BM spine whack failure # 2

[Deon]

I previously reported on my BM 830 lockback failing the spine whack test 20 out of 20 times.

I since dissasembled the knife and here are my observations:
1. the lock was clean so was the whole knife.
2. the lock spring is a round bar which sits rather loosely in the spring pocket and which allows for forward and lateral movement. There is no "shoulder" on the locking bar which could stop the forward (blade end) movement of the spring.
3. I checked the following lockbacks for spring design , Spyderco, Outdoor Edge and Cols Steel - all have a flat or square bar leaf spring that sits against a shoulder on the locking bar to prevent forward movement.
4. After reassembly the knife survived the spine whack tests - one failure out of 15 tests.

My conclusion is that the reason for the failure lies in the spring design which most probabaly allows for the spring to move forward , resulting in lighter spring tension on the locking bar.

Does the new Ascent 820, 830 and 840 also have this round spring bar or have they been changed to a flat or square leaf spring.

 

[Frantium]

Deon,

I've been suspecting that much for a long time, but my 830s never fail so I didn't investigate it deeper. In my older 830s the spring bar will sometimes travel and slide out of its slot, making the lock easier to disengage. I usually reseat the bar by pushing it back toward the butt. In my another older 830, I diassesembled the knife, put some epoxy (just a little dab) on one end of the bar, and reinserted the bar back to its slot. This seems to cure the problem. No more movement.

I also have two newer 830s, and yes, they still have the round bars. The only difference is that now the bar sits against the right hand scale and the spacer. It used to sit against the spacer only and between the two scales. I don't know if this alleviates the problem, since I only use the newer Ascents for less than a year, but so far no movement.

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Reynaert

 

[Deon]

Reynaert

thanks for the reply - I will try the epoxy!

 

[AK]

Deon,
I can say for certain that all of the 830's built since 1998 have a rectangular spring, and there is a custom built bump in the lock bar that keeps the spring from sliding forward.

 

[Frantium]

Rectangular spring? Mine still have those round bars. Hmm..., they're probably from an older batch. But I see the bump though.

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Reynaert