secret of smooth sebenza found!

DaveH

DaveH

Joined
Dec 2, 1999
Messages
12,249
OK, maybe just a secret. I pulled apart a year 2000 made classic I picked up a short while back. When I got it apart the bushing was quite easy to remove, in fact it fell right out. After cleaning and reassembly lockup was sebenza perfect.

In a sample of newer sebenzas post 2004, the bushing fit quite tightly and required a bit of force to pop out. My theory is that newer sebenza bushings are fitting tighter between the outer diameter of the bushing and the inner race of the blade, or that well used sebenza bushing has worn sufficiently so that in either case the opening of older or well used knives is much superior.

I think what I'll try is picking up a dremel felt wheel and use some flitz or possibly something more aggressive an trying to polish the blade hole where the bushing rides.
 
DaveH said:
OK, maybe just a secret. I pulled apart a year 2000 made classic I picked up a short while back. When I got it apart the bushing was quite easy to remove, in fact it fell right out. After cleaning and reassembly lockup was sebenza perfect.

In a sample of newer sebenzas post 2004, the bushing fit quite tightly and required a bit of force to pop out. My theory is that newer sebenza bushings are fitting tighter between the outer diameter of the bushing and the inner race of the blade, or that well used sebenza bushing has worn sufficiently so that in either case the opening of older or well used knives is much superior.

I think what I'll try is picking up a dremel felt wheel and use some flitz or possibly something more aggressive an trying to polish the blade hole where the bushing rides.
Click to expand...

That would be a mistake. Normal wear will smooth that fit very differently than a felt wheel on a dremel. If you want to accelerate the wear to smooth that fit consider a super fine abrasive mixed in your oil and just work the knife normally. When I say fine abrasive I mean fine. Something like the
.5 micron diamond paste mixed with oil.

Then just open the knife 100 times or so. Then clean it all out and re-lube.

I would polish the washers on a leather pad covered with the fine abrasive.
Just until they BEGIN to take a polish. Then STOP. You don't want to introduce a bunch of slop into this nicely fit system.

Jim
 
Justabuyer said:
I would polish the washers on a leather pad covered with the fine abrasive.
Just until they BEGIN to take a polish. Then STOP. You don't want to introduce a bunch of slop into this nicely fit system.

Jim
Click to expand...
I agree. Try working on the bronze bushings first. Close tolorences that Chris fits his Sebenza's are for a reason Dave. I'd hate to see you hurt one of your babies. I found also, especially on a Seb with a little time on them, flipping the washers sometimes works for smoothing! They've seemed to ware more a bit on the one side.
;)
 
I also agree. A dremel would not be able to polish the outside diameter of the bushing evenly.
 
I assumed you'd polish the inside of the blade hole

I very very lighty "introduced" the washers to a 10k grit wet&dry paper (10k is 2micron) which helped a lot
 
DaveH said:
OK, maybe just a secret. I pulled apart a year 2000 made classic I picked up a short while back. When I got it apart the bushing was quite easy to remove, in fact it fell right out. After cleaning and reassembly lockup was sebenza perfect.

In a sample of newer sebenzas post 2004, the bushing fit quite tightly and required a bit of force to pop out. My theory is that newer sebenza bushings are fitting tighter between the outer diameter of the bushing and the inner race of the blade, or that well used sebenza bushing has worn sufficiently so that in either case the opening of older or well used knives is much superior.

I think what I'll try is picking up a dremel felt wheel and use some flitz or possibly something more aggressive an trying to polish the blade hole where the bushing rides.
Click to expand...


Hi Dave,

I have a bunch of Sebenzas. All I bought new. Some are a little stiff opening at first but all are smooth. Do you mean stiff (takes more effort) to open or are yours really jerky, rough, bumpy, etc. to open?

Thanks,
Rich
 
I have a newer sebenza that is nice and smooth, but I guess there is a break in time? like most thgins, even the best shoes I ever got felt a nice when I got them, but got even better after a few weeks of wearing them...But even before the "break in period" on my sebenza I have no complaints!
 
When you take the Sebbie apart always be sure to keep the same side of the washers facing the handles. I think these get textured over time by pressing against the harder handles and, if you turn 'em around, your Sebbie will be difficult to open the first few times although they will soon burnish themselves against the blade. Remember, that's hardened steel against a copper alloy . . .
 
Dave, you might be onto something, but a demel would be the wrong tool. Try a barrel lap tool in a press with a fine grinding compound (the right tool). I would be interested to see if a Mayo'd Seb would show a smoother pivot fit...
 
They call me the butcher bwhahahahah!

I haven't tried it yet, but yes was going to do the blade hole, I'll look up a barrel lap.
 
Dave,
I have good luck with McMaster Carr diamond lapping paste. I use the finest which is .25 micron. I thought by using the finest I would not "over do it" and end up removing too much material. The item number is 4776A51.
Stu
 
WhitleyStu said:
Dave,
I have good luck with McMaster Carr diamond lapping paste. I use the finest which is .25 micron. I thought by using the finest I would not "over do it" and end up removing too much material. The item number is 4776A51.
Stu
Click to expand...

That is fine abrasive! Just a caution even super fine diamond cuts faster than you think. LESS IS MORE for this kind of operation. Be prepared to do a little bit then stop and put it back together to check. A little to far is WAY to far.
 
I find that the only real friction I get when opening my Sebenza is from the ball detent. If I hold the lockbar out of the way with the knife open (so that the ball detent does not contact the blade) the blade will fall closed on it's own.
 
slide13 said:
I find that the only real friction I get when opening my Sebenza is from the ball detent. If I hold the lockbar out of the way with the knife open (so that the ball detent does not contact the blade) the blade will fall closed on it's own.
Click to expand...

Lube the detent and it's even smoother!
 
If your man enough... While you have the knife disassembled you can VERY GENTLY bend the lock bar out a bit (be careful! You will seriously F-up the lock if you over-bend it). This will lessen the amount of pressure on the blade, smoothing it out further.

So Dave, have you tried it yet. Your welcome to come over and use my Drill Press.
 
Haven't tried it yet, maybe this weekend. If I get real ambitious I might take photo's too.
 
Just found the article . . . (http://findarticles.com/p/articles/mi_m0BTT/is_143_23/ai_56221735)

According to this article CRK knives are held to 0.0002" tolerances. You muck about at those tolerances and you knife is going back for repairs soon. If the action seems rough at first, take it apart and lube it then open and close it perhaps 25 times (don't flip it open). This should burnish the thrust washers where they face the blade and give you your smoothest possible action. Make sure you lube the ceramic ball detent and the race (that little scratch) it runs in. I put a dab in the detent hole in the blade and let that lubricate the ball.

If I were to try and lap anything at these tolerances I would never use a diamond product, they cut too fast. A regular machinist's lapping compound (I use J-B Bore Cleaning compound - Brownells or Midway) would be all I would use.
 
iamsmiling said:
Just found the article . . . (http://findarticles.com/p/articles/mi_m0BTT/is_143_23/ai_56221735)

According to this article CRK knives are held to 0.0002" tolerances. You muck about at those tolerances and you knife is going back for repairs soon. If the action seems rough at first, take it apart and lube it then open and close it perhaps 25 times (don't flip it open). This should burnish the thrust washers where they face the blade and give you your smoothest possible action. Make sure you lube the ceramic ball detent and the race (that little scratch) it runs in. I put a dab in the detent hole in the blade and let that lubricate the ball.

If I were to try and lap anything at these tolerances I would never use a diamond product, they cut too fast. A regular machinist's lapping compound (I use J-B Bore Cleaning compound - Brownells or Midway) would be all I would use.
Click to expand...

JB-bore scrub really CUTS!! I use it to settle new 1911 pistols in. I mix it with oil to make a slurry that will just drip off a stick. Load the gun up with it. Upper lugs, standing lugs, rails, and barrel hood ext. Handcycle the gun 50 to 100 times. Wash the gun out real well and relube.

Makes the gun run like a sewing machine. if you remove the springs and operate the pistol it makes it feel like oiled glass.


The point being that JB really cuts and removes metal. I WOULD NEVER put that stuff in the INSIDE of a barrel.
 
I use it on new barrels as a polish, not as a routine cleaning tool; I'd have nothing left but smoothbores!

Besides, I'd never try to lap anything produced to .0002" tolerances, you'd take that nice centerless grinder finish off the bushing.
 
iamsmiling said:
If I were to try and lap anything at these tolerances I would never use a diamond product, they cut too fast.
Click to expand...
The diamond lapping paste I use is .25 micron. No even close to a fast cutting action. I have used it on the two washers on either side of my Seb blade and it is still pretty tight. There are some fast cutting compounds, but this is not one of them.
 
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