2D Wireframe wont completely wrap around a cylinder with Projection

[KL66]

 I have a strange issue in Mastercam that i cannot seem to figure out. I am making a helix on cylindrical surface. I created the wireframe and then using projection to wrap it onto the surface cylinder. The issue is that when i make the diameter of the cylinder to what i need from the blue print, part of the helix leaves the cylinder. But when i make the cylinder larger, it works fine and wraps completely. I am including two pictures.

[JParis]

Draw your geometry in a flat 2D plane then use XFORM >> Roll

[KL66]

Thank you so much! that worked. I am curious though why projection didnt work. ive ever had this problem before

[JParis]

3 minutes ago, [email protected] said:

Thank you so much! that worked. I am curious though why projection didnt work. ive ever had this problem before

It may work on things that don't go too far around but once they start to get around the part, Projection will not give the desired result

[KL66]

Ah! I see. Thank you once again. Much appreciated

[cruzila]

On 5/6/2022 at 10:40 AM, [email protected] said:

Ah! I see. Thank you once again. Much appreciated

Imagine pouring water over the part. That's projection. now turn the part as you pour. That's wrap

[Sarlic]

21 hours ago, cruzila said:

Imagine pouring water over the part. That's projection. now turn the part as you pour. That's wrap

That's a good analogy.  Essentially project to surface moves the selected geometry in a straight line towards a surface until all points of the geometry make contact with that surface.  Looking at the profile of a cylinder creates a rectangular boundary.  Any geometry that lies within the boundary will project down to the visible half of the cylinder without issue.  Anything lying outside that boundary will not project to the cylinder, because when moving in a straight line it'll never touch the cylinder.

[cruzila]

Way back, surfacing was z oriented in many (all?) softwares. Containment and boundaries all had to be manually setup or it would crash the processor. I was taught the water theory then but software could not see the "backside of the surface like it can now.