Saturday, April 20, 2019

VR Pneumatic Recoil Rifle Stock: testing in OnwardVR

And a few tests in Onward.  Don't judge my getting my butt kicked by AI.  The recoil hack works well with onward.

EDIT: Note do not use LiIon batteries. The stock kicks too hard and after 10k rounds or so compacts the foil in the batteries.  Use a tethered 12V supply parallel to the airline or NiCd  NiMH or other batteries proven to take a beating with radio controlled vehicles.  (dont use LiPos without great dampening)

VR Pneumatic Recoil Rifle Stock:: testing in GunClubVR

Decided to try this stock out in several games and record it for fun. 
GunClubVR is pretty fun for a fairly static game.  Plenty of trigger time. 

VR Pneumatic Recoil Rifle Stock: DIY Part 7: Recoil and Air source

Ok  so this project just doesn't stop.

First, How hard does it kick.  This is difficult to convey so I shot a video of it kicking its own 5 lbs off of a floor.

Now for those considering a compressor...
I thought a bit should be devoted to air sources focusing on the
-impedance of the air line
-and on board reservoir


The next consideration, or one of your first perhaps, is the air supply.  If you have a compressor in your garage, great.  but some may not have one or are looking for a replacement, or just don't want to hear that loud thing running in the wee hours of the night.  There are many options but one many may not be aware of are the "silent" oil-less compressors.

I originally bought a Eurotec 10A with a <40dB sound level.  Awesome for airbrushing but, it needed a tank.  So I ripped apart a coleman camping compressor took its motor out and kept the valves, couplings, and <1gallon tank.  Strap 2 computer fans on it and you have a compressor that shouldn't be run for more than 20% duty cycle or so that Ive ran for roughly 10 years now at well over 50%,  often up to 100% for 2 hrs straight and its still kicking.  Just remember to drain your tank.

Tank:  If your going to buy a tank and can afford it, get a corrosion resistant one.   Never fill it beyond its pressure capacity and make  sure you have a pressure switch on the compressor that prevents over pressurization.  Most have this already but if you go ripping parts off of your compressor, make sure you don't remove this.

However, if you are in the market for a new compressor a couple lines you should consider for low sound (IE wont drive you or your house mates nuts from the sound)  are the

Silentaire line    ~30+db   --run it anytime

Eagle silent line   ~44+db   --ok for night time running

California air tools ultra  quiet line   ~56+dB    --daytime only

I would avoid paash and anything that doesn't output at least 60Psi.  It will be disappointing.  

I believe sparmax is the re branding of the eurotec 10A but it claims only about 40PSI where the pressure gauge I put on my tank says its consistently pumping up to 60PSI.     But I think the eagle line seems like the best bang for your buck in pressure, noise, and cost.  

Regardless  pick the trade offs you can deal with, and make sure it has at least a 1 gallon tank.  

Ok you got your compressor and tank, you now need to get the air supply to the pneumatic cylinder. But airlines have restrictions/impedance and the restrictions are two fold,   
1. the ability of the airline to be flexible and not restrict movement during VR play
2. the ability of the air line to deliver CFPM on demand.   

Thinner lines tend to be more flexible but greatly restrict flow limiting power at the piston.  Feeling the restriction of thicker lines and their affect on your movement may constantly remind you your playing a game, which is less fun.  

I recommend a braided hose, either a modified airbrush line or an ultra soft compressor line for the last 4-8ft,  then whatever line you can reasonably afford to go from your tank to your rig.   

I mount a quick coupler above my head with the cable tether and anchored it to make sure it cant swing down and nail me in the head.  The airline regulator is mounted there too for ease of adjustment.   I then cut a cheap airbrush braided rubber hose and re-connectorized it for my setup.  I then anchored it loosely with para cord to a few points along the sling so in game I barely know its there, I just feel the sling.   A few small carabiners on the back of my VR HMD and along the cable management tethers and I quickly snap the airline into place when needed, hook up the quick coupler and Im ready to rock.   Also the quick coupler is useful to stop explosive air bleed out when you disconnect.  

ON-BOARD RESEVOIRE:================
So making tradeoffs, there is still more restriction in CFPM than Id like limiting the power of the cylinder, especially after the first shot or 3.  This can be mitigated a bit, unless your a fan of full auto, by putting a small reservoir on the stock.   

I used PVC pipe and end caps, as well as appropriate PVC glue to make a small pressure chamber.  Beware, you are making a small pipe bomb so read the instructions and use the glue/welding sludge correctly!  You don't want the pressure chamber exploding in your face while playing.   Take care and take precautions and don't get anywhere near the published pressure limit of your materials. 

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