Power Tune FX Crown

[nebeski]

Few Months ago I found this thread and started power tuning of my FX Crown.

That is reason for me to share my results on this place that can be interesting.

My original local thread is: https://airguns-srbija.com/forum/viewtopic.php?f=4&t=1125

Second picture on local thread is from this site, I used it for explaining idea of hammer weight mods.

I made several modifications

1. I machined VS and made 6.5 mm hole and made larger PEEK seat for new hole

2. I made my own pellet probe with exchangeable tips instead of modfying original probe

3. Hammer weight mod similar as explained here, but my additional weight is 13g



4. Made wider transfer port on barrel inlet

5. Made my own Power plenum for FX Crown

Making an extra plenum for the Crown has one serious problem, which is the lack of a convenient place to insert it.
Some put it under the plenum pressure gauge, that place has some serious flaws, the first is aesthetic and the other more serious is that when the plenum is wrapped up it "traps" a gun stock that cannot be removed without removing the plenum.

I have heard that there is a version with a thread on the right side of breachblock. I rejected this variant at the start for a variety of reasons.

The most natural place is to be screwed into the opening into which the D36 Valvehouse screws. There is a 16x1 threaded hole and the plenum could screw into it. There would also be a valve pin in the axis of the plenum as it is on FX Impact.

What makes this dificult is the lack of space in the factory configuration because of:
1. Close to the bottle
2. The proximity of shrouds

Despite these aggravating circumstances, and because this is the most natural position for a plenum, I have opted for it.

In addition to the plenum itself, full implementation also required:
1. Move the bottle away from the block
2. Narrow the beginning of the shroud to the tube or shorten the Shroud and place a spacer on the tube
3. Implement a fine-tuning mechanism at the plenum

Spacer:

Plenum

Valve adjuster parts:

Original parts from Impact and my "variations"

This is rubber bed that fits hole in adjuster

All aluminum parts are anodized and colored

For this FX Crown power plenum I could not use original valve pin, becoause it is now too short.

Instead of it I made new longer with extension rod and custom spring.

This is how it looks like on my Crown:

This is speed (m/s) I got with 125 Bar pressure adjusted on regulator and 2.2g JSB MKII 6.35, that is around factory settings.

 

[weatherby]

Nice job, and great results

This mod deserves it's own thread on here as well

 

[Buckshutr]

Wow!! Nice work!

 

[jking]

If the FX Crown stays in production that'll give FX something to consider and implement to some extent as well. Thanks for sharing your vision and implementation.

Jking

 

[Eamon]

Well, looks like you could open your own airgun mfg co, That is an amazing job! 

Should you decide to make money at this please let my Crown go first in line. 

Gosh, I would love to be able to do that work, but I have a sneaky suspicion it would have required a career in machining. I'm 45 years to late. lol

 

[nebeski]

Nice job, and great results

This mod deserves it's own thread on here as well

Wow!! Nice work!

If the FX Crown stays in production that'll give FX something to consider and implement to some extent as well. Thanks for sharing your vision and implementation.

Jking

Well, looks like you could open your own airgun mfg co, That is an amazing job! 

Should you decide to make money at this please let my Crown go first in line. 

Gosh, I would love to be able to do that work, but I have a sneaky suspicion it would have required a career in machining. I'm 45 years to late. lol

Thank you all, yours opinion is very important and valuable for me.

I will continue my work and update this topic in future.

Now when I got plenty of power I will concentrate on accuracy and lot of field testing in future.

One of ideas is to make two stage regulator setting. I will insert additional regulator between bottle and spacer.

This will reduce the input pressure range and therefore reduce the output pressure variations of the built-in regulator.



Second idea is to make aluminium extension of breech block that will fit bottle hole in stock . That extension will have three holes for : barrel, plenum and spacer. Idea is also to have picatiny rail atached on it and below bottle similar to FX IMPACT.

Eamon, when I finish all tests and if I make second setup you will be notified about it . If you are now 45 years too late then it means that last year I was 46 years too late . My background is in electrical engineering and computer sciences, last year I bought lathe and mill and with friends made workshop in our shooting club. After lot of learning and practice this is result . I encourage you to try , newer is too late

 

[nebeski]

FX Crown Power plenum - valve pin v2.0

I use the unexpected free time of the last few days to optimize and fine tune FX Crown power plenum.

Because of the extra plenum, which is 15cm long, the original pin and spring no longer fit, so I made a new one with brass with stainless steel extension rod. Here in the brass part I made a thread of 3mm into which the extension rod is screwed.
My original idea was to make it from one piece of titanium because of its strength and weight. But two orders with my titanium bars did not arrive, first from China and then second from Italy. The reason is the outage of transportation caused by the epidemic.
This brass solution was temporary. This is how that version looks:

After thinking more recently, I've come up with a configuration where the original pin can be used without creating a brand new one. This makes the whole design much simpler. In this configuration I use a "joint" made of delrin, which on one side has a hole of 2.5mm with a length of 10mm. End of the original valve pin that has a diameter of 2.6mm is pushed in that hole. On the other side, there is a hole with a diameter of 2.9mm and a length of 10mm. The extension shaft is pushed in that hole. A little different spring is also required for this configuration. The middle of the delrin is full. Here you can see both variants in parallel:

Here is valve pin v2.0 with valve adjuster :

 

[Scotaty]

Very nice work 

Custom stock next?

 

[RabbitBlaster]

Wow nebeski! That is impressive! I have been thinking about how to put a power plenum onto my Crown Continuum .25 and it is interesting to see what you have done.

Would you be interested in making and selling me one to play with? I do not have a lathe or any of the tools I would need to make this, but I sure as hell want one!

 

[nebeski]

May plan is to make new version with little modifications (for example one of modifications is to move bottle adapter from breach block to the end of bottle spacer).

That new version will be finished during the may (limitation is only my free time), if you are interested I can make additional setup for you.

 

[Mask]

@nebeski, have you ever considered the option of placing a small plenum (with a pressure gauge in its bottom) instead of the pressure gauge which measures the pressure of the pre-chamber integrated in the crown? Obviously it would be necessary to flood the hole that gives air to the small pressure gauge to 5/6 mm. What do you say? Is such a work feasible?

 

[Mask]

I forgot to compliment you on your great job. I read all your original thread .... Very informative !!!! We are "almost" neighbors ... I am Italian and if you understand correctly, are you Croatian?

 

[nebeski]

@Libellule, that is similar to first versions of FX Impact power plenum. 

First problem is hole for plenum thread that needs to be bigger for efficient air flow.

Second problem is Crown's gunstock that would be locked with that kind of plenum.

The most natural place for power plenum is as close to valve as much as possible . 

Yes we are neighbors, just across Adriatic . I am from Belgrade, Serbia. I am glad that you found info that you needed in my threads.

I'am still waiting Titanium from Italy

 

[Mask]

Sin!!!!

I hoped you could simply install a small plenum of, max, 10 cc (larger would be too invasive), without making changes in the crown's aluminum castle. Installing a plenum is the only way to get so much power out of the crown, without adjusting the pressure of the pre-chamber to too high values, thus also maintaining a fairly high range of shots.

I'm absolutely not able to do a lavork like yours .... I will just do those small jobs within the reach of all the owners of this fx.

 

[RabbitBlaster]

Hi nebeski,

Yes I would most certainly be interested. I have an idea for you and this comes from the fact that since I have a Continuum with the ultralight barrel, it may be more difficult to put a long plenum under the barrel. What about if the plenum was actually two plenums, possibly shorter; but in a Y configuration below and beside the barrel? This would leave room for the original barrel. My thinking is that you could make a mini block that could be screwed into the port when the barrel and bottle are removed; then you could put the barrel and bottle on and then screw in the mini-plenums. In this way you could also make custom sized plenums that could be changed at any time. I am happy to draw it for you if this does not make sense.

Feel free to email me [email protected]