GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: oldpro on August 15, 2021, 02:36:07 AM
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does anyone have specs for the male foster fitting?
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For standard 8 mm diameter Foster fitting. Don't know why they leave that 8 mm dimension out of the drawing, below. Female fitting spec at second link below:
(https://image.made-in-china.com/202f0j00guJGKqWRbecH/Air-Gun-Pcp-Charging-Paintball-Air-Rifle-Male-Quick-Disconnector-300-Bar-Airsoft.jpg)
https://airmega.en.made-in-china.com/product/nsHmAjrbbqce/China-OEM-CNC-Manufacturer-of-Quick-Disconnector-Coupling-Filling-Foster-Plug-for-Air-Rifle-High-Pressure-Charging.html (https://airmega.en.made-in-china.com/product/nsHmAjrbbqce/China-OEM-CNC-Manufacturer-of-Quick-Disconnector-Coupling-Filling-Foster-Plug-for-Air-Rifle-High-Pressure-Charging.html)
https://airmega.en.made-in-china.com/productimage/oylJYwrdyMcF-2f1j00qrSRpfZgvLbG/China-Manufacturer-of-Female-Foster-Quick-Connector-to-Male-1-8-BSPP-Fitting-Plug.html (https://airmega.en.made-in-china.com/productimage/oylJYwrdyMcF-2f1j00qrSRpfZgvLbG/China-Manufacturer-of-Female-Foster-Quick-Connector-to-Male-1-8-BSPP-Fitting-Plug.html)
Size - 8 X 8mm, 8mm male to male connector, quick disconnect adaptor:
www.amazon.com/Foster-Paintball-Airsoft-Disconnect-Adaptor/dp/B08952KVN7 (http://www.amazon.com/Foster-Paintball-Airsoft-Disconnect-Adaptor/dp/B08952KVN7)
(https://m.media-amazon.com/images/I/51xe96JBF6L._AC_SL1000_.jpg)
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There are no specs because they are all different from whoever you buy them from.
Read this and weep.
https://airgunguild.com/airgun-tanks-compressors-and-filling/foster-parker-air-venturi-and-various-chinese-fittings/
I write companies asking for specs, and begging them to please come up with specs that all companies use if only for safety’s sake. I usually get no response.
The behavior of all the Airgun companies, HPA fitting makers, that make and use Foster type fittings etc are criminal as far as I can see.
I’ve had a brass / stainless “Foster” fitting fail at 4,000 psi and I’m lucky I didn’t get hurt and that the 4500 psi tank didn’t get damaged. The pressures we use are no joke.
Fascinating to me is that you Travis, a fellow who has actually been in the business of manufacturing high end airguns at two different companies is asking us for Foster Fitting Specifications. Since Wicked Air Rifles, and Jefferson State Raptors used “Foster Fittings”, shouldn’t you have already had the answer to your question?
If I were an Attorney I’d file class action suit against them all, because of the implied compatibility between connectors that are often NOT at all compatible.
Take an 8mm Chinese paintball female connector and mate it to a “Foster”, or “Parker”, or “Quackenbush” , or “FX”, or “Benjamin” etc connector and you have a situation where there’s a good chance that 8mm connector will fail at high pressure and send your fill whip flying at incredible speed that is enough to lose an eye or maybe even cause death.
The industry needs their collective peepees whacked.
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Summary: There are no specs. Also, you should be ashamed for not knowing the specs because you once used ostensibly standard off-the-shelf Foster fittings.
Pfffft.
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Right or wrong I’ve been sanding the male fittings to fit.
Not saying follow my lead but it’s works for me.
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By bringing up the question it brings out how broken the lack of standards are and a reminder for buyers to beware beginners as well as Old Pros. ;D
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Summary: There are no specs. Also, you should be ashamed for not knowing the specs because you once used ostensibly standard off-the-shelf Foster fittings.
Pfffft.
The truth is rather painful isn’t it?
“standard off-the-shelf Foster fittings” is an Oxymoron. Part of the problem is using the brand name “Foster” and applying it to quick connect fittings from myriad other brands even though they are not compatible.
Pardon my bluntness but the truth and reality is essential.
ASTM.org is perhaps an organization that can shed some light.
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From the horse’s mouth:
https://www.zsi-foster.com/mm5/graphics/profile/FOSTER-12MP-PROFILE.pdf (https://www.zsi-foster.com/mm5/graphics/profile/FOSTER-12MP-PROFILE.pdf)
Not a fully dimensioned drawing but it establishes the OD as 0.31” nominal with a 0.005” tolerance.
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This is exactly why I asked the question! What got me going was Manny just got a new AEA gun and the foster wouldn’t seal to the female. So I started measuring a bunch of Fosters and they are all over the place. This is sad to say the least. Thank you Steven for your reply it basically backs up what I found. I’ll bring this up in the meeting at ASTM.
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There are no specs because they are all different from whoever you buy them from.
Read this and weep.
https://airgunguild.com/airgun-tanks-compressors-and-filling/foster-parker-air-venturi-and-various-chinese-fittings/
I write companies asking for specs, and begging them to please come up with specs that all companies use if only for safety’s sake. I usually get no response.
The behavior of all the Airgun companies, HPA fitting makers, that make and use Foster type fittings etc are criminal as far as I can see.
I’ve had a brass / stainless “Foster” fitting fail at 4,000 psi and I’m lucky I didn’t get hurt and that the 4500 psi tank didn’t get damaged. The pressures we use are no joke.
Fascinating to me is that you Travis, a fellow who has actually been in the business of manufacturing high end airguns at two different companies is asking us for Foster Fitting Specifications. Since Wicked Air Rifles, and Jefferson State Raptors used “Foster Fittings”, shouldn’t you have already had the answer to your question?
If I were an Attorney I’d file class action suit against them all, because of the implied compatibility between connectors that are often NOT at all compatible.
Take an 8mm Chinese paintball female connector and mate it to a “Foster”, or “Parker”, or “Quackenbush” , or “FX”, or “Benjamin” etc connector and you have a situation where there’s a good chance that 8mm connector will fail at high pressure and send your fill whip flying at incredible speed that is enough to lose an eye or maybe even cause death.
The industry needs their collective peepees whacked.
What failed on the one you mentioned?
The bore is a critical dimension as well as material. It would be nice to know what these things ‘should’ be but we also should take some responsibility ourselves. We are the ones buying the cheap knockoff brands.
The male interface is only half of what needs to be correct as well.
Dave
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Manny has my AEA. I started making a new fill probe from a Stainless Steel Evanix probe by turning it down.
Plenty of meat on those probes!
When it got to cutting the o-ring grooves deeper my lathe suffered a broken part that I haven't replaced yet.
The probe is the thread on to a male foster adapter to avoid the problem of a bad male end from AEA.
When I tested the Evanix cut down it would blow the o-ring since I need to cut it deeper for the o-rings.
And probably cut it to small in the dimensional as that was when I found my lathe was going bad.
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There are no specs because they are all different from whoever you buy them from.
Read this and weep.
https://airgunguild.com/airgun-tanks-compressors-and-filling/foster-parker-air-venturi-and-various-chinese-fittings/
I write companies asking for specs, and begging them to please come up with specs that all companies use if only for safety’s sake. I usually get no response.
The behavior of all the Airgun companies, HPA fitting makers, that make and use Foster type fittings etc are criminal as far as I can see.
I’ve had a brass / stainless “Foster” fitting fail at 4,000 psi and I’m lucky I didn’t get hurt and that the 4500 psi tank didn’t get damaged. The pressures we use are no joke.
Fascinating to me is that you Travis, a fellow who has actually been in the business of manufacturing high end airguns at two different companies is asking us for Foster Fitting Specifications. Since Wicked Air Rifles, and Jefferson State Raptors used “Foster Fittings”, shouldn’t you have already had the answer to your question?
If I were an Attorney I’d file class action suit against them all, because of the implied compatibility between connectors that are often NOT at all compatible.
Take an 8mm Chinese paintball female connector and mate it to a “Foster”, or “Parker”, or “Quackenbush” , or “FX”, or “Benjamin” etc connector and you have a situation where there’s a good chance that 8mm connector will fail at high pressure and send your fill whip flying at incredible speed that is enough to lose an eye or maybe even cause death.
The industry needs their collective peepees whacked.
What failed on the one you mentioned?
The bore is a critical dimension as well as material. It would be nice to know what these things ‘should’ be but we also should take some responsibility ourselves. We are the ones buying the cheap knockoff brands.
The male interface is only half of what needs to be correct as well.
Dave
The brass portion of the female fitting separated from the stainless portion, sending parts flying. I was standing right next to it when it happened. I almost crapped myself.
This is a fitting that came with my Yong Heng compressor that fills 4500 psi tanks, bottles, and Airguns. They are 8mm fittings.
I’ve also noted that the female fittings come with varying numbers of ball bearings.
Also I’ve noted that I have replaced a number of male fittings than suffer from deformation. They will show ball bearing impressions in the steel.
First order of business is that fittings need to be compatible and have measurement standards on both male and female fittings.
Some companies like FX have oddball long fittings required for the female end as they connect inside of the Airgun. So this means outside measurements need to be standardized also.
Second order of business is the actual pressure rating. I’m willing to bet that many of us are running on the ragged edge of failure, since some of these fittings are Not rated on the fitting or in their packaging if they come in packaging.
If we are filling to 4500 psi, what do you think hoses, and fittings should be rated for? I would think 6,000 psi would be minimum. But perhaps 9,000 psi is more like it. I bet a number of the fittings we all run are rated at 3,000 psi.
I’m very surprised we haven’t seen hundreds of failures and scores of injuries from using underrated and incompatible fittings.
Like I said, the industry is criminal in it’s behavior.
Up next on my list is myriad fill port probe connectors coming from different manufacturers. There is no good reason why these can’t be standardized, with sizes, ratings, and even o-ring sizes.
Why do we put up with $2,000+ Airguns that don’t have have standardized fittings?
Further down my list is the fact we have a variety of threaded hose / fitting connections. 1/4 BSP, 1/4 NSP, Metric, tapered, straight threads, etc. I am gobsmacked at complete lack of standards here.
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Another possible issue with AEA guns is they have a small hole for the HPA exit or the intake on the gun, they are slow to take air in, may also be an issue with trying to use a hand pump. Though slow filling is best IMO.
My AEA Challenger 24" probe is in spec., way better than the China hand pump female connections I have encountered in the past.
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Right or wrong I’ve been sanding the male fittings to fit.
Not saying follow my lead but it’s works for me.
As an experiment I chucked up two make 8mm fittings in my drill press and “machined” them down to fit genuine Foster and Parker female fittings. (Hint, they are different). I was successful with one, and I mangled the second. But because the other dimensions also varied, I threw both in the garbage because I value my fingers, eyes and equipment.
I think it’s a bad idea to sand or file down these fittings.
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Another possible issue with AEA guns is they have a small hole for the HPA exit or the intake on the gun, they are slow to take air in, may also be an issue with trying to use a hand pump. Though slow filling is best IMO.
My AEA Challenger 24" probe is in spec., way better than the China hand pump female connections I have encountered in the past.
AEA’s slow fill issue is the internal check valve design. It’s terrible. A taper head screw with an oring. That threads into place. The best I can tell, the air has to push through the screw threads.
Dave
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Over the years I had way more problems with Fosters then I even had with probes.
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From the horse’s mouth:
https://www.zsi-foster.com/mm5/graphics/profile/FOSTER-12MP-PROFILE.pdf (https://www.zsi-foster.com/mm5/graphics/profile/FOSTER-12MP-PROFILE.pdf)
Not a fully dimensioned drawing but it establishes the OD as 0.31” nominal with a 0.005” tolerance.
i just looked at the "print" It is terrible. Three decimal places is a .005" tolerance. .31" is a .010" tolerance when not called.
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Over the years I had way more problems with Fosters then I even had with probes.
The problem with probes is there are 20+ different probes used across the industry. This needs to be standardized also IMHO
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Having a Foster fitting blow out is inexcusable. At 4500 PSI it would cause a degree of permanent hearing damage for anyone in the room. The fright alone for anyone nearby could cause such a start that they could hurt themselves from sudden body movement.
The fitting that comes flying out has the potential to do damage. The question is how much energy does it carry? A quick calculation suggest that at 4500 PSI a Foster fitting blow-out carries about 9 FPE. This based on an effective "piston" diameter of 5/16", that travels 1/4" under full pressure before venting.
The foster fitting is much heavier than a .177 pellet at that energy level, so would be travelling much slower - not likely to go as deep into flesh as a fast moving pellet. Below, I attempt to quantify the fitting's velocity.
I downloaded the compressed air coupling 3D model shown below from McMaster, at the link provided. The fitting is similar to a Foster fitting and might help ballpark a Foster fitting's mass. Yes, I could design a Foster fitting from the wonky specs posted, but this is a shortcut to a ballpark answer.
After designating the fitting's material as "alloy steel" in Solidworks, SW reports the weight as 0.0344 lb, or 225 Grains.
So, a 225 grain projectile carrying 9 FPE would be travelling at 135 FPS; or 92 MPH. Fast enough to break the skin, should there be bone directly underneath, such as the skull, fingers or shins. The potential for a broken finger or damaged joint would be of concern. That said, if the fitting hit a person in the eye, the risk of permanent blindness would be very significant. Not something I want to be hit by for sure; but nothing like a .45 caliber airgun slug launched from a 34" barrel.
www.mcmaster.com/53445K117/ (http://www.mcmaster.com/53445K117/)
(https://www.gatewaytoairguns.org/GTA/index.php?action=dlattach;topic=190515.0;attach=370507;image)
What also annoys me is PCP airguns that require an odd fitting to mate with a Foster ended pump, where the odd fitting is not included with the airgun, and that fact is not made obvious when you look at the product page. So, added cost and frustration; resulting from a possibly a deliberate omission, because it reduces the apparent price when the purchase decision is made...
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Over the years I had way more problems with Fosters then I even had with probes.
The problem with probes is there are 20+ different probes used across the industry. This needs to be standardized also IMHO
Been saying that for years now,......that would make a huge difference.
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Just to mention.
Probes with Fosters machined onto one end with an added to Foster adpator...are still basically Foster nipples that detach. Have the same size/construction issues as any other Foster fitting.
Would pretty much have to have the probe screwed directly onto the fill hose to avoid that..which might work for you if all your PCP’s took the same probe. Doubt we’ll get makers to agree to standardized probe sizes.
Fosters, even steel ones, can get buggered up just by use. The little lock-bearings in the QD can beat up the locking surface of the Foster. Obviously this wasn’t hard steel, eventually raised a few burrs (little bright spots) that wouldn’t let the QD over the burrs.
(https://live.staticflickr.com/65535/49988311748_5bbb0d9a2b.jpg) (https://flic.kr/p/2jaiavW)WIN_20200609_13_05_36_Pro (https://flic.kr/p/2jaiavW) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Taking apart (cutting open) a couple of QD’s...those little ball locks are hard. Harder than the QD itself, are the same kind of little dents in the ball seats inside the QD...worse with the brass ones.
That would let the QD’s ball locks to kind of “dent” them selves wider apart….and move the lock more towards the outside edge of the Foster.
If you see something like the above picture...change BOTH THE FOSTER AND THE QD.
Hard to get air gun (or any gun) makers to agree to much of anything. Making a unique probe size, so that you have to buy THEIR probe, seems to be part of the profit margin.
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Just to mention.
Probes with Fosters machined onto one end with an added to Foster adpator...are still basically Foster nipples that detach. Have the same size/construction issues as any other Foster fitting.
Would pretty much have to have the probe screwed directly onto the fill hose to avoid that..which might work for you if all your PCP’s took the same probe. Doubt we’ll get makers to agree to standardized probe sizes.
Fosters, even steel ones, can get buggered up just by use. The little lock-bearings in the QD can beat up the locking surface of the Foster. Obviously this wasn’t hard steel, eventually raised a few burrs (little bright spots) that wouldn’t let the QD over the burrs.
(https://live.staticflickr.com/65535/49988311748_5bbb0d9a2b.jpg) (https://flic.kr/p/2jaiavW)WIN_20200609_13_05_36_Pro (https://flic.kr/p/2jaiavW) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Taking apart (cutting open) a couple of QD’s...those little ball locks are hard. Harder than the QD itself, are the same kind of little dents in the ball seats inside the QD...worse with the brass ones.
That would let the QD’s ball locks to kind of “dent” them selves wider apart….and move the lock more towards the outside edge of the Foster.
If you see something like the above picture...change BOTH THE FOSTER AND THE QD.
Hard to get air gun (or any gun) makers to agree to much of anything. Making a unique probe size, so that you have to buy THEIR probe, seems to be part of the profit margin.
Yup. I have a handful of male ”Foster” fittings that look like this. The Air Venturi brand fittings get to this point very quickly.
I think that If the various Airgun forums and groups team up, educate airgunners about these issues, and keep hammering away at the subject we might get traction. Also pointing out the issues when reviewing airguns will again keep the subject hot.
I’ve gotten my best paired male / female fittings from Best Airgun Fittings in England. And that is key. Pair up the best higher pressure rated fittings for fill whips and Airgun fittings also.
Foster and Parker seem to work ok together mix and match but the sizes are different. Not optimal. Then you get into one manufacturer offering a four ball female fitting and another offering a five or six ball fitting. Me thinks more balls are probably better for distribution of stress.
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A different Foster….about the same use (not that I’ve kept strict count over all the years). Better steel would be my guess.
(https://live.staticflickr.com/65535/49988826301_7f5e7d2167.jpg) (https://flic.kr/p/2jakNtx)WIN_20200609_13_05_16_Pro (https://flic.kr/p/2jakNtx) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
Old stuff sometimes works “forever”, even if it’s an odd sized fitting. I just keep using it because it works, not that it’s convenient or stylish.
So rather than a probe adapted to Foster….it's a QD adapted to foster.
(https://live.staticflickr.com/65535/50872120126_975f083d5d.jpg) (https://flic.kr/p/2kvoUXq)DSCN0036 (https://flic.kr/p/2kvoUXq) by Robert Dean (https://www.flickr.com/photos/144930793@N07/), on Flickr
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On my AV Nomad II I have noticed that one end of the fill hose has a connector slightly "looser" than the other. If I use the looser connector on my AEA probe I have to physically hold it in against the fill port hard until it has about 1k psi in the hose in order to be able to let go and let the fill continue. The other, tighter fitting, end I just pop it in and go.
So it looks like not just from the same brand but even on the same hose you can have differences big enough to matter
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thinking it's contact area...that (the last picture) old big-azz quick connect spread the load over a wider area, which limited the "dents", and kept it working "forever" (in PCP terms that would be 18 years).
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@Manny
Can you change the female part on your pump?
I can send you the one from my AV compressor which didn't seem to have a problem.
It's got 6 balls inside.
(So is that REALLY a female if it has 6 balls!)
;D
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@Manny
Can you change the female part on your pump?
I can send you the one from my AV compressor which didn't seem to have a problem.
It's got 6 balls inside.
(So is that REALLY a female if it has 6 balls!)
;D
I did put the Nomad fill hose on the pump to see if it made a difference and it actually was worse,......I have a few female fosters so as soon as I get time I start try them all to see if I find one that seals.
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https://www.amazon.com/gp/product/B08VS21SMN/ref=ewc_pr_img_2?smid=AVXIK6YYZTVVG&psc=1 (https://www.amazon.com/gp/product/B08VS21SMN/ref=ewc_pr_img_2?smid=AVXIK6YYZTVVG&psc=1)
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The fitting on my little-used Chinese pump would not seal with a few of my & friend's fittings. Bought a couple of these and have been happy. Your mileage may vary...
Amazon: Outdoor Guy Paintball Remote Line Stainless Steel Quick Connect Disconnect 1/8 NPT
will not allow me to post direct link.... ???
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Being lazy...not going to do it.
Last China pump came with two QD’s.
Obvious by use, they were different sizes….so they must have expected some variation in Foster nipples.
Just not ready to cut up what is working.
NOTiCE...not automatically blaming the foster nipples.....couod very well be the "slack" ion the quik detach.
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The problem is that the male connector has a straight cone that the balls in the female connector bear against. This means point contact. Point contact means infinite stress. Even if there are 6 balls, that is a tiny contact area - until the male cone either elastically or plastically deforms to increase the contact area.
Permanent plastic deformation occurs when the contact pressure at the ball exceeds the yield strength of the material. It would take very hard material to resist permanent deformation, unless the nominal contact area can be increased.
The simplest way to increase the contact area is to increase the number of locking balls. If the male fitting had a curved surface matching the ball radius, at least there would be line contact, rather than point contact. Of course, that would require a standard size ball... But then, hardened ball bearings are a commodity. You just order them as 2.5 +- 0.01 mm (assumed nominal diameter).
I decided to model fittings to demonstrate point contact VS line contact. The standard fitting has a flat cone, while my proposal is a curved cone. Note that fittings that have seen lots of use, end up with many dimples, approximating a curved cone. I am simply suggesting the locking cone be machined to look like that from the start.
Also, the very edge of the locking cone should have a small fillet so that if the balls create simples, they do not raise sharp burrs right at the edge of the 8 mm OD.
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The problem is that the male connector has a straight cone that the balls in the female connector bear against. This means point contact. Point contact means infinite stress. Even if there are 6 balls, that is a tiny contact area - until the male cone either elastically or plastically deforms to increase the contact area.
Permanent plastic deformation occurs when the contact pressure at the ball exceeds the yield strength of the material. It would take very hard material to resist permanent deformation, unless the nominal contact area can be increased.
The simplest way to increase the contact area is to increase the number of locking balls. If the male fitting had a curved surface matching the ball radius, at least there would be line contact, rather than point contact. Of course, that would require a standard size ball...
I decided to model fittings to demonstrate point contact VS line contact. The standard fitting has a flat cone, while my proposal is a curved cone. Note that fittings that have seen lots of use, end up with many dimples, approximating a curved cone. I am simply suggesting the locking cone be machined to look like that from the start.
Also, the very edge of the locking cone should have a small fillet so that if the balls create simples, they do not raise sharp burrs right at the edge of the 8 mm OD.
Peter
can I use this in the meeting next month?
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can I use this in the meeting next month?
Absolutely, yes, Travis. Anything posted in public now belongs to the public.
I can even email you the 3D CAD assembly file so you can look at it from different angles.
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I run into the same issues with power takeoff shafts and couplers on the farm end of things also, hydraulic fittings.
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Travis,
I sent you an email with the 3D assembly files.
Subject: Foster fitting improvement suggestion (3D assembly model)
I used only four balls in the model, because I wanted the contact points to fall where the problem is most easily understood (easy to increase ball count to 5, 6 or 7 from inside the assembly model). Cluttering the view with more balls would be a distraction, for the purpose of this exercise.
To show you how simple it is to change the ball count from within the SW assembly model, I have added 6 and 7 ball images, below. 7 balls is as many as can reasonably be fit in. 6 may be better, if one took a closer look at all of the mating parts...
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https://www.amazon.com/gp/product/B08VS21SMN/ref=ewc_pr_img_2?smid=AVXIK6YYZTVVG&psc=1 (https://www.amazon.com/gp/product/B08VS21SMN/ref=ewc_pr_img_2?smid=AVXIK6YYZTVVG&psc=1)
Did any of you notice how they made this male and female fitting pack so cheap? By skipping a few details, such as deburring the holes the balls travel in - image below.
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Worst to best Foster fittings so far.
Brass
Soft steel
What I think if bronze (no one left to ask what the alloy was)
Hardened steel.
If you can eyeball steel and tell if it is heat treated hard or soft...you got me beat.
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Travis,
I sent you an email with the 3D assembly files.
Subject: Foster fitting improvement suggestion (3D assembly model)
I used only four balls in the model, because I wanted the contact points to fall where the problem is most easily understood (easy to increase ball count to 5, 6 or 7 from inside the assembly model). Cluttering the view with more balls would be a distraction, for the purpose of this exercise.
To show you how simple it is to change the ball count from within the SW assembly model, I have added 6 and 7 ball images, below. 7 balls is as many as can reasonably be fit in. 6 may be better, if one took a closer look at all of the mating parts...
Thanks Peter
When I meet with the ASTM F15.06 Ill bring samples and explain the condition across the Industry and the lack of a common sizing
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If you can eyeball steel and tell if it is heat treated hard or soft...you got me beat.
I can eyeball how fast a file cuts it (in a non-critical area) :)
I think the run-of-the-mill Foster fitting has a hardness around that of mild steel.
How hard should the body of the male and female fittings be? Hard enough to resist indentation, but not to the point of being brittle. I would vote for a spring temper, with a hardness of about 44 Rc. The thing is that heat treatment after machining adds a huge amount of cost. Unless it is done right, the parts can distort; or be left brittle. Machining from prehardened and pre-tempered steel will slow the process down and cost even more...
There is about 350 lb trying to spit out an 8 mm Foster fitting at 4500 PSI (maybe less, depending on the sealing diameter of the O-ring). Think what the contact pressure is, if each little ball has to bear 50+ lb. Double the number of balls...
The amazon fitting above stated that the material is 304 Stainless. That is nasty to machine because it work hardens drastically. However, that could be used to advantage, if a surface rolling operation is included. This could be applied selectively to lock-up surfaces, very quickly.
304 SS can only be annealed by heating; not hardened.
My idea of shaping the ball contact seat on the male fitting to match the ball radius could easily be tested. Just modify a stock part that has already been dented. If will require a form tool, or a CNC machine to do it well. If that reduces dimpling it may be an easy improvement when implemented in future products, even if not a complete victory.
Those who chamber and crown their barrels successfully by hand, would have the skill to run a dimpled male Foster fitting in a drill-press, and use a round file of appraise diameter to dress down the raised metal, following the shape already impressed by the balls as a guide. As long as you are not flaking off plating, there is nothing inherently bad about the idea (one member above spoke about dressing the dimples already).
You can test the strength of a modified joint by hanging two people from it, if you have doubts. (If you bend it, throw it away). If the idea of modifying HPA fittings scares you, don't do it. 4500 PSI may be "a lot" of pressure; but 350 lb is not a lot of force for adequately sized metal parts to carry. The problem is not the "size" of the metal parts, but the lack of size of the contact area at the balls...