3D Printing Printing a trapezoidal fin can in one piece?

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dbrent

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I am in the process of working up a fin can in Sketchup that has trapezoidal fins (5 deg sweep on leading and trailing edges) AND a diamond shaped airfoil. I'm not really seeing how this can be printed in one piece but I'm just learning so I could be wrong.

The diamond shaped airfoil is probably fine because the wedge is a very shallow angle and the leading (top) edge obviously won't be a problem but I'm thinking the 5 degree trailing trapezoidal fin edge will be a problem since the edge would be up off of the print bed at a 5 degree angle. Is this an example where supports would be used? How do I know how many and how far apart they would need to be? What do they look like?

I'm waaaaaay out over my skis on this but I thought it would be a fun project to learn with. My printer won't be here for about 3 weeks anyway so I have some time to learn a little bit about the design phase.
 

OverTheTop

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If you have a good slicer then it should do the supports where needed. I have noticed Cura get better and better with the support generation over the past couple of years. It puts them in where needed and they are super easy to strip out, and they come off with almost no degradation to the part.
 

dbrent

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Again, I'm a total noob at this so forgive me if this sounds like a naive question but...

Since the trailing edge is going to be pretty thin due to the airfoil, is that going to make removing any support material from it kind of tricky to do without damaging the edge?
 

dvdsnyd

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dbrent -
The biggest thing I have come to learn with 3d printing is tradeoffs. I will generally go out of my way in the design to eliminate as much support material as feasible.
That said, you can likely get your design to work with supports. It may be tougher around the thin edges as you are referring to. Only one way to find out.
 

chilled

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I would recommend trying supports, and if that doesn't turn out right perhaps modify the design. As OverTheTop mentioned, Cura has gotten better and better with supports and I had found that supports come off pretty easily. If you are up for a bit of investment, I've heard Simplify3D is rumored to handle supports better but I've not gone that route. I've done a trapezoidal fin can before with supports and it works just fine assuming other settings are accurate. I'd just go for it and see how it turns out.

Since this is your first project I'd first recommend a few test prints to calibrate everything with the filaments and settings you plan to use. Dialing all that in first will make the eventual fin can turn out that much better.
 

Arpak

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If you can swing it, use tree supports with cura. They use much less material than standard and I find them come off much nicer. I generally use tree supports only attached to the buildplate.
 

OverTheTop

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Since the trailing edge is going to be pretty thin due to the airfoil, is that going to make removing any support material from it kind of tricky to do without damaging the edge?
Support seems to come off quite cleanly nowadays. You can always use the "suck it and see" approach, printing just a few layers to see how it handles the edge and supports and how easily they clean up.
 

cwbullet

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Can you post an example or photo?
 

ghuber

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1622738474143.png

I designed the above in onshape (fits over 38mm MMT). Fins are tapered top/bottom, and I've also printed regular airfoil with angular trailing edge. In Cura, I print on a raft with support. I've had better luck with a raft because support more reliably stays in place. Key on removal is patience--using a razer blade if it doesn't come cleanly off.
 

dbrent

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What I'm thinking of is basically what ghuber posted above but with semetrical trapezoidal fins each having a diamond (as opposed to wedge) airfoil.
 

Jack Hydrazine

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I am in the process of working up a fin can in Sketchup that has trapezoidal fins (5 deg sweep on leading and trailing edges) AND a diamond shaped airfoil. I'm not really seeing how this can be printed in one piece but I'm just learning so I could be wrong.

The diamond shaped airfoil is probably fine because the wedge is a very shallow angle and the leading (top) edge obviously won't be a problem but I'm thinking the 5 degree trailing trapezoidal fin edge will be a problem since the edge would be up off of the print bed at a 5 degree angle. Is this an example where supports would be used? How do I know how many and how far apart they would need to be? What do they look like?

I'm waaaaaay out over my skis on this but I thought it would be a fun project to learn with. My printer won't be here for about 3 weeks anyway so I have some time to learn a little bit about the design phase.
The supports for the fins are needed since the bottoms of them will be suspended in the air. In Cura you can choose to use supports that go from the bed to the object and supports that are needed anywhere on the object.

I have designed a couple of fin cans with supersonic airfoils.
 

dbrent

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So I actually printed the Estes PRP-1G fin can for my Challenger 1 clone project (see separate thread) on an SLA printer (with Chitubox auto-supports) and it came out fantastic!

Edit - I know auto-supports are frowned upon in the general 3D printing community (Prusa slicer's auto supports being somewhat of an exception) but for such a simple shape, I think it did fine. The print came out perfect and the supports came off super easily with no scaring.
 

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Jack Hydrazine

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So I actually printed the Estes PRP-1G fin can for my Challenger 1 clone project (see separate thread) on an SLA printer (with Chitubox auto-supports) and it came out fantastic!

Edit - I know auto-supports are frowned upon in the general 3D printing community (Prusa slicer's auto supports being somewhat of an exception) but for such a simple shape, I think it did fine. The print came out perfect and the supports came off super easily with no scaring.
Looks great! Let me know how the fit is in the airframe tube.
-Jack
 

Charles_McG

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I print swept fins upside down, like in this Malemute fincan.

And from the same thread, the Terrier fincan is probably very close to what you are designing. Low angle, diamond profile. I printed with supports. Still had minor warping issues.

 
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