GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: BigBird on September 19, 2021, 02:01:33 AM
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I am working on my .44 before hunting season and was thinking about increasing the transfer port. I would use a press fit brass tube instead of orings. I was looking at brass PB cases. I'm sure I could probably find the right size. Too thin and too low a yield? I think it was 3/8 OD TP and a 3600 PSI peak fill. I was just thinking this would be an easy way to increase the flow without drilling out the valve to 1/2" Right now the TP is .281" ID.
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If the TP is too thin, and the air can get around the outside of it, it can collapse inwards.... Likewise, if unsupported on the outside, it can blow outwards....
Bob
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If the TP is too thin, and the air can get around the outside of it, it can collapse inwards.... Likewise, if unsupported on the outside, it can blow outwards....
Bob
Yes. The shape is important. If the TP is convex and TP bushing or tube is belled it may be hard getting it out without ruining it. I may not even try doing this. ::)
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i make matching plunge cuts in the tube / valve and the breech.. Then make a nylon TP , fairly thin wall that fits the connection.. As its fired , it generally seals better and better due to the flexibility of the nylon expanding torward the walls.. The tp is completely captive , so it has nowhere to blow out
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i make matching plunge cuts in the tube / valve and the breech.. Then make a nylon TP , fairly thin wall that fits the connection.. As its fired , it generally seals better and better due to the flexibility of the nylon expanding torward the walls.. The tp is completely captive , so it has nowhere to blow out
I think my TP shows a little on sides. The tensile strength of Nylon is only about 8500 psi. I think for a 5/16 TP I would need about 35,000 psi. Nylon is tough stuff though. I used to have a PB with internals made of nylon.
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??” I would need about 35,000 psi”??
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??” I would need about 35,000 psi”??
Sorry, that was for tensile strength. I was using an OD of .375 and a .032 wall for the calculation. That works out to be about 35,000 psi. Brass would work. It would be better if there were no unsupported areas.
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Thinwalled DelrinTP....
(https://hosting.photobucket.com/albums/oo221/rsterne/BRod Project/.highres/Collapsed Transfer Port_zpsdpiy5f5h.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/rsterne/a/0a8cc990-1df6-4f18-aa0b-1ed96c028474/p/29c7ceee-4acb-4153-a6e8-338e695bb47c)
Air pressure found its way to the outside and collapsed it....
Bob
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I've made several of the transfer ports from delrin however never got the wall on them thin enough to let air around the outside of them. I do prefer brass myself.
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BE gentle. It's awful handiwork. I know. Stuff slipped when end milling.
I took out the TP to find orings busted. I polished up the inside of the TP (you can see the awful scratches there) and hollow probe. I cut the oring grooves a little deeper which seemed to help. I turned down the front of the probe to fit the 310 gr without jamming the bolt. Tested out at 3000psi with a 306 and got 333 fpe. Looking to cast some new HP ones sometime for a little more fps.
I may wait on the thin walled TP (I made 2 extra but will have to wait). I would have to do something drastic to open up the top port into the barrel. Also if I get 333 fpe at and 289 fpe at 2500psi I am starting a cliff which hopefully plateaus at 3600psi (edited). Somehow I may have reduced my shot count to 4 usable. I know this has nothing to do with a thin walled TP.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8150)
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some serious power there.
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some serious power there.
Thanks Rob. Using a really heavy bullet is fun for numbers. It would be nice to have some laser beam trajectory though. I have a new mold pin that will be a little lighter, maybe 260 gr with the same ogive. Hoping it will work. I really want to get a deer with it.
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Great project! Thanks for sharing. Could you possibly use green loctite to secure a bushing to enable better o-ring seal? Or perhaps an extended boss protruding? Just thinking.
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Great project! Thanks for sharing. Could you possibly use green loctite to secure a bushing to enable better o-ring seal? Or perhaps an extended boss protruding? Just thinking.
I was thinking create some type of edge or roughed up area and melt some delrin on it or sink it in delrin to make a sealing surface. I press fit my brass ones in but based on a red marker there were still gaps (sloppy hole).
If the brass was thin enough it might expand enough to seal although it would have to do it at the fore and aft only and also not collapse like Bob's Delrin one. Even a brass one with concave entrance could collapse if it yields enough to expand.
The steel one pictured even with orings busted made 320 FPE because it hits the top and bottom and seals metal to metal. Took a while to get the proper fit.
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Is it possible to do a flat face o-ring seal? https://usmegastore.com/product/dixon-valve-fs6400-10-10-zinc-plated-steel-1-14-male-flat-face-x-7-8-14-male-sae-o-ring-connector?utm_source=bing&utm_medium=cpc&utm_campaign=bing_shopping_ads&msclkid=899157b1484f109e284d36fc6d07eb64 (https://usmegastore.com/product/dixon-valve-fs6400-10-10-zinc-plated-steel-1-14-male-flat-face-x-7-8-14-male-sae-o-ring-connector?utm_source=bing&utm_medium=cpc&utm_campaign=bing_shopping_ads&msclkid=899157b1484f109e284d36fc6d07eb64)
You would need a method to hold the parts together, (chamber & barrel).
You do not need the outside retaining diameter as the counterbore / recess serves this purpose.
And do you have any piloted counterbores to improve on the roundness of the recess?
https://www.msdiscounttool.com/catalog/product_info.php?csv=gg&products_id=98810&msclkid=404ad195a6cc19d0d4d7b0d881f4a797&utm_source=bing&utm_medium=cpc&utm_campaign= (https://www.msdiscounttool.com/catalog/product_info.php?csv=gg&products_id=98810&msclkid=404ad195a6cc19d0d4d7b0d881f4a797&utm_source=bing&utm_medium=cpc&utm_campaign=)**LP%20Shop%20-%20Drills%20%26%20Screwdrivers%20(2)%20-%20%2410%2B&utm_term=4586956356259005&utm_content=98810%20%7C%20M6%20HSS%203F%20Solid%20Pilot%20Counterbore%20%7C%20%2419.92
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Is it possible to do a flat face o-ring seal? https://usmegastore.com/product/dixon-valve-fs6400-10-10-zinc-plated-steel-1-14-male-flat-face-x-7-8-14-male-sae-o-ring-connector?utm_source=bing&utm_medium=cpc&utm_campaign=bing_shopping_ads&msclkid=899157b1484f109e284d36fc6d07eb64 (https://usmegastore.com/product/dixon-valve-fs6400-10-10-zinc-plated-steel-1-14-male-flat-face-x-7-8-14-male-sae-o-ring-connector?utm_source=bing&utm_medium=cpc&utm_campaign=bing_shopping_ads&msclkid=899157b1484f109e284d36fc6d07eb64)
You would need a method to hold the parts together, (chamber & barrel).
You do not need the outside retaining diameter as the counterbore / recess serves this purpose.
And do you have any piloted counterbores to improve on the roundness of the recess?
https://www.msdiscounttool.com/catalog/product_info.php?csv=gg&products_id=98810&msclkid=404ad195a6cc19d0d4d7b0d881f4a797&utm_source=bing&utm_medium=cpc&utm_campaign= (https://www.msdiscounttool.com/catalog/product_info.php?csv=gg&products_id=98810&msclkid=404ad195a6cc19d0d4d7b0d881f4a797&utm_source=bing&utm_medium=cpc&utm_campaign=)**LP%20Shop%20-%20Drills%20%26%20Screwdrivers%20(2)%20-%20%2410%2B&utm_term=4586956356259005&utm_content=98810%20%7C%20M6%20HSS%203F%20Solid%20Pilot%20Counterbore%20%7C%20%2419.92
It would seal well against a flat surface but it is bigger in diameter compared to a thin walled TP because of the material holding it and threads.
Outside orings work fine and you can get them with very little dead space by placing the oring right on the end. As long as it is square and no air space to let the oring get sucked through your barrel it works. The other end of my TP is like that. This may be a different TP altogether. It was .375 and now it is 10mm ::)
In this configuration,, the oring gets blasted by air and gets pushed up and against the sides of the ID of the port sealing it. You don't need threads on the TP (bushing) when you have a breech screw similar to the 4-48 SHCS on a Crosman.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8154)
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that tp made completely from delrin and press fit into the valve would work , and would seal. and id bet it wont blow out either
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that tp made completely from delrin and press fit into the valve would work , and would seal. and id bet it wont blow out either
That's so tempting because it would be so easy to make. Bevel the inside a little? What about Peek?
I tested this metal oring out at 3500 psi and it was much lower 612 fps with the 306 gr. I may have "leaned on it too much" (Wyoman) and fallen off a cliff. Maybe I'll use lighter bullets and try 3200psi and be OK with that. It's OK for a hunter who hits what he is aiming at his first shot but...
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nylon , peek , delrin ,. nylon would be best since its more malleable( e.g its better suited to take the iregular hole shape
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Ok. I shot a lot with a napkin (confetti) and finally found out my problem with my existing TP (the oring one). It had some sharp edges where the oring was that I didn't break. I polished up the TP hole too. The whole TP system wasn't made real well. I should've milled a little deeper. You be surprised what you can make in 30 minutes and get it to work but this isn't one of them.
So despite the large leak it still sealed enough for 293 FPE (245 gr SWC at 734 fps on 3000psi). After the fix I could use the napkin to blow my nose effectively. So after it did 306 FPE (750 fps). Not huge but I don't like it messing up my hair either (interdigital).
But Rob I had my peek out ready to make a TP. It may still fail and then I will.
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Yeah it didn't work. You can see my indicator paint tells no lies.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8163)
Rob, I took your advice. I made a Peek TP bushing. .408 od, back to .281 ID hole (for safety). Maybe I can go bigger?
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8164)
306 gr, 691 fps = 325 fpe,
306 gr, 649 fps = 286 fpe,
then a 245 gr to check napkin 602 fps = 197 fpe napkin survived nicely
So I like the sealing. The FPE will be good for hunting. I have to take it apart and check it just to make sure it is working. I guess I could sand the inside a little for a few thousandths.
I will still go up to 3200 psi or 3300 psi so I can get more of a bell and an extra shot.
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nice, as long as its sealing .. im betting you can go a few thou more with peek
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Along the same topic, I made a delrin TP for my 2260 .37 smooth bore. It has a little thicker walls so I am not concerned with it deforming. Works great. I hope to implement them more often because they both seal and "transfer". It did increase the power a little bit. Now I just need to figure out how to make it accurate. Maybe rifling??
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yea, when the thin walled plastic TPS are in a counterbore , they reall have nowhere to go.. effective and disposable
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I wanted to try this at some point and I'm not even sure this whole valve setup will even work so this TP is of the same experimental theme.
Its all the 1" tube stuff that bent, went in sideways and I "reworked" as a sick personal challenge. I have fun creating problems and fixing them. I know, it shows but I get to and through things instead of hum and haw.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8219)
Anyhow, this TP is a 8mm or maybe .308, a .358, speaking of the brass being repurposed from duds (split cases, berdan primed, used too much lube, etc). I plan on using the extractor groove for an oring slot. The ID will be quite large but I am seeing if I can open about a .40 throat. I failed on this balanced valve and I am still working up to a .46.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8220)
Yeah, there was a lot of chatter on the cut as I couldn't use my vice. So I may need to do a little polishing. With a 12mm hole I can always use a 1/2 peek TP if it doesnt work real well. However I am planning on bottoming the case head and press fitting the top into a barrel.
If this works, TP material abounds and will already have a semi workable oring hole (may need squaring).
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unrelated note , it appears your chatter issue is rpm related , not rigidity.. try doing the next hole at the lowest setting you have , 80-300 rpm.. you may ened up with a very smooth hole.or drill undersize , then use a reamer at low rpm , theyre cheap as dirt nowadays
https://www.amazon.com/uxcell-Straight-Chucking-Cutting-Machine/dp/B07QNHLWSQ/ref=sr_1_1_sspa?keywords=12mm+reamer&qid=1637165573&s=industrial&sr=1-1-spons&psc=1&smid=A1THAZDOWP300U&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVlc4TDVGMVFZSE1RJmVuY3J5cHRlZElkPUEwMDI3ODA4MzM1S0YyT0cxTzRGUyZlbmNyeXB0ZWRBZElkPUEwMDg0MTM4MzBMWFVRRUNEQjU4UiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU= (https://www.amazon.com/uxcell-Straight-Chucking-Cutting-Machine/dp/B07QNHLWSQ/ref=sr_1_1_sspa?keywords=12mm+reamer&qid=1637165573&s=industrial&sr=1-1-spons&psc=1&smid=A1THAZDOWP300U&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVlc4TDVGMVFZSE1RJmVuY3J5cHRlZElkPUEwMDI3ODA4MzM1S0YyT0cxTzRGUyZlbmNyeXB0ZWRBZElkPUEwMDg0MTM4MzBMWFVRRUNEQjU4UiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=)
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unrelated note , it appears your chatter issue is rpm related , not rigidity.. try doing the next hole at the lowest setting you have , 80-300 rpm.. you may ened up with a very smooth hole.or drill undersize , then use a reamer at low rpm , theyre cheap as dirt nowadays
https://www.amazon.com/uxcell-Straight-Chucking-Cutting-Machine/dp/B07QNHLWSQ/ref=sr_1_1_sspa?keywords=12mm+reamer&qid=1637165573&s=industrial&sr=1-1-spons&psc=1&smid=A1THAZDOWP300U&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVlc4TDVGMVFZSE1RJmVuY3J5cHRlZElkPUEwMDI3ODA4MzM1S0YyT0cxTzRGUyZlbmNyeXB0ZWRBZElkPUEwMDg0MTM4MzBMWFVRRUNEQjU4UiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU= (https://www.amazon.com/uxcell-Straight-Chucking-Cutting-Machine/dp/B07QNHLWSQ/ref=sr_1_1_sspa?keywords=12mm+reamer&qid=1637165573&s=industrial&sr=1-1-spons&psc=1&smid=A1THAZDOWP300U&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVlc4TDVGMVFZSE1RJmVuY3J5cHRlZElkPUEwMDI3ODA4MzM1S0YyT0cxTzRGUyZlbmNyeXB0ZWRBZElkPUEwMDg0MTM4MzBMWFVRRUNEQjU4UiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=)
Thanks Rob. I have limited gearing on my $39.99 HF drill press. I need a different motor like the sewing machine motor on my lathe.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8222)
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=8223)
Cross pin is a little snug due to the TP hole in the tube. Its a good fit and I like it so far. I guess I couldve used a 12mm drill and a chucking reamer for this too. I don't have metric drill bits except step drills.
Just looking forward to getting everything in for testing. Probably need to do a peek TP to set it in with hydraulic pressure.