# To sweep helical curve with extension curve

#### Rajesh

##### New member
I have drawn curve as spring using equation. I have created a point at the 'vertex' of the curve followed by a few more points. Then drew another curve using Thro Points-Single Radius from the end of the curve. Now I want to sweep these two curves together. But it is not accepting. It says Curves/Edges do not form a loop. Please reselect.

I understand that this is because the curves are not tangent at the connecting portion. How to solve?

Rajesh

#### gurveen

##### New member
hi Rajesh

draw another dtm curve using curve>composite>exact

in this u select both curve one by one. the new curve formed is a single curve which u can select as trajectory for your sweep

hope this helps u

Gurveen

#### gurveen

##### New member
also check the radius at bends, Which should have enough value for the section to sweep

#### Rajesh

##### New member
Thanks

Composite curve is working. But the shape of the spring when used swept blend the solid is not following the curve.

Rajesh

#### hmt34

##### New member
hello friend, Thanks for the answers. But I am facing one problem, I have generated curves using relations. but I am unable sweep along these trajectories. Please help me.

-hmt

#### kvision

##### Moderator
Rajesh, redefine the additional end curves and fix the tangency at the end where it connects to the equation curve. This may fix your problem. watch this video . What you are doing is done here completely.

http://www.kinetivision.com/freevids/drip_loop.htm

hmt34, a regular sweep won't work on a curve by equation. Use swept blend or var sec sweep to follow that curve.

#### Rajesh

##### New member
Thanks a lot kvision. Got it right. The video is very useful.