Has anyone tried using or making poppet diameters above .500'' on balance valves? And with what balancing diameter?
Balance Valves for big bore airguns
- Thread starter deathhero22
- Start date
A good ratio/balance diameter to go by is whatever keeps around 100-200 lbs of force holding the valve closed..I won't run the math..If you're going to a length of building balanced valves you should have a deep understanding of them...that includes timing the transition event via vent hole diameter / balanced volume to obtain proper transition from 'balanced' to 'unbalanced' so the valve operates in a desirable way opposed to 'blow open'...if you don't care about 'blow open' or not then again, I'd recommend whatever diameter balance chamber keeps around 100~ lbs of force holding the valve closed.
If you scale Bob/Rsternes balance valve that works in calibers up to .357's that I helped decide optimal parameters then you may get great results, maybe not...
If you scale Bob/Rsternes balance valve that works in calibers up to .357's that I helped decide optimal parameters then you may get great results, maybe not...
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I'm new to posting on any forums; frankly have been deathly afraid of it, anxious even, so I stay in the shadow of my peers..............I've read Bob's works over the course of 4 years time.............catching him unexpectedly when reading through forums......... , often rereading his data. I have quite a respect for him. I have yet experienced the effects of 'blow open' balance valves and went directly to drilling the "vent hole diameter" on my other balance valves. I was just curious about anyone using balance valves on Calibres above 45 with balance forces exceeding the closing force and maybe becoming lonely on the subject....... As far as I know.........I'm still learning and stir crazy during this pandemic. :T
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Over on GTA, MJP/Marco runs some form of balance valve in his custom 20mm gun, the Fury. His tuning style is that of max power, with less regard for efficiency. I would assume it has much greater than .5" valve throat.....
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+1 to what mackeral said, PM MJP on GTA, hes quite friendly and helpful. Although his balanced valves as mackeral mentioned do not care for efficiency / tunability and lean towards 'blow open'.
Personally, in a .50 caliber gun, I would run around .3" poppet with the rest balanced...start a bit smaller on the vent OD at around .5"~ (easier to go bigger, harder to go smaller)...with a balance volume that is as little as possible yet allows a lift of at least .125"~. That should work fine, and can be tweaked from there.
So many factors go into balanced vales that are designed to be 'tuned ' as opposed to 'blow open', such as plenum volume / pressure drop during shot cycle, dwell time due to barrel length..ect ect...
Then you have o-ring squeeze, you want it around 5-10% for the dynamic o-ring, I personally run 8% (I built a balanced valve, but don't ever intend on using it). HTH
-Matt
Personally, in a .50 caliber gun, I would run around .3" poppet with the rest balanced...start a bit smaller on the vent OD at around .5"~ (easier to go bigger, harder to go smaller)...with a balance volume that is as little as possible yet allows a lift of at least .125"~. That should work fine, and can be tweaked from there.
So many factors go into balanced vales that are designed to be 'tuned ' as opposed to 'blow open', such as plenum volume / pressure drop during shot cycle, dwell time due to barrel length..ect ect...
Then you have o-ring squeeze, you want it around 5-10% for the dynamic o-ring, I personally run 8% (I built a balanced valve, but don't ever intend on using it). HTH
-Matt
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Thank you for responding, I will PM MJP on GTA for more info on 'blow open' valves and his experiences. As for 'Sticktion' I think is the coined term for dynamic o-ring squeeze. lol Reminds me of squeezed Orange juice........My seal is compressing .003 on each side so .006 net compression in the .623 balance thimble. Also........How would I go about PM'ing MJP? Any formalities I should be known of?Upvote 0