Digital.Complex: [nerf] Stampede ECS (N-Strike) - Digital.Complex

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[nerf] Stampede ECS (N-Strike)

#1 User is offline   aotsukisho 

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Posted 22 May 2014 - 05:39 PM

I was notified by a friend that a local wholesale business had some Nerf blasters on clearance, and that he 'might have seen the yellow one that comes with the shield'. I was in disbelief so after he picked one up I had to go see what else they had. Sure enough, there were three Stampedes left on the shelf so I picked them up. The only other thing they had were Praxis blasters for $9, but I didn't like them enough to buy them even when discounted that steeply.

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Here is one of them still in the box.

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It's very well packaged, but I thought it came with that forward grip bipod attachment. Oh well

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It was quite a bit of stuff in the box, I forgot that it came with 60 darts

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Putting everything on the table

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The infamous 6-D battery tray

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Six screws on the bottom to remove the plate

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Tricky tricky

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Why Nerf why is that even necessary

More updates to come as they happen. I'm not too sure what I'm going to do with this blaster, but it does look good. Might even use it in the next Nerf War.

Just kidding Rapidstrike I love you
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#2 User is offline   aotsukisho 

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Posted 05 June 2014 - 04:28 PM

I finally got into tearing apart the Stampede to see what it's made of. Here's the photolog of the project so far.

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This is the screw pattern for the Stampede. Quite a bitch to take out, although thankfully there are no hidden screws.

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There are three types of screws used, and I have similar screws facing all the same way in the photo above

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Don't forget to peel off or cut the battery leakage sticker, cause it holds the rear half together

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Cracking the shell open

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The fire-enable safety switch is wired to the upper half of the blaster

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Closeup on the safety

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From a different angle

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Removing the switch

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Detail on the barrel

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Looking at the guts

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The rear of the blaster

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The lock by the trigger is to disable firing when a magazine isn't installed in the blaster.

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Closeup of the wiring around the main switch

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Magazine bay cover for the wires

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Bottom switch that enables firing only if a magazine is inserted

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Upper switch that enables firing only if the jam door is all the way forward. This one in particular was a nuisance to me, since the automatic firing of the blaster jiggled the jam door free when I was testing it before modifications.

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You have to unscrew the two screws holding the orange piece in before the switch will come out

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Removing both of the switches

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Open up the wire cover in order to fully remove them

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Down to the battery contacts

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Pulling all the wires off the shell

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You have to remove the mag release mechanism in order to get to the switch underneath

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Closeup on the motor

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Untangling the wires off the main switch

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Wires all gone

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This is the actual motor print. Google searching it doesn't give any meaningful results, all I know is that it's a Mabuchi RS-360 sized motor that's not a standard RS-360SH. Its nominal voltage appears to be 6.0v, compared to 3-9v of the 2885, or the 12-25v of the 10500. I'll do some measurements of the motor later.

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It's a similar size to this old 2646CM Castle motor designed for 18th scale application. Maybe a motor swap would be easier than I originally thought.

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Overall length of the CM26 is a bit longer, but still within the dimensions of the Stampede's original design.

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2mm shaft with a 10 tooth pinion. I'm not sure what pitch the teeth are, but it doesn't quite mesh with the 48p stuff I have. Maybe I'll check the Mini-Z pinions next time. I'm sure that the Stampede would benefit from a motor swap, particularly if the blaster is being modified for a person that still wants to use the D batteries for whatever reason.

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Removing the piston cover

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Now you can see the inner workings of the Stampede

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Piston size comparison. My ruined Longshot one is directly above, with the Centurion on the top.

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The plunger back cover had this squishy rubber ring on it

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Pulling the plunger and spring out. Similar setup to the Longshot

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Completely apart

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There's a small hole on the plunger face, my guess is it's there to prevent vacuum loading

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I soldered an anti-kickback diode onto the motor terminals, this should help against switch contact pitting

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Teflon tape helps the plunger seal, and I relubed it with OMW silicone grease

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Reinstalling the piston

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Soldering in some real wire

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Hooked up to the motor

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Battery connector installed

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Doing some current draw testing, not too bad

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2x 2s 6000mah Nanotechs fit inside the battery bay comfortably. This would allow us to run 4s in this configuration if we really wanted to. I highly doubt a single Nerf War would eat up the entire capacity.

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Testing the current draw when run on 3s Li-ion, for some reason it went into autofire mode. Not sure if the higher voltage wasn't allowing the plunger to return fully before pulling it back again, or if it was just the catch slipping. I'll do more investigating the next time I crack it open.

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Interestingly the current is the same on 2s lipo, I'm not sure why this is the case. I do know that if the firing action is interrupted the motor will consume 9A in near-stall when it starts up mid-compression.
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#3 User is offline   aotsukisho 

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Posted 12 June 2014 - 04:50 PM

I went through a second Stampede, and got around to tearing it apart as well.


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At the piston again

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This is the rack where the return problems supposedly stem from. The return spring gets misaligned, and the blaster goes into autofire mode.

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Shaving off the horn from the breech, all it does is force the jam door closed when the blaster fires.

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Three spring comparison, LTR: Stampede return spring, Stampede plunger spring, Handyman SP-9713 spring

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The 9713 spring is a little shorter than the stock Stampede spring, but it's very stiff and the stock spring had preload on it when in the piston.

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Piston reassembled

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A solution to the autofire problem was suggested by putting two springs on the switch body, as the switch doesn't kick back fast enough when the rate of fire is increased.

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Everything reassembled

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Wiring up the switch

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Deans plug out into the battery tray

The double spring on the main switch didn't solve the runaway firing issue, so I will look into replacing and/or reinforcing the area around the catch release slide.
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#4 User is offline   aotsukisho 

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Posted 15 July 2014 - 05:23 PM

I found out that the Xmod pinions mesh very well with the Stampede gearbox, which means that they both are 0.5M pitch (or something very close).

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This is the Stampede gearbox straight out of the blaster

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Removing the gearbox cover exposes the transmission

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Press-fitting on an Xmod 10t pinion since the plastic pinion off of the stock motor didn't fit. Either the stock motor is a 2.3mm shaft, or the Turnigy brushless motor is outside of tolerance (unlikely, since Xmod pinions are 2.0mm bore).

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After mounting the motor to the gearbox

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Looking out the back of the motor

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The motor and gearbox installed

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Test setup using my Phoenix ICE ESC, and it works. I just have to wait til a smaller one that I can mount internally arrives, and I can finish up this project.
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#5 User is offline   aotsukisho 

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Posted 30 July 2014 - 05:00 PM

Got some parts in for the project, although in retrospect I could've just done it since the multirotor ESCs from Turnigy can't brake the motor fast enough to prevent the blaster from slamfiring and I had to mount it externally anyway. Sigh.

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Here's the ESC hooked up to the servo tester connected to the trigger switch

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Drilling metal to make a standoff for the battery, as I will be mounting the servo tester in the battery bay

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Hole drilled in the blaster shell

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Mounted using a single screw, using the ribs to hold the sides of the angle brace in place

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Internal view of the spacing, I will put some padding on there after I finish up everything else

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Making a bracket to mount the ESC to

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Holes drilled in the shell

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Bracket attached

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ESC mounted using doublestick tape and zipties

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More wire routing magic using old CD player vibration dampeners as grommets

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ESC mounted extsernally. There are holes drilled on the side of the silver piece for the brushless motor's wires to exit, and also a hole drilled on the top of the battery bay for the ESC's receiver wire to pass through into the blaster.

I've tested this setup and it seems to work well, at most it only fires one extra round which is acceptable. I'm going to put another safeguard however, and use the blaster on/off switch as a disconnect for the signal wire which will basically shut off the ESC and put it in 'out of range' mode. A few more hours of work and the blaster should be ready for reassembly and testing!
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