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# Tangent on a round..

#### corydr

##### New member
I have this sheetmetal part thats bent at an angle. And of course there's a round at the bend. I want to create a tangent point directly on the surface of that round. The problem I get is that when I create one, when ever I unbend it to a flat state, the tangent point does not follow. I have tried make the tangent point on it's flat state, then bending it back up. Neither way is working... the tangent point doesn't follow... I'm getting desparate...does anyone know of a way...?

#### ProFishent

##### New member
Datums do not move with bends or unbends, only sheetmetal geometry does. If you explain what you need to define this point for(sketcher reference, drawing dimension, etc..,) maybe I or someone else can help you to find an alternative method.

#### corydr

##### New member
Well basically what I am doing, is at the bend (the tangency of it) I am trying to put a gusset there using a punch form that I created. I want to place that gusset there and have it follow the part in it's bent and unbent state. And when I assemble the punch into the part, I need a reference to assemble it at the tangency of that bend. So that's why I was using a datum point. I hope this explains better what I am doing.

#### especial

##### New member
Can you put up a picture or send me a Zip file if it's not too much trouble?

Thanks

AS

#### ProFishent

##### New member
It's been a while since I have done a punch feature, but as far as I remember once you create it you can make a flat pattern. The datum point will not move, but as the flat pattern is the last feature it will reflect the punch geometry. Or maybe I am misunderstanding you and you want to create the punch before the bend.

#### jperkins

##### New member
When you use a form it doesn't unbend with the regular unbend, you have to flatten form. How you locate the form will determine where it ends up in the end. If you use a bend edge it will follow the reference edge when you unbend it, if you use a datum plane or point it will remain in reference to that but the rest of the geometry will move to compensate for the developed length.

Your terms punch form doesn't jive, a punch and form are different things. I will assume you mean form like a stiffening rib on a bend. A form can also have an exclusion area to remove material.

This form should be a separate solid part following the contour you want on one surface. You add it like an assembly, mating the surfaces and so on.

If it is a stiffening rib don't worry where it ends up in the flat state because it is never made in the flat state.

A punch is a single cut and when you make it you should use a similar geometry as you have in the finished part for the punch.

If you need further assistance post a method to reach you.

jperkins

#### jperkins

##### New member
Just to clarify my previous message, 'locating' a form is like adding a part in an assembly. It come up as you add form.

Another thing that is needed in a punch, I forgot to mention, is you have to add a coordinate system to it .

jperkins

#### corydr

##### New member
Thanks, for all the responses. They helped me look at it in a different way. Although I was able to use a tangent point to locate my punch to create the gussets. I'm still not able to flatten it out with out a Fail Regeneration. But as one of the responses mentioned above, the gussets are created after the bend, and not in it's flat state. So I shouldn't need to worry about showing the flat pattern with the gussets...