DMR - bushings Vs bearings

[Sitting Duck]

messing about with a possible M4 type DMR build - aprox 400-425fps say

(130 spring or 140 & short stroke it 3 teeth)

Generally peeps say bushings for higher fps - but

think I saw somewhere about a bushing/bearing/bushing mixture

g/box has 8mm holes so unsure to fit all bushing - most likely

or use a couple of SHS 8mm I have maybe for spur gear in middle ?

(others will be under more stress perhaps though I suppose all will be)

Have a 32:1 gear set btw & what I think is about a 20:1-ish if I worked it out right

is there something in between say a 24/26:1 that might be better or go with 32:1

any input/ideas - experiences what worked/failed ?

cheers in advance for any replies but like to get this running ok with few attempts

and if ok would look to do same on an AK mofo sometime if this ver2 g/box is ok

 

[jcheeseright]

I honestly have no idea why anyone would ever have 8mm bearings in a gun, a decent set of bushings are so much more durable and there's really no gain in performance using bearings (especially once they start to wear!)

my vote always goes to bushings.

 

[Sitting Duck]

cheers - I will keep the bushings that are in there already then

32:1 gearset don't like 2 x ver 2 g/box's as it hits the the trigger switch pin

(bit behind switch that often breaks where switch jumps back to on semi - soz for non-techy name)

this 32:1 set might fit in another g/box type but deffo not in a ver 2 box easily unless ACSU fitted

(from from my first impressions coz that sector gear is massive)

my 20:1 might be ok but was a cheap stock gearset so may look for a quality 22:1 perhaps

and 200:100 don't look too great either

failing that might have to settle for a 18:1 maybe

 

[cyrexx]

Using bearing with M130 and above is not recommended unless you use modify ceramic bearings (http://www.airsoftworld.net/modify-bearing-and-bushing-sets-c.html). Bushings are a lot more reliable and are actually quieter than bearing, but bearings more efficient, IRC Hunterseeker5 from ASM calculated they are up to 15% more efficient than bushings, so increasing trigger response and ROF.

A few manufacturers use a combination of bushings and bearings with bearings on the bevel and spur gears and bushings on the sector.

 

[Unrustle_Thine_Jimmies]

A few manufacturers use a combination of bushings and bearings with bearings on the bevel and spur gears and bushings on the sector.

Click to shrink...

It's funny,since the spur needs bushings more than the sector. It's lying on on side on the shell,so stress is unevenly shared between the axles while the bevel and sector have more-or-less even stress distribution. I've done this mix and no report of failure so far.

 

[sp00n]

It's funny,since the spur needs bushings more than the sector. It's lying on on side on the shell,so stress is unevenly shared between the axles while the bevel and sector have more-or-less even stress distribution. I've done this mix and no report of failure so far.

Click to shrink...

when i had my old TM mp5k bearing'ed (crappy 6mm gearbox tbh), it was the loaded side if the spur gear which failed. i am now running olite bearings/bushings in it now.

 

[NH Shooter]

In almost every circumstance... Bushings beat bearings (when things are done properly). Use Bushings.

 

[Sitting Duck]

cheers for replies

looks like bushings and maybe a SHS 18:1 set

(not gonna get Siegetek 20:1 etc.... wow they not cheap)

that 32:1 set also req half tooth cylinder - screw that is me first oomphy dmr build

could use a mix of bearings/bushings - especially if single shot dmr - hardly gonna go mental on ammo

but hopefully just want it just work for a good while so stick with bushings as I said

18:1 - recently SHS 18:1 have gone from 10 to 9 teeth on bevel gear so newer 18:1's are slightly higher ratio

some say this change is good & others not as good/reliable as 10 tooth sets

but will be using a high torque motor so think the SHS 18:1 or 19:1 whatever, will still be best all round set

fanx 1,000,000 chaps

 

[Samurai]

I actually found that bearings tend to be more silent.

 

[Ian_Gere]

I've put Kanzen steel bearings in 3 gearboxes so far and had no failures. They are quieter than the bushings they replaced. The strongest spring I've used them with is a CYMA stock spring though, so about M125, so maybe they would fail with more pressure on them. TBH I doubt it though.

 

[Unrustle_Thine_Jimmies]

Kanzen steel bearings and Modify ceramics are generally the best and strongest bearings out there,or at least the most recommended. Kanzen are slowly getting popular here,enough that I've installed them for a guy I know some time ago(Though I did recommend to put bushings on the spur which I mentioned before,but TBH I could have gone full bearing since it's all 1J build stuff,but I have fuck all reputation so I have to do what I do well after all)

 

[sp00n]

i should add that my bearings were 6mm (worst size ever ... only bearing a 8mm box as the loads are too much) guarder bearings

 

[Ian_Gere]

I've got 6mm Kanzen in my ICS AKS-74U - they are sweet. So sweet in fact I got some more for my Vz61 Skorpion but haven't fitted them yet.