R3 .30 caliber problem and fix
The Problem:
I first noticed after about 2K rounds my velocity dropped off. That can be common, sometimes the HST needs to be readjusted. So I screwed in the HST 1/4 turn and I was back at the 890 fps I was before. I was fine for about another 150 rounds until the real problem started. The gun started behaving erratic when trying to find zero on my target. I put the Matador on the chrony and I found a strange phenomenon. When the gun was full (220 BAR) no manner where the HST was set the most I could get out of the gun was 750 fps. As the pressure in the reservoir dropped the speed conversely would rise until below 150 bar the speed was at 912. I concluded that the valve must be stuck and the reason for the change in speed is that the valve gets more resistance from the air in the reservoir the higher the pressure. The valve must be allowed to move freely in the regulator. The belleville washers are clean, the O rings are perfect and the regulator is assembled correctly. What I found was the valve stem was slightly bent. I know this problem developed over time because the gun was super consistent when I was new. . The valve stem was not too long as it was in Ed’s factory specs. I straightened the valve stem reassembled the gun and I still had the same problem.
The fix:
what I found was the valve stem was slightly oversized and a little rough. Because the stem is steel and the valve stem housing is brass the valve was getting caught/sticking and in my opinion the valve couldn’t open enough. When the gun fell below the 150 pressure setting the valve didn’t have to work as hard to move forward when the hammer hit the stem. I polished the valve stem with 220/20/400/600/800/1200/2000 grit paper on a lathe until I could see my reflection in the valve stem. The valve moved like it was on ball bearings inside the housing. The regulator gave me 24 shots with the average at 880 and the ES at 2.6 fps.
I welcome any criticism you may have about my fix. It’s is possible that I just got lucky. Hell, it’s better to be lucky than good anyway.
All Replies
I agree with James 100% Titanium
Interesting….
You said you were able to bend it back??? sounds like the metal is soft. maybe from normal use the OD grew… till it started to bind. then it bent.
I hate to say it.. I feel it maybe just a bandaid. I would look into making a new rod out of something Harder… (if you can just replace the pin part) Did you take any Photos….
I don’t think it became oversized. I believe it always was that way. I think the larger OD contributed to the stem bending. I have the advantage of knowing and shooting with 2 other EDgun.30 owners. All of the valve stems needed polishing. We all experienced the same problem at the same time
So over time the valve stem bacame slightly oversized and a little rough. Why?
Sounds like a great fix to me. You may check with Ernest, at one time he was making stems with Titanium rods. The 30 cal. cannon must pack a wallop!
Regards
LarryW 🙄
PS: You ask for criticism, I think your dog, on occasion, eats a turd.
My only criticism would be if you were holding the abrasive in your hand while the lathe was turning. Even at low speeds your taking a big risk. I had some pics of some fatalities around lathes. Not something you want to happen.
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Sorry I should have taken photos but I was so obsessed with fixing the gun that I didn’t even think about making a post about it.
The metal is soft but most of the valve stem sits inside a very tight tube. I am hoping that the valve stem housing provides some stability to the stem. A friend of a friend makes medical equipment and devices like heart valves and hip joints. We are going to see if he can make new valves out of medical grade titanium.