Regulator Design Idea

[michaelthomas]

FWIW.......I run my reg at 1050 for LV, and 1450 for HV and it works very well. 

Mike

[michaelthomas]

One thing that helped me immensely......was to make a miniature air tube testing rig that could use the valve setup from my gun.  I initially hated spending the time making it......but it has saved me a ton of time in the long run.  I have a very large and sensitive analog gauge on the plenum that I can use to watch what is going on when firing, setting the pressure, and making adjustments.  It's so handy for me, that I cannot believe how reluctant I was to make it.  Be sure to include any volume that is added by the standoff and the reg when making adjustments to plenum size.

Keep in mind that the regulator is only one part of the system that keeps your shot strings tight.  Valve size, valve stem drag, hammer spring variations, valve contact face, hammer spring friction, and the state of tune can are just some of the things that be very large influences on the shot string.  Don't just focus on the regulator and blame it for any or all inconsistencies.  There is a lot more at work.  Honestly......it would be best to address and alleviate all of the other influences as best you can before worrying about the reg too much.  It will give you a much better platform for analyzing the regulator itself.  All of these other things can be very time consuming and laborious to get right......but they are worth it if you are looking to improve consistency of the whole.  Just use common sense to try and see where inconsistencies can happen.

Here is a 35 shot string from one of my benchrest guns.  It is very typical of the performance that I get in LV with Exact 8.44's.  It's come a long way since I began working on this. Normally I am around 795......but his was a nearly 5 inch longer barrel.   At shot 19......I realized that I had forgot how close I was to the setpoint when I started......so I added 500 psi to the reservoir and continued.  You can see the difference in the string.  I can usually get extreme spreads of 3 over 35 shots.  The SD shows zero because my chrony (Competition Electronics) only displays whole numbers.  I suspect it rounds to the nearest......so it's probably somewhere between .5 and 0 in reality.  There were no shots omitted from this string.  In benchrest.......one wild shot out of 35 can ruin a card, so there is no point in ignoring them if you want to really improve things.  I can get these numbers with several completely different designs of regulators.....so I feel its clear that the other small things that I mentioned earlier are big contributors to consistency.  I think a lot of regulators get bad raps because the people that are testing them and posting the results are not really all that critical of their complete system.  It all has to work together.  Putting this reg into someone else's rifle might not produce results anywhere close.....and therefore the reg would probably get the blame.

1.  824    High 828
2.  825    Low  823
3.  825    Ave  825
4.  826    ES     5
5.  826    SD     0
6.  826
7.  825
8.  826
9.  825
10. 823
11. 823
12. 825
13. 824
14. 826
15. 825
16. 825
17. 825
18. 825 
19. 828 Added 500 psi to reservoir
20. 825
21. 827
22. 828
23. 828
24. 826
25. 825
26. 825
27. 827
28. 825
29. 824
30. 826
31. 825
32. 826
33. 825
34. 826
35. 826

Keep us posted, and stay diligent. 

Mike

[Airsnipe]

Well it's good to know that they will work for that pressure range but it's a bit disturbing to know the ratings on those springs are that far off.

I was thinking that making the spool as large as possible (the ID of the springs) it would counter the pressure of the large side so the spring load would be lower. So for these springs, the small end of the spool would be .188" or so and if you do the math that would counter act the large side and according to the spring ratings you could make a regulator that would have a high cut off of 2100psi. Do you have a picture of you regulator parts?   

[michaelthomas]

If you make the HP end large enough to have much influence on the spool.......you will have trouble maintaining the LP side as the HP side changes.

That's one reason why small is better.  Another reason is that it will take less pressure to make a seal on a small HP end......so you will end up with less creep.

This is a drawing of my regulator.  The only difference now is that I'm using more springs.  The spools were made on a CNC Swiss lathe.  They would be dang tough on a standard......but probably could be done.

Mike

[Airsnipe]

Thanks for all your help Mike. I really appreciate it.

[Deechord]

I stumbled in here by mistake...but find this fascinating.so...you guy's work(ed) at NASA...Boeing...Lockeed? Must be machinist's...right? Maybe got a Bridgeport in your shop? CNC? What about 3D printers. Keep posting...maybe I will learn something.

[rodbuilder]

Wouldn't those washers be flattened by 1688psi in that configuration with a piston dia of .420?

What is going on is not that the discs are that far off, it is more lack of complete calculation.  Uncertified discs can be off by a percent, but I don’t remember the acceptable % its not that much though.

We have to factor in a miniscule amount of friction from the o-rings, the high pressure resulting force, and obviously the spring friction from spring rubbing against each other and the shaft. There is another factor that usually slips pass, it is the force required to make a complete seal in the sealing material.  In other words if using delrin, how much force is required to press the piston face into the sealing material to create a seal. 

Your regulator will perform most consistently if you use your springs without stacking them.   More springs in single will also allow the regulator to reset with smaller changes.

I agree totally with Mike.

Mike I like the design, I have one similarly drawn up with the exception of the high pressure o-ring location.  I like your o-ring placement a lot better.

I have attached a picture of a regulator I found online but can’t remember where I found it.  It is not the best overall design because of the many pieces but it is externally adjustable.  This could be used as a bases for a better redesign.

[grhouse]

Like the other person said, I found this thread by accident just by looking through the posts and I have really enjoyed reading it. This is the skill level I'd love to obtain but I currently do not have the equipment to even start in that direction. I have some skills and the ability to learn whatever I want to but the equipment is beyond me currently. I can only drwam and read your great posts. Keep up the great work, Gene

[csdilligaf]

  Mike,  What have you found to work best for the spool edge/seat face shape.  I turn the spool's edge to a sharp knife edge and then have a little fixture with a perpendicular hole that is a slip fit to the spool diameter and I slide it in and use a diamond lap on the end to create just a slight witness mark to break the edge.  Have you played with all kinds of flats, radius and so on?