Post by Berdugo on Oct 16, 2006 11:37:09 GMT -5
(This is taken from pageproducer.arczip.com, I hope the author wont get mad)
This is the continuation of the Mechbox Overhaul article I
wrote a few years ago.
Introduction
Breaking in the gear set has two advatages. The first and
foremost is a noticeable reduction of whine and chatter
eminating from the gears. The second is more debateable,
when properly breaking in gears it is possible to work
(strain) harden the gears for improved strength.
When crystals yield, dislocations move through them. Most
crystals have several slip planes. Dislocations on these
intersecting planes interact, and obstruct each other, and
accumulate in the material.
The result is work-hardening: the steeply rising stress-
strain curve after yield. All metals and ceramics work-harden.
It can be a nuisance: if you want to roll thin sheet, work
-hardening quickly raises the yield strength so much that you
have to stop and anneal the metal (heat it up to remove
the accumulated dislocations) before you can go on. But it is
also useful: it is a potent strengthening method, which can
be added to the other methods to produce strong materials.*
Basic definition of work/strain hardening is: the modification
of metal structure by cold working resulting in an increase
in strength and hardness with loss of ductility.
Work hardening is similar to forging in the way that it comp-
resses the metal molecules into a very compact and hard
formation. This can only be accomplished if the metal surfaces
are lubricated and the gear temperature stays cool enough that
the molecular structure does not change. If the temperature of
the metal gets hot enough to change the molecular structure, it
will soften the surface instead of hardening it. This may seem
like a balancing act but it all happens easily & passively as
long as the oil keeps the gears cool while it is breaking in.
Procedure
Breaking in gears should be done after the gearbox parts are
finalized. If you plan on using just stock parts you can break
in the gears as is. If you plan on upgrading the bushings and
gears I would suggest doing it after you have all the parts
installed and shimmed to perfection.
Things Needed:
Vise
4.8v or 6.0v battery pack
Degree of Difficulty: Moderate, requires opening the gearbox.
Step 1: Prep
Break the gun down and get the gearbox out of the gun. Open up the
gearbox and remove the whole Cylinder Unit. This includes: tappet
plate, cylinder, cylinder head, piston, piston head, nozzle and
sping. With the Cylinder Unit out you should have only the Drive
System and Electrical Assembly left in the gearbox.
While the gearbox open you can also clean out the grease and install
a lower viscosity lube for faster break in. I use a medium weight
silicone oil.
This is what the gearbox should look like after youre done
removing the Cylinder Unit.
Step 2: Break In
With the cylinder unit removed the gearbox is now ready to be broken
in. I have to note that with different guns and different gearbox
versions you may or may not be able to run the gearbox wihtout the
lower receiver on. The box shown in the pic above is a AK47 version
3 with contained motor. For guns like the TM m4a1 you must reinstall
the gearbox into the lower for it to be able to run.
AK47 Version 3 box being broken in.
Clamp the gun to a vise as shown and then plug the battery in. Ideally
the battery should be 1/2 or 3/4th the voltage you are planning on
running in your gun. I used a 4.8v pack for the AK47 and M4S. The vise
is not 100% needed but it makes things easier.
The actual break in process is simple. Run the gun for 1 - 1 1/2
minutes and let it cool down for 30secs to a minute. This should be
repeated till you get about 5mins of total break in time. On version
2 gearboxes without the motor bracket the motor can get very hot so
give ti some time to cool down. On version 3 boxes with the enclosed
motor bracket the bracket allows transfer of heat from the motor
through the motor bracket and into the mechbox. This makes the mech-
box kind of like a giant heat sink so motor temps on a V.3 box are
generally lower.
M4 type gearbox being broken in.
Step 3: Finishing Up
After the gear set have been broken in it is adviseable to clean them
throughly before reinstallation. If you have a motor spray cleaner I
would suggest cleaning out the motor and relubing the bushings. This
is not mandatory but something that can be done to prolong the life
of the motor. Running the Gear Set for 5 mins will also break in
the motor. This is a not as refined as breaking the motor by itself
under zero load but the results are similar.
With everything cleaned and reinstalled your gun should now have
much less gear whine. If done correctly in combination with a
good shim job and ball bearings the results will be more dramatic.
This is the continuation of the Mechbox Overhaul article I
wrote a few years ago.
Introduction
Breaking in the gear set has two advatages. The first and
foremost is a noticeable reduction of whine and chatter
eminating from the gears. The second is more debateable,
when properly breaking in gears it is possible to work
(strain) harden the gears for improved strength.
When crystals yield, dislocations move through them. Most
crystals have several slip planes. Dislocations on these
intersecting planes interact, and obstruct each other, and
accumulate in the material.
The result is work-hardening: the steeply rising stress-
strain curve after yield. All metals and ceramics work-harden.
It can be a nuisance: if you want to roll thin sheet, work
-hardening quickly raises the yield strength so much that you
have to stop and anneal the metal (heat it up to remove
the accumulated dislocations) before you can go on. But it is
also useful: it is a potent strengthening method, which can
be added to the other methods to produce strong materials.*
Basic definition of work/strain hardening is: the modification
of metal structure by cold working resulting in an increase
in strength and hardness with loss of ductility.
Work hardening is similar to forging in the way that it comp-
resses the metal molecules into a very compact and hard
formation. This can only be accomplished if the metal surfaces
are lubricated and the gear temperature stays cool enough that
the molecular structure does not change. If the temperature of
the metal gets hot enough to change the molecular structure, it
will soften the surface instead of hardening it. This may seem
like a balancing act but it all happens easily & passively as
long as the oil keeps the gears cool while it is breaking in.
Procedure
Breaking in gears should be done after the gearbox parts are
finalized. If you plan on using just stock parts you can break
in the gears as is. If you plan on upgrading the bushings and
gears I would suggest doing it after you have all the parts
installed and shimmed to perfection.
Things Needed:
Vise
4.8v or 6.0v battery pack
Degree of Difficulty: Moderate, requires opening the gearbox.
Step 1: Prep
Break the gun down and get the gearbox out of the gun. Open up the
gearbox and remove the whole Cylinder Unit. This includes: tappet
plate, cylinder, cylinder head, piston, piston head, nozzle and
sping. With the Cylinder Unit out you should have only the Drive
System and Electrical Assembly left in the gearbox.
While the gearbox open you can also clean out the grease and install
a lower viscosity lube for faster break in. I use a medium weight
silicone oil.
This is what the gearbox should look like after youre done
removing the Cylinder Unit.
Step 2: Break In
With the cylinder unit removed the gearbox is now ready to be broken
in. I have to note that with different guns and different gearbox
versions you may or may not be able to run the gearbox wihtout the
lower receiver on. The box shown in the pic above is a AK47 version
3 with contained motor. For guns like the TM m4a1 you must reinstall
the gearbox into the lower for it to be able to run.
AK47 Version 3 box being broken in.
Clamp the gun to a vise as shown and then plug the battery in. Ideally
the battery should be 1/2 or 3/4th the voltage you are planning on
running in your gun. I used a 4.8v pack for the AK47 and M4S. The vise
is not 100% needed but it makes things easier.
The actual break in process is simple. Run the gun for 1 - 1 1/2
minutes and let it cool down for 30secs to a minute. This should be
repeated till you get about 5mins of total break in time. On version
2 gearboxes without the motor bracket the motor can get very hot so
give ti some time to cool down. On version 3 boxes with the enclosed
motor bracket the bracket allows transfer of heat from the motor
through the motor bracket and into the mechbox. This makes the mech-
box kind of like a giant heat sink so motor temps on a V.3 box are
generally lower.
M4 type gearbox being broken in.
Step 3: Finishing Up
After the gear set have been broken in it is adviseable to clean them
throughly before reinstallation. If you have a motor spray cleaner I
would suggest cleaning out the motor and relubing the bushings. This
is not mandatory but something that can be done to prolong the life
of the motor. Running the Gear Set for 5 mins will also break in
the motor. This is a not as refined as breaking the motor by itself
under zero load but the results are similar.
With everything cleaned and reinstalled your gun should now have
much less gear whine. If done correctly in combination with a
good shim job and ball bearings the results will be more dramatic.
