topic Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom in Inventor Forum

Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Manuelcamposcosta — Wed, 19 Oct 2022 10:50:55 GMT

Does anyone know how to reduce the constrains used when constraining a countersunk screw?

The only way I know is to use concentric then tangent and an angle to remove rotation.

Anyway even with this 3 constrains Inventor is giving me one degree of freedom, does anyone know how to solve? Or is it a bug?

I don't want to take measurements and create an insert constrain.

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Gabriel_Watson — Wed, 19 Oct 2022 14:53:24 GMT

Worked for me here in 2022.3 (see attached):

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Manuelcamposcosta — Wed, 19 Oct 2022 15:24:38 GMT

I'm not having the same result. See my files. 2022.3.2

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Gabriel_Watson — Wed, 19 Oct 2022 16:20:37 GMT

Seems like your assembly is glitched. If you copy and paste the parts into a new assembly the DoF will not show the green arrow anymore. Same constraints kept in place.

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Manuelcamposcosta — Wed, 19 Oct 2022 21:14:04 GMT

@johnsonshiue would you be interested to have a look?

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

johnsonshiue — Thu, 20 Oct 2022 00:50:49 GMT

Hi Manuel and Gabriel,

I think this is due to the Tangent constraint. I personally would use Tangent constraint only when it is absolutely necessary. The issue with Tangent constraint is that tangency can lead to multiple solutions. Also, the constraint can be solved between two base faces (full cone, full sphere, full cylinder, and full torus). You could see some strange behavior as if two components don't touch each other but still constrained tangentially.

The better constraint to use in this case is called Cylindrical Face Mate. It is still the Mate constraint by instead of selecting the axes, select the cone faces.

Many thanks!

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

Manuelcamposcosta — Tue, 25 Oct 2022 07:56:29 GMT

@johnsonshiue What?!! I didn't know you could select other things when using mate, yes it did work and it requires one less contrain. Fantastic!

What other constrain types there is this possibility?

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

johnsonshiue — Tue, 25 Oct 2022 19:41:05 GMT

Hi Manuel,

Many thanks for confirming the solution! This particular Mate type is a bit obscure. It is because the primary selection to a cylinder is always the center axis. Also, for cylindrical (conical) face Mate to work, the mating faces have to have the same radius (diameter) value. Otherwise, it will not work.

I think this is a case that overloading a command can lead to some confusion.

Thanks again!

Re: Inventor Countersunk Screw Reduce Constrain Amount and Remove Degree of Freedom

SBix26 — Tue, 25 Oct 2022 20:51:03 GMT

Slight correction to @johnsonshiue 's last post: for countersunk (conical) holes, the angle must match, not the diameter. Diameters can be very different, but as long as the angles are the same, it will constrain.

Sam B

Inventor Pro 2023.1.1 | Windows 10 Home 21H2