# Is there a way to make a five sided bolt out of a 32 sided disk opening?

I am somewhat new to blender and I am trying to hone my modeling skills with a focus on good topology.

I am modeling a fire hydrant currently and the end of the pipe openings or valve attachments has a five sided bolt, and everything from the rest of my model is 32 sided and circular as it was extruded from an edge loop from a modified cross joint.

I figure I can either manually try and move the vertices in the shape of a pentagon or take an extruded pentagon and just place it in a closed face and have the faces intersecting each other, but I feel there's a better way or more 'right' way to do this. Any ideas?

(Its just a practice exercise I'm doing for myself, I'm really just trying to focus on best practices and not learning any bad habits. thanks!)

You must already have thought about this way but I'm not sure there's any other way around (by the way you could have used less than 32 vertices):

• Create a 5 vertex circle (pentagone).
• Subdivide it until it gets 30 vertices.
• Select 1 of these vertices, ShiftCtrlB to bevel it. Do the same thing with another one. You now have a 32 vertex pentagone.
• Bridge the cylinder with the pentagone.

• Oh awesome thank you! This is the closest/easiest solution. I started the base of my mesh from a cross pipe joint and realized it had the same vertices as a cylinder, bool merged it on there, cleaned up and went from there. Thank you again for the learning experience!
– Zach
Jun 11, 2020 at 19:34

The answers here are good solutions to your problem, but, IMO, it's the wrong problem to have. I would rather have a good look over the reference before getting down to the nitty-gritty of shovelling vertices around, and work out how to make the job as easy as possible for myself.

If you're modelling low-poly, or low-poly to be subdivided for curvature, then it's rare the surface needs to be manifold - you can model separate parts as separate parts, choosing an appropriate number of vertices in the profiles. In this reference, the parts which are 4,5,and 6-based are conveniently discontinuous, and don't have to be smoothly merged. (A subdivided pentagon makes a pretty good circle)

If you do need a manifold, continuous mesh, for example for printing, then you will probably be higher-poly anyway .. you can choose a number of vertices, in this case, say, 30, as @moonboots suggests, which can be divided by all the profiles you're interested in.

If this case needed to be manifold, just for example, you could start with the pentagon, giving it a 2-segment bevel to tighten its corners. Having extruded that into one of the four arms, spreading the bevels with Loop Tools > Circle, you can Bridge Edge Loops rotated duplicates of the arms together with a good number of divisions to work on the main trunk in a way you would like:

You can then use Loop Tools > Circle again on the open boundaries top and bottom, locking Z so it is circular only in projection onto the XY plane, and extrude the trunk from there.

and then the number of vertices around the trunk is 32.

• Thank you for you detailed answer! I wish I could put two as the correct answer because this is incredibly informative and also an equal solution. I am going for manifold, I'm really just building a library and honing skills, but I like printing my models too. Would you normally start from the simplest outside shape and work in? I'm going to try a second version your way and re-read the reference for loops and bevels and spend a bit more time in pre-production reviewing the model references before diving in. Thank you again!
– Zach
Jun 11, 2020 at 19:58
• @Zach If it's something 'weird', a funny number of vertices, in this case, or a tricky junction or curvature, or a sudden change in resolution, where I have to lose edge-loops, that kind of thing, I will start with the trickiest part: the one that is most constrained. (I have to have 5x verts around the nut ... it would be nice to have 4x verts around the top) and work inwards towards the parts where the topology count doesn't matter. BTW, np, moonboots answered your actual question. I didn't. :) Jun 12, 2020 at 15:30

Bridging a 32-vertex circle to a 32-vertex pentagon works well as per other answer - I also tried 'bridge edge loops' on a 32 to 5 (I was curious) and it seems to work

Aiming for quads this is not perfect as there is a triangle touching the bottom pentagram face but it's probably good enough :)

Edit #1 Made some further changes to model the extrusion.