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Impact probe screw failure & solution
- Thread starter Pestassassin
- Start date
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SWEJaeger,
The force is directly perpendicular to the screw. The threads are not involved in anything other than pulling the metal pieces together (if machined correctly). Now,that pulling force is going to be a variable force because FX never published the torque that should be used on the screw. But if "tight" the threads are not taking the load of the force. Once it's tight, think about the screw more like a pin of X diameter that also happens to have threads on the outside of it.
The force is directly perpendicular to the screw. The threads are not involved in anything other than pulling the metal pieces together (if machined correctly). Now,that pulling force is going to be a variable force because FX never published the torque that should be used on the screw. But if "tight" the threads are not taking the load of the force. Once it's tight, think about the screw more like a pin of X diameter that also happens to have threads on the outside of it.
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How do the threads pull the metal pieces together? It looks to me like the probe has a "pocket" and it is not threaded. As such I would think the threads actually push the metal pieces apart as the screw is torqued.
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I -thought- the piece on my Impact was threaded, but I no longer have it. If it is not and if it looks like the above, then I am wrong and yea, the screw is only acting like a pin (which would take all the force).
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I don't believe FX would use different grub screws for different caliber. AoA did replaced my Impact with a "steel probe block and set screw" (according to the service invoice) back in early August when the gun went in for an air leak. Maybe they were replacing them with stronger "steel probe block and set screw" as guns comes in for service. Looks like they (FX/AoA) are not waiting for screws that begin to show problems to get replacement.
Look at how fast this thread is growing...
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and what about the fx impact holder,who is living out side USA?
I have 2 fx Impact,and I am also scared.
I have 2 fx Impact,and I am also scared.
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Sorry about your gun and glad nobody was hurt. Been following this thread since it started. Hope everything gets sorted out. I dont own an FX so I dont have a dog in the fight. I cant believe someone thought that tiny grub screw was enough on a 30cal. Huge engineering fail in my eyes. On the upside......it does look like it can be fixed. I bet they start using a screw long enough to go all the way through and threaded on the opposite side. That would be a solid fix.
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It sounds like FX &/or AoA has been upgrading misc parts throughout different stages of production. All in an effort to make the Impact safer & more reliable. So if you bought an early production Impact from an authorized dealer then you should recieve a replacement screw in the near future. If you live outside of the US or bought from a private party then simply contact AoA (or your local dealer) to get yourself a screw.
There are thousands of Impacts in use worldwide & only 1 screw (that we know of) that has failed & another that has shown signs of wear. So if you've got an original screw please make sure that its nice & tight until you recieve a replacement.
The next person that goes off topic with politics, government, lawsuits, presidential candidates, or any other crap will lose their posting privileges.
There are thousands of Impacts in use worldwide & only 1 screw (that we know of) that has failed & another that has shown signs of wear. So if you've got an original screw please make sure that its nice & tight until you recieve a replacement.
The next person that goes off topic with politics, government, lawsuits, presidential candidates, or any other crap will lose their posting privileges.
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I had two 1.5mm screws snap on a 30 cal Impact just like the photo Pestassassin posted. The 1st one I thought the screw might have worked itself out then snapped. The 2nd screw was in tight and snapped.
Posted 4 months ago: http://www.airgunnation.com/topic/fx-impact-owners-please-read/
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G
Guest
Guest
I know it's a bit off topic, but there is an easy way to apply enough heat to small screws that will disengage red loctite. Use a fine tip on the plug in only or trigger type soldering irons against the screw head/slot/key hole. It will heat the screw first and release the loctite without damaging what it's screwed into.
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So, AOA, was this fix an order given you to us directly from FX Sweden or are you guys just pro-actively stepping in?
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Hello,
I found one screw on german webshop and i will replace my with it until I get a new one from my dealer from Holland.
It is M3x8 and 12,9 the last number is very important it is very very strong and durable.
Eine M3 Schraube in 12.9 hält z.B. min. 614 kg Zugfestigkeit aus!
it stands 614 kg tensile strenght.
I found one screw on german webshop and i will replace my with it until I get a new one from my dealer from Holland.
It is M3x8 and 12,9 the last number is very important it is very very strong and durable.
Eine M3 Schraube in 12.9 hält z.B. min. 614 kg Zugfestigkeit aus!
it stands 614 kg tensile strenght.
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Resistance to shear force is more important in case of the Impact, that's something else as tensile strength
The probe in combination with the probe holder acts like a pair of scissors when a pellet is fired, with all consequences as can be read above....
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***UPDATE***
First off, I want to say that I REALLY appreciate all the response and support I've received from everyone here on AGN. It's an outstanding testimony to the tightness, if you will, of the airgunning community. Thank you all, VERY much!
Secondly, with regards to AoA, I can't think of a SINGLE thing that they could be doing better in the handling of this situation. Their quick response and willingness to go above and beyond to make this right (even though they aren't the manufacturer and, ultimately, are in no way responsible for the malfunction) has been mind-blowing. AoA, through the moderators of this forum, were trying to get in touch with me before I was even able to call them. The professionalism and thoroughness in their handling of this matter up to this point has secured me as an AoA customer FOR LIFE. They have assured me that the updated part(s) that will be used in the repair will keep this issue from ever reoccurring. Special thanks to both Kip and Kevin of AoA. They have been in touch with me to keep me in the loop during EVERY step of the process up to this time. My rifle was received at their facility yesterday before noon. Keep in mind, the malfunction occurred Wednesday evening around 6:30. Kevin called me as soon as it was in their technician's hands to let me know what the process would involve and even gave me an ETA of Tuesday, Nov. 1 for receiving my rifle back. As previously stated, their professionalism in this situation has been second to none, and I have no reason to believe that the integrity with which they've handled this situation up to now will not be carried through to the very end.
All that being said, I am quite disappointed that FX hasn't taken the time to chime in on this issue. After all, it IS their product. In my opinion, AoA shouldn't be left alone to defend the FX brand. FX should sack-up and defend their own name to assure me, and every other Impact owner that they are aware, concerned, and ON TOP of this to the extent that they're doing every thing possible to see that this never happens to anyone else. But... Again... Regardless of being left holding the proverbial bag that doesn't 'actually' belong to them, AoA has handled this matter in outstanding fashion.
Just one more thing... It would've been terribly gratifying if Ted had chimed in on this topic as well... NOT because he's in ANY way obligated to do so. But just because it would've been pretty cool to have 'The Man', himself, respond to my post... Call it vanity... Whatever... ;-)
Again... Thank you ALL for your responses and support!
First off, I want to say that I REALLY appreciate all the response and support I've received from everyone here on AGN. It's an outstanding testimony to the tightness, if you will, of the airgunning community. Thank you all, VERY much!
Secondly, with regards to AoA, I can't think of a SINGLE thing that they could be doing better in the handling of this situation. Their quick response and willingness to go above and beyond to make this right (even though they aren't the manufacturer and, ultimately, are in no way responsible for the malfunction) has been mind-blowing. AoA, through the moderators of this forum, were trying to get in touch with me before I was even able to call them. The professionalism and thoroughness in their handling of this matter up to this point has secured me as an AoA customer FOR LIFE. They have assured me that the updated part(s) that will be used in the repair will keep this issue from ever reoccurring. Special thanks to both Kip and Kevin of AoA. They have been in touch with me to keep me in the loop during EVERY step of the process up to this time. My rifle was received at their facility yesterday before noon. Keep in mind, the malfunction occurred Wednesday evening around 6:30. Kevin called me as soon as it was in their technician's hands to let me know what the process would involve and even gave me an ETA of Tuesday, Nov. 1 for receiving my rifle back. As previously stated, their professionalism in this situation has been second to none, and I have no reason to believe that the integrity with which they've handled this situation up to now will not be carried through to the very end.
All that being said, I am quite disappointed that FX hasn't taken the time to chime in on this issue. After all, it IS their product. In my opinion, AoA shouldn't be left alone to defend the FX brand. FX should sack-up and defend their own name to assure me, and every other Impact owner that they are aware, concerned, and ON TOP of this to the extent that they're doing every thing possible to see that this never happens to anyone else. But... Again... Regardless of being left holding the proverbial bag that doesn't 'actually' belong to them, AoA has handled this matter in outstanding fashion.
Just one more thing... It would've been terribly gratifying if Ted had chimed in on this topic as well... NOT because he's in ANY way obligated to do so. But just because it would've been pretty cool to have 'The Man', himself, respond to my post... Call it vanity... Whatever... ;-)
Again... Thank you ALL for your responses and support!
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The original screw from FX is most likely 12.9 quality as well.
Unless they have really searched the fastner market for someting of lower quality.
I think it would be alot more difficult to find a lower quality set screws in Sweden or Western Europe.
So most likely they used a standard set screw that has 12,9 quality because the are most common.
Its only when they are silver color you might suspect lower strength, if it is electro zink plated. Then it goes down in strength because of the
hydrogen brittle effect from the surface treatment. Normally it wil then be sold as 8,8.
This is why high yield screws are always black or without surface treatment
12.9 means tensile strengt is 1200mpa and yeild is 90% of tensile.
So the max stress in a M3 would be 1200*0,9*1,3²*3,14 = 5731N . Sher is approx 75% of this = 4300N (437kg)
The force on the pellet probe would be for .30 (if the pressure goes to 150bar)
15*3,14*(7,62/2)² = 683N
683N load vs 4300N set screw strenght
The problem is not the static strength of the set screw. The threads and crack initiations is probably the problem.
And the reason why one should never use threaded screws or similar to bend or take shear force.
Pins are uset for that.
If threaded coils where used to make suspensions springs for cars.
It doesnt matter if the thickness of the coil is the same, or if the material is super tough.
The springs would brake after only days.
Some reservation about everything above. I dont know exactly how the pellet probe works, or how the set screw is mounted.
Have never taken it apart.
With this said, I still love the FX guns nad everything about them. Better to lead the development and take some risks.
Nobody remembers a coward
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Ok then my previous post is "valid" (with the exception of heavy generalization and that it does not apply if the screw is loose
and takes no consideration to friction if it was tight.....and beer ).
The design is pretty much as I thought.
I would think best solve is to increase existing hole to M4 and use set screw with pin tip.
OR place steel ball in the hole before set screw
and takes no consideration to friction if it was tight.....and beer ).
The design is pretty much as I thought.
I would think best solve is to increase existing hole to M4 and use set screw with pin tip.
OR place steel ball in the hole before set screw
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Thank you Ernest.
I think if the probe can be screw inside the block that would make it much more secure and simple.
But FX would have to send all of us a new designed block and probe ,,screw in probe.
Hope you understand what I mean.
Regards
GQ
I think if the probe can be screw inside the block that would make it much more secure and simple.
But FX would have to send all of us a new designed block and probe ,,screw in probe.
Hope you understand what I mean.
Regards
GQ
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