Gearbox jamming

[MultipleParadox]

Hi peeps, me again :/

I changed my piston, piston head and cylinder head recently, and decided on trying to shim those gears as thy didn't seem quite perfectly shimmed by the factory to me. Plus, the shims used were quite small in diameter and some of them seemed to start to distort a bit.

So I bought a stainless shim set, and got going. I didn't get the result I really wanted to but it seemed acceptable. More details about this below.

So I reassembled the whole thing, plugged the battery and tested a single shot. At the first trigger press, the piston cycled half-way and started to get stuck. Second Trigger press, got to the back (fully cocked) and never budged from there. The motor probably started to force (duh) and I got the battery wire (the red one if memory's good) to go spark and "disconnect" from the solder near the Deans. Seems to have overheated in that part. Motor and battery are still good to go, by chance.

So I tried playing around a bit more and still no luck, same results.

--

More details:

When I first got into the gearbox, and the gun was still good as new: The lowest gear (spur gear?), when all by itself was looking like it wanted to rub on the side of the GB's shell. If perfectly straight, no issues, but if I turn it by hand and tilt it just wee bit little, it rubs and jams. I'm not even sure if being able to tilt it by a degree or two (or three?) is normal or not.

When I close the shell with all gears in, and I turn the gears by hand, it doesn't seem to create that problem. But it's obvious that everything is not perfectly smooth.

What should be my next course of action? :/
I'm thinking abound grinding a bit of the shell to help, as a work around, but it won't really solve the real issue. Bad bushings maybe? Should it be really nice and tight or is it normal that there's some side play?

Thanks for your help



EDIT:

You can see a quick video I made with the ORIGINAL Shims (that was before I change the piston and stuff)
When I remove the gear and put it back, I took the top shim and put it under to see if it would help. As you can see it worsened the problem.
Soorry for the bad lighting conditions

[Jimski]

if it jams it means there are too many shims and the gearbox is squeezing the gears.
reduce shim thickness, put the box together and try to move the gears from the bevel gear with a big flat screwdriver: it should be relatively easy and smooth.

were the spur gear seems to touch the box, there should be a very thin+wide shim.

Also you need to adjust shims so that they optimize contact in between gears, not only gear vs box: if the spur gear gets to be higher, then you need to lift the other gears accordingly.
a good shimming will require you to take apart the box several times especially if it's new for you so don't worry and go back to it

[MultipleParadox]

Thanks Jimski, I appreciate the input.
It makes sense, as some gears seemed to "need a lot of shims" O_o At least it was in my impression. I'll try to lower all that tonight.

I'm just wondering though: If I reduce the amount of shims, chances are the gears will have of a "lot" of side play I guess (perpendicular to the gear's shaft), I do I reduce that? Or is it not that bad to have some play like this?

Note: In the video, I think the spur gear only had a single shim, quite thin, and was still jamming like that. O_o

[Varjeal]

Try watching this:

‪Airsoft Minigun V2 V3 Gearbox Shimming Different Technique‬‏ - YouTube

Also try mechbox.com for a walk-through.

[Styrak]

You need to test how your gears spin with the mechbox halves screwed down. If you were just holding it together and testing that's not good enough.

[MultipleParadox]

Probably didn't help my case yes, I was testing without screws

But in the end I lost patience and gave it to Ninja_en_Short :P

Thanks guys

[CDN_Stalker]

^^Ditto^^

Also, could be a piston/mechbox rail interface issue. What mechbox, what piston? I had the same issue with a few guns years ago, client bought various parts and had issues with piston jamming at times, zero'd it in to the piston rails being a bit too tight for the mechbox, filing the mechbox rail down eventually fixed it. When you have the gears out during reshim, put the piston in and screw the box back together, and cycle the piston back and forth manually, see if any sticking.