Face Shield Model

eric_schimelpfenig

Hey all! I realized I never posted this here:



https://cad.onshape.com/documents/3eb48dd2e897742bfd684ccd/v/e104c3a0953f7996ac8c7787/e/f88ff88aa0fe388898bb902b

I designed and created a reusable, serviceable face shield a few months ago. It can be cut on a CNC using HDPE and some thin polycarbonate sheet. The whole design is meant to be serviceable so one can break it down, clean it, replace parts and keep them in service. 

If anyone wants to make some of these go for it. I've been donating them to people that I know that need them. 

matthew_stacy

@eric_schimelpfenig I only recently learned that designing inside corner radii slightly larger than tool radius is preferred for CNC machining.  So for example, your visor has several R1/8" faces that might be increased.  Growing up around manual milling machines, I never considered this.

• https://wiki.imal.org/howto/good-cnc-design-practice
  

Another recommended practice is to limit cut length to 3x the tool radius to maximize tool stiffness and allow more aggressive feed rates.  This may not be a huge concern for plastic parts.  But for you 1/2" thick visor it might be possible to design for a Ø3/8" diameter end mill (perhaps R0.2" design radii on all the faces).

eric_schimelpfenig

@eric_schimelpfenig I only recently learned that designing inside corner radii slightly larger than tool radius is preferred for CNC machining.  So for example, your visor has several R1/8" faces that might be increased.  Growing up around manual milling machines, I never considered this.

That's a good tip for sure. In this particular model the tool enters and exits at pretty good angles so there's not too much of a slowdown when you're in the corners. I had pretty good luck cutting runs of these pretty aggressively. The hardest thing is hold down!

Another recommended practice is to limit cut length to 3x the tool radius to maximize tool stiffness and allow more aggressive feed rates.  This may not be a huge concern for plastic parts.  But for you 1/2" thick visor it might be possible to design for a Ø3/8" diameter end mill (perhaps R0.2" design radii on all the faces).

I thought about that, but 1/4" bits cut through HDPE really well, and with a bit that big I'd lose the ability to have some of the smaller details, and it would then increase the thickness of the band making it heavier.

I think a 1/4" bit is the best compromise of detail and speed. Although I've seen people use 1/8" bits at full depth through this stuff with good success...