Prometheus galore- PROJECT COMPLETE (Sept 11, 2010)

[turok_t]

Originally Posted by Azathoth

This depends on which stage of the break in you are in. If it's tight and it's Pre-break in I would personally leave it and do the break in and see how tight things are. If it's post Break-in and it's a little lose I would let it go; again depending on how lose it is.

The biggest noise your gun should make is the sound of the piston head striking the cylinder head. And in the case of some oddball setups the sound of the spring vibrating after semi. I don't know what other people do to ensure proper distance between gears when they are shimming but if you where to place a 0.20 shim on your bevel gear it should cleanly pass underneath the sector and bevel. when you rotate the gears.

Also 1 thing I forgot to mention. Helical gears exert strain differently than flats. if you take your gears on your left side of the box only and rotate them freely by hand you will see them twist themselves off the bearing hold. Flats will just turn freely and not rock free from the bearing axle slot (imagine a top losing its momentum and starting to wobble off axis). I've found that when shimming helical you want to use the largest outer diameter shim you have available. It makes a noticeable difference in the noise department. I went digging on ASM when I discovered this and it's happens to be standard advice over there.

To answer your question on the other issue. I have seen many off spec safety levers (the arm that acts on your trigger to prevent trigger pulls) try another one. If the component is part of a complete gearbox you shouldn't be having the problem so check the install. Other major cause is the trigger. Many triggers just are not on spec either. This is REALLY bad on G&G cansoft guns. Also make sure that you have the arm that interacts with the trigger installed correctly. I cannot tell from the picture but you may have the arm upside down.

PS. It doesn't look like you have done it but you may want to consider smoothing the piston guide rails on the gearbox, and the tappet plate are as well.

Thanks again for your reply Azatooth, I got a few questions if you dont mind...

1. How do you know if the trigger arm is upside down? They look the same to me on both side. The one im using is from classic army, but i couldnt find any other stores that sell one (i dont even know what the trigger arm is called).. Im hoping to get a G&P to match my gearbox.

2. When u suggest "smoothening" the piston guide rails, do u mean sanding? I dont want to sand off too much that it will become loose.

3. Do u have any experience where your fire selector plate broke at the narrowest point at the bridge? I realized that when i switch my gun to auto, the switch pushes the plate backwards and down, creating alot of stress on the most narrowest point. Ever happened to u?

4. For the switch assembly, is it better to have the mechanical one, or the electrical one (ie. the one with 2 prongs)?

[Azathoth]

3. I have only ever broken a selector plate on a g36 in the location that you describe. And that was my fault for trying to pry it from the gearbox without taking out the guts inside it first. I suspect that your problem is probably caused by an alignment issue between your gearbox and your body. If your fire selector is straining the selector plate you could try sanding off some material.

2. When I mean smoothing i mean lightly sanding or more accurately polishing with jewelers wax or with the finest grit sandpaper you can find. You want to make it look like a mirror ideally without removing too much material (as in nearly nothing). There is a guide on mechbox.com on doing this. PM oborous and he can send you a picture of his systema gearbox shell which is, and i'm not exaggerating, shiny enough for you to read a newpaper from the reflection (both inside and outside of the box). He must have spent days polishing it, but you don't have to go that far. Ask him about removing all the right angles at the cylinder head.

1. My trigger arm is different from yours. It will only fit 1 way. It's not symmetrical. I don't have my gun in pieces to illustrate this.

[Amos]

Oooh shiny!

Edit: Aww camera doesn't show it well... ALOT shinier in real life lol

[turok_t]

Originally Posted by Azathoth

3. I have only ever broken a selector plate on a g36 in the location that you describe. And that was my fault for trying to pry it from the gearbox without taking out the guts inside it first. I suspect that your problem is probably caused by an alignment issue between your gearbox and your body. If your fire selector is straining the selector plate you could try sanding off some material.

2. When I mean smoothing i mean lightly sanding or more accurately polishing with jewelers wax or with the finest grit sandpaper you can find. You want to make it look like a mirror ideally without removing too much material (as in nearly nothing). There is a guide on mechbox.com on doing this. PM oborous and he can send you a picture of his systema gearbox shell which is, and i'm not exaggerating, shiny enough for you to read a newpaper from the reflection (both inside and outside of the box). He must have spent days polishing it, but you don't have to go that far. Ask him about removing all the right angles at the cylinder head.

1. My trigger arm is different from yours. It will only fit 1 way. It's not symmetrical. I don't have my gun in pieces to illustrate this.

Oh when it comes to shiny, I can do a GREAT job on that Wait till you see my hicapa frame, its so shiny its ridiculous.. Im going to try sanding the rails and polishing it so its buttery smooth. After its smooth, do u still put grease on it? Wouldnt it slow down the piston??

Also, i just added the 4th question to my post above, but is it better for mechanical or electrical safety? Im tired of all these issues with my mechicanical switch and im wondering if its easier if i just stick with an electrical one..

[Azathoth]

You still need to lubricate the rails.

Mecahnical/electrical safety... It doesnt really matter.

@AMOS

Did you round the corners where the cylinder head meets the inside front of the gearbox?

[Amos]

Originally Posted by Azathoth

You still need to lubricate the rails.

Mecahnical/electrical safety... It doesnt really matter.

@AMOS

Did you round the corners where the cylinder head meets the inside front of the gearbox?

Doesn't really matter for my build, it's a G&P reinforced gearbox running under 400 FPS with a MASK cylinder head, If I was going for anything higher I'd send it off to get everything machined properly

[Azathoth]

If you're going to spend time to polish that you may as well go all in and do the corners as well.

[Amos]

Lol the polish was an idle thing really.. I got a new type of polish and I tested it out on the part of the gearbox... then... didn't stop lol

[yuhaoyang]

not like it matters enough for someone to do it meticulously over like 20 hours on an already high-end mechbox shell =p

[turok_t]

Anyways, ill post up my results when i get some parts in... i hope im able to fix this stupid problem so i can get my gun back in working order. Here is my to do list:

1. Sand the piston rails on the mechbox.
2. I need to drill a larger hole in the mechbox for the rear pin because it doesn't line up with my receiver..
3. Test fit my safety selector with my new selector plate. I may have to sand the circle part of the selector switch if it pushes the plate too forward or too back causing my plate to break.
4. When all the above is done, im going to check shims again, make sure there is no side to side movement, and break in the gears as advised by azatooth.

[turok_t]

IVe got a quick question for you guys if you dont mind. I know that when i put the fire selector on SEMI or SAFE, the arm of the cut off lever goes up. How does the arm engage the sector gear so that it only spins once for SEMI? Also, on the other end of the cut off lever, there is a longer arm that hides underneath the trigger assembly. What does that arm do?

[yuhaoyang]

sector gear protrusion pushes arm down, other end goes up, cuts off power in trigger assembly.

[Azathoth]

http://forums.airsoftmechanics.com/i...p?topic=2521.0

[turok_t]

ITs been a while since I posted on this thread.. but shimming is almost done, it took me many hours! And i finally figured what the problem is for my safety.... Here it is:


When i put the fire selector on AUTO, the cut off lever moves up, allowing the trigger to contact... this works fine.

When i put the fire selector on SEMI, it works for a while, I can see the cut off lever bouncing up and down everytime i pull the trigger. After a while, either one of these situations would happen:

1. the cut off lever moves slightly up and blocks the trigger block from contacting the trigger assembly resulting from the inability to pull the trigger. I tried to use a very thin flat head screw driver to push down the cut off lever, but it wouldnt budge.. i think its because the arm is caught on the sector gear... thats why if i put the gun to full auto, fire a few shots, i can put the gun back to semi and it will fire semi.

2. the cut off level goes completely up as if it was on FULL AUTO, causing the gun to fire full auto..


The screw that fastens the cut off lever is not too tight, its loose allowing the cut off lever to move freely. Do u think this has to do with the selector plate?
Any experience with fixing this problem?

EDIT: I was doing some research on this site.. and most ppl have mentioned about the shimming, charging batteries to the full, getting a larger battery, and pulling the trigger fully (ie. no feather weight pulls)... I when through each of the solutions.....if i got a 10.8V battery, would this help?

[turok_t]

I finally fixed the problem with a little bit of advice from Riley. Anyways, my Prometheus upgrades have finally been installed after several hours of installation and troubleshooting. I was going to use the Prometheus Neo Strike Chamber, but for some odd reason, im getting alot of feeding issues (double feeds, bb looping, etc). So I opted back to the CA hop up chamber with Prom soft rubber instead. My gun fires great now with no feed issues at all.. SEMI works as its supposed to, SAFETY works perfectly, and AUTO works flawlessly.

In terms of the sound, my gun sounds more consistent, and more "muffled", as if there was a silencer. Before I can hear the gears creaking and a whiney noise, but its slightly quieter now, all I hear is the piston, and not the gears. Here are some pictures of my final build:














Anyways, I learned alot from this upgrade. At first, I was abit apprehended, but after lots of research, asking questions, and problem solving, I figured everything out. I wanted to give everything to a gun doc, but I figured this would be the perfect learning opportunity...

Here is a list of all the parts I used:

Prometheus double torque helical gears
Prometheus tappet plate
Prometheus hard piston
Prometheus aero cylinder head
Prometheus cylinder "type C"
Prometheus air nozzle
Prometheus MS120 spring
Prometheus smooth ball bearing spring guide
Prometheus anti-reversal latch
Prometheus hard cut-off lever
Prometheus 6.03mm 363mm inner barrel/KM 6.04 469mm inner barrel
Prometheus soft rubber/Guarder soft rubber
SCS nub
Modify steel trigger
Modify selector switch (this is by far the best one ive used since its thick and sturdy.. the ones i used before were all thin and broke)
Modify selector arm
G&P 8mm gearbox
G&P trigger assembly
G&P M120 motor
G&P/Prometheus shims
Kanzen 8mm bearing