FOLDER MAKERS... how much clearance for pivot holes?

[gixxer]

I posted this over in custom knives and guns but I wanted to see what you guys had to say also. I have some .1875 pivots , and drilled my pivot holes to .1870 and reamed with the .1875 reamer. I then chucked up the pivot in the lathe and spun it on some 2000 grit till I could get the pivot in the hole. Still fairly tight friction fit, I can push the pivot in with my fingers but I cannot spin it (unassembled in hand). How tight is too tight? My clearance is probably .001 (just throwing a number out there for that one).

So should I stick with what I got and spin the pivot with the 2000 to take a couple thou off or maybe ream to a .1890 (actually looked for a .189 reamer but found .188)? Or would that be too sloppy?

 

[flatgrinder]

I use a 0.003" clearance, so if your pivot measures 0.1875", a 0.188" reamer should do the trick.

I may be wrong, but this has worked for me. :thumbup:

 

[Nathan the Machinist]

You can sand off a few tenths (.0001") fairly easy, but you're not going to sand off a few thou (.001").

I think ideal clearance would be under a thou. A .188 reamer should be perfect.

 

[Alpha Knife Supply]

Our 3/16" pivots are machined to .1870 (+.0002" -0.0000"). We recommend knifemakers use a .1875" reamer. The pivot has raised shoulder of .1875" so it can be press fit into the liner.

 

[David Wesner]

I posted this over in custom knives and guns but I wanted to see what you guys had to say also. I have some .1875 pivots , and drilled my pivot holes to .1870 and reamed with the .1875 reamer. I then chucked up the pivot in the lathe and spun it on some 2000 grit till I could get the pivot in the hole. Still fairly tight friction fit, I can push the pivot in with my fingers but I cannot spin it (unassembled in hand). How tight is too tight? My clearance is probably .001 (just throwing a number out there for that one).

So should I stick with what I got and spin the pivot with the 2000 to take a couple thou off or maybe ream to a .1890 (actually looked for a .189 reamer but found .188)? Or would that be too sloppy?

You mention that you can't spin it.

IMHO, you want a captive pivot pin, either by staking on a flat or the press that Chuck Bybee mentioned

The only thing spinning should be the blade on the pivot pin, when you open & close the knife

 

[balibalistic]

It's getting tougher to find on spec precision pivots. i use pivots that are turned to .1870.., and use a .1875 reamer. order from the Bybee's and you'll be all set!

 

[gixxer]

Our 3/16" pivots are machined to .1870 (+.0002" -0.0000"). We recommend knifemakers use a .1875" reamer. The pivot has raised shoulder of .1875" so it can be press fit into the liner.

I have seen the pivots on your site, they are pretty sweet.

You mention that you can't spin it.

IMHO, you want a captive pivot pin, either by staking on a flat or the press that Chuck Bybee mentioned

The only thing spinning should be the blade on the pivot pin, when you open & close the knife

I guess I should have mentioned that the pivot pin is a barrel and not a press fit like the ones AKS sells. When I had said the fit was tight that was pertaining to the pivot hole in the blade itself. Once again not passing on all of the pertinent information. My bad guys...

I have a good idea now of what clearance I need, so another reamer purchase is in order. I found a couple places that sell .1880 reamers, that gives me .0005.

 

[Chuck Gedraitis Knives]

Just grab the pivot in a tap handle to hold it and buff it till it shines. You can also wrap a piece of sand paper around a round file and just give the pivot hole in your blade a couple of turns polishing it. That's all you should need.

 

[David Wesner]

I have seen the pivots on your site, they are pretty sweet.
I guess I should have mentioned that the pivot pin is a barrel and not a press fit like the ones AKS sells. When I had said the fit was tight that was pertaining to the pivot hole in the blade itself. Once again not passing on all of the pertinent information. My bad guys...

No problem :thumbup:

When a hole size is within a .0005 or so undersize, I've had the best results using a barrel lap. Load it with some clover compound or diamond paste and sneak up on a perfect slip fit.

Here's an excellent link for reasonably priced Barrel Laps @ $4.79 for a 3/16"

http://www.moldshoptools.com/catalog/list.php?category_id=102

Just trying to help here , FWIW, you can easily isolate your barrel type pivot pins by milling (or grinding) a small land or flat on the very end of the pivot pin, then "staking" a flat into the applicable liner.


EDIT TO ADD : (since Chuck was posting the same time as me)

Just grab the pivot in a tap handle to hold it and buff it till it shines. You can also wrap a piece of sand paper around a round file and just give the pivot hole in your blade a couple of turns polishing it. That's all you should need.

Or, what Chuck said





:thumbup: