# Lines perpendicular to surface within tolerance

Hi Everyone,

For our customer we need to make a simple 3D checking fixture (just make upper and side surface). The customer send us the basic surface (actually it represents e.g. front door glass in cars). Our company has Surfcam with 5 axis trim and we need to make the side surface which is perpendicular to the basic surface.
I start with offsetting basic surface by 35mm with Solid option On. The result is solid, which I explode to get side surface (other option is to get 2 edge curves from upper and bottom surface).
After finishing these steps I cannot continue because I do not know how can I create lines perpendicular to upper surface or edge curve within tolerance, e.g. 0,05mm. These lines are used as driving vectors for toolpath creation. The fixed distance is not suitable. I know how to do it in Surfcam, but I would like to make all operations in Rhino.
Thanks for ideas

I’m just guessing, but I think that Line>Normal to surface should help here… --Mitch

Unfortunately, this does not help me (I know this command- I use it for aligning the surface before milling)
I do not know where to place the points within the tolerance. Surfcam generates this points and lines automatically according to tolerance. The number of points is almost 150-200.

I don’t quite understand what you need when you say “within tolerance” (and cite a tolerance of 0,05)… You want lines every x distance along the edge? (Use the Divide command for that). Or is it turning the edge into a polyline that has a deviation of less than 0.05 from the original edge curve and uses the vertices for normals? In that case use Convert with the proper tolerance, then get the vertices and use those for Line>Normal. (there might be a workaround with Fin here).

If you need o generate a series of hundreds of lines, you will probably need a script though…

–Mitch

A workaround would be to offset the surface, duplicate the border and _Convert it to a polyline using your tolerance. Extract the points of that polyline and check the _PointDeviation towards the offset (with the option to ‘make hair permanent’)

If you need the normals ordered or labeled somehow, then you need a script like Mitch already suggested.

Oh, that’s exactly what I need. Thank you so much, Jess.
The steps are similars to Surfcam, but I didn’t know the commands ExtractPt and PointDeviation.