As mentioned by Drew in this post
, here's the build log of...
This is the story of how I merged an Airsoft ICS MP5A5 and a WiiMote and Wii Nunchuck into a WiiZapper substitute.
While I'm a little late to the party
and this sort of thing has been done before
, previous modifications have always left
something to be desired, usually a good solution for the nunchuck.
I also didn't like a number of things about the Wii Zapper.
- The Zapper has no sights, so aiming is difficult.
- The Zapper has no stock, you hold it in midair which can become tiresome, offset your aim and feels weird.
- The Zappers button configuration is the reverse of an intuitive layout, with B as fire and Z as action, leading to your trigger hand being in
front of your supporting hand.
After playing Ghost Squad for about five minutes I decided the Wii Zapper wasn't up to much, so I thought I'd see if I could do it better.Waste Not Want Not
I decided to use an Airsoft ICS MP5A5 Sub-Machinegun
this project due to several reasons, partly because it was one of the more "realistic" items in my airsoft collection, featuring a metal body
and several compatible accessories, but mostly because the little bastard had never fired more than five shots before breaking since the day I
bought it. I'd spent way too much money trying to get it to work as an Airsoft gun, so I figure turning it into a WiiMote couldn't do any harm.
I'm not one to waste a perfectly good airsoft body however, especially since the Violent Crime
came into effect, banning the import and sale of "Real Imitation Firearms" without being registered to an airsoft site
within the UK, so this was going to require some planning before I risked fucking up one of my guns.
To begin with I just held the MP5 as I would normally, then I traced with a pencil around my hand on the gun, and I'd repeat this process until
I was certain of where my hand would naturally grip the gun. I then taped some pieces of hard foam togeather to represent switches and the
analog stick, then I gripped the gun again and adjusted the placement of the foam until they were in comfortable locations.
Using some 3d models from a previous project of mine
that didn't go as far as
I'd have liked, I was able to produce some plans of where buttons and other items could be located on the foregrip of the MP5.Foregrip left side
Most buttons remain in a Wiimote layout as the switch heads are too small to label. This makes it easy for me to remember what they are each
used for.Foregrip right side
The A button is placed on the tip of my index finger, while the Z button is on the tip of my middle finger, and the C button is accessible by
the base of my middle finger.
Power and Sync buttons are also on harder-to-press click switches well out the way.Inside
While most buttons fitted without issue there were some concerns about the internals, as the highlighted areas were intersecting, where the PCB
of the nunchuck and the legs of a switch collided with a piece of metal from the MP5. I could have re-planned the position of these components,
but my chosen method was to bend the legs of the switch and cross my fingers about the nunchuck PCB. The intersection was only 1mm, and that
was well within the margin for error on my diagram.Its full of stars
With my concerns about stuff fitting alleviated, it was time to take the bitch apart and figure out what needed to be done to fit the WiiMote
inside.An Airsoft ICS MP5A5 and WiiMote
To begin disassembly you need to remove the two locking pins, one in the stock and one by the magazine release catch. You can then pull the
stock away from the receiver, and pulling backwards on the lower receiver will allow it to slide out from the upper receiver.
This is an important point to note, in that the lower receiver and gearbox must slide into the upper receiver from the back, otherwise the gun
cannot be reassembled.
I'll also remove the magazine and foregrip, which is released by taking out the forward locking pin and tilting the front of the grip
downwards, then pulling it forwards away from the receiver. Again, this is the only way this item can be removed or reattached.MP5 Disassembly, separated receivers
Here you can see the gearbox and lower receiver removed from the rest of the MP5. You can also see the battery connector and brass barrel,
which are to be removed.
Unscrewing the butt of the grip reveals the motor of the MP5, which is then just disconnected and pulled downwards straight out of the grip.
Below the motor are a pair of screws which hold the gearbox onto the lower receiver and when removed you can pull the garbox off the receiver,
as is the picture.Gearbox and lower receiver separated
Prior to this I had also removed the fire selector, another important piece I wanted to integrate into the mod. The fire selector is comprised
of two parts, a lever connector to a rod which runs through the gearbox, and another lever with a grub screw which grips the rod from the other
The airsoft implementation of the fire selector has the rod run through a piece of plastic which when rotated pushes the black plate (shown
attached to the gearbox) back and forth, toggling between safe, semi and fully automatic fire modes.Gearbox internals
From this stolen image you can see the internals of an airsoft version two gearbox, of which only the trigger mechanism would survive into my
mod. The trigger mechanism is basically two open poles which can be shorted (closed) by another pole which is spring-loaded to return to the
open position. This pole is pushed into the closed position by the spring loaded trigger. Nice and simple.Upper receiver
Removing a single screw from just above the rear of the barrel lets you detach the front of the receiver, usually hidden by the foregrip.
Only three more screws hold the receivers two halves togeather, and comes apart surprisingly easily.Upper receiver separated
Inside the receiver there's little to look at now the gearbox is gone. The brass barrel runs into the hop-up assembly and the power cables run
from the foregrip into the receiver via a small recess.WiiMote PCB and the Upper Receiver
The previous picture failed to show this too well, but the WiiMote PCB is just slightly bigger than the space above the upper receivers
indentations. The receiver has ample metal on these joints, so it is possible to cut a few millimeters into the receiver and create a recess
big enough for the WiiMote to set in comfortably.Gearbox Plans
With the knowledge that the upper receiver can comfortably house the WiiMotes PCB, I worked out what modifications needed to be made to the
gearbox to accommodate the WiiMote.
As I mentioned before, the gearbox has to slot in to the gun from behind, so the areas marked with black lines needed to be removed. I had
hoped to leave some of the front and top gearbox segments intact, so they could rest of pieces inside the upper receiver and ensure a snug fit
between the upper and lower receivers.
My plans for the fire selector were also fairly simple - as the fire selector would pass through the gearbox, I could attach an arm to the rod
of the fire selector at a fixed angle, and place microswitches above and below the arm which would be toggled as the fire selector and arm were
rotated. Springs could be attached to the arm to supply tension and ensure the arm always returns to the center position.
The only way I could think of effectively attaching an arm to the 3mm rod of the fire selector was to use a 3mm bore collar
, which would clamp onto the 3mm rod of the
fire selector. Using a long screw to tighten the collar, you would then have a rod (the screw) protruding from the collar on the other side,
which could hit a pair of lever-action
Perfect !Mr. Stabby
Now it was time to crack out the dremel and cut some chunks from the gearbox and receiver. I began working in the kitchen due to how cold it
was outside, but this wasn't to last very long.It begins
After covering the floor with a fine layer of aluminium I was relegated to the garage:
Which of course needed tidying
Slightly better, minus the dust.Gearbox Cuts
Here you can see what I ended up with - to accommodate the PCB a vast majority of the piston guide and spring housing has been cut out, leaving
only a small chunk to keep some rigidity on the top bar. The front of the gearbox has also had its top half removed.
A tiny amount was removed from the upper and lower areas around where the fire selector mechanism needed to go, as otherwise the microswitches
and collar would not fit. I also drew on a few lines to indicate where the arm should be able to reach, and added some crosses where the holes
needed to be drilled in order to attach the switches and spring anchors. More on this shortly.Receiver recess
Both sides of the receiver needed to lose 1mm from the middle bar in order to accommodate the PCB. I ended up using tape to show myself the
boundaries of where to cut. I had intended on making an elaborate setup with a ruler and a dremel attachment so I could cut in a straight line
without too much thought, but alas nowhere could I place the dremel attachment where it could reach the area I needed to cut... oh well.Gearbox Drilling
Back to the gearbox and you can finally see the fire selector and collar in the final stages of planning the fire selector.
SW2 changed location a few times as i confirmed the extremes of the fire selectors reach.
After I drew on the final crosses of where the microswitches would be placed, I took the gearbox downstairs, smacked four dents into the casing
with a punch, and took them out back for some vandalism.Fuck my ass.
My first major mistake is made; after drilling the first hole for SW1 I neglect to confirm the location of the second screw hole. As a result I
drill the hole way too far over. Luckily this is far enough for me to drill a second hole beside it, and thread it effectively.Fuck my ear!
Mistake number two isn't quite so bad, but in the process of tightening the bolts on the microswitches I go a little overboard and crack a
chunk out of the casing. Luckily there's no damage to the internals of the switch.I should have planned this better
After attempting to put the gearbox togeather for the first time it became abundantly clear that there is no way in hell the collar or spring
mechanism were going to stay in place long enough for me to fit the fire selector rod. Let's not forget that the way the gun goes togeather,
the gearbox must be closed, done up, attached to the lower receiver and screwed on before the fire selector can be attached.
My new plan is to have a plate made to fit the gearbox and bolted over the top of the collar. Several screws around the collar will help to
keep it in places while the rod is not present. I decided to use one of those murderously sharp pieces of aluminium from new PC case 5" drive
bays, and in the above image you can see the pencil marks of my planned cutout on the piece of metal.Spring loaded
Four very short screws hold the collar in place, while two more have springs pulling the collar to a middle point. A third screw makes sure the
assembly stays level.
This setup works perfectly with the gearbox open, but trying to close it reveals two problems:
1. There isn't enough room for the trigger mechanism.
2. The uppermost bolt, Anchor 1, in placed in the exact location of the spring anchor for the trigger mechanism.
Mother f..Trimmed fire selector plate
Some minor adjustments, two drilled and threaded holes later and the gearbox can be closed.Hindsight: When I relocated Anchor 1 I neglected that I would be offsetting the midpoint of the fire selector. This turned out not be a huge
problem, but it was certainly less than optimal.Cracking open the Wii Mote
There are guides all over the internet on how to open up the wiimote - a tri-wing screwdriver and a little determination, although what most
guides neglect to mention are the difficult-as-fuck-to-remove clips at the front of both the WiiMote and nunchuck. In both cases the best way
to deal with these is a good penknife and some leverage. Remember to point the blade away from you, and the top should be levered outwards. I
managed to get my WiiMote innards free with minimal damage to the casing, so I might turn it into WiiTorch or something like that, I don't
know.WiiMote Bits and Bobs
As it stands there wasn't too much to do to the WiiMote, mostly it was going to be a case of carefully attaching cables and removing switches.
To begin with however we needed to have the nunchucks analog stick available so we could begin on the foregrip.Drilling the foregrip
If I drilled a hole wrong on the foregrip there wasn't much going back, so my approach as to do as little as possible and double check every
holes distances. Using my caliper I put a number of small indentations into the foregrip itself as distances taken from the 3d layout I
Clamping the foregrip to my workbench and wedging a piece of wood between the left and right sides to dampen vibrations, I slowly drilled into
the plastic with a small drill bit, and slowly scaled up the hole with the next size bit. This seemed to keep the hole nice and straight, and
stop the bit from biting on the plastic at slower speeds.
Cutting out the hole for the analog stick was done in much the same way, however once I drilled up to the largest bit available it was time to
crack out the dremel and a coarse sanding attachment. In order to cut out a circle I first scored a circle into the plastic using my caliper at
a fixed radius, which was taken from the opening on the nunchuck body itself, and then I used tape to mark out the edges of this circle. I
could then sand the plastic until i reached the edge of the circle and started to cut into the tape.
Once the rough circle had been sanded out, I used a fine sanding attachment to repeatedly go around the edge. At this point I began to place
the detached analog stick inside the hole and rotate it to its extremes, and look for any edges which were not angled correctly.
I could also use this method to see if any light was showing through between the analogue stick and the foregrip, and could sand more off as
needed.Hindsight: Drilling holes onto an angled surface is very weird. Always use a guide to confirm you're drilling at a right angle to the
surface, as even your best guess could be way off.Securing the nunchuck assembly
My original idea had been to use nylon thread and some nylon spaces to secure the nunchuck in place. Essentially the PCB would have two legs
sticking out the back and pushing the analog stick into the hole. Unfortunately this was a very flaws way of doing things:
- The legs needed to be attached before they were placed inside the foregrip. The result was incredible frustration when trying to position the
- Extending the spacers/legs when the assembly was in position was nigh-on impossible
- The nylon spacers offered almost zero friction, and the assembly would slide out of alignment
- With the analog stick pressed up against the foregrip hole, there was too much friction to use it.