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PostPosted: Mon Apr 27, 2015 1:57 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Last week one evening I was pumping up my Brocock Atomic carbine after some practice when suddenly the QD fitting connecting my Gehmann FX pump to the rifle QD'd more suddenly than the usual manual release at about 2,200psi with a very loud bang. It was like a .22LR pistol going off in my workshop. Seriously loud, ears ringing for a bit loud. After reassuring my wife that I was okay I checked over the fitting and hose, found no obvious problems, and tried attaching and pumping again. Pffft Pffft Pffft was all I got for my pumping efforts. Obvious leaking at the Foster nipple, no seal at all. So I looked inside, and could see nothing but stainless steel. Dismantled the QD thing and cleaned the spring, bearings, whatever, put it back together and tried again. Still nothing. So I figured there must have been a seal in there of some sort to press against the conical part and that the seal must have been an O-ring which finally got tired after several years of use. So digging through my parts bins I found an O-ring which fit the 1/4" diameter recess and gave it a try. And it worked!

Until Sunday at the Mission HFT gathering. It filled the HiPAC on my Crosman carbine just fine, but when I went to refill the Atomic for my son to carry on after the sighting/plinking session in preparation for his first match it just wouldn't seal. I didn't have time to mess with it much, but luckily one of the guys had a tank with a fitting which did seal and got the Atomic up to 2,700psi, enough to get my boy through the short match. I fiddled some more afterwards trying to cut a second 1/4" O-ring in half and putting that under the intact O-ring, but that was too thick and wouldn't let the QD close all the way. It was okay for the day as my son was done shooting and busy with his Dragon Quest 9 on the Nintendo...

So when I got home last evening I made a series of different thickness seals out of 90 durometer urethane rod, all 1/4" outside diameter, but varying in thickness from 0.075" to 0.085", that last, thickest one finally working. Just. The initial couple of pumps into the Atomic still hiss a bit but then it 'catches' and fills fine to 3,000psi. The O-ring I had been trying, which worked just fine on the HiPAC, is 0.070" thick. The new urethane seal would NOT close on the HiPAC at all, not even close. So obviously a difference in length of the two fill nipples, supposedly built to the same Foster standard. I never did find the blown-out seal from the QD, so don't know for certain, but suspect that it was a slightly fatter O-ring which could squash enough for the HiPAC to fit while still being thick enough for a weaker but successful seal on the Atomic, though eventually blowing apart due to the lack of adequate compression and no doubt considerable stretching fatigue of all that pressure distorting it to conform to the fitting many hundreds of times.

Doing some research after getting this to work on the Atomic I found that 'Foster' can mean a number of different things, but that apparently there is considerable room for variations in dimension within the 'standard.' That's frustrating. But at least I had something to work with; I know that there are no complaints online (that I could find anyway) regarding Brocock airguns having ill-fitting Foster nipples. So I decided to shave down the tip of the HiPAC so that the two matched. I used a caliper on both, and found that the HiPAC nipple was 0.0195" longer. Not wanting to go too far and create a new problem I plugged the nipple with plastic and filed it down by just 0.016", then polished lightly after using a small diamond file to put a slight bevel all around the edge and a countersink to bevel the inside edge. Pulled out the plug and used a powerful magnet to remove any remaining steel dust. Tested it, and it's a very snug fit into the QD female fitting I bought from BestFittings in the UK but it does work fine. I may shave it slightly further if the added effort to disconnect it proves too annoying.

So it seems this is primarily one more problem with my HiPAC. The last one. I've fixed everything else about it which didn't quite work, which included leaking at the extension threads, leaking at the fill poppet, and leaking at the valve seal, as well as some sort of red-brown paste crud filling the extension tube. Glad to have the pump working on both airguns again. The urethane has proven to make an excellent seal replacement in the HiPAC fill poppet, performing flawlessly where the original tiny O-ring blew out sideways after a couple of dozen fills. So this perfectly fitted seal on the pump head ought to last a very long time. But if it wears out, or if I decide to get fancy and make a better one (with an even sharper tool on the lathe - urethane is NOT fun to turn as it tends to bend in such small dimensions; I used a razor knife to part off while turning the chuck manually as no parting tool would work), I'd probably attempt a bevelled outside edge and countersunk bore on the exposed face to lend a bit more compression to the seal, accommodating slight variance in nipple depth better, and perhaps going as deep as 0.090" so there's better contact on the Atomic nipple. Here's the 0.085" thick x 0.25" diameter seal shown by itself and installed. The bore measures 0.11" but I actually used a sharp 0.125" twist bit; the urethane stretched to accommodate the bit as expected, leaving a nicely smooth under-sized hole.

Image

Image


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PostPosted: Mon Apr 27, 2015 7:31 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Minor edit, but the forum won't let me edit the initial post: I said 90 durometer urethane rod, but after digging into my eBay history I found that it's actually 95 durometer. Not a huge difference but perhaps important to someone seeking to make their own seals.


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PostPosted: Mon Apr 27, 2015 8:34 pm 
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Joined: Sun May 04, 2014 1:56 pm
Posts: 215
Location: British Columbia
I had the same thing happen once. Here's what I did to fix the problem,

Step 1. Remove Foster Fitting
Step 2. Drive to Greenline fittings (this step could be replaced with "search internet")
Step 3. Give man $3 for replacement
Step 4. Reinstall fitting.

Granted not as creative as your solution but I don't have as much time as some of the people on this forum it seems.


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PostPosted: Mon Apr 27, 2015 8:54 pm 
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Joined: Sat Feb 28, 2009 12:28 pm
Posts: 662
ratdoctor wrote:
I had the same thing happen once. Here's what I did to fix the problem,

Step 1. Remove Foster Fitting
Step 2. Drive to Greenline fittings (this step could be replaced with "search internet")
Step 3. Give man $3 for replacement
Step 4. Reinstall fitting.

Granted not as creative as your solution but I don't have as much time as some of the people on this forum it seems.


X2 ....but you do what you have to ..kelly


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PostPosted: Mon Apr 27, 2015 9:27 pm 
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Joined: Sun Jul 15, 2012 10:49 am
Posts: 6029
Location: Victoria, BC and Clarkston, WA
Gerard?
Could you send me one? The original connection on my Benjamin pump flew out long ago and never did reseal right after it came out the first time!

Thanks!

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Pardini K10
Brocock Concept .22
3 Custom Crosman 2260
Benjamin Discovery .22 w/Joe Hickey stock!
Crosman 150 pistol .22
4 Crosman MK 1 pistol .22
Mrodair CP-1M .22 and .177


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PostPosted: Mon Apr 27, 2015 9:40 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
When you've got an 8 year old boy to look after and you don't drive (I've never driven) just bopping down to Greenline (using $5 worth of gas) doesn't seem all that friendly an option. More like a 2 hour adventure. As in 4x as much time as I used making the seal. I actually spent more time taking pictures and typing to share this information with folks online than it took to make the several versions including the one which ended up working. So yeah, for me this was the more efficient route. Do I value my time? Sure I do. $50/hour. That's what people pay me to set up or repair their instruments. But Translink isn't going to pay me $50/hour to travel down to Greenline, they're going to charge me $2.75 for myself and another $1.75 for my son, so there's another $4.50 added to the actual cost of this cheap seal, bringing it up to about $107.50 in lost time and cash paid out to get a $3 seal. Does this math make sense ratdoctor?

A few tidbits I've noted from your posts might almost make it seem you've got some sort of terminal illness or something, with time waste being such a grave concern:

ratdoctor wrote:
...but I don't have as much time as some of the people on this forum...


ratdoctor wrote:
I was just pointing out that you guys should spend more time shooting and less time trying to make your guns better.


ratdoctor wrote:
In anycase you are obviously one of his groupies, so I won't waste anymore time on this.


ratdoctor wrote:
Seriously though, WOW! You have a lot of time on your hands.


For my part, above all I am a craftsman. I make things. I try to make them well. That pursuit of the past 45 years or so (I started carving in earnest when I was 8, blew my highschool wood shop teachers' minds in grades 8 and 9 with the way I made things without drawing them first, learned to make violins by reading every book the library had on the subject and my first violin placed 7th of 21 instruments in my first competition, the rest of the entrants being experienced makers) has established in my mind that if a thing needs fixing I can probably fix it. Computers and phones. Bikes and household appliances. And airguns are pretty obvious. If it's broken, or more interestingly if it could use improvement, I'm going to take up that challenge. And sure, it does annoy the odd person. A girlfriend once started a fight with me about how I put a better handle on the lid of a brand new pot. Said I couldn't leave things alone, had to change everything. Well heck, sure. She had serious self-image problems, thought she was fat when in fact she was fitter than me, and I was pretty dang fit at the time, but I suppose my cooking her excellent meals and treating her like she didn't have a problem with food made her nervous so she had to start a fight about something. I heard she almost starved herself to death a year after she left. Oh well, I tried. Heard she eventually got healthier...

Anyway, just posted this crap in case it was of use to anyone with modest skills and a lathe. If that's not you guys, so be it, I didn't post it for guys without modest skills or a lathe.


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PostPosted: Mon Apr 27, 2015 9:42 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
rrdstarr wrote:
Gerard?
Could you send me one? The original connection on my Benjamin pump flew out long ago and never did reseal right after it came out the first time!

Thanks!


I can try. You've got those lovely depth gauges right? Could you email me specs on the existing seal and the bottom and top depths on the recess made for the seal? I'm almost certain the Benjamin pump fitting is slightly longer than the Foster type used on the Atomic or HiPAC as I've tried before to pump your Benji and the fitting didn't fit at all. Don't want to make the wrong sized seal for nothing.


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PostPosted: Tue Apr 28, 2015 8:13 am 
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Joined: Wed Feb 17, 2010 6:04 pm
Posts: 841
Location: Nova Scotia
GerardSamija wrote:

Anyway, just posted this crap in case it was of use to anyone with modest skills and a lathe. If that's not you guys, so be it, I didn't post it for guys without modest skills or a lathe.


Modest skills and a lathe, that's me. :D I always enjoy your posts and photos, making a part instead of buying one is a large part of the airgun hobby.
I appreciate the time anyone takes to post information about their mods and tests that help improve an existing product.


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PostPosted: Tue Apr 28, 2015 9:40 am 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Well you know that and I know that, 'that' being the enjoyment one derives from engaging in tasks which not only get a job done but at the same time emphasize our independence from being mere consumers. Seems the odd member here is just here to pick on that impulse. And perhaps to show off their latest unmodified purchases. The latter is something I find both mystifying and annoying. I'm more interested in seeing someone's home crafted fuzzy dice hanging from their rearview than the as-stock automobile they've hung them in. Same wth airguns. More fun in admiring even a lame attempt at repairing something or enhancing it than it looking at bad pictures of what can be seen more clearly on some airgun sales website. And when the mods get really good, that's cool.


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PostPosted: Tue Apr 28, 2015 9:41 am 
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Joined: Mon Feb 11, 2013 12:46 am
Posts: 4121
GerardSamija wrote:
the rest of the entrants being experienced makers) has established in my mind that if a thing needs fixing I can probably fix it. Computers and phones. Bikes and household appliances. And airguns are pretty obvious. If it's broken, or more interestingly if it could use improvement, I'm going to take up that challenge..

yep!... that's just like me.... :wink:
now if I can only figure out were to put a lathe :D

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PostPosted: Tue Apr 28, 2015 10:22 am 
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Joined: Sun May 04, 2014 1:56 pm
Posts: 215
Location: British Columbia
:roll:


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PostPosted: Tue Apr 28, 2015 12:25 pm 
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Joined: Thu Feb 02, 2006 11:35 pm
Posts: 3099
Location: Alberta Canada
Its my opinion that self fullfillment can be acheived in a variety of manners. Spend the money and getter done aspect. Or with a bit of mechanical enginuity, build it yourself.
The end result is one is up and shooting. Just a different way of enjoying the sport.
Personnaly I choice the latter :D

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PostPosted: Thu Apr 30, 2015 11:51 am 
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Joined: Mon Mar 09, 2009 6:46 pm
Posts: 1395
Location: r Alberta
Some times it is fun just to make the stuff your self.


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