GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: scion19801 on July 08, 2020, 02:41:37 PM
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ok so my jsar super tune kit hammer spring took a dump..
Anyone know where i can get gauntlet hammer spring assortment in different weights?
I put the stock spring back in as a temporary fix. .25 cal is very inefficient now running at 1400 psi on regulator to keep speed down. were talking 32 shots from 3000 psi to off regulator with a .380 cc bottle. i know its currently way over sprung.
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See if you can match one up here.
https://www.mcmaster.com/springs/springs-and-shock-absorbers/compression-springs/mil-spec-compression-springs/ (https://www.mcmaster.com/springs/springs-and-shock-absorbers/compression-springs/mil-spec-compression-springs/)
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k gonna see what i can figure out. done testing or today. not happy with current setup. got it at 1600 psi reg set point. shooting 875 fps, 48 fpe with 28.4 grain noe 250-27-rf pellets. and major air hog. around 3 mags on a massive .380 cc bottle before it comes off setpoint.
guessing factory spring is massively over rated, especially with aftermarket poppet and .1875 through tp and barrel port. probably be way over 900 fps at 1900 psi factory setpoint. thinking i can make a spacer that is shorter behind the hammer and go back to 1900 psi and then shorten spacer to bring speed back down. I DON'T want to clip or shorten factory spring to get the efficiency back
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McMaster Carr doesn't have the size i need.
Apparently i need a "qb series" hammer spring. Anyone know a source for the qb78 hammer springs.
my spring spec i need for replacement are:
id = .23"
od = .34"
wire dia. = .051
coils = 18 or so maybe even 20
length =2.3" or so may be max 2.5"
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would this spring work?
https://www.centuryspring.com/catalog/compression-regular?page=product&cid=compression-regular&id=S-297CS (https://www.centuryspring.com/catalog/compression-regular?page=product&cid=compression-regular&id=S-297CS)
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This may sound pretty basic, but my local "old fashioned" hardware stores sells a great selection of compression/expansion springs. I just find the ones that work and cut them to various lengths in combination with the hammer adjustment found built in on many airguns.
Together, you can adjust to whatever is needed.
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hadn't thought of that. have to go check the local hardware store tomorrow. Pulled out my hammer spring spacer and put in 6 small washer equalling about .436" or so (stock spacer is .658") and set regulator to 1800ish psi. now got 25.4 grainers going 875 fps. if i put in another washer i get 910's or so. But cocking weight had dropped of and efficiency has picked back up and it's not as loud as it was so all headed in the right direction.. :D
if i try for factory 1900 psi. my fps drops off. with the same spacer(washer) stack.
now once i get a usable spring replacement i'll be able to put my rear velocity adjuster back in.
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would this spring work?
https://www.centuryspring.com/catalog/compression-regular?page=product&cid=compression-regular&id=S-297CS (https://www.centuryspring.com/catalog/compression-regular?page=product&cid=compression-regular&id=S-297CS)
It probably will, however, Never/ever order stainless if possible. It is much weaker than music wire or spring steel, and they tend to break.
Stainless is NOT very dependable for long life and will get weaker and weaker. not go mention get metal fatigue fractures easily.
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Ty for the tip on stainless knife. Hadn't thought of that. Will try to stay with music wire then. Found this that looks promising.
https://www.grainger.com/product/SPEC-Compression-Spring-54MU80 (https://www.grainger.com/product/SPEC-Compression-Spring-54MU80)
Seems that the spring I'm looking to replace from the jsar kit is a 20 lb spring. According to a spring calculator I tried. So these 18 lb ones should work. May have to add a small spacer to add a touch of preload. Kinda bummed that I got to get a 10 pack in order to get a spring, but it seems they aren't going to last very long so now have many needed extras. just hope the 2 lb difference won't be a big issue. Next time I pull the gun down I'll measure the factory spring to try to figure out its spring rate. I know I got a lot of free travel in stock spring currently to keep speed of pellets in optimum range and reg pressure down as well. At least now it is getting better efficiency and shot count it back up, but no current way to fine control velocity and the stock spring with the jsar rva is way too much spring and putting it in the 920-930 fps area with 25.4's. Too hot for good accuracy. Sure the 56 or 58 gram hammer doesn't help much either. Especially with the aftermarket peek poppet. Was almost going to try shortening the rva length to try and gain control over factory spring. But that didn't seem like a good idea.
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Seems the slightly light spring may very well help in this case. ;)
Knife
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https://www.grainger.com/product/SPEC-Compression-Spring-54MN28 (https://www.grainger.com/product/SPEC-Compression-Spring-54MN28)
heard from hajimoto. was told the jsar tune kit spring was 22 pound for the .25 cal. so i went with the above spring. so now patiently waiting for it to arrive by the end of the month.
I hope this will allow other who have bought the kit to find a replacement spring easier.
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They sell them on Amazon, search for music wire spring in small parts
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ty sbak. i checked it out but the majority of their springs are stainless steel. not a good choice according to what knifemaker said. i ended up going with the ones in my last post. waiting for them to arrive. i'll update this as to how well they work as a replacement for the jsar tune kit spring once i get them tested out.
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When I was still actively in business, I did a lot of business with Granger. Back in the day it took forever. No idea how it is now.I do know that McMastercarr is annually two days. I'll bet
Granger is faster now days as well, as dealing with businesses, time if paramount for jobs.
FWITW, I have broken many a ss spring. Not one music wire! Well, not in an airgun at least. ;) ;D
Knife
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.051 music wire is quite common. Making springs is quite an easy task, just have to cook them in the oven at 450 for about 30 minutes when done. I keep several sizes of music wire on hand just for this type of situation.
Hope you get it going like you want.
Dave
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.051 music wire is quite common. Making springs is quite an easy task, just have to cook them in the oven at 450 for about 30 minutes when done. I keep several sizes of music wire on hand just for this type of situation.
Hope you get it going like you want.
Dave
Now that would be worth investigating how to do. i tried to find info on making springs but it seems people were just coiling wire around and arbor and that was that. I know there must be more to that just that. one would really be able to do some trick spring work making your own and probably be cheaper and easier as well. definitely easy to get repeatable results.
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That’s really about all there is to it.
The hardest part is finding an arbor that is the correct size smaller than desired final id.
And there is not an easy formula. But a little trial and error gets you there.
Then draw out some marks to guide you to get the correct pitch. And wind it....WHILE WEARING SAFETY GLASSES. Music wire needs it’s respect.
After shaping, it will have some work hardened areas that create stresses. You need to relieve those stresses by cooking at 450 for half an hour.
If you have access to a lathe, it’s even easier if the lathe has threading capabilities.
Dave
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Interesting.... Wish I had a lathe. Oh the fun that could be had with one.
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just did a quick shot count test....
with current 1700 psi reg set point. 43 FPE with .25 cal. factory valve measurements. Custom tp .194" valve side - .1875" receiver side, and .1875" through to barrel port. 1000 psi used from full fill 3000 psi shot down to 2000 psi = 48 shots. Factory hammer spring, with no spring preload or tension on spring. Average FPS 882.
Did find that gun has a leak...Pretty sure it is my foster fill fitting on my JSAR Flex reg. gonna see if i can use the fill fitting off my ninja reg till i can find a replacement or a new o'ring for it possibly if it is replaceable.
edit>>>
this is not the factory bottle. I have a .38l or 380CC. the factory is 13 cu in which is 213 cc.. not quite double the tank size, but twice or better than the factory bottle. Gun is heavier due to it as well.
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leak found and fixed. it wasn't the foster fitting after all. Did a water dunk test and it was the replacement gauge i had put on the flex regulator. Blow dried the water off and out out it after testing with air compressor. Then tested settings and it looks that my current shot count above wasn't at 1700 psi afterall, it was 1650 psi. regulator now set to 1700 psi. my replacement gauge is apparently 100 psi off to the high side. reading more than what its at. Good info to know when further adjustments are made in the future.
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just got an email this morning....not happy or impressed at all. they now say that my springs are on backorder. they couldn't have told me this prior to my order. So much for using a big name company to get my springs from.
Now on the long dreaded search for another source to get a replacement JSAR super tune kit spring. this &^^& is getting out of hand with supply chains be all messed up. Almost makes me want to buy my own lathe, so i can try to create my own custom parts.
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ok so the factory gauntlet hammer spring is 2.775" long, .343" od, .227" id, and .057" wire, 21 coils.
i get a measured depth inside the uncocked hammer of 4.101" to the back of the tube., and 3.619" when cocked.
spring guide is .453" in length, with a .659" long spacer, and with a .379" rear cap.
spring rate of 31.861 Lbs/In
max load of 27.872 lbF
minimum load height 1.900 In
max travel of 0.875 In
these are the stock setup measurements.
the jasar super tune rear cap is .987" long
maintain same spring guide at .453" long with what i think is possibly a 2.25" - 2.5" spring????
current setup is running factory spring and spring guide with a custom mds spacer .430" long and factory rear cap
If i try to run factory spring with jsar rear cap, with no spacer, i get preload right off the bat. I'm trying to eliminate any preload.
I'm trying to figure out what spring length to get so that i can put the jsar RVA cap back into service. and also what my compressed length for the replacement spring should be. i have found two possible springs to get.
one has:
Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.047" Wire Size, 1.487" Compressed Length, 2.25" Free Length, 16.1 lbs Load Capacity, 21.1 lbs/in Spring Rate
the other:
Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.049" Wire Size, 1.526" Compressed Length, 2.25" Free Length, 17.98 lbs Load Capacity, 24.8 lbs/in Spring Rate
spring rate of 24.939 Lbs/In
max load of 20.523 lbF
minimum load height 1.427 In
max travel of 0.823 In??? unknown coil number
final one:
Music Wire Compression Spring, Steel, Inch, 0.30" OD, 0.051" Wire Size, 1.732" Compressed Length, 2.5" Free Length, 20.17 lbs Load Capacity, 26.3 lbs/in Spring Rate
I don't want to collapse another spring so I think need to pay attention to the compression length.
i know that there is 2.661" from the uncock hammer to the back of the jsar cap using the spring guide, and 2.179" when cocked. so i guess i say all this to figure out what would be a good length and weight spring so as not to over stress the spring. should i be paying attention to load capacity or to the spring rate? i don't want to have a wicked hard cocking effort. i'm also a bit lost on the load versus spring rate numbers.
Or is it that when the springs get close to the compressed length they are producing their respective load capacity? i know when i initially setup my jsar kit i had it turned in 11-1/4 turns which is around .340" beyond the end cap and was giving me my 890 FPS, but i would like to eliminate that much stick out, even if i have to make a custom mds spacer to get it so there is very little stick out and still have no preload. also current setup had .085" no preload gap. running 1700 psi at 886 FPS
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wow... I almost hate to do anything else to this gauntlet. just shot 64 shots with reg set at 1700 psi, on my .38l bottle through flex regulator and factory spring with a .085" gap. efficiency of 1.34 fpe/cc @ 44.3 FPE average. next will be to do a full shot string over the crony to see what it is doing shot to shot.
I'm thinking hammer and valve work may be next, to calm down the shot cycle.
58 gr hammer just seems way too heavy, for the way it is currently setup. I may need to get heavier ammo to get it up to the 55 FPE range.
I need to pull it down and get all the valve measurement out of it. i know that it has a .194" valve exhaust. but don't have the throat, or actual valve body opening around the poppet. the valve is stock, except for the aftermarket poppet. custom transfer port .194" inlet- .187" outlet. then .187" the rest of the way to the barrel.
I know my poppet diameter is .343"
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Update....
New springs arrived from grainger.... they are the 54MN28 springs. Put the jsar rear cap and new spring in. playing with different options to limit the max low point. so between the jsar adjuster and hammer spring guide i put a small washer that is .835" thick. at 1600 psi it gave 580ish FPS. A .176" spacer gave me mid 800's. effortless cocking. they are closed and ground ends and 22 coils with 2 half closed ends. 2-1/2" long. and man are they consistent. shot at two different loads settings and managed multiple duplicates back to back.
cranked back up to 1900 psi to see what i max out at, and getting 930 fps, no coil bind in sight, 5 turns in from flush. this is with my NOE 250-27-rf 25.4gr pellets of pure lead.
Mind you there is no valve work done other than aftermarket peek poppet. running factory 60 gr hammer.
At 1700 psi max FPS is 900.
Almost seems like i need more lift in the valve. i could be wrong. i does only have .101" stick out on the stem
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Maximum flow is attained when the poppet is lifted by 25% of the throat diameter. I didn't find the throat diameter listed here but I suspect it's no larger than 0.25" which means that the valve is flowing the maximum amount at a lift of just 0.063" or so. Therefore you should be in good shape with the 0.1" of exposed valve stem, particularly with the fairly hefty 60 gram hammer allowing for plenty of dwell.
FWIW, even when I'm using a lightweight hammer (10 - 15 grams) I only leave about 0.120" of the stem exposed under otherwise almost identical circumstances. Despite the reduced dwell arising from the light hammer, I haven't encountered a case where I ran out of valve travel. In other words, I've always been able to achieve the same velocity with the lightweight hammer as with the much heavier hammer. Perhaps I could shorten the stem a bit but I've never had reason to chase an extra 0.020" to 0.060" of hammer travel.
I also wanted to point out something that could potentially trip you up. You described trying different spacers to change the hammer spring preload. Be advised that if you happen to go too far such that the valve stem is driven flush and the hammer impacts the back of the valve body, the hammer will rebound quickly. The result is much reduced valve dwell and a lower velocity. Based on your description above, I don't think that has happened yet but I wanted you to be aware of it because you may encounter it as you try to squeeze out the last bit of velocity. That's especially true when doing the trial-and-error approach with spacers as compared to a fine adjustment like a screw (RVA or similar device).
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thanks for the info. will keep it in mind. the main reason for playing around with the space was to limit the amount of turns needed to achieve the FPS. With just the stock Jsar tune kit for the .25 cal gauntlet, i had to crank in 11-12 turns in from flush to get to where i wanted to be. the result was a lot of adjuster screw stick out. i figured that if i put in a spacer at the lowest FPS point i wanted to see, then be able to maybe only use 4-5 turns to get to my target speed. current spacer is just a washer at .083" and i think around 5 turns is and hitting 876 FPS with 27.2 gr.
I wasn't even considering that i might overdrive the stem with a spacer. was only looking at it as any change behind the sear wouldn't affect the valve stem side. i do still think i'm to the point were valve mods may be needed to get more FPE/FPS. The max was 930 FPS from the current conditions. Won't truly know till my AVS .2505" slugs arrive for further testing.
Had a few other odd issues pop up that i've been trying to figure out.
out to my 43 yard target, it's scary accurate.
at 52 my shorts are drifting high, and left by maybe 1/2 mildot.
out to my 100 yard plate, i'm way high and left.
Trying to figure out what is causing this. I know for sure that I'm not clipping. i know it can't be the ammo as they will stack at 43 yards no issue. I did pull my custom barrel band and found that my bottle had change relation to the shroud. got bottle back in place and custom band go's back on perfectly. re-sighted in. closer to being back on target, but still same issue high and left from 50 -100 yards. I'm almost thinking that it could be a precession (spiraling) due to speed. i can definitely see the pellet curve in to impact at 43 and closer to 28 that my zero is at. Crown is good and chambering is no issue. Odd trying to fight/figure out the precession issue. 1:20 twist is an animal it seems.
I visually check, and roll test each pellet. so i know they are consistent in that extent. I actually roll test before they even go into the mag. I have fully tested mags versus single shot tray, same outcome. probe orings are good. slight blowby, oiled every 10 mags, and changed every 3 tins. I have both the .254" od rings and the 6.35 mm's. i know my chamber area is .254". May just chalk it up and and be only a 43 yard with correction for 50 yard max.
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had another set of springs show up today. the grainger ones i got were 22# spring rate 2-1/2" long. the now ones are 24# spring rate 2-1/4" long. Need to figure out a spacer size before i test the 24# to see how they are in the gauntlet. Might be a good spring to use to set up my light weight hammer. Maybe not drill the hammer spring hole as deep and try them that way. that would leave more weight in the hammer with the hole not as deep.