Sunday, March 3, 2019

VR Pneumatic Recoil Rifle Stock: DIY Part 2: Trigger Mod

Trigger Pull/Trigger Guard:  -----------------------------------
Seriously even an airsoft GBBR has trigger pull of half a pound or more, at least for the better ones.     The Oculus has a trigger pull of about 1 Oz  This I had to fix and the fix is fairly simple.  First you cant replace the spring easily as its hard to get to, and you may damage a flex cable, so leave the internals of the trigger on the touch controller alone.

With this mod, you can no longer just slap the 1oz trigger, you have to carefully squeeze and use better trigger discipline.

 A 3d printed frame that clamps or mounts to the front of the controller giving a fake trigger that you pull which releases with more force and more crisply is fairly cheap and easy to implement and doesn't necessarily have to change the base controller at all.  With the right clamp on or wrap around design it seemlessly converts your shooting hand to one that learns a bit better trigger discipline.   And please remember to always keep your finger off of that trigger until your ready to pull the trigger on a valid target, even in VR!  Thats what the trigger guard is for!   *sigh... seen a few buddies get shot by some idiot screwing with their rifle stock in VR at the start of a match*

You will want to drill out the 3d print's trigger pivot hole to 1/8"  and the magnet for the trigger pull force  to about 4.6-4.7mm for a press fit. Do not glue either!

 Glue trigger magnet in, wipe excess away,  leave a bit on the end to prevent impact damage to the magnet.
A completed assembly ready for installation. 

 Use your phone to align the assembly to the Oculus touch to minimally occlude the LED's.
lightly sand all interface surfaces then apply a thin layer of JB weld.  Tape over any moving parts or parts you dont want epoxy getting on to so you can later remove the tape  and extra glue.

Let it Dry overnight 12-24 hrs and your ready to rock n roll.  Adjust pull weight by slipping thin layers of electrical tape between magnets. This also dampens the impact and reduces VR gun bounce due to impulse.  Use a food scale to adjust to about 1lb breaking force.

Then remove all tape and install a stack of electrical tape about 1cm long by tape width, by 8-12 layers thick between the trigger and the Oculus trigger.  Install a single layer of scotch tape over the electrical tape for friction reduction.  This will allow you to dampen the impact on the trigger and use the shape of the metal trigger to force the Oculus trigger to travel much faster when the trigger breaks free thereby converting a short sharp pull to the long pull of the Oculus trigger.   Alternatively stack 12 or more layers to pre-compress the Oculus trigger to just under the point where the VR gun fires to get a nice quick acting trigger as soon as the magnet breaks free.    You may need to adjust the tape stack position higher or lower along the trigger to get it to break at the right point and take advantage of the lever action of the trigger mating shape.

 A bit of green epoxy putty helps brace the trigger guard to the Mamut mount to help transfer stress and load bearing up into the stock without stressing the ring on the touch controller too much.

 Finally, if you choose to cut up a cheap airsoft pistol grip and install it over the controller.  Use a respirator and vaccuum before cutting and dremmeling out the inside as many are glass filled nylon.  Cut it down the center, then trace patterns for the button and form fit.  Then dremmel out the inside to mold around the controller.   Tape sections of the controller with scotch tape to prevent gluing the controller shut, then very carefully glue the halves onto the controller.  Take special note to protect buttons from glue.  Also take extra special note that the side with the battery cover is taped entirely around the battery cover so glue only dries to the cover which slides off.   Perhaps we can get someone like Mamut to make overmold pistol, 1911, glock, handguard grips.... Hint hint.

You can order parts for the trigger here, or go design your own.
Need one trigger and one frame to make an assembly.

Part 1: Intro and disclaimer
Part 2: Trigger and grip mod:
Part 3: Fore grip Mod:
Part 4: Modifying the Haptic for a signal
Part 5: Pneumatic Recoil parts and Fire Control Circuit 
Part 6: Scent Module

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