(Proper) Parametric Modeling

I just wrapped up a smallish job, modeling up a hull attachment that is driven by around 70 parameters! The rationale behind this was that while the number of model components remain fixed, the hull attachment has to be able to be modified to suit a wide variety of hulls. And as such the geometry needs to be flexible enough to be manipulated for each new drawing that needs to be generated for Class. So the idea is to have 1 master drawing where the key dimensions and geometry will adapt (without blowing apart) as the key parameters are changed. As opposed to the company’s present method of re-doing the whole drawing for each new hull.

I initially experimented with inputting parameters into the table before starting a sketch, and then referencing them, when I first learned Inventor. Although in all honesty I haven’t touched it since. I always find that inputting the parameters as dimensions within the sketch suits me just fine. But this job was different as I am not going to be the one manipulating the parameters. And considering the complexity in components referencing off each other and knowing which one comes first, I decided to input the parameters first.

I then called out all the parameters on a 2d drawing, showing which one goes where. Luckily this morning I came across a free plugin for Fusion that exports the parameters table as a CSV file, so I could open it in Excel to use as a reference sheet while calling out the parameters/dimensions on my 2d drawing. Unfortunately there is no way of importing either the parameters or a spreadsheet onto a Fusion drawing, but hopefully some day..

My workflow had to be very particular for this job, and I had a few false-starts to get a sequence of components that could be manipulated without the model blowing apart. The most challenging part was the revisions I had to do after I had completed the model, going back and inserting extra parameters to be referenced early on in my history. On the whole this was easier than I thought, and didn’t need much rework. Although I had a couple of very sticky ones that required some serious brain power to work out and get right. Using Fusions ability to ‘go back in time’ by dragging the history marker was the only thing that kept me sane. Allowing me to pinpoint which sketch or feature was causing an initial failure, and of course the failure of all subsequent features. There is always a moment of panic when your whole model blows apart when you change 1 parameter by 5mm!

In comparison to how I normally work, this job has taken far longer to complete a fairly simple model. But the fact that it is a master model that can be used time and again more than makes up for it. And as always I have learned a new niche in 3d modeling and expanded my knowledge of my program. Never a dull day for a freelancer (well actually quite a few) but that’s a different matter entirely!

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