How to make a spiral around non circular/conical body

lorenz_poiger

I would like to know if it is possible to have a line wrap around a body like the one shown in the picture below. The line should wrap around it with a constant pitch and no gaps. I want to use the line as a sweep path for some tubing (yes I have to draw the tubing). I cant think of an easy way, I can't even really think of a hard way either. Using the sketch wrapper feature script only allows for cylindrical/conical surfaces. Does anybody have any suggestions? Thank you in advance. 

NeilCooke

Here's one way to do it. It's a bit convoluted but gets the job done.

https://cad.onshape.com/documents/6d0ca20817c386e277330785/w/40202c839705efb451f3b81c/e/f7d6a7e99ec45da1c276d881

John_P_Desilets

@lorenz_poiger

In this situation I believe a projected curve is your best option.  




Sketch 1.  Top Plane. Make sure the sketch is split at the centerline.  




Sketch 2: Front Plane. Draw the pitch of the helix. Only one step is needed. 







Projected Curve 1 and 2

The first projected curve will be made from half of sketch 1 and the first line of sketch 2. The second projection will be made from the second half of sketch 1 and the second line of sketch 2. 




Linear Pattern the Curve.

Since Onshape sees curves as parts, they can be pattered, scaled, rotated, and copied. In this case, simply pattern the curve the exact distance of the step or pitch. 





Here is the link to the Document. Hope this helps!

https://cad.onshape.com/documents/40828daf7af93e9befd9a5a0/w/d47b410175eda5400abe9c58/e/82fb5859ad81a4b28b37f03f

konstantin_shiriazdanov

You can also use contour spiral feature https://cad.onshape.com/documents/59007ff281e43510ea3797a2/w/a6cb15bca8f1b2bf6e312ccd/e/da24ed59289e4bf68e180e6c

NeilCooke

Here's one way to do it. It's a bit convoluted but gets the job done.

https://cad.onshape.com/documents/6d0ca20817c386e277330785/w/40202c839705efb451f3b81c/e/f7d6a7e99ec45da1c276d881

John_P_Desilets

@lorenz_poiger

In this situation I believe a projected curve is your best option.  




Sketch 1.  Top Plane. Make sure the sketch is split at the centerline.  




Sketch 2: Front Plane. Draw the pitch of the helix. Only one step is needed. 







Projected Curve 1 and 2

The first projected curve will be made from half of sketch 1 and the first line of sketch 2. The second projection will be made from the second half of sketch 1 and the second line of sketch 2. 




Linear Pattern the Curve.

Since Onshape sees curves as parts, they can be pattered, scaled, rotated, and copied. In this case, simply pattern the curve the exact distance of the step or pitch. 





Here is the link to the Document. Hope this helps!

https://cad.onshape.com/documents/40828daf7af93e9befd9a5a0/w/d47b410175eda5400abe9c58/e/82fb5859ad81a4b28b37f03f

NeilCooke

Huh, @John_P_Desilets way is better 

lorenz_poiger

Wow, that was fast! Both very good solutions. Will definitely try them out. Thank you!

konstantin_shiriazdanov

You can also use contour spiral feature https://cad.onshape.com/documents/59007ff281e43510ea3797a2/w/a6cb15bca8f1b2bf6e312ccd/e/da24ed59289e4bf68e180e6c

lorenz_poiger

@konstantin_shiriazdanov The answers keep getting better, thank you!