Advice needed from commercial designers

T Chap

If anyone has knowledge about commercial design I would appreciate any input.

I designed a PCB that mounts under the glass panel shown in the pic. There is a fingerprint scanner sensor that needs to be mounted on the front of the panel. Shown in the pic is the sensor just lying on top, not in the right position, but it will be in the lower right corner.

I have no idea what is the best material to use for the fingerprint shroud. I can CNC any material, but it can't be metal or conductive. Delrin never finishes well for me on the machine. I can cut acrylic with a laser and get a pretty nice edge on the parts. The shroud has to look very slick, not home brewed. Also, nevermind the glass appearance, the paint has all been scratched up on the rear during experiments, but it will be very slick. The LEDS are too bright on some locations. I need a shroud to look just as elegant, only glass isn't an option.

Shown in the CAD drawing, a .25" rear structure that will mount to the glass/PCB with screws, a .25" bottom piece, a .03" top piece that holds the fingerprint sensor(will be flush, matte finish to hide prints), the green parts are the .125" triangular sides that enclose the under side.

Mounting the sensor flat or parallel with the glass is bad ergonomics. Mounting it perpendicular to the glass is rather awkward as well. The best 'feel' is at around 50 degrees, as the panel mounts on a wall.

The main concerns are: 1) does the design shown look amateur and hacked together, and 2) what material to use to make this so it looks profession and 'expensive'.

Ideally, a matching gloss black on all parts except the top surface that supports the scan sensor. This is all new territory, just trying to sort it out.

Any suggestions welcome. Thanks

Post Edited (TChapman) : 6/2/2009 10:13:41 PM GMT

T Chap

glass

Phil Pilgrim (PhiPi)

Is there any kind of hi-temp composite you could machine that could then be powder-coated? The powder-coated stuff I've seen looks really slick and professional. But it has to bake at 390F to melt the powder.

-Phil

Nick McClick

I would suggest lexan.

It's hard to tell how the shape will look, but I would suggest doing a rapid prototype.

Hope it helps!

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T Chap

I like powder coating, great idea. The sensor requires a non conductive housing. I will call a place tomorrow and see what options exist if any for non conductive.

Somebody said...

"The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin." The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as "whiteware", aluminium extrusions, and automobile and bicycle parts. Newer technologies allow other materials, such as MDF (medium-density fibreboard), to be powder coated using different methods."

Lexan(polycarb) is fine to but it still needs a finish after machining.

Someone else suggestion machining a mold, pouring it in various stages.

Post Edited (TChapman) : 6/2/2009 11:45:15 PM GMT

T Chap

Update: In the pics, ABS injection molded one-piece module.

Phil Pilgrim (PhiPi)

Okay, how did you manage to get an injection-molded part so quickly?

-Phil

T Chap

The parts didn't take long at all. It was an interesting turn of events. I had made a two piece mold in aluminum like what you see, and had taken the parts out to the industrial aerospace area past the burbank airport to meet with a plastics guy to help me make the rubber molds. On the way home I drove by a sign that said 'custom molds, injection molding, prototypes'. Went in and said hey can you make these parts for me and when. He said 3-4 days. I sent him dxf files and he converted to a one piece mold of what I had as two. He made a first batch in nylon, looked bad and had minor design problems as far as releasing from the mold without distortion. Tweaked the mold (carbon based, EDM process) and ran more samples in ABS. Didn't even take a week total. Probably paid 800 for 20 samples.

The abs doesn't have a finish that I like, I am experimenting with wet sanding and flat paint to get the right aesthetic. Ultimately this will be a glass part, not plastic. Still trying to sort that out.