Docv400 Posted April 1, 2011 Report Share Posted April 1, 2011 I'm doing an SRC MP40 for someone at the moment, FPS downgrade and general check-over. Cleaned it all up internally last night, then just now, while Dry-Film Lubing the gears, the Sector gear's axle fell out (well, half of it did) I checked the others, and the Spur gear was exactly the same. You can see that the axles have a series of indents formed at the centre, to keep them tight in the gear (similar to the ones on the end of some body/mag pins). I'm sure this is the cause of the failures, the indents are an example of a classic 'stress-raiser'. You can also see that the pins are made from a fairly brittle metal, judging by the surface at the failure point. Link to post Share on other sites
DarkLite Posted April 1, 2011 Report Share Posted April 1, 2011 I've had a similar failure on CA gears before - the entire axle just fell out of the bevel gear. IIRC the SRC MP40 uses standard Ver 2/3 style gears, right? Link to post Share on other sites
Docv400 Posted April 1, 2011 Author Report Share Posted April 1, 2011 Came out in one piece? That's not uncommon. They are standard Ver2/3 gears, yes. Only slight difference is the tappet pin diameter, which is 4mm as opposed to 3mm. Got the axles out completely now, compare them to a 'normal' type... The swaged grooves are much deeper than usual, and the material looks to be some sort of brass(?) alloy (or maybe just a plating), good for wear resistance but much more brittle than steel. It's running ball bearings, so no real need for wear resistance anyway. Link to post Share on other sites
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