Modeling a nice screw



Well I need just the Head of a screw, that is already screwed in. It should be a screw, that can be screwed with a six-edge screwdriver, somehow like this: but not concave, just straight in the shape. I want to model it out of NURBS, and I already have a acceptable thing done, but I really would like, that the edges are round. I tried the roundtool, but it messes up geometry and then it looks really bad.
Someone knows a tutroial, or has an idea, what to do, so the edges are round and smooth?

Thanks alot for your help,


PS: phew… bad english this time… :hmm:

edit: huh, can anybody explain why I may not post attachments? I s that the forum standart, or is it just me?

edit2: Well I uploaded the screenshot of my current screw to my webspace, unfortunately a direct link wont work, so please go to and then click on screw.jpg. thx.


If you add some Isoparms and scale them, you can get a rounded look with what you have already modeled…hope this image will help…if not, let me know and I’ll try and describe it better.


Yeah, I still get some geometry faults, but that idea was pretty smart! :applause:

Just have to cleanup a bit and then its allright!

Thanks a lot!



Hm, do you know why thi looks so weird: [ then screw3.jpg]

The two surfaces are sharing the same curve but the outer looks very odd. I’ve put the tesselation extremly high, but the fault is still there. Stiching doesent work, cos it says that it cant stich trimmed surfaces…




thats weird looking…Does it Render that way? or is it only like that in the viewport?


yes it is rendering it like that. in that image i put “show render tesselation” on, so thats the way it renders. Th tesselation od the outer surface is around 40000x50000 - extrem, so theres weird geometry…

the .mbfile of the screw with mountinghole (or how’s that called…) then


Did you try recreating the surfaces, but this time use the curves you got only once. In the other cases where you would use that curve instead use an isoparm of an other surface. It may help.


Thanks for your help, but I just made it another time, it was done quite fast. This time there weren’t any faults. I think they were caused by the curve, cos I didn’t knew how to make a sixtangle, and just made 6 curves and attached them, and this time I created a 6 edged Polycylinder and draw a curve, snapped along the top.
It’s ok how it is now :wink:


If the round tool doesn’t work and that is what you want here is another solution:

-Select the two surfaces (this doens’t work for more than two surfaces)
-use the circular filet tool.
-you may have to uncheck the create curve on surface tool and trim it manually.
-this is usually the key step.

Check your tollerances. If you are modeling with a loose tolerance, then the more you intersect and trim, the more you get ugly surfaces.

As far as the screw goes, if you want to not use the round tool make sure and do the circular filet before you trim. Otherwise each surface will have multiple trims on it. What a waste of time. That can also confuse the calculations creating wierd geometry like you have in the picture. One of the downsides to the round tool is that it does just that. you first have to create a two trimmed object. Then it trims those surfaces again, and creates a trimmed filet. Using the circular fillet it merely does one trim each, and the filet is not a trimmed surface, meaning, you can select the isoparms, not trim edges.


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