Rotation-Translation constrain problems

[Anonymous]

Hello all,

I'm currently working on a project where I'm modelling a traditional bench vice. However, I have run into some problems in my final assembly, especially regarding a rotation-translation constraint. I have attached a pack-and-go *.zip file with the relevant parts and assembly to this post.

1. As you can see in the assembly, Part 5 - Shaft screw is constrained to Part 4 - Nut with two constraints. The first is an axis constraint to line up the shaft with the nut, and the second is the rotation-translation constraint. As I understand it, this should give the effect that the shaft screw rotates as it is being moved in and out of the nut. As you can test yourself, this does not work at the moment. 

However, if you suppress Mate 3 for Part 4 - Nut (which is one of three constraints holding the nut to the base) the rotation-translation for the shaft screw starts working as it should. Although the nut is now free to rotate in one of its three axes, which it can't be for the final assembly.

Does anybody here have a good explanation for why this happens? Or possibly an alternative method of constraining the parts which achieves the same result?

2. You will also see a handle with a ball on each end in the same assembly. This handle should be mounted in the hole on the end of the shaft screw. It should ideally be free to move side-to-side, stopping when the balls hits the hole in the shaft screw. I have tried many methods of constraining this part into place, so far without success. Either the handle constraints breaks the functionality of the rotation-translation of the shaft, or it is under-constrained, allowing the handle to move beyond the limits of the balls. Sorry for the long explanation, but it should be clear for anybody who have seen or used a bench vice in real life.

Thanks a lot for any assistance

EK

[karthur1]

I took at look at your assembly.  Why are you wanting the screw rotating and translating?  Is it for a presentation.... or are you just trying to get it to show that way?  The rotational constraint does not do what you described.  If it did, you would have to enter the thread lead some point..... and there is no input for that.

On the issue with the handle balls, dont use the free form to create the ball.  I know you didnt ask about that, but that is just something for free.   Look at how I modeled it.

Normally you could use "Contact Sets" to do what you are wanting, but for whatever reason, that does not work here.  Maybe because it is two curved surfaces intersecting.  Regardless, I was able to do it with a Flush constraint with limits.

I am only included the two parts that I edited here.  All the others are your original parts.

Edit:  I looked at some of your other parts and it appears that you dont know how to reuse a sketch.  Do you know that you do not have to recreate a sketch everytime you want to create a feature? 

Kirk

[karthur1]

A quick animation that I did using Studio.

[JDMather]

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@karthur1 wrote:

 The rotational constraint does not do what you described.  If it did, you would have to enter the thread lead some point..... and there is no input for that.

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Sure there is.

[karthur1]

ok.  JD corrected me.  There is a way to get the rotation-translation.  I could not get the Rotation/Translation :1 constraint you made to work without editing it ( you did not pick the right things for selection 1 and 2).  Here is what I used to get the movement.

Still dont know why you have to supress MATE:1, MATE:2 or MATE:3 in order for this to work.  Maybe JD can expalin that.

[lena.talkhina]

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