Subject: Re: Knife blade bearings

From: osan
Date: Fri, 16 Sep 1994 17:09:06 GMT

James Dollar writes:
> I recently examined a fine automatic knife by the Benchmade knife company.
> It had black scale/liners and an ATS34 bead blasted steel blade. $120.00

	Are you sure this is Benchmade?  Your description of the mechanism
	sounds very much like the Al Mar.

	If it really is benchmade, did they license the design from Al Mar,
	or are they doing the boiler plate "steal the competitions designs"
	routine?

> It does not use the traditional leaf spring design, instead it uses a coil
> spring wound around the pin that also acts as the blade's pivot pin. It was
> recessed nicely into the bolster area an was completely covered by the
blade's
> cam/pivot end. I think this is a Ranger design???

	Dunno, but the Al Mar version is supposed to be for military/police
	only.  In reality, of course, anyone can get one.  Of course I
	decided that the Mar knife was not worth the $200 price.  Besides,
	I have a far better design I will be putting together in the coming
	monthhs.  Yippee...

> It does have one drawback. The blade side to side play is dependent on
> the clearance of the liner/scale. This is accomplished through locktight on 
> the hex bolt that passes through the scale/liner, and into the pivot pin. If
> you want minimal blade side to side "flop" you start to loose smooth action
> when you press the release button. To achieve good opening characteristics
> you must open the liners up, allowing the flop. The locktight solution
> could be improved on also.

	On the Mars that I have played with, there was another weakpoint:
	a *very* lackadaisical spring rate.  I was astounded to find this
	to be the case, especially for a weapon intended primarily for
	military personnel.  If I were in combat, I would want no part of
	those knives, not even for a backup.  
> 
> Is it possible to set a bearing in the blade cam end? This would allow you to
> set the liner clearance to zero and the blade would perform much better. I
> am guessing there are no bearings you can weld or solder on (you'd want a
> sealed bearing) and a press fit on something that thin would seem out of 
> the question also. Can you (have they) used bearings on knife blades?

	I think bearings, ball bearing in particular, are generally a bad
	idea.  Knives should be as simple as possible.  The fewer the
	moving part, the less there is to go wrong.  I've built knives
	with small oilite bearings set into the blade pivot.  This works
	nicely, but is unnecessary.

	-Andy V.	[email-masked]		(Mr. X)

	"I have a high art; I hurt with cruelty those who damage me."

						-Archilochus, 650 BC