How to create feature-unrelated piloting dimensions

[tleati]

Hallo,

anyone knows whether it is possible to create dimensions (not necessarily related to a feature) that pilot other dimensions?

I make a (I hope) clear & simple example:

I extrude a bar which is 600 mm long, then with another extrusion (removing material) I cut off 200 mm. The final length is 600-200=400 mm

...is there a way to command directly the final length (and given the inizial length, the cut adapts to it)?

I know this could be done with parameters and relations, but I find it more immediate to see it as a dimension on the 3D model...

I think maybe this "pilot dimension" can be obtained with an annotation associated with a parameter??

thanks

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[JonathanHodgson]

I would probably create a plane at the cut position...

[tleati]

Hallo Jonathan,

in the example case yes, I was saying in general terms just to know about that possibility as it happened to me to face this problem.

thanks

bye

[dgschaefer]

This is almost always possible, but can frequently can require creative thinking and multiple additional datum features.

In your simple example, there are a couple ways of handling this:

1. Create a datum plane offset from the one end at 400mm and tie your 200mm cut to it.
2. Create the 200mm cut at 90 degrees to the main 600mm extrusion and dimension the end of the sketch 400mm to the far end of the original.

I'm sure there are more, depending on the specific geometry. Bottom line, you can probably create construction / datum geometry to do what you want to do.

I'm a huge fan of what you are trying to do - finding ways of building directly to your design dimensions. This requires a bit of planning and may require a couple more steps, but it pays off in a more predictable model, a more easily modified model and less errors (from doing the math yourself).

[tleati]

Hallo Doug,

yes in fact as Jonathan suggested it can be done adding a datum plane, in the example.

But often (In my opinion) datum references are a bit invasive. And yes, it requires planning above all I think in the relations you have to put it...but at the end this thing would be really comfortable as you say.

(probably this way of designing depends also on personal preferences and/or habitude...)

bye