Gotcha. I guess you must be pulling a slight vacuum on the return stroke until the piston passes the vent hole then?
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No,I have nothing like that. Your original pump also has the air hole. But the piston is quite different - it is not serviceable. Mine is. Just replace o-rings and you are good to go.
Yes!!!!!!!!!!!!!!!!! I moved it as far to the end as possible to increase the working volume of the pump. On the Mares pump that hole is too far from the end thus reducing the volume. My pump's ID is 9.5mm as opposed the original 10mm but because of the location of the air intake hole the internal volumes are comparable. 550 strokes take my Cyrano 850 to the optimum powerGotcha. I guess you must be pulling a slight vacuum on the return stroke until the piston passes the vent hole then?
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Yes!!!!!!!!!!!!!!!!! I moved it as far to the end as possible to increase the working volume of the pump. On the Mares pump that hole is too far from the end thus reducing the volume. My pump's ID is 9.5mm as opposed the original 10mm but because of the location of the air intake hole the internal volumes are comparable. 550 strokes take my Cyrano 850 to the optimum power
Couple of ideas:
1) make a piston only with one o-ring instead of two and make it as short as possible. This way the air intake hole can be moved toward the end. The piston has to clear this hole for the air to get sucked in. This way you will increase the working volume even further given the same length of your tube
2) Use a silicon spray for the internals of the pumps. Once it dries, it turns into powder that fills tiny scratches inside making the internal surface smoother. Use silicone grease for the o-rings, not some liquid crap that does not stay in one place.
3) If you get a tube with ID of 10mm you will need the same O-ring diameter for the piston and that internal piece. Get like 50 of those and you will be set for life
If you get an ID of 10mm - you will find the o-rings. My pump's ID is 9.5mm - I could not find the 10mm one (to match the gun's valve ID).
I do not recommend titanium. The main precaution for a pump is to avoid scratches on the inside so you need a hard grade of titanium. It is difficult to thread. Also there is another issue. When you drill that air intake hole in the back the exit opening (on the inside) needs to be polished because the piston's o-ring will catch on the chip and get damaged. Polishing that opening up is a bitch on a hard metal. I agree with you that the lighter is the pump - the better. I travel myself and sometimes come within grams of the weight limit. So I suggest to use aluminum, reduce the OD to 12mm except for the threaded part and make sure the piston is also aluminum (should not be harder than the body, you can probably even use delrin). You can get a Chinese die 14x1 that is good for aluminum for $5. Just be careful when you screw the pump into the gun to avoid crossthreadingYeah. I have a few of those on my wishlist already;-). I’m actually based in China though I haven’t been back “home” for a long time now. So, I can get pretty much everything on Taobao within a few days at very affordable prices. And often a bit cheaper than the same vendors sell their stuff on eBay for. I’ve bought titanium, brass, SS and alu in lengths of just 10-20cm and had it shipped to my door in two days.
The only reason I didn’t order the titanium tubes yet was because the seller couldn’t really tell me how well polished the inside of the tubes are. I might just buy one and see how they look and if I can polish them myself. Otherwise, the mirror polished SS tubes will be my backup solution. It’s been a year or more but I think I was looking at USD15-20 or so for a meter for a pump.
I do actually care about weight when traveling as it all adds up. But that said I really like that with titanium you don’t really have to worry about corrosion or dissimilar metal issues. That said, it’s not fun to turn ti on a mini lathe at all. I’ve done it, but far from easy.
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I do not recommend titanium. The main precaution for a pump is to avoid scratches on the inside so you need a hard grade of titanium. It is difficult to thread. Also there is another issue. When you drill that air intake hole in the back the exit opening (on the inside) needs to be polished because the piston's o-ring will catch on the chip and get damaged. Polishing that opening up is a bitch on a hard metal. I agree with you that the lighter is the pump - the better. I travel myself and sometimes come within grams of the weight limit. So I suggest to use aluminum, reduce the OD to 12mm except for the threaded part and make sure the piston is also aluminum (should not be harder than the body, you can probably even use delrin). You can get a Chinese die 14x1 that is good for aluminum for $5. Just be careful when you screw the pump into the gun to avoid crossthreading
I do not hunt on scuba so I have no compressor. You will get crucified in Europe for hunting on scuba and I will gladly be there to run the last nail throughA push in gauge sounds like a good idea, but I decided to stick with a threaded one. Push in would take quite a lot of force. Easily 30kgf on a normal 13mm gun and 50-60kgf on a Mirage and I just wasn't sure how well it work in reality. Did you find you could hold the push-in gauge in fairly easily or do you think they leaked because of the force pushing them back out?
I tinker with my guns quite a lot so it's just nice to have a gauge and since I have the scuba tank way of filling them and a fridge compressor, too I have come so used to having gauges. Also, I am beginning to try to "map" how much power different shaft thicknesses need to really work well. So, for my use, I still need gauges.
I do not hunt on scuba so I have no compressor. You will get crucified in Europe for hunting on scuba and I will gladly be there to run the last nail through [emoji4] - I hate that.
Very easy to push since the area is small. I used an air pump needle integrated into my gauge - that tip is a bitch to machine
Do you hunt in China?Fridge compressor... not tank compressor.
And my scubafill adapter is not for hunting on scuba - which you’ll never ever find me doing. But since I got into using 125-135 guns at +30bar I no longer see the charm in using a hand pump.
I’ve taken my gun on a motorbike to a local dive shop to pressurize it a handful of times. On other trips, and basically why I made the adapter in the first place, I was going to locations where friends of mine ran dive shops and I would squeeze in some freedive spearing - so always tanks around.
On my latest trip to Indo I rented a tank for a few bucks and put it in my bungalow. Normally this wouldn’t be needed but I had a highly “experimental” gun with a lot of DIY parts on it and honestly had a few issues over the weeks I used it there. But having the tank just next to me made it so much easier just to pull the gun apart and fix it for the next day.
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Do you hunt in China?
I was in Philippines on a scuba trip long time go. Very bad experience - not much fish. I am not sure I can handle South-East Asia. I prefer a minimal interaction with peopleHaven’t managed to yet. But they are catching some really nice snappers and groupers on the reefs in south China and some beautiful amberjacks in the north.
Also, supposedly some oil rigs in the south that hold some nice pelagics.
But I do freedive, mostly, with Chinese divers. Right now for example I am training at a friend’s shop in the Philippines. Did spear a little here but not an easy place at all to catch fish. But it’s getting better
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I saw blown-up reefs. And I understand what you are trying to say but the judgement must be rendered. They grow amberjacks in cages in many places. They can do it in Philippines. But they don't. They are either too stupid to rob their children of a decent future, too corrupt or don't care. I have been to many countries and despite observing a lot of attempts to vilify the USA - here they actually care way more about the environment than most places I have been too. There is a reason a lot of countries are poor - people there are actually too dumb to be decent. And I must know, I came from such a place. They do not pay taxes, give bribes and destroy the environment. Cheat, steal and do other nasty stuff. And they do it in Africa, Asia, Europe, America. Some people just could not figure out that when you do all that - you actually cheat yourself.Yep. Poverty and over population makes it hard to sustain a healthy fishery here. There are some nice pockets left and some being brought back. I’ve had some very nice scuba dives here a few years ago. But on freedive spearing days I’ve seen literally miles of bombed out reefs. Not kidding you, I’ve even been in the water when I heard them blast off up ahead of us. And I’ve seen local fishermen hide their little bags of cyanide when we meet in the water. But when you know how many mouths they have to feed, you stop judging. They know it’s not cool. But it’s better than putting your kids to bed hungry.
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Very easy to push since the area is small. I used an air pump needle integrated into my gauge - that tip is a bitch to machine
NoWhen using a push-in gauge I would think it doesn’t matter how small you make the needle itself in terms of the forces at play. Once the air comes out of the valve, I think the force of the pressure would be acting on the full area of the 14mm bore, hence the high numbers (30-60kgf) I put in that previous post. As always, I could have missed something.
When you release air from the gun - what do you do? You take a piece of hard wire or a nail and push the pin in the valve to release air. A very minimal effort is required because the surface area is tiny. Actually in case of my adapter it was difficult because I wanted to ensure that there is no air leak so it was a struggle. Anyway like I said I do not need it plus it is one less piece of equipment I have to drag around on my mighty back.The only reason I can see for it to be a “no” is if the OD of the pin is such a tight fit into the inlet valve that you don’t leak air into the rest of the space. Because it it’s a categorical “no” then why would you even have an o-ring in the first place;-)?
I could see one potential way to make a push-in gauge work with less force on it and that would be to use a much smaller o-ring on the front face of the gauge adapter (in a trepan/face groove) which would seal on the floor of the inlet valve and not the ø14mm side walls. But the sweet spot for the length of the depressor pin would be much, much smaller so in reality, it might not work too well.
Ah Shoot! Sorry! Wasn’t thinking straight or even reading my own drawings. The bore in question is not 14mm only 10mm.
The numbers would be more like 16-32kgf (for 20-40bar pressure).
Sorry about that;-)
Still, it probably doesn't change my preference for keeping the threads on the gauge vs. push-in - especially on a high pressure gun.
@popgun pete besides my mess up on the bore diameters, what do you think about the above?
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