How do I create a groove that follows a set of lines?

I have two lines, which describes the path of a pin through its centre. The first line is for one end of the pin, then second is for the other. These two lines are of different lengths due to the curve the path takes. I’d like to create a grove that would follow this path. I need a tool that will extrude a face along a path but appropriately rotate the face to stay in the same orientation to the line as it was at the start. Follow Me doesn’t do that (I’m actually not sure what it is doing).

Is there a tool available to do this?

I’ve attached a model for anyone who is interested to play with.
path guides.skp (88.7 KB)

FYI, the block’s inner edge should begin at the inner path, but you get the idea.

I’m having a hard time visualizing this … a picture would help :slightly_smiling_face:

Like Jim, I’m having trouble following your words (pun intended). Without meaning to offend, I’ll break down your post and comment bit by bit in an effort to explain why I’m confused.

Do you mean that the desired path consists of two sections attached end-to-end? To treat that as a single extrusion you need to select both and weld them together.

I don’t understand the importance of this at all, that is, why would the lines need to be the same length?

Follow-me keeps the profile perpendicular to each segment of the path, an segment-by-segment approximation of what a real curved extrusion would do. Do you mean that you want the profile to skew to the path so as to maintain a fixed orientation in space along the path? So, for example, a circle would change to an ellipse depending on the local orientation of the path?

1 Like

Hmmm, a picture? Not easy to do. If I could make a pic, I prolly wouldn’t need to ask the question. :smiley:

I think I am getting approximately what I need by changing the Follow Me line into a polygon. Not sure why that is. However, there is a bit of cleanup at the points where there is a large change of direction.

No, I was referring to the different paths that each end of the dowel would traverse. I was trying to indicate that each end of the dowel are actually move a different distance.

Yeah, that is what I was thinking it should do. Looks like if I weld lines together it acts funny. Converting the welded line segments into a polygon seems to have fixed the issue.

The last thing I am having some trouble with is that when path abruptly turns at corners, I don’t get a rounded corner, but pointy bits instead. I’m thinking that I might be able to fix this by making arcs at these locations. I’ll see if that works.

I guess I’m mentally blocked today. This makes even less sense to me!

1 Like


Think of a sword. When you swing a sword, the tip traverses a greater distance then the handle.

Which has nothing to do with follow-me or extrusion! That’s why I am lost regarding what you actually need to model. You seem to be describing an animation, not an extrusion.

Ok, so the following image shows a blue line, which is the path that is being traversed nearest the axis of rotation, and the red line, which is the furthest.

Now, the Follow Me tool gives the following when following the blue line:

Note that the when the path changes direction abruptly, the red path is no longer in the centre of that side of the extrusion.

That is the problem that I am getting. I need to extrude the exact path that the dowel will be following, both nearest and furthest from the axis of rotation.

To be clear, the first part of the path, before it turns abruptly, is following a path that is in a plane. However, after the turn, it is rotating at different rates at perpendicular axes at each line segment (if that is indeed clearer :rofl:)

Ah, finally it becomes clearer. Follow-me’s algorithm doesn’t do well with paths that curve in a non-planar 3D way. The cross-section gets twisted while trying to traverse the curve. You might give eneroth3’s Upright Extruder extension a try (look for it in the Extension Warehouse).

Also it makes a difference where your path is going around a corner. especially tight corners. If it the outside of the turn or radius there may not be enough room for the inside faces to make the turn.

I thought you were talking about changing edges on a face to grooves in the face, which is a plugin request that seems unattainable.

Thx. Tried the Upright extruder. I don’t think that it is what I want to do. I do want the cross section to twist. It needs to keep aligned with the dowel, which means that if the path were to do a spiral, the open end of the grove must be pointing into the rotation axis. Upright extruder will try and force the opening to look a specific way along the path.

The problem is that Follow Me tool outer edge isn’t keeping up with the rotation.

I’m aware of this, but thx for the reminder.

I attempted to flatten the path between inner and outer path traversal, use Follow Me along one of either path and then use Flowify. Unfortunately, it looks like Flowify doesn’t like a winding path. This might be because the width of the path isn’t constant around turns. sigh

Can you attach the model, or at least the parts in your image above.

I’ve added a model to the first post.

Bump. Just wondering if everyone got scared off when I posted a image/skp file. ::rofl:

Just for fun, I tried making a face along those two paths using curviloft. Then gave it thickness with Joint Push/Pull.
Dont know if it’s what you are after or not.

1 Like

I was thinking the same thing, looks like @Shep nailed it. Good call in thickening the faces equally from the top and bottom separately which is smart as it keeps the pathway lines on center of the pathway. I had thrown this together so I’ll post it here roughly showing the process Shep is talking about.

Curviloft eh? I’ll try that. Looks like it will be what I’m looking for. Will have to fix up the transition corner so that it’s rounded, but that should be easy. Thx.