Re: CAM--Iges STL

Date: Thu Jul 09 1998 - 18:11:17 EEST

     Terry Wohlers wrote:
     "If you have STL data with fine resolution, you can produce good
     quality parts on RP systems. The same is true with CNC machining of
     STL files."
     You are missing the point that Steve was making.
     I have almost always found it necessary to edit the data file that I
     wish to create NC toolpaths from. This is because the designer or
     engineer left off the finish stock or the draft or the fillet needed
     for production.
     The data is not editable as features or parameters in the stl format.
     In other words, the hole in the stl model is not selectable as a
     parameter that can be changed. Sure, by using the right software it
     may be possible to do things like offsetting the surface to change the
     hole size in the stl model but it is much easier to do it in the cad
     Try to change a fillet radius on an stl model and you will see that
     the problem is even worse.
     So unless the stl model is saved exactly as it will be machined, it
     will usually be better to machine the cad data instead.
     If you are only doing contour milling of the data file than this works
     fine, but there are usually features in the data that would work best
     ifthey are setup and machine in other ways. Pins holes and slots are
     simple machining features that might be better to do as seperate
     operations instead of as a contour mill.
     Also, some of the parametric modeling programs allow machining feature
     definition within the solid model file. This means that the designer
     specifies the features that are machined using rational tooling
     definitions (drill, counter-bore, tap, turn, mill...) and the cam
     program understands the desired operation when toolpaths are
     Larry Blasch
     System Administrator for Engineering Services
     OPW Fueling Components
     P.O. Box 405003 Voice: (513) 870-3356
     Cincinnati, OH 45240-5003 USA Fax: (513) 870-3338
     Disclaimer...The views expressed are personal opinion and not those of
     OPW Fueling Components.
     * "Always remember you're unique, just like everyone else." *

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