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Member Since 30 Sep 2010
Offline Last Active Jun 30 2020 10:23 PM

Topics I've Started

Bay Area Ultra Stock #9, BAUSton Tea Party BBQ

12 July 2018 - 12:31 PM

BAUS is on Nerfhaven? Gotta pay respect to where it all started.

Come join us for a good ol summer Nerf and BBQ at Sugarloaf! They're not kidding when they say Open Space because this map is huge!
BBQ will be hosted with more details to come as we plan it out. Bring something to share and we'll provide Burgers or Hot Dogs (Maybe both?), possibly drinks and sodas and obligatory (Iced) Tea to qualify as a "Tea Party"
Limited to ages 15+. Dart rental is $3, we have full and half lengths but you have to bring your own Rival, Boomco or Megas. FPS cap is 225, with a bonus exception of 250 for single shots. Shields are allowed, up to 4 square feet.

July 22nd, 11am-5pm, Sugarloaf Open Space, Walnut Creek CA


And if you can't make it this month, next month will be at Crissy Beach in San Francisco.

Computer Vision Accuracy Measurement Software

16 January 2018 - 06:35 PM

Thantacles, MTB Ryan and I have been thinking for a while about how to empirically and efficiently measure the accuracy of various darts and blasters. The advent of chronographs and widespread fps testing has sparked an arms race in blaster performance, but for accuracy testing we're still mostly going by gut feel, or measuring how many darts hit a target at a certain distance, which is never the same between two people testing. The accuracy testing that Bobololo and Coop have done in their videos is great, but extremely time consuming, because they go through the video footage and mark the location of every dart hit by hand. We've thrown around ideas ranging from shooting a sheet of Play-doh to a big sensor grid based on capacitive or resistive touchscreen technology. But the one that seems to show the most promise so far is Computer Vision. Here's the criteria:

Low hardware cost and construction time, so that this can catch on and we start seeing more empirical accuracy data. Giant sensor walls would require significant time, experience, and hardware to build.

Empirical, with large data volumes. Not subject to people's aim. Additionally, having more data is better, eg the location of every dart on a target is better than just a group size number which is liable to subject to outliers, or a number for what percentage hit the target.

Low testing effort. Play-do or inked darts require setting up for every test, and then you have to manually digitize them. You're probably not going to bother recording the location of every dart, and just measure group size, which doesn't give you as much to work with.

So the solution we came up with on Sunday was to shoot the darts against a white wall, and place a microphone on that wall to record the impact of each dart. Take a video of the whole thing, and extract the frames that correspond to the audio spikes when the dart hits the wall, and then do a computer vision analysis of those frames to get a location for every shot. I've never done computer vision before, but I hear the OpenCV Python library makes it fairly straightforward. Let me know if you're interested in helping.

Modulus Storage Stock Mod Guide

12 March 2017 - 01:05 PM

No, not the terrible one that stores magazines. The new one that stores darts, or snacks, or battery packs. It's retractable, the same length as the Raider stock, and pretty great for Stryfes and other flywheel blasters, where you want a large battery without a bulky battery door. Unfortunately it's a bit of a pain to get open, so here's how. Overall, it's a pretty simple mod.

First, the finished product:



To open it up, first remove all the screws. You won't be able to butterfly the shell because of the hinge pin connecting the two orange pieces. I have tried several methods, including hammering and pressing it out with a soldering iron, and have not been able to remove it. However, you can get the shell open far enough to remove the stock tube.




After the tube is removed, you can bend the two sides apart far enough to rotate the two halves of the body, to get access to the inside.


To prevent the stock from collapsing under load, which it does pretty easily, put some hot glue or epoxy putty under the ratchet nub while holding it as far out as it will go. The stock will still collapse if you put a lot of load on it, so you probably wouldn't want to use this for a high spring load blaster, but it's totally fine for a flywheeler. You can't glue the tube into the shell, because you need to be able to remove the tube in order to swing the two halves of the blaster apart, and I haven't figured out how to remove the hinge pin. If you figure out a solution to this, let me know.



If you're using this as a battery stock (and why would you use this stock if you aren't?), cut a slot in the internal wall of the body for your wires to pass through. Then use a long drill bit or dremel grinding bit to reach down the back of the tube, and put a hole through the wall there. I would recommend maybe 3/8", so that your connector cannot pass through and get lost in the stock. Cut two wires to roughly 10" long, solder a connector to one end, pass them through the hole, then solder the other end. Don't forget the heat shrink.

Reverse the disassembly to put it back together.


I'm using a Bolt 3S 1300mAh 65C Lipo, which fits pretty well, but still should have some foam padding. The internal space is 23 x 65 x 100mm.


To attach a sling with this, I drilled two holes in the tube and tied a loop of paracord through. It works great.


And that's it! Enjoy your battery storage stock. I might add some grippy foam or rubber to the back so it's not as slippery against the shoulder, but other than that it's great.


Brushless Stryfe Project

27 October 2016 - 12:06 PM

Hey NerfHaven it's been a while, but I just got to college and there's a decent HvZ scene here so I'm getting back into Nerf.My first project, a custom flywheel cage for a Stryfe with brushless outrunners as the flywheels.

I've seen a couple people do this before, but none of them have any documentation, so I'm mostly starting from scratch. I'm starting off with these 26x27mm motors, which are rated for 47k rpm and 300W on 3S, as well as some Simonk speed controllers and a Zippy Compact 1Ah pack I have laying around. The other, more powerful, motor options are this one, which is 56k and 365W at 4S, and this one, which is 44k rpm and 755W at 4S, but I'm not sure they'll fit without cutting the shell as they're both 36mm long. I also don't have a 4S pack of the right size on hand, so we'll see if the first motors have enough power. If they can spin up fast enough, I'd love to put the rev switch behind the trigger like the FDL-2 and eliminate the separate rev trigger.

Another question is the flywheel surface. I have about 3mm of thickness in my current design to add another material with better grip to the outside of the motors. I'll do some tests with the stock steel cans, then with polished steel, before moving onto gluing on rubber tubing, like Mcmaster's 35A and 50A hardness silicone tubing. I'm surprised nobody's tried anything like this before, I think it would give a significant increase to the friction against the dart, and therefore the velocity, but I'm not sure they'll stay glued on properly. It sounds like a silicone based adhesive like E6000 or silicone caulk is my best bet.


And of course, flywheel spacing has a big impact on dart speed, but I haven't seen more than a few anecdotal numbers, so the motor mounting holes are slots so that the spacing is adjustable and it will accommodate different sized flywheels.


As you can see, there's a lot of things to experiment with, and I haven't even gotten into barrel guides or canted flywheels. I'm super excited to get back into this community. Here's what I have so far for the CAD model, I'm currently debating whether to 3D print it or CNC it out of aluminum.



Minimum Hopper Requirements

15 May 2011 - 04:13 AM

Everyone knows that hoppers require high pressures and large volumes. But how high, how big? The only data I could find was CaptainSlug's Pepe, where he used a 10 psi 7 ci tank with a hopper. I was thinking of using a 3-5 ci, 55 psi tank. Will this work? Could I go smaller? And does using higher pressures allow me to use less volume, or vice versa?