Kings arm box shs gears

[Sitting Duck]

Ahhh - well you got travel on selector plate:

Left & it engages safety arm to stop trigger being pulled

Middle = semi but COL lever is down to operate correctly with spring returning it

Right = COL is raised right up for auto as explained

Normally most stuff or bits do work ok with a smidge of tolerance

However some selector plates like most stuff, certain ones work better/worse than others

yes M4 & MP5's are different plates but I'm saying just M4's can vary

the "arch" or "horseshoe" exact location can vary a bit from one to another though not too common

but in cases it can throw stuff out and the smooth selection can be thrown right out

After a few headaches after more headaches you learn to make careful comparisons between parts

replace a badly worn part or broken part with just anything can get you into more grief...

If you compare parts as a routine you may find before fitment - " well that ain't right.... "

sadly in your case there wasn't a selector plate there to compare

but check it operates left/center/right as described

soz - it is a bigger pain to get a completely newly built box running than a quick fix of existing box

as you really really need to triple check everything works 101% as it should - difficult if all parts are newly built

so we learn by mistakes & obtain a tiny bit more wisdom - f*cking PITA way of learning but you fully learn imho

back on topic - yeah could be a worn COL too - sounds like it was an older box ya got hold of

so who knows it could be worn on COL - ah well you got some pointers and getting a steep learning curve

no doubt it may need stripping again to check the operation - rolling sector back as described etc....

then compare the COL's old & new if you feel it needs replacing - compare side by side:

 

[Sitting Duck]

The only real caution is to ensure you replace parts that are the actual problem.....

It does happen that we steam in and change stuff we don't need to thinking THAT is the issue

BUT sometimes changing parts that don't need changing only adds to the problem(s) further

That is why we need to really check stuff out thoroughly first - best wishes

 

[Gazzalesta]

Ok just stripped the box down again the cut off leaver definitely has wear. But what I'm noticing is that the selector plate is catching on the casing bearing should I get a kings arm selector to go with the casing or does it not matter ? I still don't really understand how semi auto works though lol

 

[Sitting Duck]

Selector plate can catch on:

sector bushing/bearing

or

spur bushing/bearing

some plates should have recess to avoid catching on any bearing/bushing protruding slightly

like this one:

most likely the sector gear bearing is catching but this might shed some light on the possible issue:

See now you could buy this one, that one, or another one but there have been times when some plates

don't always fit well - had one plate that was a bit fat to fit in the guides/runners on box and was damn stiff to operate

you could order up a SHS selector plate with or without the copper strip:

or

that "should" operate quite well

you may need the copper plate on a selector plate if there are prongs/contacts on the trigger switch

Some switches must have a copper plate but to be honest get a selector with a plate if unsure

As for how the trigger switch & COL & trigger sear all work it is hard to explain...

so here is an ICS video that explains it more

Now you may have to watch it a few times but you should get the idea...

in SEMI the COL slips under the trolley - bit that makes contact to complete switch circuit

it slips under the trolley's " lug " and when trigger is pulled the trolley engages....

after firing the COL rises and lifts the rear of trolley popping it off the trigger/sear to reset

trigger releases & relatches at rest blah blah blah.....

AUTO - the selector plate lifts the COL upwards out of the way so it doesn't pop the trolley no more

full auto fire until trigger is released - trolley never lifts off the trigger/sear

watch it a few times and you should get a rough idea of what id supposed to do what...

 

[Gazzalesta]

Rite I'm getting there full auto working fine trigger lock ok but still when I put it in semi auto it fires once then the whole gun jams until I take it apart ? Ideas

 

[Sitting Duck]

Sometimes - it can be because another factor....

I say SOMETIMES because it all depends on the switch installed.

Some old style switches have 2 prongs at the rear which MUST have a copper plate

on selector plate AND MUST make good consistent contact when firing.....

It is a crap old design than can cause issues when firing - often in semi than auto

I'm not saying this is the exact case in your instance but another thing to check

see the copper plate may not be making good contact in semi and some resistance ?

In auto the plate slides further back and makes better contact with these 2 prongs...

So you "can" get intermittent firing issues if these prongs are not bridged by the selector plate

NB - I'm not saying for certain this is the case but it is a fairly common issue at times

Most modern switches do not have these rear prongs - eg: shs switches G&P & G&G plus others

But others like Cyma SRC - these two I know have the prongs at the rear - ooh APS as well I think

If the prongs are not bridged soundly you will have issues...

NOW there is a way you can bridge these contacts with say a staple/wire and solder them

BUT you should ONLY do this if you run a mosfet

mosfet's run very low juice at the switch so it is fine

DO NOT JUST BODGE IT IF YOU ARE NOT USING A MOSFET !!!

pic says a 1,000 words...

 

[Gazzalesta]

I've put a shs selector plate and shs switches on it. Il pull it apart again and have another look see if I can see what is happening

 

[Sitting Duck]

Ahh right then if it has the SHS switch assembly, not just a SHS trolley then you won't have those prongs.

Now another thing is risk of piston/spring bottoming out or get close to it.

If you shortstroked then this won't be the case

But it is hard to pinpoint as to why a lockup might be happening without seeing, hearing it or checking the amp current draw etc...

 

[Gazzalesta]

Yes I've short stroked it. I'm lost to know what's going on. It be any kind of gear locking up

 

[Sitting Duck]

Weird it is locking up on semi but ok on auto ???

especially on stronger motor - stock motor & poor battery yes if precocked it might not shift easily

The semi issue led me to think the copper plate/prongs not touching but that is not the case

if it is shortstroked then piston can be bottoming out at back of box then - nope

piston binding - some pistons are very tight fitting in some boxes that they bind

normally this slows the rof down and with a strong motor it should still fire coz it has the grunt

if you have shortstroked 2 teeth then the piston will just pass the window at rear of box

if you shortstroke 3 teeth the piston just reaches the far rear end of window

it could be catching at the window - file these rear guides of pistons at angle to reduce any chance of catching

BUT tbh I doubt if if this is the real issue if she is firing ok on auto....

I'm leaning towards a tight binding piston either too tight piston or rails

the piston inserted in box should fall freely if tilt box up/down

google some vids coz the copy/paste feature is not working - but you will need to check for binding

slightly file the rear of the runners on piston right at back to assist or reduce the risk of catching on window

Really tbh - you need to maybe check the amps if possible - I'd say you are well over 20amps

if the motor is straining a bit to cycle on auto & locking on semi

it is either a bad bad connection on motor or wiring (not the prongs but along those lines)

or you got some mechanical lockup to extra stess which kinda overcomes on auto but not on semi from start

possible chipped tooth on gears or a bit of plastic can lock up stuff - but I don't know

your shimming MUST have some tiny play side to side when box is finally assembled

bevel must be shimmed as close to possible the perfect height...

too low and pinion will try to jam or push the bevel right through the box as tries to mesh - straining and ramping the amps

too high and the tip of pinion will nearly hit the bevel's AR lugs the AR latch uses

(not a common thing but some boxes have a bit more shimming space in say bearings than bushings and you can shim too high)

It is something daft, that is for sure but I'm seeing nothing and the new host isn't too clever for posting links/pics/vids either atm

so I suggest to strip it ( AGAIN ) and really really check just how silky smooth them gears turn

how smooth that piston glides back & forth in the runners - how the piston falls or slops about

Deffo worth checking piston out - loads of agro I know but welcome to the world of toy guns

How hard can it be ???

I reckon it isn't until you reach the thried build you start to get a better idea

around about 6th build you are sort of getting there by overcoming previous issues

and I reckon about 9th or 10th build you finally build a box that you are really proud of that lasts

and we are ALL STILL LEARNING - think we never stopping saying WHAT THE F*CK on these poxy toy guns

hope some of crap helps

 

[Gazzalesta]

Mate you have helped me so much already thanks. il pull it apart tomorrow had no time today. And check everything you said and post results on here

 

[Gazzalesta]

Yes it fire fast and strong on full auto but soon as I fire on semi it fires once then locks up fully even if I put it bk on fully auto

 

[Gazzalesta]

This is doing my head in now checked everything nothing catching or rubbing gears moving smoothly re shimmed with new ones still no change

 

[Sitting Duck]

Check your amps & new battery higher burst....

what spring you using - should only need a m110-115 if Shortstroked a couple of teeth

weak motor connections, bad joins etc.....

try another motor just in case

did you correct AoE properly ?

if not it could be getting bolloxed on the next cycle or pick up but then wouldn't it screw up on auto

wiring - mosfet - contacts at switch

if it all operates smoothly mechanically then it must be some sort of electrical issue

worse case scenario it is a number or mixture of issues

I would try a higher brust lipo 25c 7.4v - NOT 11.1V if using 12:1 gears ffs

it will smash up using a high burst 11.1v on speed gears

ensure all connectors are sound tamiya/deans deans is best but reckon some electrical problem perhaps

really need to check amps well over 20amp you may have undue stress in the box maybe ?

check motor spins outside the box/grip - had one with an iffy armature - rare but can happen if a winding blows

try another motor

chrono the sod on auto - you may have a m150 spring in there but you would notice it tbh when closing up box

it is something bloody weird or a few things or a bad part of some description

but I can't tell coz I haven't got it front of me & not even got a pic of your box/work to look at

try a few things above if not open the thing up & take some pics - upload to imgur of stuff

don't worry if it isn't a perfectly neat job - I've done worse bodge or bad teching in the past

(not that great now tbh but have f*cked up loads in my quest to get it better)

somebody - one of us can look at it and likely shed some more light/suggestions on the bastid box

 

[Gazzalesta]

I have no way to check amps and only standard motor I tryed my 7.4 wouldn't work with it only with 11.1. 120 spring or that's what I was told

 

[Sitting Duck]

I have no way to check amps and only standard motor I tryed my 7.4 wouldn't work with it only with 11.1. 120 spring or that's what I was told

Click to shrink...

Ahhhh that might be part of the problem.....

With higher speed gears you are placing more strain from start position

12:1 or 13:1 is like you trying to pulling much higher spring than a m100

then add in a higher spring on top & the poor stock motor is trying to start pulling say a m150

but due ratio's it doesn't have an easy start

like trying to do a steeper hill start in fully loaded clapped out fiat panda or something

even if you rev the thing the lame engine is going to struggle no matter

I suggest you look towards a shs torque & try her on 7.4v 25c lipo

the motor upgrade is going to be required imho

some stock motors are ok but most are not for an upgraded mechbox

try looking out for a shs torque - not speed motor - long type most likely

check ak2m4 and others for shs or RA torque or at a push zci balanced

reckon that should sort it out

sorry thought you had an upgraded neodym magnet already

but obviously I got confused with similar post

do not get a speed motor - you want a good balanced motor like a shs torque

run on 7.4v - not 11.1v as that may be too much and could wreck the box if you go too quick

depending on what you get rps then 11.1v will be 50% again...

problem is at 25rps you start getting a bit close to PE or PME

you should be ok to say 27 - 30 rps but finally rps can vary

if you push it too much the sector engages the piston and makes a nice mess inside

trust me - if there is one thing I have done often it is taking the pi$$ and smashing f*ck out of a half decent box

 

[Gazzalesta]

The problem I got it's all money and this time of year I have next to nothing so gonna have to shelf it till got spare cash