Thx for the detailed informations

Sorry if i was not clear in my explanations
The object was not in the good orientation in my previous file :(
I was fumbling and deseperate to not find the good solution!
(so the false image and file! :)
(but thinking that is possible to start from any position to anotehr one
--> perpendicular abode the curve)
Object on the top curve surface is the result wanted

So what must be the deductive reasoning for ovoid to test all orientation of the tripod axis :)
Of course I will exam all your infos above!

Here the new file! :)
http://piloumaison.weebly.com/uploads/3/6/2/0/3620514/slide_on_curve1.3dm