Is there a generic way to keep one dimension always less than another?

[tluxon]

I have an arc whose center I don't want to constrain, but I need it to always be on one side of a line it's tangent to. The proplem is the line it is tangent to is coming off of the face of a coil end. As I edit the helix of the coil to various revolutions, sometimes the aforementioned arc "pops" out to the wrong side of the tangent line.

Is there a simple way to control this?

One thing I thought of was forcing the dimension from the axis of the coil's helix to the center point of the arc to always be less than the radius of the helix, but I'm not sure how to do that without putting a hard dimension on the center point of the arc.

It seems that I'd probably have to use Equations somehow, but it doesn't allow less than or greater than conditions.

Any ideas?

Thanks,

Tim

 

[MechEng13]

Instead of using equations, you could use a design table, allowing you to use the < or >...I haven't done it myself, but I know it has been done.

Al

 

[jbknudsen]

hey Tim,

Hmmm lets see if this will help, havent done this before but a quick sketch on my end worked, however it is not a full part.

I used the equations option.

1. I placed a radius dim on the large circle/arc
2. I made a smaller arc within the large arc and made them tangency
3. placed a radius dim on the small arc
4. equation; made the small arc = the large arc *.25,
in other words I made the small arc 25% of the big arc
5. placed a radial dim from the center of the large circle/arc to the small arc and applied the same equation as above ie: radial dim to small arc = large rad *.25

What I am hoping to do is to place a constant ratio on the arc. The hard number/ratio could be modified as needed but it may give you a hand up in keeping the smaller arc within the larger arc or circle until you get the results you need. Additionally by only using the radial dim to the small arc, you will not constrain the entity.

Hope this helps
Good Luck,

-Jay

 

[tluxon]

Thanks for the replies so far.

Jay, I've done something very similar to what you did and I'm still having a problem. I think I've eliminated the issue of where the center point of the tangent arc is. What I have now is the tangency condition is not preventing a reversing of the direction of the arc. This results in the arc flipping from CW to CCW.

So my next obstacle is how do I force tangency to go a certain direction without locking in a dimension to the center of the arc (i.e., forcing the arc to be less than 90°)?

Thanks,

Tim

 

[meintsi]

Add your two dimensions as you intended and try using an equation using the IIF function to keep Dim1 > Dim2.





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