# Catia counter sunk screw constraint

Hello,

I am trying to apply constraints to a countersunk screw.

1- I apply “contact” to the conic surface of the head of the screw and the conic surface of the hole.
Afterwards I wanted to apply “coincidence” to the axis of the screw and the axis of the hole. But I am getting that they are redundant.

2- I don`t know if the right solution can be to apply
- “contact” (like in 1) and “angle” constraint to the planes of the screw, with the planes of the part where the holes are.
- “coincidendce” (like in 1) and “angle” constraint to the planes of the screw, with the planes of the part where the holes are.

Thanks a lot

Hi friend good morning!!

I dont know if you mean to this, as you can see in the picture below:

Hi there Hugo,

But there are still 2 degrees of freedom.
- Linear translation in axis direction
- Rotation around axis

Don't we need more constraints?
- Rotation can I constraint using "angle constraint" between defence plane of screw and reference plane of washer.
- But Translation?

You like to know what constraints are best suited for bodies with countersink.

Let me tell you this before hand, There is no such thing as right solution.
Any of the below 3 Cases are correct. The more the freedom you want between parts, the more constraints you need to provide.

Case-1:
1. Coincidence - Screw Axis with respect to Hole Axis.
2. Offset - Screw Surface/Plane with respect to part containing Hole feature.
3. Angular.

Case 2 :
1. Contact - Screw Countersink face to Hole Countersink face.
2. Angular.

Case 3:
Use 'Manipulation' to place where exactly you need the screw.
1. Then use Fix constraint.

so called "optimised solution" depends on the project you are working on and the location of the mating parts.

Hope this is the explination you are searching.

I agree with Bhanu Chinni.
Usually, case 2 is sufficient, if you want the conical part of the countersunk screw to be in contact with the surface of the countersunk hole.
Else, if the two surfaces should not be in contact or if the angles of the countersunk hole and screw are different, use coincidence, offset and angle.

Hi friend!! Could you send us a picture about your issue!! This is to much for all of us, I can give you a solution!!!

Best Regards,