|The Completed Revision 5 VIUD Prototypes|
The magnetic cap works great and is strong enough to hold the VIUD to the fridge door or other metal surface as designed. I haven't tested the lanyard attachment but my initial concern of the edges being too sharp were fortunately unfounded. I've only done a quick 3000 psi pressure test so far but both test units passed easily.
|Adding the Internal Epoxy|
- The anodized threads were just barely too tight and required manual retapping. I'll specify a looser thread tolerance for the internal threads to compensate.
- The slots for the magnets were just barely too small and had to be made a bit larger. Slightly larger OD dimension for the slots are needed depending on how shock testing goes. I fear if I make it too loose the cap magnet will come free too easily.
- Weighing the amount of epoxy in the base worked great but the magnet caused havoc with the scale. Adding a few non-magnetic spacers fixed this easily.
- The scale used has an annoying tendency to turn off in the middle of deploying the epoxy into the base. Hopefully there's a way to disable the auto-power off feature or a different scale will be needed.
- The amount of epoxy needs to be reduced slightly as when it is cooked in the oven it expands and overflows. The overflow is actually good in a sense as it means there are no air pockets in the base but it requires more time consuming clean up afterwards.
- Oven baking to cure the epoxy worked just fine. The magnets help to keep the base secure the metal pan.
|Baking at 90°C (200°F) to Cure the Epoxy|
What Next?There will have be a small break in the VIUD development this summer due to my personal schedule...who knew getting married would keep you so busy! Sometime in the fall I'll get back into more testing of the finished revision 5 VIUD prototypes to see exactly what sort of punishment they can take.
Assuming no significant design change is required (I doubt it but you never know) I hope to be able to get a KickStarter going for the initial VIUD production run later this fall. Stay tuned to the blog for the eventual announcement.