Curved inside pipe chamfer - Velocity Stack Conecpt

Hello all. I’d like to begin by saying I am but a lowly mechanic with MINIMAL sketch up skills. I use to play around a tad with simple shapes. I am making a concept for velocity stacks for my CV carburetors. I have looked online (maybe not hard enough) but am needing to make a curved inside chamfer on a pipe. I have attached my file for reference. Hopefully I am not so out of date you can see it.
On the 56mm end, I’d like the inside of the tube to have an inside curved chamfer. The wall diameter is about 6mm. Ideally the curve is uniform and bell shaped and the transition ends smoothly 6mm from the end face. Is there any way someone can either instruct me on how to model this or complete this modification for me?

The idea is to run larger diameter but shorter length filters and put the stack opening inside the pods to

  1. Allow for filter movement and allow tuning for the end cap to “choke” the inlet
  2. Prevent crosswind airflow from causing turbulence
  3. Create a more uniform vacuum with a Venturi effect, speed airflow across the emulsion tube and atomize fuel better.

Here is the file, thank you in advance!!!
VelocityProto.skp (197.7 KB)
Risky T

I’m not following your description totally and what I’m showing may not be the right profile but hopefully it gives you an idea. Draw the cross section profile you want to use as a profile for Follow Me with a circle as a path. Note that I’ve set this up so its centered on the origin. This gives you a nice fixed reference to work off.

Dave! You are the man, very cool design that probably replicates a better Venturi effect than I had planned - although much harder to machine, further prototypes will look much more like a combination of both your and my ideas with your design being machined deeper into the tube. While much more primitive, my design is easy to manufacture on a lathe as a proof of concept. I will definitely play around more with follow me for future iterations. As for now I have tried profiling in a curve and attempted to use follow me but say it cannot extrude a curved face. Your thoughts? You can also tell me to beat it and figure it out on my own lol. Thank you so much
VelocityProto2.skp (229.8 KB)

OK. Sorry to complicate the shape.

In your latest model I’m guessing you were trying to use the little arc as the path for Follow Me. Really you need to work the other way around. Since your arc doesn’t fit anyway, I just started over.

You want to sweep around the circle like this.

After the Follow Me process completed, I selected all of the geometry, right clicked and selected Reverse Faces.


#1. Wow am I embarrassed that the arch did not line up
#2. SO cool!!!
#3. You are very very talented, kind and prompt. A stand up gentleman
#4. This makes future designs with a curved inlet and interior Ventruri possible

Pot of coffee is on, time to get down to business. Seriously, thank you so much.


VelocityProto3.skp (343.7 KB)

How did you teach a knuckle basher like me to run on the compu-tators?
I got so excited I made a simple double reduction tube. Furthers will be made, perhaps increasing the length of the larger diameter portion to allow for a more gradual reduction. Maybe a curved profile like your first idea - off to the engineering department. I will try to remember to update you with a picture of the first prototype off the lathe. Vroom vroom!

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