Airsoft Canada - View Single Post - Yes or no? Systema high speed with m120 spring?

mcguyver · October 29th, 2005, 12:16

you don't have to use high torgue gears with an m120. if you were going to use a 210%pdi or something like that i would say maybe, but not necessary. a good quality gear will go along way without failure. the key is in the assembly. alot of guys use the g&p guns with 210% pdi springs with reinforced gears and many thousands of rounds and no gear failures. i've removed 4 sets of "super torque up helical cut" systema gears in the last month that were toast. some people think they are the shit, but you don't realize how finnicky the are. you have to pay special attention to the gear shaft/bushing tolerance and shimming because any "wobble" gear or lateral movement relative to the other gears will destroy them. arnie's guide is interesting if you have no experience in a gearbox but that's it. use common sense and quality workmanship and you really won't have any problems. my g&p uses an eg700 motor with zero pinion gear wear and unnoticable gear wear. and as the only "gun doctor" in my area, i see every kind of gun and every kind of problem. and don't think that it's only 1 or 2 guns here and there. i have 5 on my bench currently awaiting parts/owners decision and several more in que. so i think that qualifies my decision more than some guy that says "there must be a reason arnies says that" and you haven't taken a gun apart before. i never advocate the use of stock gears, plastic bushings or stock piston/ head sets or plastic spring guides. and i never let a gun go without a few thousand rounds thru it in harsh fire conditions if i'm not satisfied it will be reliable. and i have never had a failure after my test regimen. and my work i do because i enjoy it and it's not for profit.

as for motor life in my first post in this thread i recommended increasing battery voltage and capacity. for those who have not read my previous posts regarding batteries and motors let me repeat it. as illusion has said you will eventually kill your motor IF you keep to the 8.4 volt battery and here's why: a motor is not turning but is given voltage and current under load ( the spring in an aeg provides this load) will draw massive current (maybe 100 amps) and the motor will fry in a split-second. as the motor turns it generates it's own magnetic flux that in turn generates current in the motor windings that OPPOSES the original current drawn by the motor. this is called counter-emf. as the motor speed increases this counter-emf increases until the synchronous speed of the motor is reached and counter-emf nearly equals current drawn by the motor at zero speed. the net result is a small "running" current that is easily manageable by the motor. altering speed up or down will alter c-emf up or down and running current up or down. increasing the load on the motor by installing a stronger spring means more current will be drawn by the motor upon start-up, and lower speed will result from the motor. this lower speed means lower counter-emf which means the running current of the motor will be higher and eventually it will fail. increasing voltage to the motor will increase its speed and thus increase the counter-emf in the motor, resulting in lower running current and increased motor life. those who don't understand these principles (taught in every trade school and university enginnering class in this country) or frankly don't believe them have no place offering advice pertaining to this subject. if you think i'm wrong, go to university, spend four years in trade school and 15 years working in this field and then you and i can have an intelligent conversation on the subject.

October 29th, 2005, 12:16	#15
mcguyver Trader rating Join Date: Aug 2005 Location: Northern Alberta	you don't have to use high torgue gears with an m120. if you were going to use a 210%pdi or something like that i would say maybe, but not necessary. a good quality gear will go along way without failure. the key is in the assembly. alot of guys use the g&p guns with 210% pdi springs with reinforced gears and many thousands of rounds and no gear failures. i've removed 4 sets of "super torque up helical cut" systema gears in the last month that were toast. some people think they are the shit, but you don't realize how finnicky the are. you have to pay special attention to the gear shaft/bushing tolerance and shimming because any "wobble" gear or lateral movement relative to the other gears will destroy them. arnie's guide is interesting if you have no experience in a gearbox but that's it. use common sense and quality workmanship and you really won't have any problems. my g&p uses an eg700 motor with zero pinion gear wear and unnoticable gear wear. and as the only "gun doctor" in my area, i see every kind of gun and every kind of problem. and don't think that it's only 1 or 2 guns here and there. i have 5 on my bench currently awaiting parts/owners decision and several more in que. so i think that qualifies my decision more than some guy that says "there must be a reason arnies says that" and you haven't taken a gun apart before. i never advocate the use of stock gears, plastic bushings or stock piston/ head sets or plastic spring guides. and i never let a gun go without a few thousand rounds thru it in harsh fire conditions if i'm not satisfied it will be reliable. and i have never had a failure after my test regimen. and my work i do because i enjoy it and it's not for profit. as for motor life in my first post in this thread i recommended increasing battery voltage and capacity. for those who have not read my previous posts regarding batteries and motors let me repeat it. as illusion has said you will eventually kill your motor IF you keep to the 8.4 volt battery and here's why: a motor is not turning but is given voltage and current under load ( the spring in an aeg provides this load) will draw massive current (maybe 100 amps) and the motor will fry in a split-second. as the motor turns it generates it's own magnetic flux that in turn generates current in the motor windings that OPPOSES the original current drawn by the motor. this is called counter-emf. as the motor speed increases this counter-emf increases until the synchronous speed of the motor is reached and counter-emf nearly equals current drawn by the motor at zero speed. the net result is a small "running" current that is easily manageable by the motor. altering speed up or down will alter c-emf up or down and running current up or down. increasing the load on the motor by installing a stronger spring means more current will be drawn by the motor upon start-up, and lower speed will result from the motor. this lower speed means lower counter-emf which means the running current of the motor will be higher and eventually it will fail. increasing voltage to the motor will increase its speed and thus increase the counter-emf in the motor, resulting in lower running current and increased motor life. those who don't understand these principles (taught in every trade school and university enginnering class in this country) or frankly don't believe them have no place offering advice pertaining to this subject. if you think i'm wrong, go to university, spend four years in trade school and 15 years working in this field and then you and i can have an intelligent conversation on the subject.