what is the material thickness of the ring and spokes? It looks a bit fat :slight_smile:

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The twisted spokes lokes familiar! I believe this is the duct we made a few years ago or a modified verson of it.

Awsome you made it parametric.

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Awesome. Thanks so much!.. you’re the man!

The ring thickness is about 13mm in the thickest part.

It is almost an exact copy of the original, only parametric. You can see it overlaid here with the original (highlighted in different colors).

The change to 7.5 in is done. There is 193 mm = 7.6 in of space in the duct. I changed the angle of the support beams to keep the leading edge of the duct flush with the support. Let me know if you want anything changed. It is easy at this point.

Here is the new version overlaid with the original:

New version by itself:

Download SolidWorks native files + STL and STEP for 7.5 in version:

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Thanks for sharing, in which version of SW is this part made? I’m running 2018 but it won’t open. I can try in 2014 as well.
For reference; my duct design for a PM setup with custom prop has a wall thickness of approx 7mm and is more than strong enough when printed in PETG or PLA_carbon.

It’s made with 2021 SP2.

I can reduce the thickness if there is a need and actual reasoning for that. Airfoils are weird. It might perform better like this than if I simply make it thinner, or what do you think? @Hiorth must have had some reasoning behind the shape.

Ah, is it possible to save the parametric file in a lower version of Solidworks?

No, the only way is to go through a transfer format such as STEP or Parasolid but that will cause you to lose the feature tree among other details.

You could update your build. Usually your license already works for the latest version as well, and you can have multiple versions installed at the same time if you want to.

As I recall it was made thick to have increased thrust at takeoff speeds < 8knots,
I would lean towards decreasing thickness and the chord length, this way it can give you a small advantage at takeoff, prop protection and not a huge efficiency penalty at cruising speeds.
Hard to know what works the best, but looking at lift and flite they appear to have thinner and shorter ducts.

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