Counterbore

D

Dave Hub

Joined
Dec 10, 2014
Messages
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I am working on my first folder. If I were to countersink my 1/4” pivot screw, what tool would I use? I think I am going to get the caged bearings and counterbore from Ticonnectore.com. The pivot screws have me a bit confused though. Do they differ in size depending on the site? I want a 1/4” barrel. Not sure what tool to get.
 
The best place to start is to contact the maker/supplier of the bearings and ask them. They know which counterbore fits which bearing. They also can give you info on using them and fitting the bearings.
 
You don’t have to use bearings unless you want to. You can get washers and take the thickness into account when you make your backspacer.
McMaster Carr also has counterbores.

If you order pivots or bearings from Alpha Knife Supply they have the dimensions on their website.
It would be awesome if they carried counterbores to match their stock.
 
If you are using titanium liners, I suggest investing in a carbide counterbore for both the pivot screw and the bearings if you using them. Ticonnector sells the carbide counterbores and the counterbore pilots that will fit there screws and bearings. I use bearings mostly from Alpha knife supply and had to search far and wide for a counterbore but did find one. I use pivot screws from ticonnector often and did purchase there counterbore for the screws. The pivot screws do vary in size from every manufacturer. I have about five different carbide counterbores for different pivot screws.
 
Counterbores typically have two dimensions: The OD of the cutter, and then the "pilot" od, which should correspond to the ID of your bearing, or more specifically, to the OD of your pivot hole. Pilots also have "stems" which fit into the "pilot hole" on your counter bore. Depending on the size of the counterbore, the pilot hole might be 1/8, 5/32, 3/16 etc....
A lot of times you can just buy your counterbore set up with the proper cutter OD and a corresponding pilot, but if you need a specific pilot size, and/or you already have a cutter, the pilots can be bought seperately. If you have a lathe, you can make your own, or turn one down as needed.

For caged bearings, the OD doesn't have to be super precise, and can run a little larger if necessary, as the pivot will keep the bearing from moving side to side.
 
Perhaps your knifeparts supplier is best source.
All my counterbores are standardised size for their appropriate sockethead screw. Dunno how that may relate to thrustbearing diameters.
Lucky me, most anything I want counterbored or spotfaced nowdays is done CNC with an endmill.
 
Alan Davis Knives said:
If you are using titanium liners, I suggest investing in a carbide counterbore for both the pivot screw and the bearings if you using them. Ticonnector sells the carbide counterbores and the counterbore pilots that will fit there screws and bearings. I use bearings mostly from Alpha knife supply and had to search far and wide for a counterbore but did find one. I use pivot screws from ticonnector often and did purchase there counterbore for the screws. The pivot screws do vary in size from every manufacturer. I have about five different carbide counterbores for different pivot screws.
Click to expand...

Do you remember where? I'm sitting on a pile of AKS bearings I have to interpolate cbores for due to the odd OD.

I can't find a combination of cbore diameter and pilot diameter for 3/16 pivots anywhere.
 
kuraki said:
Do you remember where? I'm sitting on a pile of AKS bearings I have to interpolate cbores for due to the odd OD.

I can't find a combination of cbore diameter and pilot diameter for 3/16 pivots anywhere.
Click to expand...

I picked one up on ebay for the 1/8" bearings that was I believe 19/32 and had to order one for the 3/16" special. I think it was at rock river tools and there was a charge for cutting it down. If I remember correctly, it was around a $100 total.
 
I don't recommend using a counterbore. I found counterbores to be uneven and inaccurate. Tight tolerances are critical to having bearings work well. The biggest advantage of using a rotary table is it compensates for your milling machine column and/or head not being perfectly straight up and down.

If you use a rotary table and an end mill you will have a much cleaner, more accurate pocket in any diameter you want.

Chuck
 
Alpha Knife Supply said:
compensates for your milling machine column and/or head not being perfectly straight up and down.
Click to expand...
That wont compensate against straight up/down. Assuming was meant as not perpendicular to table.
If not perpendicular, a milled counterbore will be slightly conical. Insignifigant to a pocketknife, but none the less...
Our Bridgeport had too much saddletime, the old girl is swaybacked about .008, I need to keep table centered within the sweetspot if something calls for extra precision.
 
Bill DeShivs said:
On a machine as simple as a folding knife, bearings seem to be overkill.
Click to expand...
The same thing could be said for making a knife that opens by pushing a button or lever to release a spring loaded blade.

Bearings may be overkill, but collectors like folding knives that are easy to open with a finger. Bearings are an easy way to make flipping folding knives.

It is easier to buy groceries by making what collectors like.

Chuck
 
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