Re: [CAD_CAM_EDM_DRO] Re: Software options

On Jun 26, 2006, at 7:26 AM, John Stevenson wrote:

>>
>> One objection that I have is that if you dimension something
>> and then you later change that something the dimension
>> does not reflect the change. Is that the normal way this is
>> done. I am a CAD newbee so I don't know how other
>> CAD packages do it.
>>
>> Pete.
>>
>
> Pete,
> That's called parametric where it updates changes.
> Most solid modeling programs have it and a few CAD programs but it
> tends to be pricy.
>

Actually John, that's simply auto-dimensioning. Parametric CAD is the
other way around, where you can edit the dimension and the CAD
program changes the drawing automatically to reflect the new dimension.

Real parametric CAD actually goes further than that, the values for
the dimensions can be parameters (hence the term "parametric"), so
for example, one dimension might be 2 times the value of another
dimension plus half an inch. The when you change any given dimension,
all the other dimensions that rely on that value update as well and
your part is automatically redrawn to match the new dimensions. A
parametric CAD program can have complex formulas for dimensions and
it will solve them like a spreadsheet does.

Alibre is an example of a parametric 3D solid modeler that hasn't
been mentioned yet. It's powerful, easy to use and learn (has built
in tutorials and intro videos) and affordable (the Xpress version is
free). We have a low priced hobby license available on our web site
as well at:
http://www.TabletopMachineShop.com/

Peter