My Field Target Project

[AmBraCol]

Here's a fall picture of the finished rifle..... .

It was a beautiful shooting day here......sunny, mid 60's, and 1-4 mph winds.  Very nice.

Mike

That pic makes me homesick.  It's all green down here - sure miss the fall colors up in Montrose (and the rest of the Rockies). Thanks for sharing your build with us.  I hope you get the FT group off the ground.  Where are you shooting?  Years ago I put a lot of lead down range at the Montrose Rod and Gun club out on HW50 east of town, but that was with powderburners.  Also put some time in at the San Juan range south of town. They were (are?) mostly CAS oriented but had a rifle range across the road from them. Anyway, hope you get the FT group going there.

[michaelthomas]

With 4 giant Maple trees in my small yard, I'm kinda wishing for the green again......lol.  I like the colors, but could do without the leaf pickup.  Snowed here last night......supposed to be back near 60 through the weekend.  Kinda funny.

We will likely end up shooting on private property.  One of my friends has a lot of land off Jade rd......they farm and raise cattle.  Lots of interesting places to shoot there.

Do you come back through here ever?

Mike

[AmBraCol]

With 4 giant Maple trees in my small yard, I'm kinda wishing for the green again......lol.  I like the colors, but could do without the leaf pickup.  Snowed here last night......supposed to be back near 60 through the weekend.  Kinda funny.

We will likely end up shooting on private property.  One of my friends has a lot of land off Jade rd......they farm and raise cattle.  Lots of interesting places to shoot there.

Do you come back through here ever?

Mike

My mom was born and raised out in Shavano valley and there's still uncles and cousins in the area, plus MCC is one of our supporting congregations so we get back up there every couple years or so.  It's one of my favorite areas in the US of A, just wish we'd time to spend there more often.

[michaelthomas]

MCC is a stones throw from my house on York.  If get over this way.....make your presence known.

Mike

[AmBraCol]

MCC is a stones throw from my house on York.  If get over this way.....make your presence known.

Mike

Sure thing. It'd be good to see your project in person.   And the person who did the project, of course! 

[michaelthomas]

I finished up my regulator over the weekend, and was able to fool with it quite a bit since then. 

The regulator has a moveable seat, and it was a bit of a task to get it at the pressure that I wanted.  I made a small test rig, but all I had for a gauge was a poor quality little Ninja jobber.  It was graduated in 500 psi increments, and wasn't really accurate at all.  I eventually was able to just do testing in the rifle using an air tube that was 1/4 the size of the normal one.  After a lot of trial and error, I got the reg set to what I believe is about 1950 psi.

I wanted to try out the regulator installed in the coupling between my air tube and valve block, since it could be easily vented to atmosphere through the coupling.  This gave me a plenum volume of about 12cc.  Based on Bob's calculations, that wouldn't be enough to maintain the energy that the gun was tuned to prior to the regulator (18.4FPE).  I figured I could try it out in this location, and if I wasn't happy......I could move it more outboard and drill a hole in the reservoir.

Long story short......I stayed with my same solenoid voltage and shot some strings with a lower power output than normal

I charged to 3000psi and shot down to 1850.  I used the gauge on my Hill pump for the start and end pressures.

220 cc adjusted reservoir volume.

I got 85 shots at an average of 831 fps.  16FPE average.  1.28 FPE/ci

Extreme spread was 15fps with a standard deviation of 3.

I'm happy with that spread, and I believe I can get another 15 shots or so if I charge to 3200.

I'm gonna shoot the gun for a while at this speed and see what I think of it. 

Mike

[michaelthomas]

Well......I didn't really do any shooting with the lower power.  I made a new coupler that moved the regulator outboard by 8cc to get a plenum volume of 20cc.  Obviously.......this cut down the reservoir volume to 212cc.

I got a good quality large diameter gauge that displayed 50 psi increments......but 25, even 10 could be read since the gauge was so big.  I checked the regulator setpoint and it was actually 2050psi.  The new regulated air gauge matched the Hill pump gauge exactly.....so that was good.

It seems that my reg takes about 30-45 seconds to settle.  I guess that's not a big deal since that's about what it takes (at least) in a competition.  I would like it to recover quicker, though.  Not sure what would help it, though.

Any Ideas?  I'm using single stacked Bellevilles....but I'm guessing they are pretty close to their limit arranged that way.

Charged to 3000
Shot down to 1850
High 864
Low 853
ES 11
SD 2
Shots 75
17.1 FPE Average
1.25 FPE/CI efficiency

Seems pretty good.....I like the SD of 2.   there were about 4 wild shots in there that kinda hurt the string.  I was hoping to be under 1%.  I just shot pellets out of the tin, so I suppose that could have accounted for some of the variance. 

Mike

[Bent]

It seems that my reg takes about 30-45 seconds to settle.  I guess that's not a big deal since that's about what it takes (at least) in a competition.  I would like it to recover quicker, though.  Not sure what would help it, though.

Any Ideas?  I'm using single stacked Bellevilles....but I'm guessing they are pretty close to their limit arranged that way.

Charged to 3000
Shot down to 1850
High 864
Low 853
ES 11
SD 2
Shots 75
17.1 FPE Average
1.25 FPE/CI efficiency

Seems pretty good.....I like the SD of 2.   there were about 4 wild shots in there that kinda hurt the string.  I was hoping to be under 1%.  I just shot pellets out of the tin, so I suppose that could have accounted for some of the variance. 

Mike

If you use a harder material for the seat, it allows more flow... I made one for my scubatank, first try was using a hard type of nylon... it was creeping slow the last 20 bar from 180 to 200 bar... changed to a Delrin seat instead...

[michaelthomas]

Hi Bent,

I am using white delrin as the seat.  I removed everything last night and closely inspected the seat.  I could see a very, very slight inconsistency in the marking from the spool.  I took an extra spool and made a makeshift arbor for it so I could spin it against the seat with some polishing compound. I did this until the seat marking looked good all the way around.

I also removed any silicone grease from the belleville stack.  The current stack is very near flat when pressured up, and I figured that the grease was creating more "stiction" at that point.

I put everything back together and reset the setpoint, and now it charges pretty quickly (5 seconds or so) to within about 25psi of the ultimate setpoint......then takes another 30 seconds or so to creep that last 25psi.  This seems like it will be very good for the application.  Shooting at 3000 psi gives shots of 358-361, and shooting just above the setpoint gives me 356-359.   I'm sure there will be some variables from pellets, but it looks like it's gonna be good for FT or bench to me. 

I believe I can improve it further on the next one by using a smaller low side piston to get the bellevilles much closer into their working range.

If I set the reg at 1200 or so.......its rock solid, and takes way more movement of the seat to produce pressure differences.  At 2050 psi, a .001" change in length will up the pressure by 50 lbs or so.  I believe that operating the stack where it is more linear will improve things.

I'm using a single stack()()()()() of 10 bellevilles.  I tried double stacking(())(())((, and the performance was total junk.  It would creep 200-300psi.

I didn't do a full string because it's just a pain in the neck to fire off that many wasted shots.  I'll do some target testing pretty soon.

Thanks for the input.

Mike

[rsterne]

Sounds like you need thicker Bellevilles in a single stack.... You could also try polshing the edges of them with 600 grit paper or finer....

Bob

[Motorhead]

Well......I didn't really do any shooting with the lower power.  I made a new coupler that moved the regulator outboard by 8cc to get a plenum volume of 20cc.  Obviously.......this cut down the reservoir volume to 212cc.

I got a good quality large diameter gauge that displayed 50 psi increments......but 25, even 10 could be read since the gauge was so big.  I checked the regulator setpoint and it was actually 2050psi.  The new regulated air gauge matched the Hill pump gauge exactly.....so that was good.

It seems that my reg takes about 30-45 seconds to settle.  I guess that's not a big deal since that's about what it takes (at least) in a competition.  I would like it to recover quicker, though.  Not sure what would help it, though.

Any Ideas?  I'm using single stacked Bellevilles....but I'm guessing they are pretty close to their limit arranged that way.

Charged to 3000
Shot down to 1850
High 864
Low 853
ES 11
SD 2
Shots 75
17.1 FPE Average
1.25 FPE/CI efficiency

Seems pretty good.....I like the SD of 2.   there were about 4 wild shots in there that kinda hurt the string.  I was hoping to be under 1%.  I just shot pellets out of the tin, so I suppose that could have accounted for some of the variance. 

Mike

Fooling with QUITE A FEW PCP regulators, production and prototypes .... find the type seat and sealing diameter play a huge part in recovery speed and quickness is stabilizing.

Also found out was WHAT type Seats work and which ones don't 

[lloyd-ss]

Getting regulators to work the way you want them to can certainly be exasperating.  I am glad some of you guys have the patience to follow it through.
Lloyd-ss

[rsterne]

Also found out was WHAT type Seats work and which ones don't 

How about sharing, that's what Forums are for, IMO....

Bob

[Motorhead]

Without a photo gallery of what Not too do .. photos, drawing and such on what works, getting into a dissertation on all these fine points would be a very in depth thread all by it's self.

If OP wishes to share his regulator pictures, would be more than willing to engage in a conversation on whats felt right or wrong with the design as it is now, then suggest what may be a course in taking correcting the slow stabilizing, pressure drift or creep. 

Scott

[rsterne]

Sounds like a great thread, I'd look forward to seeing what you have learned....

Bob

[michaelthomas]

Here are my drawings.

After shooting a few hundred shots today, the setpoint climbed just enough to need a bit more hammer.  This happened a few days ago when I was out shooting some doves.  Maybe it was the cold....or maybe everything finally took a set.   I don't know. It seemed to stay there......until i took it apart again.  I was in the shade, today, and it was about 47 degrees.  It worked great for about three hours, then the setpoint climbed.

Anyway......my initial plan is to reduce the spool diameter on the low pressure side to .370" ish.  That's going to be one Oring size give or take.  This will put the stack I have in the working load (or at least a whole lot closer)......rather than near flat at 2050psi.  That will also create less differential so creep over the 1000psi working pressure should be reduced.

The thing seems to perform great (quick reacting) at 1200psi......and I'm attributing that to the bellevilles being in the working range.  I could be wrong, of course.

These are the thickest bellevilles I could find in this size.  I will try sanding the edges that contact each other.  The washers ID's are about .012" larger than the spool shank.   The ID's were larger than listed.

Anyway......that's what I have.  I'm open to suggestions. 

Mike

[michaelthomas]

I'll post in JPG, too.....so it should show up without downloading.

Mike

[rsterne]

I looked at your diagram, and I notice that the O-ring grooves are very wide and have a lot of compression on the O-rings (I assume they are "0" series, eg 010, with a 0.070" cross section).... A Ninja regulator has very narrow grooves, only about 0.002" side clearance, and minimal compression, again only about 0.002".... I assume this is done to reduce friction also play in the groove....

FWIW, I never use the "proper" specs on O-ring grooves, I always make mine deep and narrow.... Crosman seem to agree with me (actually, I copied them)....

Bob

[Motorhead]

What i would like to see is PATH HP air takes getting to the seat ?
Diameter of HP end of spool and if seats sealing edge is at that diameter or less than ?

[rsterne]

If I understand it correctly, the HP air enters through the ports above and below the seat into the chamber surrounding the seat and then travels into the conical end on the spool, up through the spool to pressurize the large end.... When that pressure overcomes the Bellevilles, the conical end on the spool seals on the (Delrin) seat.... so yes I would say that the seat diameter is basically the OD of the small end of the spool, ie the diameter of the open end of the cone.... I'm thinking that design may make the diameter of the seat irrelevant, but I'm not positive about that.... The pressure differential across the seat is at 90* to the motion of the spool, is it not?.... However, the tank pressure, which varies of course, is pushing on the smaller O-ring all the time, which would require varying amounts of pressure on the output side to close I would think....

Bob