Cricket Mod Valve stem testing with Titanium Rod & Acetal de
Tired of seeing broken valve stem at the end of the rod inside the body, the aluminum body don’t help the delrin from braking but only add weight—see photo.
the mods:
1. use Titanium grd5 rod with slightly reduce OD around the TP.
2. use a larger OD 9.35mm delrin that’s larger then stock metal body at 7.75mm delrin OD is 6mm
3. longer spring guide from 5mm to 9mm
Weight of stock metal VS: 3.48g
weight of mod VS: 2.45g
Test bull pub: cricket Standard .25 smooth twist barrel, reg set at 135b
using stock valve stem: Max speed with king heavy 840fps
using mod valve stem: max speed with king heavy 855fps
not tested shot count or ES yet, but looking through the crony over 100+ shots all within 850-857fps. had constant air supply to shoot just air over 500 rounds just to see if it break and hold a seal.
So if your a power hungry guy that shoot a lot, that know how to replace the valve stem —-> this one is free for you to test–mind you have only one available and 1st to email me gets it.
Also testing one on a 9mm cricket with reg of 140B.
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Viewing 7 replies - 1 through 7 (of 7 total)
Ernest…I’m waiting for mine too. A question…can regular HSS tooling machine these rods? Guess I can find out through trial & error, but what tooling do you use on your lathe to take these from 3.03mm down to 2.75mm? also to make the step-down for increased air flow? My lathe is fully tooled but was just curious if I need a special cutter to work Titanium.
thanks again
218bee
Do you can post a direct link to picture?
Thanks.
here’s the link to the photo, waiting on more Titanium rod to make more,
http://www.MyEasyPics.com/is.php?i=1176108&img=9147cricietvs.jpg
A cant see the pictures¡¡
Do you can post a direct link to picture?
Thanks.
Don’t have the .25 but the valve stems definitely are the weak chain in the link on these .25 and .30 cals (any brand) when you turn them up a bit and shoot a lot. Even the .177 Delrin in my Compact Cricket went with enough shots at 900 fps but it was over 5000.
Use only hard dense delrin.
The rod Is hammered in place while on the L/machine
Rod is 3.03mm and my hole is 2.75mm
You have to lightly taper the rod so it will self aligned
Drill bit is to heavy, got the titanium rod on EBay it’s light as aluminum but stronger then stainless.
Drilling your hole depth and making sure the rod is bottom out when hammered is critical, actual pressure testing will set the
rod —–> then you can grind the final length of the rod—-if you don’t you will end up with a short rod and that’s not good.
The sealing seat on the delrin is slightly tapered to center of rod. A straight cut is no going to seal properly.
I have already made one for the colibri—easier to make!
Good Luck!!
Looks good, Ernest,… I made a few spare black Delrin heads, but haven’t yet found a reliable way to anchor them.. I also have a nice cylindrical piece of hard, white Machinist’s Nylon that I might try for my Colibri’s…How’s the rod anchored to the inside of the Delrin? Crazy Glue? JB Weld? Just pressure/pushed in? Where’d you find the Titanium rod? can you use a drill bit instead? Seems hard enough..
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thanks again
218bee
Got my T-Rods today!
I use a mini carbide cutter that I shape to cut vary small material, on the chuck only 1/2″ of rod sticking out so I can cut the 2.95mm end. so the rod won’t flex off centered while being cut. I cut the step down after the rod has been press in the delrin.