# Screw Heads for Andrew



## SketchUp Guru (12 Jun 2006)

I thought I'd start a new thread for this so it might be found in a search more easily in case someone else needs it in the future. Sorry about the size. Description below.






From upper left to lower right.

1. Circle for path and arc for head profile.
2. After Follow Me.
3. Using construction lines and then the Rectangle tool I drew a rectangle the size and shape of the bottom of the slot.
4. Push/Pull the rectangle into the dome. I pushed it down to the intersection of the vertical construction line with the dome.
5. Select the rectangular solid, right click and choose Intersect with model.
6. Delete the unwanted geometry and reverse the faces in the slot. They are backwards because they were inside the box. Note because of the faceting of the dome, Intersect with model leaves some tiny triangular faces at the ends of the slot that need to be erased.

Hope that makes sense. Now of course once you've done this and completed the rest of the screw as desired, you should save it as a component so you don't have to draw it again.


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## andrewm (12 Jun 2006)

Dave, 

thanks for that. Is there any advantage to rotating a full cross-section about 180 degrees over rotating a half-cross section over 360 degrees which is the approach that I took.

Andrew


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## SketchUp Guru (12 Jun 2006)

Andrew, you're welcome. I don't know that there is any advantage of one over the other . I think it might be easier to draw the arc as I did. Otherwise you have to draw a vertical line at the center to give you an endpoint for your arc. Actually , yes, I can think of another benefit. SU draws arcs with a given segment count--either the default 12 or some number of your choosing. Whether you draw the arc as I have or as you describe, you'll get that number of segments. Drawing the shorter arc with the same segment count would result in more faces. I just did a quickie comparison. Drawing the arc as I did at the default settings gives 288 edges and 145 faces. With the same settings but drawing the arc from the center to the edge I get 576 edges and 289 faces. :shock:


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## Johnboy (14 Jun 2006)

Or 

Create the arc





Revolve it to create the head





Draw the slot wireframe





Extrude cut to create the slot





No faces to delete, the cut automatically does this.

Check the properties of the part





5 faces and 7 edges. Any of the dimensions can be modified and there is no need to draw it big and scale down. This is 10mm dia and 1.5mm high with a 1mm wide slot.

Created in Alibre, sorry couldn't resist it  

John


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## SketchUp Guru (14 Jun 2006)

John, that's not very useful for a SketchUp user, though.


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## Johnboy (14 Jun 2006)

Hi Dave, I hoped the smiley at the end would have been a clue that I was just making mischief. I am using sketchup myself a fair bit and think it is great, as are your tutorials.

John


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## andrewm (14 Jun 2006)

Johnboy":oevnnf5l said:


> Any of the dimensions can be modified and there is no need to draw it big and scale down.
> John



This was always one of the things that impressed me with AutoCAD. Dimensions seemed to be limitless. You could just as easily draw something at the sub-millimeter level as you could at the kilometer level, and on the same drawing.

Indeed at one time there was a demonstration of this which started with the solar system and you could zoom in to a plaque on the moon.

Andrew


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## SketchUp Guru (14 Jun 2006)

John, I knew you were making mischief.  I forgot to add a smilie myself.


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