Slot on cylinder (Bolt action pen)

[Matt32 (Matt)]

Hi everyone,

I’m working on a Bolt action pen and have trouble modelling the J-slot. The slot runs along the cylinder. The way I have it now, the sides of the are tapered, is there a way to get an even distance?

I made the current one with the following steps:

1. Extruding a hollow cylinder
2. Unrolling it
3. Sketching the slot on the unrolled cylinder
4. Using the flow command to wrap it around the cylinder again
5. extruding the lines along the normal of the cylinder
6. cutting the excess surfaces and joining them together

Some reference images of what I’m trying to get.

[Tom_P]

you have to model the (ruled) surfaces that is created by the movement of the axis of the bolt.

if you want to stay close to your workflow above:

1. as is
2. as is
3. sketch the (unrolled) center-Curve of the movement
4. extrude it both sides
5. _flowAlongSrf to bring it back to the cylinder (now you have the center-surface of the axis-movement)
6. optional: rebuild with reasonable tolerance (0.05)
7. _offsetSrf , both side (2mm)
8. trim / join

instead of flow, flowalongsrf you might draw the inner surface using _fin command directly in 3d.

hope this helps - kind regards -tom

[Matt32 (Matt)]

Hi Tom,

Thanks for the reply, I’m going to try and see if it works.

[Matt32 (Matt)]

Okay it worked (mostly)

The only issue is that the corners near the bend are a bit weird. I think I can work around this by using the outer/inner-curve of the movement, and extruding the surface 4mm. or is there another way to do this?

[Tom_P]

try with a bigger radius in 2d.
the lower / horizontal part is a simple revolve.
the upper vertical part is a simple extrusion.
so the fancy workflow is only needed for the curvy part.