Joining spirals


#1

I’m trying to join the ends of two identical spirals. I’ve tried TIG-weld to no avail. Images:


#2

Here’s the skp file…


#3

Am I correct that you created the spirals by extruding a circular profile along the spiral path? In your third image I can see some off-alignment edges that suggest you did not orient the profile perpendicular to the start segment of the path. The result is that the ends of the two spirals do not line up and can’t be joined together.


#4

Yes I extruded along a spiral path. Sounds like I need to start over an extrude the full length that need. Would you explain what you mean by not orienting the “profile perpendicular to the start segment of the path”. I want to be sure I do it right this time.


#5

When using follow-me, one must be careful about SketchUp’s approximation of curves using straight segments. The first segment is generally not perpendicular to the plane where you started the curve, instead it is a chord of the ideal curve. Then if you extrude a profile, follow-me starts by projecting the profile onto a plane that is actually perpendicular and that can distort the shape.

Yes, I’d suggest being very careful to get the start and end segments of the spiral parallel before starting the followme.


#6

I fairly well understand what you’re saying. I’ll do my best to get those segments parallel though I’m not quite sure how. I keep it in mind as I’m working. The bright side is that even if the spiral isn’t perfect it will work OK for my purposes as long as I extrude it in one piece rather than trying to joint two pieces later. Thanks for your help.


#7

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