This is a small telescoping, magnetically mounted safety hammer for the Fiber Force competition.
This is to be printed with the Carbon filled Nylon because it gets too bloody hot in my car in Texas with the windows up for most filaments(145 F +) , and Nylon has superior bonding between layers, ensuring a solid print. Other filaments can't handle the shock of swinging a hammer at the glass!
The contest calls to showcase the high temp, and high strength of the carbon filled nylon. The car environment is one that speciffically requires something like the Fiber Force filled nylon because (1) it has to be able to withstand daily heating in a hot car, (2) not break down or biodegrade in UV light from the sun, and (3) be strong and have good layer bonding properties to withstand the swings of the hammer.
These rescue hammers are a good idea, but in practice are often lacking. Most people I know store these in thier glove compartment or center console. There's a couple problems with this. The problem with storing it in your glove compartment is you often can't reach it when your seatbelt is locked up from an accident, and you're held rigidly against the seat. The glass breaker is mostly meant to be used if you go off the road into water. Well, in most of those cases, the car rolls and you're upside down, due to the air in the tires. So, if you have the glass breaker stored in your easy to reach center console, as soon as you open it, everything is going to fall onto the cieling (you're upside down) and you're going to have to look for it in the murky water. If your seat belt is locked as well, it's an even worse situation. If you can't reach your life saving device, it's going to do you no good at all. The ones with a mount are sometime too complicate to release in an injured/confused state, are large and obtrusive, weigh too much so that over time they fall off due to the adhesive breaking down or are dislodged in the force of an accident
For this reason I wanted it to meet 3 criteria.
(1) Small - this way it's easy to place anywhere within reach so it's handy in an emergency situation.
(2) Lightweight - won't become dislodged in an accident
(3) Strong enough to withstand repeated blows
I made it small so it can be mounted anwhere. Magnetic mounted, so it's easy to remove, but at the same time won't be thrown forward away from you in an accident. Also, the magnet keeps any rattling down, because you're just as likely to put it away if it's noisy. It's also relatively light so again, the force of an accident won't knock it loose and leave it out of your reach. Due to the size and lightness, the glass will be a little harder to break, so I made it telescoping to increase the force of your swing. The carbon fill is neccesary to give the slide the required strength and rigidity to hold up to your swings.
Just attach the mount anywhere easily in reach with an adhesive pad, and you won't even notice it there, until you truly need it.
The non printed parts are easily sourced and are;
-#2 exacto blade (easy to find online or any craft store) for the seatbelt cutter
-M4 set screw to connect the ball bearing to the nut inside the hammer - may want to use threadlock to ensure it never comes undone
-15mm bearing with m4 threaded hole - get from ebay or you may have leftover from a delta printer design (that's where mine came from)
-OK, these bearings are harder to source than I thought, (the ones I originally used that are 15mm with a 4mm screw hole are now on my delta printer) , so you can use an easier to find 10mm bearing w/4mm hole and use an 8mm nut as a spacer to ensure the bearing is tight, adds a little more heft (more force imparted to the window), and keeps the same spacing as the 15mm bearing
-adhesive pad to attach the mount anywhere within the vehicle close at hand
-4 m3x16 nuts and bolts for assembly
-a little super glue/epoxy to further cement the blade in place, especially helps with the assembly to keep it in place.
-threadlock to keep the 4mm set screw from coming lose.
Don't use your normal plastics for this. Remember you want to make sure it works when you need it to!
PLA - won't work. The heat is too much inside a car with the windows up.
ABS - some layer bonding issues and warping that nylon doesn't have. I wouldn't trust my life to hammer I had to swing with ABS, because it'll most likely snap apart in your hand when you do.
Polycarbonate - Probably your best option, but shrinkage makes precision prints and dimensions more difficult and often require temps above 300C requiring an upgrade to a thermocouple in most cases (depending on printer of course)
PETG - would work for the handle, but is a little to flexible to impart the full force of the swing to the glass.
Regular Nylon - Same issues as PETG, a little too flexible
Assembly is easy; just mate the matching parts, apply a little glue to the exacto blade and place it in the inset, and screw together. Use a strong adhesive on the mount to place this anywhere within your car for easy reach in an emergency.
Printed using Fiber Force filament