Locating parts to holes on curved sheet metal plate

[beachcomber]

A user here has a curved sheet metal plate with holes in it for screws/rivets etc.
The holes have been created in the flattened state which means thay are not cylindrical in the bent state, so we can't use an axial align constraint in the holes at assembly stage.
I have tried creating a sketch consisting of a grid of lines for the hole positions and then wrapping the sketch back onto the bent plate. This then creates the grid as curves on the bent surface (it has to be done before the holes are added otherwise the curves get trimmed to the hole).
The problem is that these curves do not coincide exactly with the hole centres in the bent state.

Any ideas why?

I know we can create the holes on the curved plate quite easily and this would have been my preferred way, but the plate and holes have already been modelled.
modelled

bc.
2.4GHz Core2 Quad, 4GB RAM,
Quadro FX4600.

Where would we be without sat-nav?

 

[beachcomber]

Found the reason -

The holes centres get projected onto the neutral plane, but the wrapped sketch curves are on the outer surface. Therefore the hole centre on the outer face is further from the base edge than the sketch curve.
One solution is to make the neutral factor =1 (the outside face), but this affects the flat pattern size - not ideal but in this case it doesn't matter.

bc.
2.4GHz Core2 Quad, 4GB RAM,
Quadro FX4600.

Where would we be without sat-nav?

 

[HDS]

Did you try the connect constraint?

 

[beachcomber]

Yes we tried that but the problem with putting the hole in the flat plate then applying the bend results in a hole that is not a true cylinder.
This prevents you locating the cylinder axis or the centre keypoint.

bc.
2.4GHz Core2 Quad, 4GB RAM,
Quadro FX4600.

Where would we be without sat-nav?

 

[HDS]

Are there quadrant points you can pick on the edges? You could align the planes of the screw to them.

 

[beachcomber]

No, the edge is a spline curve
What you really need here is to be able to bend the sketch with the plate.
It doesn't matter now anyway - I'm leaving next week.

bc.
2.4GHz Core2 Quad, 4GB RAM,
Quadro FX4600.

Where would we be without sat-nav?

 

[HDS]

I am not surprised it doesn't work.

Good luck, I hope the move is good news.