Any engineers know why the metal dangerously failed on DIana trigger

[Barryg]

We are awaiting Diana's explanation (they had better be quick)do
any metal experts on here have any ideas?
So far it seems a one off.
I thought that some of you DIana owners might be interested as it's a safety thing.
You can see the broken part in this thread.
http://www.network54.com/Forum/18447...en+T06+trigger

[bighit]

possibly powdered metal?

[NickG]

looks like a sintered part to me , not a good part to be cost cutting on

[Solvo]

It's impossible to tell without a high rez image of the face of the break.
Those pics show it failed on an obvious weak point (the 90 degree angle) however you cant tell what caused the failure without seeing the metal composition and type of failure.

If it's a sintered part it's a terrible design flaw especially given the lack of a relief radius on the angle.

There could be any number of issues shown in the face though. Two tone radial would show a gradual failure initiated by older damage. but there could be anything from contaminates and corrosion to air bubbles shown in the break.

[bezzer]

Certainly looks a cast part, shame an end grain pic wasn't posted. No room for casting or treatment error when there is such a sharp angle on a part which becomes the weakest link.

edit- too slow....wot modski said

[blooregard]

I might be wrong here but I wouldn't think anyone would use Sintered metal on a sear.

We are awaiting Diana's explanation (they had better be quick)does
any metal expert here have any ideas?
So far it seems a one of.

Why do you need a quick response? Seems like the issue is resolved and as you say it is a one off. Doesn't matter what you are shooting, if there is the potential for something to come out of the business end it should be pointed in a safe direction so no harm done as long as you are handling the rifle safely.

[pastie]

I might be wrong here but I wouldn't think anyone would use Sintered metal on a sear.



Why do you need a quick response? Seems like the issue is resolved and as you say it is a one off. Doesn't matter what you are shooting, if there is the potential for something to come out of the business end it should be pointed in a safe direction so no harm done as long as you are handling the rifle safely.

That design is prone to failure, as there is a stress raiser in the right angled corner...it is where the crack propagated from. If this is made with any type of secondary flaw such as a void in the steel or any imperfections / impurity, then it will do exactly as it has here.

One would hope that this Safety Critical component is not made of any Sintered or Cast process, as that would surely result in a metal part not fit for purpose if any minor flaw was present.

Take a look at HW Sear, which is a very much tried and tested piece...it has no significant right angle to act as a stress raiser.

Diana should look at this as a matter of urgency. If there was an accident then they would have liabilities I suspect.

[Barryg]

Diana should look at this as a matter of urgency. If there was an accident then they would have liabilities I suspect.

And they can't say that they didn't know about it now it's been reported.

[lensman57]

Looks like a failure due to either stress or fatigue fracture to me but it would have been helpful if a photo of the face of the failed parts were taken. Without that it is difficult to pinpoint the cause. It may just be that the metal used in making the part was defective in one way or the other. Did it mention anywhere how old the gun was and how frequently it was used?

A.G

[look no hands]

Well this is very coincidental, I've had a T06 conversion kit for a while which has been in a XS208 and is now in a 90's Diana 34, I recently bought a Original 45 barrel to fit to my 34 but it wouldn't lock up properly on the breech due to the detente ball being smaller than the 34's, after firing a couple of shots I cocked the gun and decided to give the barrel a bit of a slam shut to see if would seat any better, the gun went off on it's own without my finger being anywhere near the trigger (luckily pointed in a safe direction), it wouldn't cock after that, I haven't stripped it down yet but I think it might be a job for today to see what's happened but I think this may be the problem.

I'll keep you posted.

Pete

[andrewM]

Barry, this is a grave complaint and it seems that it is not being taken sufficiently seriously, although we shall have to wait to see the result of Diana's investigation. Their agents/distributors, here, should be on top of this at once and it should not be necessary to have to go directly to Diana.

You could, however, speak to the 'trading standards' division of your local council and the 'health and safety' department too. This is something that they would take very seriously and they have the power to close down a business if necessary. Assuming it is a new rifle, it should be replaced, new for new.

The above steps are lines you might not presently wish to take but I think you might drop Diana an email to inform them how strongly you consider this issue to be, which could, in extremis, have resulted in a fatal injury. You might also care to inform them of the relative disinterest of their agents - assuming this to be the case. Indeed, you may wish to inform the agents (go to the CEO) of the steps you will be taking (as above) unless this problem is solved entirely to your satisfaction. You might also inform Diana - as necessary - that their reputation is at stake and that a keen interest is being shown on the blogs.

I am sure that will have a salutary effect and, frankly, it should go all the way to the top of Diana and land on the CEO's desk.

The production number should be quoted - which will enable Diana to check to see which staff were on duty and attending to which parts of the weapon at the time.

A carefully worded letter always has a sound effect and it should always go to the top. Fortunately, there was no injury but it would not have been difficult to envisage a situation where that might have occurred.

Regards
Andrew.

[blooregard]

That design is prone to failure, as there is a stress raiser in the right angled corner...it is where the crack propagated from. If this is made with any type of secondary flaw such as a void in the steel or any imperfections / impurity, then it will do exactly as it has here.

One would hope that this Safety Critical component is not made of any Sintered or Cast process, as that would surely result in a metal part not fit for purpose if any minor flaw was present.

Take a look at HW Sear, which is a very much tried and tested piece...it has no significant right angle to act as a stress raiser.

Diana should look at this as a matter of urgency. If there was an accident then they would have liabilities I suspect.

What you say is perfectly reasonable, but lets not assume Diana are less experienced or competant than yourself when it comes to design of a component, and lets also not pretend that a HW component is incapable of failure. Despite the glowing reports the HW rifles often receive they are not without their ridiculous oversights.

Without being present when a component is designed it is very difficult to place liability as the reason for the design may be perfectly defendable.

Any component in any device can fail, when it comes to guns that is why you ensure you know what their condition is and you keep them pointed in a safe direction.

[Artfull-Bodger]

That design is prone to failure, as there is a stress raiser in the right angled corner...it is where the crack propagated from. If this is made with any type of secondary flaw such as a void in the steel or any imperfections / impurity, then it will do exactly as it has here.

One would hope that this Safety Critical component is not made of any Sintered or Cast process, as that would surely result in a metal part not fit for purpose if any minor flaw was present.

Take a look at HW Sear, which is a very much tried and tested piece...it has no significant right angle to act as a stress raiser.

Diana should look at this as a matter of urgency. If there was an accident then they would have liabilities I suspect.

This ^^^

A simple radius in the corner would eliminate the stress failure point, I take it these parts are milled?

[Modski66]

The part looks like a powdered metal (sintered) component, 3D printed parts are a bit beyond mass produced goods just yet.
Powdered metal is pressed into a mould under high pressure, then fused at high temperature. I think the trigger parts on my Tempest are made this way, including the sear. Looking at the design, the high load corners are radiused to prevent stress induced fractures.
Manufacturing processes like this can be appropriate if the design is right. In this instance, I think that Diana have got it badly wrong on a critical part.

[airgunnut]

possibly powdered metal?

You beat me to it, have they started using metal printing? (it starts off as a tray of powdered metal) I'm assuming if this is the case then the hardening and tempering process is substandard or the printed parts are under more stress than the printed metal can stand.