Playing with the pivot on Axis Lock

sjhong

sjhong

Joined
Jan 28, 2010
Messages
299
I was playing with the tightness of the pivot on my BM 940 and when I manage to remove all side-to-side blade play on it, the blade gets too stiff.

By "too stiff" I mean:
- I can still flick-open it without any wrist movement, but
- The blade doesn't move freely like before when the axis lock is disengaged. For instance, when I hold the knife parallel to the ground (blade spine facing the sky) and disengage the axis lock the blade doesn't "fall" like it did before.

So, what's normal on a BM axis lock: a little side-to-side blade play but free blade or no side-to-side blade play but stiff blade?
 
My experience with Axis lock BM's is that the sweet spot in pivot tension is fleeting. Even the most minute adjustments can make them too tight or too loose. I suggest adjusting it just to the point where there is no blade play then use it. It should get better as it gets broken in a bit. Keep adjusting it as it loosens up. If the pivot area and washers are clean and lubed properly you have a good chance of having the best of both worlds after some periodic adjustments and use.


sjhong said:
I was playing with the tightness of the pivot on my BM 940 and when I manage to remove all side-to-side blade play on it, the blade gets too stiff.

By "too stiff" I mean:
- I can still flick-open it without any wrist movement, but
- The blade doesn't move freely like before when the axis lock is disengaged. For instance, when I hold the knife parallel to the ground (blade spine facing the sky) and disengage the axis lock the blade doesn't "fall" like it did before.

So, what's normal on a BM axis lock: a little side-to-side blade play but free blade or no side-to-side blade play but stiff blade?
Click to expand...
 
Last edited:
sjhong said:
By "too stiff" I mean:
- I can still flick-open it without any wrist movement, but
- The blade doesn't move freely like before when the axis lock is disengaged. For instance, when I hold the knife parallel to the ground (blade spine facing the sky) and disengage the axis lock the blade doesn't "fall" like it did before.
Click to expand...

As long as it opens without effort, I don't really see anything wrong with it. Axis locks are very difficult to find the perfect sweet spot where the blade opens smoothly and easily.

You may want to make sure that there's no debris in the pivot area that could be distorting the washers and making the blade bind slightly when pulling the lock back.

If you really want to smooth it out, get some stiff cardboard and polishing compound and gently polish all the contacting surfaces in the pivot area (liners, washers and blade tang). Do it carefully so you don't remove too much material and make the problem much much worse.

After years of EDC and heavy use, my 710 still opens as smoothly as the day I got it with little to no blade play (and this is with a home made omega spring in there as well).
 
Psychopomp said:
As long as it opens without effort, I don't really see anything wrong with it. Axis locks are very difficult to find the perfect sweet spot where the blade opens smoothly and easily.
Click to expand...
Yeah, I rather have no blade play at all and have it a little stiff. It still opens and closes fine.
 
I've always thought Benchmade would be well served by adding a bushing system to the axis lock folders. It wouldn't add much, if anything at all, to production costs and would certainly eliminate the headache the end user suffers trying to find the sweet spot.
 
Psychopomp said:
I've always thought Benchmade would be well served by adding a bushing system to the axis lock folders. It wouldn't add much, if anything at all, to production costs and would certainly eliminate the headache the end user suffers trying to find the sweet spot.
Click to expand...

Then comes the headache of setting the overall length of the bushing to achieve the "sweet spot".
 
orthogonal1 said:
Then comes the headache of setting the overall length of the bushing to achieve the "sweet spot".
Click to expand...

True, but let them worry about that :p

There's no perfect solution with any pivot system and there is always going to be some play somewhere, even if it is just handle flex around the pivot. Even a bushing system will develop play eventually and there's not a lot that can be done about that aside from replacing the bushing or enlarging the pivot which isn't feasible in production knives.

In the end, the only reasonable solution is to adjust your knives to the limit that you prefer. A little tighter with no play, or a little smoother opening with slight play.

Some wobble here and there is fine as long as lock integrity isn't compromised.
 
I have a BM Rukus. I can find the sweet spot and do minute adjustments, but after 10-20 openings it'll start to develop lateral play again.
 
Apec said:
I have a BM Rukus. I can find the sweet spot and do minute adjustments, but after 10-20 openings it'll start to develop lateral play again.
Click to expand...
Even if you apply loctite after finding the sweet spot?
 
Good lubrication helps.

A combination of lube and minute adjustment to pivot tension will deliver smooth action with zero play.
 
Try adjusting the pivot screw and adding some lube IE Breakfree CLP works for me, I had the same problem with my new 940 I bought, I adjusted pivot screw and added lube and had zero problems since..
 
The sweet spot on 'em is tiny, but worth the effort.

Clean polish and lube, use plumbers tape or locktite for the pivot screw.
 
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