Thanks for all the helpful replies, guys. I figured I'd have to run it parallel with the motor. I'm in the process of getting my hands on a stampede, and I can't wait to to get this project going!

Chewy.

I'm waiting on it. I'm hashing out a mysterious project with electronics that are sensitive to fluctuations in voltage and current, and I'm still not 100% sure on the Stampede's characteristics.

The key here is to wire the resistor-LED circuit in parallel with the motor at the switch, or the LED will only illuminate when the blaster is being fired.

This is a great idea and the adjustable-ness is a nice touch. The only improvement it needs is a more secure way to mount the handle to the +bow.

 

Another quick status update: Electronics are fully assembled, tested, and confirmed functional. Unlike the previous pic, the display is actually showing dart count, and set its mag size by reading the RFID tag in the magazine.

 

The Hellcat pusher motor responds exceptionally well to active braking; the pusher homed on the first try after all 90 test shots.

 

I can't install the heatsink and fan until I build the motor driver enclosure (which is also why the motor driver is awkwardly zip-tied to the front of the blaster). Until then, I'm running the motors at half speed to prevent overheating. 

 

You can't see it from the picture, but the lower display is showing accurate temperature, battery voltage, and runtime. I need to figure out the conversions for the other metrics.

 

Once the motor driver enclosure is done, I can reassemble the blaster and do full-powered testing. I expect it to run like any Rapidstrike running triple Hellcats - fucking well.

 

Anyone have a pusher motor cover STL? I had to punch a hole in the shell to fit the 180 hellcat.

This project is done!

 

Enjoy some preview pics while I make some videos and a proper write-up.

 

 

Internals shot shows the wire routing, processor in back, and Artifact flywheel setup

 

 

Except for the crazy motor driver, it looks almost like a stock Rapidstrike

 

 

Close-up of the motor driver, with color-coordinated heatsink, caps, and mounting bracket

 

 

Mag size and firing parameters are loaded from the RFID tag in the magazine. You can see the red RFID receiver on the mag well.

 

 

Close-up of displays. Upper indicates that there's no mag installed. Bottom tracks my loadout, battery voltage, and game time

 

 

When the blaster is locked, triggers and motor driver are disabled.

Interesting, how are you getting the motor rpm?

It's a mock-up in these photos, but the wiring is there to do it for real.

I'm using sensorless back-EMF feedback to detect RPM. When a motor is freewheeling, it acts like a generator, and the voltage is proportional to the angular velocity of the shaft.

So, every once in a while, I freewheel the motor for a few microsexonds, sample the voltage, infer the speed, and adjust the drive. Of course, this isn't done while firing, because I don't want to decrease torque.

More information on this feedback system is available at https://www.precisio...m-from-back-emf .

It's worth noting that you need an H-bridge or half-H driver to use this method. A simple transistor follower, SPST relay, or switch leaves one end of the motor connected to voltage and makes it impossible to read the EMF.

That's determined largely by the characteristics of the magnets and should be specified on the motor datasheet. MTB's motor datasheets include it.

EDIT: Worth noting that in this prototype, the back EMF was readable but too noisy to be useful. A future version with better grounding and filtering should give me relevant readings.

I've been working on an electronic Rapidstrike driver board, and I thought I'd show youse guyses as I build it up.

 

 

Working title: The Hot Beef Injection.

 

 

This first PCB is the motor driver. It replaces the Rapidstrike's front tactical rail and enables more sophisticated control than bare microswitches. Each driver is rated to 40A; a heatsink and temperature-controlled fan keep heat under control. This includes:

• Full PWM - the system can ramp up the flywheels slowly, and keep them running at reduced "idling" speed
• Dynamic braking - Prevents pusher overshoot, and lets me quickly halt the flywheels for "stealth mode"
• Sensorless closed-loop control - I can tune the flywheel speeds to maximize energy transfer
• Current sense - For fun. Also detects shorts and breaks for self-tests and safety.

 

 

This PCB holds the Teensy microcontroller and has a 5V buck converter for efficient power. This slots into the empty space where the retractable stock used to be. The large connector on the end links this to the motor driver. The other sockets are for I/O:

• Top left: Trigger and rev button inputs
• Bottom left: Two OLED displays connected with I2C
• Top and bottom right: RFID board in mag well to detect magazine sizes
• TBD: Stock pusher endstop switch and mag detect switch

I used a goofy layout, fat traces, and too many vias are because I'm etching these prototypes by hand. The copper clad should arrive soon, so I'll update the post when I etch them up.

 

Thanks for reading! This is an exciting project, and I hope to finish it by the 17th to bring to CPNO.

What motor drivers are you using?

 

EDIT: I found some that should work: http://www.digikey.c...INCT-ND/4772019

Those are actually the motor drivers I used in this mod! They're ludicrously overspecified for Nerf motors, but they were very easy to build around.

 

The displays work!

This looks awesome. I'm not as fluent electrically as I should be. Will this run brushless systems?

 

Most brushless motors need a really complicated multi-phase driver. This fire system is intended for DC motors; it would need more complicated drive circuitry to handle brushless motors.

 

The boards are etched and populated! Testing is in progress. The motor controller board is shown without the heatsink or fan. I'll add them both after testing, when I know I don't need to rework anything.

 

 

Bonus! This 3D-printed adapter replaces the Rapidstrike's upper sling mount point with two OLED displays. The model for this part is attached for noncommercial use by any NerfHaven member in good standing.

 

EDIT: Not sure why the pictures came in upside-down, and I can't figure out how to flip them back over

Looks nice, but some cons.....

If the kid gets on the back the vehicle will wheelie or even flip backwards

If it does get flipped over, he can just hold down RB to put it back.

I found this when I was checking my RSS feeds:

This dude modded his son's Power Wheels Silverado into a working Oompa-Loompa-scale Warthog from Halo. Best part: He modded a Vulcan to look like the chaingun and mounted it on the back!

YouTube Video!
Worklog!

For all the real nerds in the audience, he found that an 8.4 volt power source in the Vulcan gave the best balance of ROF and reliability.

That's some slick stuff. I hope you have a custom barrel running through the 'silencer', or you're losing some major range.

If you want to make a lot of friends in a hurry, post a write-up and templates for cutting the plexiglas.

Would you think about making a variation for the 1/2" Lee's tubing?

 

What about a 17/32" brass insert variation?

 

Some day, I'll remake the model in OpenSCAD so I can upload a parametric model to Thingiverse. That will let you customize the model to fit your barrel of choice. If you want to move faster, you can download the SketchUp .skp file from the link in the first post and tweak it yourself.

 

 

I added .stl files as an allowable file extension, let me know if you need any others, or if it gives you any trouble.

I tried to attach the .stl file, but it said I wasn't allowed to post that type of file. 

It is a five-round cylinder. Increasing the capacity would require a new ratchet mechanism, which is beyond SketchUp's capabilities... and probably mine!

Mind posting a pic, Drac? I'm curious how it looks in other colors.

 

I made a 3D-printable replacement cylinder for the HammerShot that fits standard 1/2" PETG!

 

It uses the existing ratchet mechanism and requires no dicking around with the seal. Ranges are 30-60 feet with my ancient Slugs, but better darts will probably fly further. This is a really fun blaster and makes a great sidearm.

 

Because I can't attach the STL file or the SketchUp CAD file here, I hosted the files on Thingiverse. You can download the STL and editable CAD file, and read the installation instructions, at http://www.thingiver...m/thing:1621677 .

 

 

 

What?! Zack the Mack?!

 FTFY. Sketchup is capable of the task.

 

I've never been able to efficiently work with undercuts in curved surfaces with SketchUp.

 

The ratchet isn't hard to model, but it will be hard to modify and tweak. Some day I'll model it in SCAD, which does this trivially.

Count me in as a maybe. I'll need to check out the logistics and wait to see if I have tests or shit.

And to solve the naming problem, this war's name is now Chelsea.

Do you want me to rig up a Core? The Tupperware last time didn't work too well...

Also, what ranges would you say are too high?

Anything that outranges and/or out-ROF's his Lanard Shotgun. Such as a quad-RSCB'd Signal Launcher.

EDIT: Ice, you should PM Langley to add this to the war schedule.

Anyways, my guns aren't war capable at the moment and I'm probably not going to be able to complete them in a month with no break from school, so I can't make this.

Don't worry about it - there will be plenty of loaners. I'll make sure to bring at least one extra.

I'm up for Nerfing in the rain, I just wanted to know in advance if you guys were planning to pussy out. Neither rain, nor snow, nor sleet, nor hail shall keep the Nerfers from their appointed rounds of 3-15.

I'll try hard to get there. Bring a halloween mask. Hopefully I'll have the +Bow-Lanard Shotgun-Wipeout ready by then...

I'll be bringing at least one friend.

DX, where are you leaving from?

Is this an insult? lol. I use the rules of no multi rotational springers with more then four barrels hitting over 65 feet flat. And nothing that shoots over 130 flat. I erotically massage RSCB'ed +bows (or anything of the like) with more then 5 shots (Damn you Zach!), but I will not stop them from play. Integrations can be a hastle if it's a really good combo (+bow's with lanard shot guns on them), but are pretty much always aloud.

Well, that's convenient, because I'm probably bringing a 5-shot RSCB'd +bow with an integrated Lanard Shotgun. And a Signal Launcher with an integrated Marvelous Salvo. Mwahaha.

And it's a lot easier to just say "No Doomsayers".

For the record, the best integration is probably Gears' Ellen.

It's supposed to POUR on Saturday. Is this going to affect the date?

I shall be there!

This will break my Nerf War cherry, guys. Don't shoot all your darts in the first five minutes.

That was an awesome first war! My BBB broke and my Longshot chewed up darts, but thanks to Koree and Icespartan, I could borrow the firepower to get back in the game!

Highlights:
- Talio's shorts tearing wide open, for easy access
- PRINCE CASPIAN WRIST CROSSBOW!
- Nailing Koree in the back from six inches with his L+L
- Being the last man alive in the last round
- Meeting you guys, especially Koree, Ice, Dean, Dizzy...
- That bitchin L+L I borrowed from Koree. Got 90 feet, easy. I'm making like five of 'em.
- Checking out the StrikeFire
- I want to make fuck with you, BERSERKER!
- Losing 300 Stefans
- Pistol round in open, flat field with the wind blowing
- Getting my hand sliced open by a razor-sharp brass NiteFinder barrel
- Patching my hand up with e-tape
- Awesome, varied battlefields
- Mutton's backpack/laptop/webcam first-person video rig
- Discovering that I hate two-handed weapons and love pistols
- Just feeling like I fit in to the Nerfer community

I ache all over, have a mammoth dart bruise on my right bicep, and my hands are blistered and cut. You guys rule.

The NYC Nerf Ops FB group is stoked to announce our next superstock war.

 

Date: 4/29/2017, 10:00 AM - 5:00 PM

Location: 40.782278, -73.963951 (Manhattan, Central Park)

Blaster ruleset: Superstock (~150fps max), melee weapons permitted

Game rotation: 3-15, Turf War, Sticks and Stones, Harambe Escort, Flag Push

 

Up-to-date info and non-NIC attendee list are available on the Facebook group page.

No rain date - the war continues in all weather. 
The battlefield is a five-minute walk from the Metropolitan Museum of Art.

 

The venue is a small, open field surrounded by trees. There's a lot more cover than a standard public park, enough to make Rival blasters competitive.

MANDATORY EQUIPMENT:
- Primary blaster. See Weapon Info below.
- At least 200 rounds of STOCK ammo. Homemade and modified ammo is banned.
- Eye protection. All players must have safety goggles. Glasses, toy goggles, and masks are not sufficient.

RECOMMENDED EQUIPMENT:
- Water. There are no water fountains or 'street meat' stands nearby.
- A pistol, melee weapon, shotgun, or bow for Sticks and Stones
- 500+ rounds of ammo
- Garbage bags, for cleanup

WEAPON INFO:
- Blasters must be colorful. 
- We highly recommend using modified flywheel blasters.
- Melee weapons must be fully padded, including the shaft and pommel.
- See below for info about the "Sticks and Stones" special weapon restrictions.

SCHEDULE AND GAME RULES:
The first round begins when four players arrive. We generally alternate elimination with objective games. After each round, we will have 10 minutes of downtime, or 20 if we need to sweep.

Game rules:
 

Turf War Elimination:
- Teams may have any number of players. Each team decides on a color.
- Each team has ten shared lives. When you're hit, yell your team color and your team's new life total.
- 15-second respawns
- When your team runs out of lives, all team members are eliminated.

Sticks and Stones Elimination:
- 5-15 ruleset
- You may only use pistols, melee weapons, shotguns, and bows.
- Nerf Clip System blasters and compatible blasters are not pistols.
- The Nerf Apollo is not a pistol.
- Shotguns must fire at least two darts with every trigger pull.

Harambe Escort:
- Objective: Escort Harambe to freedom, or gun him down.
- Harambe the gorilla has two lives and is unarmed. Other players have infinite lives and may use any blaster.
- While Harambe is standing still and beating his chest, he is invincible.
- Harambe is escorted by four memelords. The remaining players are zookeepers.
- Harambe begins at Point A. If he touches Point B, the memelords win. If he dies, the zookeepers win.
- Memelords respawn in 15 seconds. Zookeepers respawn in 30 seconds.

Flag Push:
- Objective: Attackers attempt to carry the flag from Point A to Point B. Defenders must hold them off for ten minutes.
- Attackers begin at Point A. Defenders begin at point B. All players have infinite lives.
- Attackers respawn by touching Point A. Defenders respawn by counting to 15 WHILE touching Point B.
- Before the timer begins, defenders have 30 seconds to set up and may position themselves anywhere on the battlefield.
- Defenders may not touch the flag, except to stand it up.
- To carry the flag, an attacker must hold it in one hand, clearly visible. Nothing else may be carried in that hand.
- When an attacker is hit, he or she must immediately drop the flag.

Yes, I'm going.
Yes, this war will be excellent.
Yes, I'm looking forward to re-connecting with everyone.

The Stevens crew is rolling out! I'll be there with 3+ friends. This will definitely be the highlight of the summer.

Now THAT was a war. When my PistolSplats broke, I used my Signal Launcher. When I was too tired to pump the Signal Launcher, I used the LpL. I nerfed until I was ready to drop and then nerfed for three more rounds.

Highlights:
- Handling BadWrench's Lanard Shotgun, dropping it into the ground, and firing the divot
- Putting up with Faddle, then chasing him down in the last round
- Buying that delicious LpL from Koree
- Explaining how an RSCB works about 5 times
- Inventing and playing Titan Football
- Hookah
- Insane RSCB-fueled killing spree with Koree (Victims included JLego, FA, and plenty of 4B's)
- Reuniting with Ice, Gears, JLego, Koree, Mutton, et al
- Consuming 9 bottles of water, 3 bottles of Gatorade, a king-size BK drink...
- Defending against the entire team in Resurrection Forest using an LpL
- The only tacticool word we know is 'flank'
- Firing the Signal Launcher without closing the RSCB, then getting shot
- Watching [forgot your name] rebuild a singled Longshot in the field
- Mutton's ridiculous head wound
- My Gunslinger partner and I getting tapped in a drive-by
- Getting nailed in the head by Gears in Resurrection Forest
- Getting lost in the woods
- Facing off against The Original Doomsayer, and shooting FA 3 times anyways
- Dodging a firing squad of 4B's. Originality, people!
- Firing 100 darts in one round... from an LpL
- Meeting the canucks, Mag7, and the LGLF
- Did I mention shooting Faddle?

Kruhl... whatever, great war. Really well-planned, awesome attendance, bombastic atmosphere. See y'all at GnomeFest!

Oh, hell yes. I will be there with a cooler of Gatorade.

Probably no need to cut yet. Try making a cup of hot (almost-boiling) water and put the plunger tube inside. After a few minutes, the heat may have softened the glue, letting you pull the pieces apart by hand.

The same technique works with Recon plunger tubes, the Longshot barrel, etc.

Post a follow-up if this works!

Dude, I guesstimate you have about three minutes to post a write-up and revise your grammar before some admin slaps you with a trout.

Anyways, spiffy mod, especially for Humans vs Zombies.

Shield usage is steadily becoming an interesting addition to Nerf games that i've attended recently.

Of everyone who's posted an opinion in this thread, only SG has actually played a goddamn game with the shield, so he's the only one who knows what the hell he's talking about. For the record, the gun/shoelace/equipment hit rule is there to prevent arguments and keep the game moving.

Anyways, SG, does the presence of shields really disrupt the game enough to merit new rules? Does it create deadlocks and turtling? Most importantly, is there ever confusion/arguments about whether a shot hit the shield or the player?

If you can find these, I'd say go for it. Seems perfect for quick-n-dirty beginner barrel replacement, especially for BBB's and spring pistols. No need for a pipe cutter and probably slim enough to jimmy in without busting out the Dremel. Just make sure to reinforce it, or you'll lose your barrel.

And might I add, how thirsty must Canadians be to need half-inch straws?