GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: TheBman on October 11, 2014, 09:13:15 PM
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Ok guys, as I promised, here is some pictures and some narrative about what I did. I can’t and wont tell you this is how to do it, or the best way, or even the right way. It’s just how I did it, right or wrong. I have no experience with PCP’s and how to regulate them, other than what I learned by doing this and what I researched . I don’t think this is a task to be taken on by a novice. Not only is there too many dangers involved, but there are just some things mechanically speaking your just gonna have to figure out on your own. However, if you have some mechanical skills, mechanical knowledge and can use precision measuring instruments, you can do it. Some things you may need to outsource, such as making the hammer or the adjuster unless you have your own lathe or access to one.
My goal was to have a regulated gun at 20FPE or a little under. So, the springs, weights and port sizes of what I used to get there are specific to that goal. If you want a 12FPE gun for example, the principals will be the same, but the springs, weights, ports etc will be different. I think with some effort, you should be able to find the pertinent information you need.
I used a regulator I purchased from a fellow GTA member, Milo74. His product came highly recommended. I did however spend a good amount of time watching videos on youtube by Robert Lane (don’t know if he is a member here). Just search for robertlanedesigns on youtube or go to airgunregulators.com and it should provide you with links. I learned a lot by doing this and highly recommend you do to.
I am hoping that by putting this all together that those that have wondered what is partly involved in installing a regulator into a PCP will have a basic understanding of it. I also truly hope that those with more experience will chime in with hints, tips, or directions on how to better do it.
This is the second post by me on this topic, so if you haven’t read
http://www.gatewaytoairguns.org/GTA/index.php?topic=75570.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=75570.0)
pleased do so to get the story of how we got here.
Pictures/narratives will be added as fast as I can, as I know that tells the story. I still have several to edit, resize etc.
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I read your other thread, and I am really looking forward to this one.
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Suggested reading:
http://www.gatewaytoairguns.org/GTA/index.php?topic=70970.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=70970.0)
http://www.gatewaytoairguns.org/GTA/index.php?topic=74900.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=74900.0)
http://www.gatewaytoairguns.org/GTA/index.php?topic=53141 (http://www.gatewaytoairguns.org/GTA/index.php?topic=53141)
http://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0)
"the book" http://www.lebedev.com/airgun/technical_details_for_adjusting_the_bam_b50_51.pdf (http://www.lebedev.com/airgun/technical_details_for_adjusting_the_bam_b50_51.pdf)
and anything else you can find. There is a lot of good info in these topics.
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Step One, what are your goals with the gun
In other words, the single most important thing I think you need to do is determine your goals for the build. Are you gong to build a 20FPE Field Target Hunter class rifle, or a 12 FPE higher shot count vermin exterminator. It really does dictate a lot of things you will need to research..and solve. One of the considerations I had was "what if I want to turn my power up or down"? Am I just stuck with a 12 FPE gun forever and ever? What are your shot count expectations? I got better than 90 shots at right around 14 FPE, 100 at 12 should be realistic but 75 @ 30 FPE ain't gonna happen
Seriously, it lays out what can or can not be accomplished...now and in the future. So before you dig in and start cutting and drilling, have well defined goals and realistic expectations...not only for the gun, but within your resources available.
Once you've got that sorted out, get some paper and develop your plan.
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Step 2, develop your plan
This really runs hand in hand with your goals I think. For example mine looked something like this:
A. Just under 20 FPE so it's legal for Hunter Field Target
1. What FPS and pellet weight gives me the flattest trajectory at this FPE? (play with GunChair and look at graphs)
2. what pellet shoots well in this gun (research web)
a. what speed does this pellet work well at (research web) and does that FPE fall within my needs?
1. Figure out what pressure is required to have pellet/weight at that FPS (make note for reg set pressure)
Those are just some of the notes I had down. Ask yourself a lot of questions, it may seem overkill, but it will start the foundation of your plan. When your laying this out, look at your resources, skills, cost expectations etc. If you have to outsource something like say machining the hammer...what are the costs for that...have you got a friend that can make it for you...when can they get to it. It all plays together so sort it out now.
Now for the best part...work your plan.
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For my 20FPE build, I used the following parts:
Hammer spring and valve spring McMaster Carr spring 194125K125 you need 2 and it comes as a pkg of 5 $13.28
Hammer material (MDS nylon was recommended highly) McMaster Carr 8554k29 1ft $6.33
Regulator from Milo74 $80
1--1/2-20x2 setscrew for adjuster Local hardware store $1
1--6-32x1/4 setscrew for locking striker in place Local hardware store $.25 (you could reuse your metric from existing hammer)
1--10-32x3/8 setscrew for locking hammer spring adjuster
O-rings for the valve, end cap, transfer port, check valve...change them all save your self a headache (sizes in "the book")
Any taps and tap drills you do not have
Your B50/51
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Step 3, Disassembly, inspection and measurements
Your plans all ready, your goals are established and you've gathered data from your gun via the Chrony. Lets do it.
DEGAS BEFORE YOU DO ANYTHING.. Disassemble your rifle down to the only 2 things left are the cylinder with the valve still installed. I used a storage case like the one in pic #1 to keep track of all the parts. I don't think a play by play on the disassembly is needed as the schematic in the book shows you where everything is and you have the skills needed to get it apart.
At this point, I got my length from the end of the cylinder to the face of the end cap of the valve. I squared a piece of 1/2 pvc pipe, inserted it into the cylinder until it made contact, marked the end of the cylinder on the pipe and removed it. I used some electrical tape and wrapped the pipe at the length marked (as markings sometimes get wiped off!) like in pic #2 and then measured and recorded the info
You need a non-marring tool of your own design to loosen the cap on the valve. The book gives a few examples of sockets being filed or ground. I simply used a piece of 1/2 PVC water pipe, filed the end like the sockets in the book and used it (pic #3). Worked like a champ and it took about 2 minutes to make. Now, unless the threads are galled or whoever assembled it really cranked it down, it should loosen pretty easily. If not, you may have to resort to something a bit more sturdy.
Remove the valve by using your PVC pipe and push it out the end of the cylinder.
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Get yourself a notebook and your measuring tools and measure and record everything. I drew myself a print of each part and recorded all the data about it. This allowed me to refer back to my parts and make decisions on what was going to have to be machined to make things work.
If you haven't ran any of the calculations for the standoff length required, now is a great time to do so.
Inspect each part, remove any burrs, clean, polish what your going to polish etc and basically get everything your not machining ready to go back together.
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Step 4, machine the valve
Reading through the suggested reading posts, you'll find a good bit of information given by MotorHead (Thank You!!) about some of the things he has done . I simply took that information and ran with most of it.
Pic 4...I opened up the valve inlet to .375, broke the edge with a 45
Pic 5..I opened up the spring seat to facilitate the larger diameter spring
Pic 6...I cut down one of the McMater Carr springs, bent the cut end square, polished the ends a little.
Pic 7 and 8...I machined a new bushing for the valve stem. Larger size required as the new spring is bigger. I lightly radiused the inlet side edge. I also resurfaced the stem seat.
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I did a mild lapping of the valve seats using some JB's bore paste, opened the outlet port to .150, cleaned with alcohol, replaced O-rings and reassembled the valve without the spring. I then tested the seat by applying some very low pressure air to the valve inlet and cycled the stem repetitively ensuring I turned it and checked for leakage. All good here, installed the spring and placed it in a plastic ziplock bag for stowage.
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Locate and drill weep hole
I used some gray electrical tape and placed it on the cylinder directly under where the barrel sits. I put the barrel on with 2 screws and traced the edge of the barrel onto the tape with a marker. I removed the barrel and then inserted the alignment pin into it's hole with a gentle tap...pic #9
Pic 10...with the cylinder flat, I rotated it toward me and placed the valve onto the pin, and then placed the standoff in place and then the regulator.
Pic 11---You can see my tracing of the barrel on the tape much better here. I elected to use the center point between the orings of the regulator as my reference point for the weep hole in the cylinder. I simply marked it out on the tape. This hides the weep hole out of view. Consideration as to the placement of the weep should be one of your concerns in your plan. If you place the hole closest to the o ring toward the breech, you can turn use a shorter standoff if you reduce power, or vice versa/ I went in the middle as it allows me to go up or down, but to a lesser degree.
Remove your valve, standoff, regulator and alignment pin
Center punch the mark thru the tape and drill the hole. Size...I've read from 1 - 3 mm in size.
Deburr the hole...inside the cylinder is especially important to avoid nicking or cutting the O-rings during installation of the Regulator.
Now you get to deburr
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Thats probably it for today. If I need to clarify anything, ask. I'll try to answer the best I can. Feedback???
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Nice Bman,
The post will be very helpful to many BAM 50/51 owners; I don't think prospective tuners need tremendous Lathe skills to make things, just an accurate (lathe) set-up and measuring tools. Overall, great combination of PCP theory, machining, mechanical and computer skills shown to present the tune ;).
All other owners "On The Fence" should have their BAM PCP Motorheaded by Scott!!! :D
Kirk
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Mmmmmm. This is not for the average tinker.
Hindsight can be the B-word, but perhaps I should have taken less lab science and more metallurgy back in the day.
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Reading back through this this morning I realized I skipped a step, and that is the standoff. It is nothing more than a bushing. Just be sure to use something of sufficient strength and that it won't corrode. I used 300 series stainless 1/16th wall thickness and it was 1.875 in length.. Your length is determined by the the volume you need. The volume you need is determined by FPE you choose. MOTORHEAD and RSTERNE have previously given recommendations as to volume required per FPE. Machine and deburr.
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How much clearance is there between the 0.570" OD washer you put on the valve poppet for a spring seat and the inside of the valve?.... It would seem that it might restrict the flow at that point, which could negate the opening of the valve inlet?.... Just a thought as I haven't been inside my B-51 yet, in fact it's never been fired....
Bob
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Bob,
I measured the ID of the inside of the valve at .788 according to my notes.
Brent
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Should be lots of clearance.... Not the most streamlined shape with the washer on it but flow volume shouldn't be an issue....
Bob
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Install the valve, standoff, and regulator
You will probably have a good bit of prep work here in deburring the cylinder to prep it for installing the parts. My cylinder needed a fair amount of TLC as most edges were pretty sharp. Cleanliness is important when finished!
All I did was remove the end cap from the valve, applied lube (less is more) the O-ring and reinstalled the cap leaving it just barely loose
. If you are applying pressure to the O-ring, you are expanding it. Simply align it as close as you can and insert it into the cylinder. Get things aligned and insert your alignment pin, screws in the side of the valve, and the screw and nut on the bottom of the valve. I then used my PVC valve tool and tightened the end cap on the valve seating the O-ring.
I inserted the standoff. I made a vertical mark on the face of the Regulator in relation to the weep hole location on the side of the regulator. As suggested form one of the videos, I kept that mark on the face regulator pointing up towards the weep hole in the cylinder and simply pushed the regulator into position against the standoff. A light rocking motion was used to get it past the threads in the end of the cylinder
Installed new O-rings on the cylinder end cap, installed it and then the fill valve.
Leak test is important.
Note: Milo74 said he used wire affixed to the regulator to aid in it's removal for adjustments.
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nice write up i fitted a robert lane to my b51 last year as our limits only 12fpe i lightened the hammer considerably and found fitting very easy but i did increase the stand off to twice the one supplied as i'm a firm believer in having enough prechamber
i found the consistency very good but i haven't really done much set up as i'm waiting for a .20 barrel for it
ped
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Hey Ped
Did you do any shot strings with it at 12fpe and if so what was your shot count at that power level? Some people might interested in the data at that level.
Thanks,
Brent
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i did but i lost all my data when my computer went pear shaped and as i'm going to be fitting a .20 barrel when it gets here i never repeated the strings
the results were promising though and as a result i've just fitted one of the same regs to a disco hows 180 shots from a 3000psi fill (valve pinning is uprated for the higher fill) only done one test at present and need to fit a gauge to find the most efficent reg setting then adjust port ,hammer weight,spring preloade and valve spring
i'll try to find a graph of this one
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Hammer and adjustments
Pic 12 is the original hammer and spring guide. Reading Motorheads previous posts he gave us the information to make the hammer out of nylon and the weight suggested was 30-35 grams and he increased stroke length by approx. 3/8 inch.
I made my hammer to the same dimensions as the original, snubbed the nose by 3/8th's and tapped the striker threads deeper into the hammer. I reused the original striker and drilled and tapped the vent hole for the striker grub screw. The vent hole is now blocked by the striker...so, you'll have to relocate that, I went linear. The spring guide I originally made is the same with the exception of the the stem extending into the spring. I increased the diameter to better fit the spring.
The second shot string I posted was shot with no hammer spring adjuster, just the spring inserted and adjusting via the striker. So you could simply machine reduced/increased spring tension into your design and not have a hammer string adjuster.
I elected to make an adjuster for the hammer spring. I used a 1/2-20x2 allen head setscrew for mine with a 1/4 hole drilled through it to allow striker adjustments. Just remember, if your overall length is too long, the spring guide length will need to be reduced or it won't cock ;)
This area is kind of vague I know, but I chose to make some length adjustments to the spring guide after the second shot string to facilitate a greater range of adjustment which would allow me to turn power down somewhat more should I choose to do so.
So, the design is really up to you and what you want to be able to do with it.
There are a multitude of ways to make the adjuster and make it work. My suggestion is to research several and look at the pros/cons of each and choose one.
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Barrel port and transfer port
Pic 13 shows the barrel port. I opened it up to .150, which is getting close to max for a .177. I have not experienced any loading issues or pellet damage issues at this size.
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Well, at this point I decided to assemble and take things for a test drive to get an idea of where I was at. I knew I was going to have things that needed to be tweaked or fixed, but there was no way of knowing what unless I put some lead down range over the chrony. It was a shot in the dark… a rookie with a regulator running on some info found here as posted by MotorHead. What could go wrong…right??? Honestly, I was pleasantly surprised the first time I pulled the trigger and it actually shot!
The second shot string that I posted in my original post, rsterne said I was within 2% on all my shots right at 20 FPE. As I understand things, that aint to shabby. However, as it was to fast for where I really wanted to be (and wanting more shots ;D), meeting my goals of the build, and of course tinkerer I am I just had to put in that hammer spring adjuster in. Now I am learning to adjust things out…because I have to...and thats a great thing so I understand it better. Here is a string after the adjuster was installed. I am around 4% here and need to spend some time getting it lined out.
Fill pressure 3000psi JSB 10.34 .177
1-10 858 854 865 873 868 867 860 856 853 854
11-20 858 865 857 859 854 858 858 855 850 851
21-30 852 849 852 855 848 847 844 850 845 849
31-40 845 845 843 845 848 844 839 837 829 837
41-50 844 842 841 844 848 847 840 834 839 839
51-60 836 842 841 840 836 843 838 835 835 836
61-70 845 840 838 848 841 840 840 847 842 842
71-80 842 840 843 848 846 846 846 844 848 846
81-90 854 858 864 874 872 879 880 886 890 887
91-100 895 891 891 891 892 890 890 890 888 885
101-110 875 874 871 870 862 859 861 857 859 853
110-113 err1 err1 err1 err1 ( really overcast sunlight gone..clouds)
refill pressure 1125 psi
So, thats where I am at at present. Still have work to do, but it was cheap, I did it myself, and I can hit what I aim at...lots of times now ;D As my Uncle Goosey used to tell me when I was learning to drive..."Get in the middle and go boy".
Motorhead...dude...thank you sir for the information you unselfishly put out here about this gun for us to run with to get a start. Not many guys would do that...especially being a tuner! I can only imagine what one of your tunes must do to one of them. Again...Thanks!
Mr RSTERNE thank you too sir for continued help you give to countless people on this forum in many areas.
I think both of you guys neck's have to hurt carrying around all that stuff in your head! ;)
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Looks like it is coming off regulation @ shot 82ish .... Need to LOWER Regs set pressure @ 100-200#, reduce hammer strike a tad getting back to same velocity. Doing that rifle will shoot under regulation to a lower pressure and when coming off the Reg hammer strike is a tad less as well which should reduce the velocity rise. ;)