Need help in designing the frit border pattern of automotive windshield glass - specifically the Dots Pattern

Dear Dan, could you please tell us how to design the dots pattern and lines, needed for automotive glass. Thank you.

Well let's see
1. First if you a have a 3D drawing convert it into 2D drawing , I use Autocad or Catia to ge correct conversion.
2 .Once you have a correct sized 2D pattern import that into Corel
3. You and the designer must now decide how wide the solid frit line will be,
4. Once you have the shape and width of the solid line designed, you duplicate the the shape line shrink it to your design and duplicate again and reshape as this will be your inner line of the decided pattern.
5. Combine those two line and color black.
6. At this point I will print a full size pattern on vellum or transparency and place over bent windshield to see if that's what we really want or if changes in the solid line need to be made. If the vehicle is within driving distance or short flight I like to do this myself. If the vehicle is overseas I will send the file electronically they will print it out let me know of changes the designers want done.
7. It is at this point that the width and shape of the dot matrix will hand drawn on the vellum by the designers of the vehicle. Also very critical at this stage the placement of the VIN plate will be marked as a visibility of the plate is mandated by law. Depending on ergonomics the legal placement of the AS1 arrow will decided and marked. Also the placement of the manufacturers is usually included and marked at this stage as well as manufacturers DOT numbers, US, European, and Asian symbols if the vehicle is to be sold in those markets, all legally mandatory.
8. Once I get the vellum back with the necessary marking, I break apart the solid black frit line previously created, duplicate the inner line shrink it to fit the marking of the dot matrix design, This will be the line that the blending toll will follow in future steps.
9. I assume by now you know how many dots the matrix design will be 3,4,5,6 etc. You place a large dot on the center of inner line of the solid frit line and small dot on the most inner line, most commonly at a 45 degree angle, then you use the blending tool 3 or 4 steps to finish your initial design.
10. Combine those duplicate, place on opposite of the windshield design and use the blending tool to connect both dot patterns and have follow the most inner line you designed.
11. Chance are you will have different patterns throughout the design, those you will have to connect manually.
12. You will also notice that the pattern will not look right around the corners, you will have no choice but to break apart and manually maneuver those dots until you have a visually pleasing pattern.
13. Now you will need to find someone that can print a full size transparency in laser for you to burn an oversize silk screen, The company burning the silk screen should tell you whether they need a film positive or film negative
14. The pattern is silk screened onto the flat glass before slumping in the furnace.
15. The paint used to silk screen the pattern is also very very important, It is an actual part of the structure not just decorative. It must be compatible with the urethane used to glue the windshield in place. the urethane used must be DOT approved as it must hold the windshield in place throughout storms and such, but still a person must be able to kick it out in an emergency. So frit line and urethane are part of an assembly.
16. The paint that you use ill also determine the mesh size of the silk.
I assume that you are working on a new vehicle design, if not don't mess with this it is a very expensive and time consuming task, find a post production windshield. Any little step that you miss or place in the wrong spot might force you to start over and all the steps are expensive.
I have worked in automotive glass design for over 30 years, and we are based in southern California, where most of the design studios are located. But still even I want to pull my hair out (not that I have much left) at the requests of the designers. I hope my answer was satisfactory.
Regards,
Daniel

Dear Daniel, hope you are fine. Thank you very much for your valuable reply.

Actually yes, it's not a new vehicle design. I had a project to accomplish, they asked me to make the design of a rear automotive windshield of a car model, this car is already available. They want me to make the design of the black area around the edge, the black dots, the defrosters lines, identical to this car windshield. But of course they want the defrosters lines to be straight, not curves. Then they want to take this design, print it, and use it to make the same pattern on blank rear windshield glass. Then they will continue the process on the windshield to make it curvy to be ready to be installed on the car.

So I was wondering what is the most appropriate and accurate way to copy "Black area, dot pattern and the defrosters lines" from a certain car model in order to have the design ready to be used elsewhere? or
As you stated above how to "find a post production windshield" of a certain model, for example Mitsubishi Lancer 2011 ?

I do appreciate your feedback. Thank you very much.

Hmmm, personally I wouldn't waste my time with this, you are looking to spend thousands of dollars to reproduce a glass that can purchased for a couple of hundred at the most. The defroster is usually done with conductive paint, although in some cases wire is still used. And that's a whole separate procedure. The back glass is usually tempered not laminated, not sure what the effects of a defroster on a laminated piece of glass will be on the defroster capabilities. The tooling alone for a compound curvature tempered glass like the lancer will cost thousand of dollars plus the tempering furnace used is very expensive, so I assume you are going to using laminated glass. Again I don't see the sense of spending thousands of dollars to make a 200 dollar glass that is readily available. If you insist though, I would try contact paper on the back glass, trace the existing frit line, then lay flat carefully measure everything and then try to copy that into corel but chances are the measurements will be off and it will be very labor intensive. I cannot stress enough that it will much much easier and much much less expensive to buy an replacement glass than to try to reproduce one, it would probably be easier to hand make a metal fender rather than buying a replacement than trying to make a new glass. You might notice that car body change slightly form year to year but the glass remains the same just because glass production is so expensive and complicated