# Making a Slot in a Cylinder - Did it with curves long ago, forgot how!

I have a cylinder I’m using in a 3D printing project. For this, you can ignore the threads on the inside. I’m focusing on the slot I made on the outside:

I did this well over a year ago and I can’t find my notes on how I did it. I know I made the tube usin a Bezier curve and, at some point had an object follow the curve. Flaring the end wasn’t hard. Then I used that object as a boolean modifier to cut into the cylinder and produce the slot.

I have to do the same thing with a new part with a different radius and I can’t remember details of what I did - especially creating a Bezier curve that either had the same radius as the outside of the cylinder or followed along the outside. It’s also possible I might have made the tube first, then, somehow, curved it to match the radius of the outside part of the cylinder.

If I can match the radius of the cylinder, I’m pretty sure I can reconstruction what I did to do the rest of it, but I just can’t imagine how to make the boolean modifier with the same curve as the cylinder. (My notes were in that file, but somewhere along the line, the part on this object got cut or deleted.)

How can I either make a path that follows the curve or has the same radius as the cylinder?

1. Apply the Shrinkwrap modifier after attaching the curve to the Cylinder surface using the Shrinkwrap modifier.

2. Apply thickness to the curve, convert it to mesh, and then round and boolean the ends.

vxv.blend (1.5 MB)

I don’t know if there’s a better way.

1 Like

Looking your blend file over, I think I did things in a different sequence than you did. And I may have rounded the end of the cylinder created on the curve differently. Did you get that rounded end just by subdividing?

I think I made the curve, then made a circle and had it use the curve as a path, then added the flared end and, after that, used the Shrinkwrap modifier. I’m not sure, so I’ll have to experiment with that.

I’m running into a problem with the object, once I add a circle curve as a bevel object, not conforming to the curve fully:

I took the curve and added a Shrinkwrap modifier to it and the curve, all alone, wraps right around the cylinder part of the object, following the outside contour of it properly.

But then I add a circle curve as a bevel object. I get a mess, so I go to the Shrinkwrap modifier and apply it. Then I get the pipe, as seen in this picture, using the curve that’s wrapped on the cylinder. The curve follows the outside surface, but the tube version of it does not.

I tried adding the Subdivide modifier and it doesn’t help.

The Shrinkwrap modifier may not function properly depending on the surface of the target object.

Alternatively, you can use the Bend of the SimpleDeform modifier to match the cylinder.

dgsd.blend (1.3 MB)

I got it!

I looked more closely at the original Bezier curve and realized it wasn’t matching as closely as I thought. The mismatch wasn’t obvious with just the line and became clearer when I made it into a tube. I subdivided the horizontal part of the curve a few times and it matches the cylinder very well.