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Bolt and nut : interferences after a few turns of the nut

Question asked by John Smith on May 14, 2013
Latest reply on May 15, 2013 by John Smith

Hello everyone,

 

I am new to SW. I use the 2012 version.

I have done a couple of tutorials to learn the basics. I worked for a while on a nut and bolt assembly.

I built both in the same file, then splitted the bodies and created an assembly from the split.

I mated both with a screw mechanical constraint. The mate works great. If I don't touch the bolt, and do an interference check, I get no interferences. After turning the bolt a few times, I try a new interference check, and then.. boom ! I get some interferences (not coincident interferences). If I look at a profile view, I can see that the grooves are not perfectly lined up anymore ! (see attached screenshot)

 

I have redone this a few times to make sure I didn't build the model wrong, but I didn't. I think the problem might be coming from little errors (0.00000...) in the dimmensions. My pitch is 2.5mm (per revolution). The "2.5" screw mechanical picth constraint is probably a little different than the "2.5" pitch I used to build the bolt (the groove in the nut was built combining the bolt and the nut so i could have a perfect match).

 

I would be very interested to know why this is happening, and how to fix it. I would like to be able to have a perfect fit, no matter how many times I turn the nut.

 

I have tried another way to do it too : I would split the parts, then create a new assembly, and import my bolt and my nut separately. I would then add a screw machnical constraint, but this time, the grooves wouldn't match, even after applying the constraint. I was suprised, and tried to search for a way to adjust the offset, or something. The faces I selected for the mate were the right ones, but the screw constraint didn't align them !

 

Please anyone, feel free to help me out.

 

Thanks a lot !

 

Cheers.

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