Author Topic: XS60C PCP Repeater project (Read 455440 times))

rsterne · « **Reply #940 on:** February 18, 2015, 01:05:39 AM »

Nah, I'm a boring kinda guy.... I haven't access to powdercoating or anodizing.... and I hate bedliner, much prefer wood.... The stock actually looks great, I matched the stain (walnut, wiped off at the right time).... I'll waterproof the modified areas with a bit of oil and it's good to go.... All my guns end up with unfinished aluminum bits on them, it's kinda my trademark.... Comes from being lazy and no other choice anyway.... *LOL*....

I'm topping up my tanks with the Shoebox today and tomorrow, when my air supply is back up I'll probably try some different hammer springs.... just to see if I can improve the efficiency.... Did you notice the barrel band is done?.... It uses a # 113 O-ring of 70D in a hole just over 3/4" and ends up real tight on the barrel.... Locates it well but allows the gun to move under it with temperature and pressure changes.... I like that system, and my tank blocks are made for it.... The Grizzly looks great on a BiPod, BTW....

Bob

Kailua · « **Reply #941 on:** February 18, 2015, 02:17:53 AM »

Quote from: stalwart on February 18, 2015, 12:57:37 AM

Quote from: Kailua on February 18, 2015, 12:37:16 AM
Thanks for taking the time to share every step of the process. Now I'm just waiting on Eric.
Tick... tock...

I haven't been taking deposits on new work, as I'm kinda buried in non-AG matters right now... and slowly moving SA into a bigger space.

This doesn't mean we can't start planning something... email me with your thoughts. I'm making progress here... there's a light at the end of the tunnel, I'm just hoping it isn't an oncoming headlight.

By no means in a rush to see your finish product. Its just a hobby that should be enjoyed with no time lines. I just appreciate your folks for taking the time to share your projects.

stalwart · « **Reply #942 on:** February 18, 2015, 02:58:03 AM »

The bear is loose!

http://www.airgunhome.com/agforum/viewtopic.php?t=10278

http://www.airgunforum.ca/forums/topic66732.html

RMM · « **Reply #943 on:** February 18, 2015, 10:59:18 AM »

She's a beauty. My hat is off to the two of you..

RMM · « **Reply #944 on:** February 18, 2015, 02:39:30 PM »

Quote from: rsterne on February 17, 2015, 11:29:11 PM

Here is the finished result....

This has been a really fun and satisfying project, from conception nearly a year ago to being able to shoot it this week.... I'm delighted with the way it turned out....

Bob

What did you use and how many to fasten your reverse block to the plenum??

rsterne · « **Reply #945 on:** February 18, 2015, 04:00:56 PM »

Three 10-32 low profile, high tensile screws with the heads taking the load in the tube.... similar to a Disco valve, but wayyyyy better screws.... Lloyd figures they are easily good for 3500 psi with a 4:1 safety margin, the tube would go bang by then.... When he tested the screws, they didn't shear, they peeled open the pockets in the tube.... Thread and Video in the PCP Gate a while back.... I use this system all the time, my Hayabusa uses it in a 1" CrMoly tube at 3000 psi.... I've tested it at 4000 psi in a 1.125" OD CrMoly tube and the pockets in the tube (and the screws) look like new.... although I wouldn't recommend pushing them that far, the safety margin on the tube pockets is just over 2:1.... just out of fatigue range....

Bob

RMM · « **Reply #946 on:** February 18, 2015, 10:02:20 PM »

Quote from: rsterne on February 18, 2015, 04:00:56 PM

Three 10-32 low profile, high tensile screws with the heads taking the load in the tube.... similar to a Disco valve, but wayyyyy better screws.... Lloyd figures they are easily good for 3500 psi with a 4:1 safety margin, the tube would go bang by then.... When he tested the screws, they didn't shear, they peeled open the pockets in the tube.... Thread and Video in the PCP Gate a while back.... I use this system all the time, my Hayabusa uses it in a 1" CrMoly tube at 3000 psi.... I've tested it at 4000 psi in a 1.125" OD CrMoly tube and the pockets in the tube (and the screws) look like new.... although I wouldn't recommend pushing them that far, the safety margin on the tube pockets is just over 2:1.... just out of fatigue range....

Bob

Thanks Bob.

I've been having a ball machining and remachining parts (good practice for a newbie), design changes etal on my Bobcat and I'm throwing around the idea of going away from the 22mm X 1mm nut and going to your system of retention (I have everything needed). Seeings my barrel is fixed and above plenum TDC and the reverse tank is below tube BDC I can not install a screw @ TDC or BDC but can @ 90° from either then the other two screws 120° from there but I just may do that. But I find these decisions to be a great part of the fun.

rsterne · « **Reply #947 on:** February 19, 2015, 12:03:00 AM »

So screws at 1, 5, and 9 o-clock?.... perfect !!!.... If the 1 and 5 are too close to the barrel / tube, you can go with 1:30, 4:30 and 9 as well.... or even 4 screws at 90* to each other on the 45's.... Just make sure you have enough room for the 1/8" air passage inside the O-ring and missing all the screw holes with enough meat between everything....

Bob

RMM · « **Reply #948 on:** February 19, 2015, 10:32:47 AM »

Quote from: rsterne on February 19, 2015, 12:03:00 AM

So screws at 1, 5, and 9 o-clock?.... perfect !!!.... If the 1 and 5 are too close to the barrel / tube, you can go with 1:30, 4:30 and 9 as well.... or even 4 screws at 90* to each other on the 45's.... Just make sure you have enough room for the 1/8" air passage inside the O-ring and missing all the screw holes with enough meat between everything....

Bob

Yes to 1, 5, and 9 but I'll also check screw accessibility with 4 screws. This will be another good project for practice.

rsterne · « **Reply #949 on:** February 19, 2015, 01:13:57 PM »

If 1 and 5 o-clock will work, 1:30 and 4:30 are obviously OK.... Check the room for the 1/8" air passage, you don't want a nasty surprise.... I don't think there is room with four #10 screws, buy maybe with #8s.... Three I have no idea....

Bob

stalwart · « **Reply #950 on:** February 19, 2015, 04:29:53 PM »

Guys, some good news... Lloyd (airgunlab) is willing to make up custom double tube kits for me, for the 60s. His barrel band will not fit them, but I have already figured out a nice R mount. It will be stout, and clean.

He does very nice work, and is easy to work with... I'll have something to show you all, very soon.

It just keeps getting better, no?

RMM · « **Reply #951 on:** February 19, 2015, 08:19:36 PM »

Quote from: stalwart on February 19, 2015, 04:29:53 PM

Guys, some good news... Lloyd (airgunlab) is willing to make up custom double tube kits for me, for the 60s. His barrel band will not fit them, but I have already figured out a nice R mount. It will be stout, and clean.

He does very nice work, and is easy to work with... I'll have something to show you all, very soon.

It just keeps getting better, no?

YES!!!!

rsterne · « **Reply #952 on:** February 19, 2015, 08:43:45 PM »

Perfect setup for an unregulated XS-60c with lots of power that needs lots of air at 3000 psi.... If we assume about the same total volume as my Disco Double (250cc), and since we know that the valve in the Grizzly breathes just as well and we have enough hammer strike to handle it, we can expect similar performance to my DD.... Here are the "best" tunes with that gun, with pellets and bullets, in .25, .30, and .357 cal....

I see no reason that a double tube XS-60c with the Grizzly valve and hammer, running at 3000 psi, could not duplicate these strings....

Bob

stalwart · « **Reply #953 on:** February 20, 2015, 07:56:06 AM »

What does that Disco weigh?

I ask because the DD weighs in at 6lbs 3oz with the supplied stock, but the weight of the Blaster might be more help than hindrance. For hunting, the balance can sometimes be far more important than total weight, if within reason...

Where does your gun balance?

rsterne · « **Reply #954 on:** February 20, 2015, 12:33:57 PM »

The DD Repeater with the Blaster stock balances in the middle of the swell in the foregrip, I find that very comfortable.... It weighs exactly 8 lbs. as shown below....

Bob

moorepower · « **Reply #955 on:** February 20, 2015, 05:11:15 PM »

Is there a reason 2, 1/4" screws can't be used, or is the loading on the tube the reason for more, smaller screws?

rsterne · « **Reply #956 on:** February 20, 2015, 07:48:25 PM »

Two 1/4" screws have plenty of shear strength, but slightly less area for bearing load in the tube than three 10-32s.... still enough, depending on the tube material and pressure, it just changes the safety margin....

I spend the last couple of days repairing my ShoeBox, one of the sprockets on the jackshaft had come loose and the setscrew wore the shaft so I had to make a new one, and then while I had it apart I replaced ALL the O-ring, something I have never done before (not all of them).... I figured it was time, it has over 500 hours on it.... Then I had to refill my tanks, and got back to testing today.... I tried a couple of hammer springs made from 0.055" wire instead of the 0.051", which meant that they went from a slight preload to negative preload (ie they were rattling around loose when uncocked).... This often improves the efficiency by reducing or eliminating hammer bounce, and I wasn't disappointed.... I tried a 3" one, and the adjuster was right at the outer end of it's travel, so I replaced it with an identical spring that was only 2.5" long, which put the adjuster back in the middle of it's travel.... It is quite possible that with that spring, at 3000 psi, I might run out of travel on the spring, but I didn't care as this gun will always be on the regulator from now on, it's 3000 psi testing days are over.... I didn't bother running a complete set of preload curves, as I knew from previous experience that the dwell, and hence the velocity, was the critical thing to find the knee of the curve, so I just played with the preload until I got close to the velocities I had with the original spring, and then fine tuned it to reduce the shot count and increase the power until I got a full two magazines from a 3000 psi fill with the Daystate 49.4 gr. pellets.... I actually ended up with 15 shots averaging 98 FPE, with an ES of only 11 fps, and a big increase in efficiency to 1.10 FPE/CI.... At that setting the 44.8g r. JSBs were a little too close to 1000 fps for my liking, and I only got 13 shots, so I backed the preload down 1/2 turn for those, and got 18 shots averaging 94 FPE at 1.16 FPE/CI.... I could get the 15ish shots I want at the 1/4 turn in between at about 95-96 FPE, but never bothered.... Here are the shot strings....

I then locked up the hammer spring preload, put the action in the stock, and shot it that way for the first time.... I did two 5-shot groups, as below....

Now this was only inside my shop at 20', but those are pellets sitting in the holes, and the top one (the Daystates) met the FWB test, you could hold the target vertically and the pellet wouldn't fall out of the hole.... Any time I have a gun that will do that, even at close range, for a 5-shot group, I know I've got a shooter on my hands....

Bob

stalwart · « **Reply #957 on:** February 21, 2015, 12:23:03 PM »

Quote from: rsterne on February 20, 2015, 12:33:57 PM

The DD Repeater with the Blaster stock balances in the middle of the swell in the foregrip, I find that very comfortable.... It weighs exactly 8 lbs. as shown below....

Bob

I would too... that is precisely where I like it. Is the Carnivore (9.3lbs) considered porky, or is that a common weight range?

Would it be easy to space the DD tubes out 2mm? If so, I could fit nearly 3.5" more tube under a 60.

FWB, huh? Until I came to GTA, I would not have thought that possible... Kudos, Bob.

rsterne · « **Reply #958 on:** February 21, 2015, 01:50:15 PM »

IMO, the Carnivore is wayyyyyyyyyyyyyy too heavy, I dislike the BT-65 platform (which is all it is), that is why I own an AT-44S Long.... Even so, with a 6-18X scope, mounts, and a folding BiPod it tips the scales at 10 lbs., so it's only my bench gun....

I don't think that would be an issue at all, but it would require a longer front connector between the tubes from Lloyd, so you would have to ask him about that.... He could also program the CNC to make a barrel band with the correct spacing for all three holes, that should be a simple task.... can't hurt to ask.... On the other hand, a gauge under (or on the side of) the receiver might be a good place to mount it, IMO you really need one on the gun, be it regulated or not.... I'm not a fan of counting shots, and not knowing if my gun leaked down since the last time I used it or not.... You could incorporate a gauge block into a front valve half easy enough.... there is enough room for the conical valve spring, against a 1/2" shoulder, and then the forward section with a 3/8" ID stopping flush with the front of the receiver and the gauge mounted in that, either on the side or bottom.... Each valve front would have to be made for the valve rear to get the thread "clocking" right.... but on the other hand, you don't need to use compression of the valve O-ring to get it to seal, an O-ring in a loose groove works just as well.... I have forgotten to tighten the front valve half more than once without leaks, and I did a QB79 where I just used a ring of threads for a front valve half, glued on to form a conventional O-ring groove with no issues.... Or, you could use a separate gauge block and avoid the clocking issues, but that needs two more O-rings....

I never heard of the Feinwerkbau test until about 3 years ago, and I have only done it, inside, with a few guns.... This is the only time I have seen it with a .30 cal.... so I guess that CF sleeved 1/2" TJ's really does work the way Tim showed it could at the Extreme Bench Rest Contest.... I'm PUMPED !!!

Bob

moorepower · « **Reply #959 on:** February 21, 2015, 03:22:32 PM »

I can't wait to see this thing shoot at 50-100 yds.

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XS60C PCP Repeater project

Author Topic: XS60C PCP Repeater project (Read 455440 times))