How to Motorize An Airsoft BB
Gun Magazine
One Hitec
HS-322HD servo, cheap, as you can
see.
Get a
high-speed if you want fast,
get
high-torque if you have a long feed to the hopup.
This procedure
uses about $20 in parts to make.
Although these
instructions do not allow dis-assembly of the finished unit
(considered disposable in the event of malfunction),
simple
planning would allow a unit that can be completely broken
down.
1/8"
drill.
With the servo
still assembled, drill the hole out slowly with a
variable-speed drill.
All servos have 1 screw holding the
wheel/arm on. Remove this screw, and drill the hole out to 1/8".
This is much easier to do at this stage.
don't panic, I'll show you why we
do this in a
bit.
Make SURE you use a drill no larger than
1/8"/.125""!
You only need to go in about 3/8" or so,
but if it bottoms out, no harm.
take care not
to crack the tube you're making here.
Remove the
bushing/bearing, middle gear, and output shaft in order
numbered.
Under the
output shaft location will be the pot shaft sticking
out.
Lop it off flush, sand smooth with top of
hole.
Another view.
Two chops usually work better than one.
On brass
shafts, you may need a small file to take it down flush.
As
long as the shaft can turn freely when temporarily placed,
that's good.
Like
this.
BE CAREFUL
HERE- Make a small nip at the outside end of this
tab.
Repeat again coming in from the
top.
THEN snip it off completely. Try to do
this too ham-fisted, and the shaft will break.
I know, so use
little nips to work the stop tab
off.
The little
speck below the cutters is what we've removed.
Place the
shaft through the bushing/bearing, and temporarily place it in
the servo cover. Make sure it turns
freely.
Re-assemble
the geartrain, slide the cap back on. Some alcohol will remove
any gear goo.
Tape the cover on if it won't snap on and
stay.
Just chop off
the wires. Don't worry about being careful about the
connections, they won't be reused.
If you're
fastidious, you can desolder them.
I chop them
off flush with the trusty Sandvik cutters I've owned for
almost twenty
years.
Positive and
negative hooked up on the motor leads themselves.
Servos vary as
to which is which.
A test connection to a drycell battery
for a moment (hold the cover on to avoid gear
damage)
will show you which way to hook up. this
of course depends on which way your servo needs to
turn.
Screw the cover back on, it may not go
flush where your wires come out,
if you went
with bigger wire (no problem reusing the stock harness), but
this is OKunless you shoot underwater a
lot.
Snap the nub
off the winder key from your mag,
or use a
Dremel to make a 1/2" length of 1/8" allen key.
This becomes
the drive
shaft.
A pair of
Vise-Grips, push the shaft 1/2 way into the servo
shaft.
Again, take care to push straight in, or
you may crack the output shaft of the servo.
And we have
our finished drive unit.
Now to rework
a normal M14
magazine:
about $10 online, and proven
reliable.This will be a magazine for one of my
Brownings.
It goes into an ammo box, and needs a way
to feed the gun a few feet
away.
Milsim folks,
look away. My trusty band saw took the "un-need" part right
off.
Yes those are latex gloves. Latex gloves
are great, so much hand-scrubbing time
eliminated.
NOTE: If you are
building one of our miniguns, skip the next 8 pictures, as
parts to replace the putty are in the design.
A chunk of
normal 1/4 aluminum rod stock is pushed into the BB-hole,
after a mild deburring.
5/16 coil
spring from McMaster-Carr slides right over the aluminum
shaft.
This keeps the feed tube (spring) aligned
with the mag body while the Oatey #31270 epoxy
hardens.
Use a chunk
about the size of a
bon-bon.
Kneaded into a
rope
shape...
Wrapped around
the spring somewhat evenly this
way.
And pushed
into shape with a small card.
Let set for
about 8-10 minutes
.
Then stretch
the spring slightly, and (use the Sandvik's you ran right out
and got)
pull the aluminum rod free.
Work it up into the spring, it
will
fall
out
Works every
time.
Wiggle the
spring loose by tugging and twisting.
Look close at
the spring
you use, one direction
will make
the spring shrink as you twist, the other
will make it grow.
You want the spring to shrink, so it can
move in/out of the hole you've made from cast putty.
Make sure you
get any loose particles!
So much
happening here*. The epoxy has been smoothed over a shop vac,
so no dust got inside.
The hole has been slightly chamfered.
Fingerprints are from the cheap latex gloves. A little alcohol
on a paper towel takes them right off.
*See the
sandpaper? It's six months old. I spray-adhesive'd it to
plastic sheet. I score the back and pop off any shape "nail
file" I need. Lasts almost forever.
A test-fit to
the now painted servo.
A 1/8 hole,
drilled in line with one of the servo ears. Make this
hole
in a spot where it is outside of the BB
path. Looking at the edges of the servo, you will find a good
spot.
Location will depend on clearance for your
needs.
A #6 screw
self-threads into the new holes.
Adjust so the
servo does not bind while turning.
It is OK to
turn the wheel slowly to check. A little wobble is just
fine.
Another
view.
Hot melt
glue WON'T come off, like
nuts that
vibrate
free.
This picture
is biggest for a reason. take care not to glue the wheel to
the servo case or the mag body.
If you get
sloppy, DON'T touch it. Let it harden, and trim it off
later.
Add 36 of new
spring, you could feed ????
McMaster-Carr
#9664K49, 5ea for ~$14.
Same principle
applied to M4 magazine.
Use a rubber
tire from a toy car if your mag has a tiny wheel.
You'll need to
devise a bracket of sorts. Larger tire=faster winding.
Sorry, we do
not sell motorized units, except with finished gun packages.
This information is provided for entertainment only, and no
warranty of suitability to your needs is implied. Use of this
information is at your own
risk.
