Tuning FX Maverick full beans!

[Ignoto]

The top changes I'd make is: (A) A double cocking rod to prevent the rod from bending with higher spring settings. (B) A change in how the lever attaches to the cocking rod, and a heavier built side lever connection. (C) A redesign of the the valve section to allow for a larger valve seat. (D) A larger opening on the breech to handle longer lead and maybe Panthera magazines.

Woa.. let me rollback and apologize for assuming your cocking rod was barely holding its own and saying that your best bet was to decrease the surface area behind the valve pin but bear with me with the info i had back then that led me to believe that it was the actual cocking stress that was causing your rod some issues derived from the extra hammer pre-load and a stiffer hammer spring.

it never ocurred to me that it could be related to the energy tranfer during shot cicle and at the time i had no idea that there was rod slippage/bending ocurring.

I did not ignore your suggestions for improvement and for what it's worth i don't have any affiliation with fx. I did get a 30 barrel from a friend and tryed it up to 160bar without issues but seeing people now mentioning this made me feel like an ignorant asshole. Just for clarification that second rod is only to prevent the main rod axis being thrown off am i correct?

I think if rod slippage is in play and cutting a grove in it is not great for multiple fine adjustment and an increased point of failure i think it would be best to make a c-clamp (just like the barrel support attaches to the plenum) for the best grip. Putting a sleeve around the rod in the section just after the main block would also help with the bending since it is the longest part.

One could also make a tiny spot on the rod with a small drill by removing one screw at a time and using the thread hole for guiding the bit to help with grip without weakening the part too much and still mantaining adjustability do it at own risk of ruining the threads though.

 

[Ignoto]

If you used basically used 2 rods there and made the clamp into a turnbuckle style connector, you could then use one of the rods as an adjuster. Would probably say to also mill one small part of the rod with wrench flats that make it easy to turn.

You just had an excellent idea of an on the fly adjustable seating depth knob.. this is gonna be fun!

 

[Rallyshark]

No worries at all Ignoto You weren't necessarily wrong. The problem is two fold. It is a result of high spring tension/cocking effort AND the force of the larger .30 probe pushing back on the rod during the shot cycle. These aren't really an issue, until you start running reg pressures over 160 bar in .30. High power in .30 is where the Maverick's weaknesses start to show up. Keeping the same settings and swapping to my .177 heavy slug shooting barrel gives me max power with the power wheel on 2 or 3, and PW4 for .22 will all other things being the same as the .30 setup. It just gives you a really simple example of the extra stresses needed to make the power in .30 vs the other calibers. But yeah, the extra cocking rod is there to take some of that deflection stress of the off center tension of the cocking mechanism during cocking, but it also helps with the lesser deflection caused during the shot cycle of the .30. That single rod just has a hard hanging on with the higher cocking force/shot cycle force that's a result of super high power and reg settings in the 200 bar range. I mean many of us are pushing these guns way past what they were ever designed to do, so we're gonna break some stuff, haha.

 

[revenger]

Woa.. let me rollback and apologize for assuming your cocking rod was barely holding its own and saying that your best bet was to decrease the surface area behind the valve pin but bear with me with the info i had back then that led me to believe that it was the actual cocking stress that was causing your rod some issues derived from the extra hammer pre-load and a stiffer hammer spring.

it never ocurred to me that it could be related to the energy tranfer during shot cicle and at the time i had no idea that there was rod slippage/bending ocurring.

I did not ignore your suggestions for improvement and for what it's worth i don't have any affiliation with fx. I did get a 30 barrel from a friend and tryed it up to 160bar without issues but seeing people now mentioning this made me feel like an ignorant asshole. Just for clarification that second rod is only to prevent the main rod axis being thrown off am i correct?

I think if rod slippage is in play and cutting a grove in it is not great for multiple fine adjustment and an increased point of failure i think it would be best to make a c-clamp (just like the barrel support attaches to the plenum) for the best grip. Putting a sleeve around the rod in the section just after the main block would also help with the bending since it is the longest part.

One could also make a tiny spot on the rod with a small drill by removing one screw at a time and using the thread hole for guiding the bit to help with grip without weakening the part too much and still mantaining adjustability do it at own risk of ruining the threads though.

Oh yeah just the force to cock it back I could see aluminum rod return guide bending and eventually the cocking rods would permanently bend from the side load. A stainless rod guide and a hardened rod will work but you need a way to keep it perfectly secured to the cocking block as the hardened rod makes it tough to get a grip on it. At one point I thought if you had the cocking block in the perfect position and used aluminum set screws then you could drill a small hole through the aluminum set screws and the cocking rod together and then pin it all in place. Plus side to that is you would always have perfect positioning of the cocking block if you had the gun apart and were reassembling. Pinning it in place may be a decent option but the only downside I see is you would have to do it to an unhardened rod first to mock it all up then harden and heat treat it to give it strength.

 

[Ignoto]

Ok so just ran some math here and at .30cal with 200bar that tiny rod at peak shot pressure is under 205lb force and in .22 shoul be 106lb force. Didn't ocurred to me the tremendous area difference affected by the smashing pressure people get these toys under.. jeez.

 

[Ignoto]

Here's one of the springs that I use with my valve:


There's also a potential safety issue with high power and big slugs in hard lead. Going back to the drawing board on how to beef up the cocking rod attachment to the lever clamp. I got some more hard lead 62 grain slugs from Varmint Knockers recently and retuned my Maverick for 200bar on the reg.

View attachment 327302

The problem that I'm running into with the tighter bore TJ barrel and this ammo is the pressure makes the probe give way before the slugs obturate and travel down the bore. In other words, these two little M3 set screws clamped to my music wire rod are no longer sufficient to hold the cocking rod in place and it winds up breaking free from the clamp.

View attachment 327305

I'm weighing my options, but I'm kind of drawing a blank beyond machining a newer, beefier clamp that would allow for more set screws to be used to secure the rod in place. It would be too much of a pain to thread the rod into the clamp, since I always micro-adjust the position of the rod/probe in the clamp to optimize the ammo seating depth in whatever barrel / ammo that I'm using. There's not enough meat to add more screws in the factory clamp.

I noticed you are or had used a thicker wire (much stiffer) spring even if it is a bit bigger in diameter (softer) compared to the stock valve spring which should get you a quicker valve cycle (providing you use the same valve travel) is it because you are using a short barrel? Im curious, i would think if you use a long barrel one could attempt for a longer cycle by using a lower spring rate and a heavy hammer for increased inertia..

 

[Ignoto]

The valve design i mentioned at an older post for reducing hammer spring preload still to be tested. 4mm shaft instead of 3mm

 

[mtnGhost]

I noticed you are or had used a thicker wire (much stiffer) spring even if it is a bit bigger in diameter (softer) compared to the stock valve spring which should get you a quicker valve cycle (providing you use the same valve travel) is it because you are using a short barrel? Im curious, i would think if you use a long barrel one could attempt for a longer cycle by using a lower spring rate and a heavy hammer for increased inertia..

The heavier valve spring is needed for maximizing the valve dwell time with a heavy hammer weight (it slows my extended length / extended travel valve pin from bottoming out too quickly). It does also help to produce a snappier high pressure shot cycle with lighter hammer energy with shorter barrels.

As for that rod linkage clamp, I'm just going to have to machine a thicker part from 7075 and run M4's. My rod is 4.09mm music wire, which absolutely sucks to machine (it had taken me a couple of hours to make and some broken carbide when I made it a couple of years ago).

I'm also using a tiny ~3-coil (free-floating) spring between the rod guide and that rod clamp, which helps dramatically to keep the lever locked in the closed position. I had already beefed up that lever linkage pin when I made my titanium lever, so the weakest link for now are just those two little M3's not having enough bite at 200bar (weird that it's fine at 190 lol).

 

[mtnGhost]

I just went through all this. If you can get your position perfect on the rod you can put small notches on the rod itself so the set screws have something to sit into, but it needs to be really close to perfect. I did this when I made a hardened rod and then my screws were not hard enough to bite into the rod. The pressure from the shot would blow the pin probe back and the gun would lose all power. Eventually my hardened rod snapped as I believe I did not temper it properly... Now I have went the way of Rallyshark and have done a dual rod set up. You also could try using an actual 4mm bolt to hold your cocking rod. I can't actually get enough force using the Allen head set screws and tend to round them out. Below is pictures of my brand new set up. I ditched the original return guide in favor of an stainless one for strength. The secondary rod is actually very tight fitting into the guide and has a set screw on the front scope mount holding it. That rod also goes full length into the rear scope mount. So essentially the cocking block just slides over the secondary rod and adds lateral stability.

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I have an idea to try out before I go to plan B and fabricate a new attachment. I'm going to thread and counterbore the factory part for an M4 cap screw going through the opposite side like this:

I think that would provide enough grip to keep it from moving.

As for the two little M3 factory screws, if this doesn't wind up providing enough grip then I'll try and figure out what the largest size up is for retapping them. M5's would be too big and I'm not comfortable retapping M3's with M4's, so I'd probably use some SAE screws that are between an M4-M5 (11/64's or 3/16 maybe).

You just had an excellent idea of an on the fly adjustable seating depth knob.. this is gonna be fun!

This is difficult to explain, but the original idea that I had for an adjustable probe system was kind of similar with some different design principles. First, I would relocate the rod guide back behind the rear barrel support on this side:

Not that high up, just a visual representation of the barrel support that I'm talking about and which side it would be relocated to. I think that would be enough to properly guide this music wire rod, but I could see adding a second guide for support like others have shown.

The main reason for the relocation is this - it would then be possible to use a nut threaded into the muzzle end of the rod on the muzzle side of the connector. The nut would clamp against the connector with a fine thread for micro adjustment of the probe position.

It would also be a LOT easier to adjust the position using a nut than it would by threading the entire connector (having to to a partial disassembly every time you wanted to adjust the probe would suck). That rod would never slip again with the nut holding it in place.

 

[mtnGhost]

 

[Bigragu]

I switched those grub screws out to M4 x 6 Torx socket head two years ago, and although my 30 wildcat isn’t at your lower levels, that rod no longer slides or slips thru the cocking block. With Torx you can tighten to your hearts content

 

[mtnGhost]

Well this appears to have resolved the rod slip issues (in .22 cal at least). I just shot somewhere between 225-226 .22/40gr Griffin RBT slugs at 200bar and the rod stayed put. I atill need to test it out with those hard 62gr, but the rod definitely would have slipped back after ~25-40 of those 40gr at 200bar.

I'm pretty blown away at how accurate this thing shoots 40gr at 957FPS (just fast enough for me to consider it for NRL22). The 0-50y G1 BC was 0.175 consistently, and I can't really see this Maverick shooting any flatter to 200y in another caliber.

 

[Ignoto]

Well this appears to have resolved the rod slip issues (in .22 cal at least). I just shot somewhere between 225-226 .22/40gr Griffin RBT slugs at 200bar and the rod stayed put. I atill need to test it out with those hard 62gr, but the rod definitely would have slipped back after ~25-40 of those 40gr at 200bar.

I'm pretty blown away at how accurate this thing shoots 40gr at 957FPS (just fast enough for me to consider it for NRL22). The 0-50y G1 BC was 0.175 consistently, and I can't really see this Maverick shooting any flatter to 200y in another caliber.

Glad you found a way to sort out the issue! That's a neat work by the way i must say i never had a reg up that high but will eventually get bored and order a huma reg to test stuff over transonic cause we in europe to my knowledge don't have anything heavier than 40gr in .22

Maybe i will have issues in the rod just like the big boys in here and hopefully i will then sort out some system to adjust the probe travel and stiffness. I tightened those screws as hard as i felt safe to and loctited them from day one.

In the meantime i am testing a new hammer since the original started getting marks from the sear after probably 25-30 thousand shots and oh boy happy times so far.

The goal was to try to ease the ping noise and increase mass to prolong dwell for a longer barrel and i can report in my experience it is going on the right path. The noise i now hear is the pitch of the plenum vibrating (long and high frequency) and the mechanics of the spring releasing. Of course this was with light pellets to isolate the sound of the shot and with a moderator.

About the valve dwell with increased mass, previously @140bar i could shoot 40gr Zan's at 940 and now they are peaking at 960. I found that micro adjuster to be very sensitive just before the valve overtravels and loose dwell time and will do further tests with more and less holes in the hammer to test how the "air brake" while the hammer travel affects consistency.

So far the extreme spread if just like it was before about 10~15fps with this slugs.

I have tested Zan 40gr @940 HN 30gr @1040 and Norica 25gr @990 BC recently up to 625 meters and gave up on the G1 and found RA to be a way MuCH better match for slugs by the way so anyone enjoying ELR give it a try (i know this is nothing new but to me it made life easier since G1 starts really high at high speeds and slowly degrades and the way i see it should be a constant.)

Happy modding
Happy shooting

 

[Rallyshark]

Ignoto, your valve work is clearly showing with those numbers! To be able to get that level of power from a 140 bar reg setting is impressive, as is your new hammer! Your gun is a true beast in the power department, awesome work man.

 

[Ignoto]

Ignoto, your valve work is clearly showing with those numbers! To be able to get that level of power from a 140 bar reg setting is impressive, as is your new hammer! Your gun is a true beast in the power department, awesome work man.

Thanks man, i only mean to share and learn and i don't need to remind you it was your posts that drove many of us along this path. I will post drawings and 3d models of modded parts for anyone interested in trying out or even improving upon in the future.

 

[Rallyshark]

Awesome!

 

[RabbitBlaster]

Just to add some extra beans to this thread that rallyshark created. Here goes some more. I do not have a peek poppet but a nylon one. My valve seat is 6.85 and my hammer weight is made of tungsten carbide and around 21grams with a stainless steel spacer that combined make about 6mm pre tension. Made a brand new stainless valve pin with reduced diameter of 2mm around the valve seat segment instead of 2.75mm. i use a 800mm barrel and a single 500cc bottle. Using for the .22 an fx pin probe and a stock hammer spring. Return spring i am using is 6mm OD x 0.3mm thickness by 15mm lenght. Since i run the gun from 15 grain pellets to 40gr slugs i needed a lot of adjustment in the hammer wheel so made a 20 position with 0.35mm increment one that uses the full travel of the adjustment screw at the back. For fine tuning created a valve return knob like the impact has.
It is using a plenum with 146cc.
Polished reg piston and screw for consistency although it remains sensitive to temperature change since it is still the plastic one.
My prefered reg pressure is 125bar for target shooting at close to medium ranges (up to 300m) shoots 30gr at 1010 or 40gr at 915 (bc is the same as higher speeds).
At 170 bar shoots 40gr at 1025
At 185bar shoots 40 gr at 1105-1110 (109ft/lbs) so the receiver is the limiting factor for longer slugs. (If anyone knows a supplier with heavier quality slugs please tell me.)
If i use it for bench the longer bottle location is definitely a plus for stability with the added plenum section.
If used in standing position you can remove the extra reg section and place a 600mm barrel and go for it. 990fps with 41gr slugs in .25 tested at 170bar.
Thanks to rallyshark for inspiring me with this great post , and the modding will continue.
Cheers

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Wow, very cool! Can you please share pics of your valve adjuster and tell us how you made it work in the Mav?

 

[Ignoto]

Today i finally tested the "more balanced" valve i meant earlier and i have some good and bad news to report.

I would also like to know what sizes have anyone tried as offset diameter for the poppets made and how well they sealed at first try.
I think i have finally nailed how to make and assembly them because for the 2 new valves they sealed first time without a shake or a shot at low 70 bar pressure.

The valve stem conical diameter is 7.4 and the poppets are 7.8 (0.4mm offset) and 8.2 (0.8mm) with sucess using acetal and nylon. But i would like to know what offset should be ok for peek.

Moving on to the valve results it is crystal clear no more tungsten or even heavy hammer weights are needed since the valve could easily overtravel with the lightest hammer weight for the maverick (the one with 1mm preload) at 170bar.
This means 200bar pressures no longer needs the hammer to twang the valve nor peek poppets are needed anymore.

This came with serious drawbacks so far.

Namely the shot consistency wasn't good anymore and this arrangement would sometimes overhang the dwell time too much and full throttle air downrange for half a second partially locking open the valve.
This is where fine tuning comes in, tomorrow i will test with the original hammer(lighter than the current one) and a harder return spring just for the peace of mind before tweaking the valve further. This has a 4mm shaft, but probably 3.5 or 3 should be better.

Obviously not reinventing the wheel but this should make high pressures easier to handle and with enough tweaking one hammer could fit all pressure ranges and still be reliable to control speeds.

Comparison between the original valve and this one achieved max travel in each with a diference of 5mm less preload on the hammer.

The following was my preload at 140bar

Also the hammer adjustment range sensitivity was greatly increased between 16 to 110joules which was before about 6mm and was today about 1~1.5mm preload on the hammer (too sensitive in this configuration)

This was handled with different power wheels i had made previously.

From initial testing i think a lighter valve could also make the cycle snappier, this can be done by making the shaft hollow but it's just a thought for now.

 

[Ignoto]

Wow, very cool! Can you please share pics of your valve adjuster and tell us how you made it work in the MaMav

I shared the 3d model to europe airguns just so everyone can benefit from more stuff since until now i cannot afford a cnc mill to do everything it comes to mind and believe me i could do with the income. Any sponsor for CNC mill here!?

The idea is as follow.

I have the ability and knowledge to create many stuff but i am still raising funds to apply the skills on what i love.

 

[mtnGhost]

Today i finally tested the "more balanced" valve i meant earlier and i have some good and bad news to report.

View attachment 359843

I would also like to know what sizes have anyone tried as offset diameter for the poppets made and how well they sealed at first try.
I think i have finally nailed how to make and assembly them because for the 2 new valves they sealed first time without a shake or a shot at low 70 bar pressure.

The valve stem conical diameter is 7.4 and the poppets are 7.8 (0.4mm offset) and 8.2 (0.8mm) with sucess using acetal and nylon. But i would like to know what offset should be ok for peek.

Moving on to the valve results it is crystal clear no more tungsten or even heavy hammer weights are needed since the valve could easily overtravel with the lightest hammer weight for the maverick (the one with 1mm preload) at 170bar.
This means 200bar pressures no longer needs the hammer to twang the valve nor peek poppets are needed anymore.

This came with serious drawbacks so far.

Namely the shot consistency wasn't good anymore and this arrangement would sometimes overhang the dwell time too much and full throttle air downrange for half a second partially locking open the valve.
This is where fine tuning comes in, tomorrow i will test with the original hammer(lighter than the current one) and a harder return spring just for the peace of mind before tweaking the valve further. This has a 4mm shaft, but probably 3.5 or 3 should be better.

Obviously not reinventing the wheel but this should make high pressures easier to handle and with enough tweaking one hammer could fit all pressure ranges and still be reliable to control speeds.

Comparison between the original valve and this one achieved max travel in each with a diference of 5mm less preload on the hammer.

The following was my preload at 140bar
View attachment 359866

Also the hammer adjustment range sensitivity was greatly increased between 16 to 110joules which was before about 6mm and was today about 1~1.5mm preload on the hammer (too sensitive in this configuration)

This was handled with different power wheels i had made previously.View attachment 359868

From initial testing i think a lighter valve could also make the cycle snappier, this can be done by making the shaft hollow but it's just a thought for now.

I commend your efforts for thinking outside of the box!! I know how much time and effort it is to get them working, i personally find balance valves of the knock open valve style to be way too frustrating to build and tune, especially with regards to dwell time.

The 26 gram "King Kong" tungsten hammer is actually pretty damned awesome. It unlocks ALL of the power potential regardless of the valve bore diameter. The snappiest / quietest / most efficient shot cycle is setting the reg to 180-190bar with a short / heavy spring with very light tension. Just enough to tap the valve and send heavy lead at high transonic velocity. Shooting hard lead 62gr / 600mm TJ feels more like shooting 16gr JSBs with the Mutant than anything else to me.