In my experince when there is a gap like that, the tabs on the gearbox just simply break off. Here's one thing: when I see a gearbox crack from the other size first, I think it means that the gearbox halves have not been perfectly aligned, causing the other half take more load on the piston impact. The misalignment may be caused by a bad cast tolerances or burr's on the alignment tabs. Just throwing this on here.. :P
You are on point my friend. It's all about load contact to disperse energy transfer. When I machined my own one piece, you bet the front touches. The lugs should act nothing more than to prevent cylinder head rotation.
The type of epoxy used in the video is more gelatin type providing cushion rather than ultra hardening epoxy. I use this as a alternative, since loctite is rare in Japan. It seemed to work quite well after stress testing. However if it gets stuck and hex gets stripped when wanting to replace internals, i'll just drill out the head and force the screw out. Than replace with new screws, since I can get a bag full of screws for very cheap here.
Good video, I subscribed. A simple mod I sue alot to reduce stress is adding epoxy to the 2 holes in the cylinder head and pushing it all the way forward to be flush against the gearbox. After it's dried double check to see reduction in play. Also it reduces alot of stress on the 2 gearbox prongs which under high ROF causes alot of vibration which leads to alot of gearbox cracking.
Even though your video is dated, not a lot of techs realize their errors not matching the cylinder head to the gearbox. Also I noticed that some of the new aftermarket heads have a piece of rubber now on the front which help cushions the blow to the gearbox.
You want the cylinder head to completely press against the front of the gearbox. If it doesn't, it will move all the impact to the mounds and therefore very close to the edges of the shell where it cracks.
However yes on gearbox, I use super glue, only epoxy on the 2 screws for the blowback arm. The gearbox doesn't need alot of tightening, just enough super glue or loctite to keep it from getting loose.
70D, you want the larger number. You also want to add a neopad on top or remove the previous pad from the cylinder head and glue it over the sorbothane.
In my experince when there is a gap like that, the tabs on the gearbox just simply break off. Here's one thing: when I see a gearbox crack from the other size first, I think it means that the gearbox halves have not been perfectly aligned, causing the other half take more load on the piston impact. The misalignment may be caused by a bad cast tolerances or burr's on the alignment tabs. Just throwing this on here.. :P
You are on point my friend. It's all about load contact to disperse energy transfer.
When I machined my own one piece, you bet the front touches. The lugs should act nothing more than to prevent cylinder head rotation.
That's what I thought 7 years ago. :)
@@ZaCkOX900 I find it more amazing that you have the same account!
@@willacewallace5905 Well because of my chronic stomach problems I can't really play airsoft anymore but I do game design and a lot of programming.
@@ZaCkOX900 I'm sorry, bro. That's got to be more than an inconvenience to deal with. Hope you can overcome it.
U can use a silent POM piston head as a alternative if you can't find sorbo pads. I find them quite useful in reducing alot of stress.
The type of epoxy used in the video is more gelatin type providing cushion rather than ultra hardening epoxy. I use this as a alternative, since loctite is rare in Japan. It seemed to work quite well after stress testing. However if it gets stuck and hex gets stripped when wanting to replace internals, i'll just drill out the head and force the screw out. Than replace with new screws, since I can get a bag full of screws for very cheap here.
Good video, I subscribed. A simple mod I sue alot to reduce stress is adding epoxy to the 2 holes in the cylinder head and pushing it all the way forward to be flush against the gearbox. After it's dried double check to see reduction in play. Also it reduces alot of stress on the 2 gearbox prongs which under high ROF causes alot of vibration which leads to alot of gearbox cracking.
Even though your video is dated, not a lot of techs realize their errors not matching the cylinder head to the gearbox. Also I noticed that some of the new aftermarket heads have a piece of rubber now on the front which help cushions the blow to the gearbox.
You want the cylinder head to completely press against the front of the gearbox. If it doesn't, it will move all the impact to the mounds and therefore very close to the edges of the shell where it cracks.
However yes on gearbox, I use super glue, only epoxy on the 2 screws for the blowback arm. The gearbox doesn't need alot of tightening, just enough super glue or loctite to keep it from getting loose.
gah.... I dont remember the exact part combinations. But they were not stock gearbox + stock CH.
It varies, you could need 1/8. I carry multiple sizes.
I have never seen them break but I am sure a weaker material gearbox probably could break off those mounds.
what spring were you using when your gearbox cracked? and how many rounds approx before it cracked?
So if there is a gap on the cylinder head, it is better than not having a gap?
If you epoxy it in place how the heck do you get it out???
I've actually seen it happen quite many times and not just on some crap gearboxes.. sadly I dont have any pics of them.
70D, you want the larger number. You also want to add a neopad on top or remove the previous pad from the cylinder head and glue it over the sorbothane.
Did you watch the video? I said I had that and better material for the gearbox then it still cracked. Are you a troll?
The problem are the material of the gearbox.... i would machining new one with steel😒
Or you could just state which ones it happen to... :)
They are made of cast aluminium, just make it of another metal and it will be fine! why do they make it so cheap!