Chain dimension issues

[ngowans]

I have an extruded component with an adaptive hole pattern along one side, the hole pattern places holes at minimum centres, if the profile length increases the holes will increase in distance until the centres reach their specified minimum, then additional holes are added to the pattern.

This works perfectly and is easy to set up without using any ilogic. However, I have hundreds of variants of this components and I need to fully automate the drawings. I want to be able to change the length parameters and then export the suitable PDF with a single click, so far it works brilliantly but the hole centres of this adaptive pattern will not appropriately dimension themselves. I have tried increasing the length of the profile to the maximum possible, then dimensioning it using chain dimension, then as the part length is reduced the unattached dimensions are hidden from view, the chain dimension seems to work, showing the exact information that I want to see, that is until I try to increase the length again and display the previously unattached dimensions, at this point the dimensions seem to just randomly attach themselves to any geometry they can find rather than the holes they were previously attached to.

This seems like it would be such an obvious thing to want to do, where am I going wrong? 

Can this be worked around using iLogic or VBA to delete then recreate the chain dimensions on update? If so, How? 

[Gabriel_Watson · Accepted solution]

Why not dimension one sample distance between first and second holes only then include "TYP." for typical? It seems a waste to have dimensioning on every single occurrence.

Perhaps try to add a 3D annotation between two holes and see if you can call upon those at the 2D.

[cadman777 · Accepted solution]

The way I've always dimensioned patters of holes is w/text like this:

10@5.5"=55.0"

The spacing is what's counted, not the holes, so there would be 11 holes.

I use a single dimension that spans from the first to the last hole and use derived parameters from the model.

So in your model, you can make the first and last hole as separate hole features, and then space them so they can included all intermediate holes using a pattern of the first hole, minus 1 hole (which is the last hole)?
That way, your hole pattern changes w/the part length, but your dimension always sticks to the first and last holes?

You can derive the dimensional value for the pattern using parameters from the model, so the dimension values update w/changes in the hole pattern.