Bushings flogged already?

Hey all, I built this box a week ago with fresh gears, shims and bushings and after maybe 5 mags runnings through it the bushings are worn out already. Any ideas what the problem could be ? It’s running 16-1 Kublai gears, m100, stock aps motor, short stroked 1 tooth on a 70% cylinder.

Is this normal to have on your cylinder head ?

Soft bushings and piston hammer

That’s impressive for the run time

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What bushings did you use?..

Tac edge aps bushings is all I know about them

How do you remedy piston hammering ?

shorten the spring if you really want to use that one.

hammering happens when there is enough force left in the spring at piston start to continue to drive the piston head into the cylinder head

what spring are you running in it? could be that the sorbo is crap and just fell apart

Note to self, replace bushing when you (I) rebuild the virgin aps


With bushings, they tend to wear like a key hole shape, so turning the bushes 120 degrees can get you more use out of them, then maybe another 120 degrees). So you can re grease these after turning and still use your blaster for a while, while you order in some hardened bushes… like pop


K apparently missed out on the shitty bush thing

And i mean “missed out”

I’ve probably done 4 sessions with this blaster and I’m now onto what will be my 3rd set of bushings :joy: thanks to @zeHamish I’ll be changing springs for something gentler and adding in some hardened bushes :ok_hand: the shs ones I ordered earlier will be my back ups

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Be really anal about bevel backlash with the shs

I often need to lap them

1.18? I don’t experience fps drop like that

What barrel id?

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I’m in the same situation with some shs bushings on the bevel gear have keyholed like that just after a little bit of trial use, I haven’t even sorted my t-piece yet and what I found is the ends of my bjx gears a really worn and have the grooves from the bushes worn into them I’m thinking of dropping to an M100 spring currently running a m110 and going to bearings, I think I’m up for a new gear set too :man_shrugging:

How much damage?

Caught it early so just the flogged bushing and the ends of the gears, i went bjx light weight and they seem like cheese, i think a cnc carbon steel set would be better, maybe a better hardened bush set? I have bearings in another built with a cheap cnc cast gear set m100 spring and months later no sign of wear!

what box and bushes do you have?

i rarely have issues with such but i also spend a fair bit of time run testing before i commit the build to finish.

It’s a cnc mk tactical v2 and running shs 8mm bushing with bjx gears, I’ve spent hours shimming to get it perfect, pinion to bevel was bang on, i lubed the bushes with grease. I’ll take a photo tonight

i ditched the shs bushes in my mk tac… put in the mk slims.

still needed to lap one to get the bevel mesh correct (shs gears)

the other issue i had with the shs bushes was that they were a little fat to seat perfectly without excessive force, freezing and considerable determination.

High impact on brittle material. How does pistonhead look?

The M110 spring will be the culprit 1076219837DDA0F3C5E868F92C8C871FF7987F26AC

A good quality, equal M90 is the gopop

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