I would like to make a knob to 3D print, but I have no idea how to start it

I am attaching a picture of what I want to make. This plastic knob slides over this brass shaft. As you can see, the brass has grooves spaced closely together for the knob. The knob has the same grooves inside and these grooves keep the knob from spinning on the shaft.

Also, the outside of the knob has these grooves as well. I have no idea how to make these. Can SU do this? If so, are there tutorials for this? I could not find any. How can I make this knob in SU?

Thank you for your help
PS. Yes, I know the grooves on the brass shaft are boogered up but I can fix that with a small file.

maybe like this. Obviously you’d have to enter specific dimensions for the parts, but the principles may work? drag out circles with a high facet count for smoothness, push pull, scale about center to get taper. Use offset, or draw out another circle from the ceter ( use right click find center) figure out the seration specs and make that profile, push pull it down to specific depth. You could knurl the exterior part of the know too for better grip, do that profile with first circle.

I would attempt to reuse a knob in such good condition…

it looks like a retaining ring on the base may hold it on tighter…


WOW… you make it look so easy. I’m not sure what buttons you are pressing to copy the individual grooves around the circle but I will try that. This is cool!

Once you have the “V” shape drawn on the edge of the circle, I selected it and then used the “rotate” tool from the center point. As you use the rotate tool hit ctl/cmd which will make a copy of it. Once the first copy is made and before touching any other tool, just type *24 and it will repeat the copy that many times (24 in this case) around. If it isnt right retype *25 and it will update the amount of copies to the new number. You might be better able to predict the amount of times based on how you draw that profile on a know amount of segments on the circumference. In the first gif I copied it 10 times around but it needed to be 11 to total 12

Here is a video on how to make arrays.

Fantastic. Gonna try this now. The brass post is 5 mm (so I drew the circle 2.5 mm)
and the number of grooves is 16.

But then how do I know how big to make the “V” so I get 16 grooves? Or will inputting a number resize it to fit?

Thank you for your help

OK… I counted the grooves on the brass post twice. I get 16. Given the size of the post and the number of grooves, it don’t work. How do I distribute these evenly. Best I can figure, I have to make the “V” bigger, but I don’t know how much bigger I need to make to get it to fit.

Perhaps you could start with the polygon tool set to 16 sides. This could be a template for whatever splines you care to make.


Thanks Shep. That worked. I think I did it! Took me a while tho. Now I have to figure out how to knerl the outside. What do you think so far?

knob.skp (106.7 KB)

draw out the circle with a 16 count of sides? then the line will already be divided

You are correct John. I intend to re-use it. However, I need 6 more.

ok…I looked. How do I put a knurled finish on the this knob?

Think it through, do the knurl before you extrude and scale.

■■■■ it. I should have realized that!
Can I have your drawing since it is already done?

I didn’t save it.