Buck 591 Paradigm Auto Disassembly

Culprit99

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I just set a new world record: the longest I’ve made it before disassembling a new mechanical gadget to see how it works. LOL! But now that my family from out of state have gone home…

The Buck 591 Paradigm Shift Auto:

Observations:

The blade shape and opening/closing mechanism is obviously related to the 293 Inertia. They both use the same coil springs to open the blade.

The blade washers/bushings are notched so they stay fixed relative to the blade, so the smoothness of opening closing is between the bushings and the liners - interesting choice since the liners are likely less precisely machined than the sides of the blade. Mine was sticky upon closing. Opened perfectly, but when you released the lock and started pushing the blade closed, you had to overcome some stick before it would move freely. I tried a drop of oil before disassembly but that didn’t solve it. While apart, I rubbed both sides of each washer in circles (approximately 20 each side) on an old Buck hard Arkansas stone. That fixed it - and helped me resist the temptation to drill the three rivets securing the liners to the backspacer so I could smooth the inside of the liners on a stone as well. If I had drilled the rivets, it appears M2x8 pan head bolts would fit for reassembly with just a couple thousandths filed off the length to fit the recesses in the G10 scales. The M2 hex nuts I have would need the peaks files down in order to fit in the recesses. Maybe another day, but not tonight.

The cross pin that locks the blade both open and closed is actuated by a ramp in the rotating bolster. It is greased from the factory with a heavy good old fashioned machine grease - something that will stay put. I reassembled with similar.

During reassembly I used a lighter grease - hinge and high pressure grease - to hold the blade washers/bushings and coil springs in place. The knife functioned great with this grease in place after reassembly, but I washed it out with Strike Hold - a dry film lubricant that won’t attract as much pocket lint and dust as the hinge and high pressure grease does. The knife functions just as well with that as it did with the light grease, and just as well as it did from the factory.

Found remnants of blue Locktite upon disassembly and reassembled with the same.

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Interesting.

I once rebuilt a 440 from an old Charger.
I was very careful to keep track of everything.
When I got it all back together I had a bolt left over.
I couldn't figure out how.

Of course later my buddy admitted to placing it amongst the parts.

I didn't ask for help next time.
😉
 
Interesting.

I once rebuilt a 440 from an old Charger.
I was very careful to keep track of everything.
When I got it all back together I had a bolt left over.
I couldn't figure out how.

Of course later my buddy admitted to placing it amongst the parts.

I didn't ask for help next time.
😉
Everyone needs a friend like that! LOL!
 
I just set a new world record: the longest I’ve made it before disassembling a new mechanical gadget to see how it works. LOL! But now that my family from out of state have gone home…

The Buck 591 Paradigm Shift Auto:

Observations:

The blade shape and opening/closing mechanism is obviously related to the 293 Inertia. They both use the same coil springs to open the blade.

The blade washers/bushings are notched so they stay fixed relative to the blade, so the smoothness of opening closing is between the bushings and the liners - interesting choice since the liners are likely less precisely machined than the sides of the blade. Mine was sticky upon closing. Opened perfectly, but when you released the lock and started pushing the blade closed, you had to overcome some stick before it would move freely. I tried a drop of oil before disassembly but that didn’t solve it. While apart, I rubbed both sides of each washer in circles (approximately 20 each side) on an old Buck hard Arkansas stone. That fixed it - and helped me resist the temptation to drill the three rivets securing the liners to the backspacer so I could smooth the inside of the liners on a stone as well. If I had drilled the rivets, it appears M2x8 pan head bolts would fit for reassembly with just a couple thousandths filed off the length to fit the recesses in the G10 scales. The M2 hex nuts I have would need the peaks files down in order to fit in the recesses. Maybe another day, but not tonight.

The cross pin that locks the blade both open and closed is actuated by a ramp in the rotating bolster. It is greased from the factory with a heavy good old fashioned machine grease - something that will stay put. I reassembled with similar.

During reassembly I used a lighter grease - hinge and high pressure grease - to hold the blade washers/bushings and coil springs in place. The knife functioned great with this grease in place after reassembly, but I washed it out with Strike Hold - a dry film lubricant that won’t attract as much pocket lint and dust as the hinge and high pressure grease does. The knife functions just as well with that as it did with the light grease, and just as well as it did from the factory.

Found remnants of blue Locktite upon disassembly and reassembled with the same.

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Hi, are the washers plastic, phosphorus bronze or something else? I've been interested in these, but wondered what the washers are.
 
Hi, are the washers plastic, phosphorus bronze or something else? I've been interested in these, but wondered what the washers are.
The washers are metal, but not bronze phosphorus. Black oxide, maybe?
 
Interesting. Thank you for getting back. So, do you suppose they are oil impregnated like an oil oxide or something else? Also, how is the lockup on it? Il've only handled one once and it was a bit loose
 
Interesting. Thank you for getting back. So, do you suppose they are oil impregnated like an oil oxide or something else? Also, how is the lockup on it? Il've only handled one once and it was a bit loose
I'm guessing the washers are not oil impregnated, but with the two coil springs providing power through 80-90% of the range of motion, they don't need to be oil impregnated to reduce friction like a flipper - as long as they are smooth and consistent then you can set the torque on the pivot appropriately and be good to go.

The two that I have (mine and my son's) both lock up tight with no play. Mine both before and after my disassembly/re-assembly. I haven’t handled any others.

I think my son has carried his daily since Christmas, and I’ve carried mine at least three times a week since then - usually more. No complaints this far!

And no, I didn’t buy a matching flashlight on purpose - that was just a happy coincidence. :)
FDE4430D-BECF-4A69-AF24-F08B52E18CB6.jpeg
 
I'm guessing the washers are not oil impregnated, but with the two coil springs providing power through 80-90% of the range of motion, they don't need to be oil impregnated to reduce friction like a flipper - as long as they are smooth and consistent then you can set the torque on the pivot appropriately and be good to go.

The two that I have (mine and my son's) both lock up tight with no play. Mine both before and after my disassembly/re-assembly. I haven’t handled any others.

I think my son has carried his daily since Christmas, and I’ve carried mine at least three times a week since then - usually more. No complaints this far!

And no, I didn’t buy a matching flashlight on purpose - that was just a happy coincidence. :)
View attachment 2504469
Thanks I really appreciate all the info. I've been eyeing these for a long time and just haven't tried one yet. They are going for around 200 right now so I have been thinking of it again. Kudos for taking it apart. Just out of curiosity when you tension the pivot do you have much to work with to get the lockup tight without too much trouble?
 
Thanks I really appreciate all the info. I've been eyeing these for a long time and just haven't tried one yet. They are going for around 200 right now so I have been thinking of it again. Kudos for taking it apart. Just out of curiosity when you tension the pivot do you have much to work with to get the lockup tight without too much trouble?
It went back together pretty easily - I didn’t have to fidget with it much to get the torque right to where it was working well.
 
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