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Thicken surf vs extension normal to surface

Thicken surf vs extension normal to surface

Thicken surf vs extension normal to surface

(OP)
  I am currently building carbon fiber window
  check and assy. fixtures. the nuts and bolts to these
 fixtures is basically triming a surf (thru curve mesh)
 typ. to a spline that represents edge of glass.
 At this point I thiken surf. by say 50.8 mm
 sounds easy right. My problem is this one of my custermers
 do not use solid models . they build side walls
 by free form featue extension normal to face.
 The fixs can be fairly large say 6foot by 3foot
 I am allowed +-.13 mm deviation on gage.
 ther models seem to average .04_.05 different from
 mine. (half of my total tol.)
  Dev is random not top edge or bottom
 and typ only 1 or 2 spots are different from my
 model to there model
 and say 3 out of 4  models are close enough
 I had one out by.079 to theres?

  What I need to know is why there is any difference
 at all?  we both build from same data set.
 I have set dev to .005mm for trim and thicken opps
 the reason i thicken is 90 return wall is req.
 I also have had corners come out concave rather than
 stright (90 to sheet body) this I suspect is
 due to the small corners that I some times deal
 with .  I have about 20 years cad exp but only
 2+ on ug. even worse i am basically self tought
 on ug. I have been threw the cast files (seam very basic)
 our sys is lagit but maint is out of date.
        (before I started to work  here)
 we currently use nx2. Perhaps I dont fully understand
 thicken vs extension. The closer our model are the more
 tollerence I have to build my fixtures. The reason for
 second data set is custermers second sorce cert.
 This is supposed to get rid of any modling errors.
 I even tried offsetting isg (in side of glass surf)
 and projecting edge of glass curve (outer spine)
  normal to face I offsetand manually building side walls
 ten sewing together
 these walls were slightly diff. from the other 2
 (slight variation to other ways of building)
 Also i am not sure if tollerence or dev is angular?
 
  any help would be great

         Mike Tucek cad man vision mach inc.



 

 

RE: Thicken surf vs extension normal to surface

Mike,

You are on the correct track.  Most of the time Thicken Sheet is the best solution for models like yours.  I believe it still is in your case.  The excessive deviation is most likely due to the default modeling tolerance.  When creating surfaces to datasets provided with such tight tolerances, you should reduce your model tolerances when generating your initial sheet body, then play with the specific tolerances of your thicken.  I always start with the smallest tolerance the model will let me make and relax as necessary.  Also check your surface deviation prior to thickening.  You may actually need to remove specific data points to avoid wrinkles.

Basically, most of the time, tighter modeling tolerances and few actual definition curves and points will generate the better sheet.  Better sheets produce better solids.

I hope this helps you.

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