How to remove a center pin

[Johnm1]

Smith and Wesson call it a base pin. I have seen it called a quill. I just call it a center pin. It is the pin the cylinder revolves around on many, if not all, top break revolvers.

It's a press fit and not meant to come out. I've been able to remove one, but at the expense of the pin. I need to figure a way to remove one without destroying. I figure this will involve dry ice to freeze/contract it but don't see a practical way to pull it.

Any thoughts?





Removing and replacing the center pin on my second 38 DA was really the correct fix for a bent Center pin. This will come into play on my next series of revolvers that I'll restore. I have two H&A 1901 double action revolvers. Both need to have the center pin removed so I can install a replacement cylinder latch. But the concept is the same. In my mind I can't see a tool that can pull though I can envision modifying a press to push it into place.

Here are some pictures of the H&A. It is a little more difficult in that there isn't a symmetrical place to grab the center pan. The slot in the side of this center pin is where the cylinder release spring is installed unfortunately it is installed with the center pin.

 

[a5werkes]

Just spitballing here.
1.Consider drilling a cross thru-hole into which a piece of drill rod could be inserted effectively creating a T-tool handle that could be wiggled / twisted / tapped upon after some Kano kroil set in press fit part mating.
2. Consider tapping the open end of the cylinder with a fine pitch thread for 1" or so that a bolt could be threaded into the cylinder, again providing a point to apply a twisting - pull action or even a sliding hammer to separate the parts.
3. Consider supporting the interior wall of the cylinder with a rachet socket or again drill rod so the cylinder could be clamped firmly in a vise, then protectively tap the frame of the revolver to separate the press fit.

I fabricated a slide hammer to install a replacement magazine throat tube on an FN shotgun.

 

[Johnm1]

Just spitballing here.

Spitballing is what I asked for. I like the idea of a custom slide hammer. The H&A revolvers could be threaded to assist in providing a point to grab onto. This idea has legs.

 

[doubleh]

Heating the pin red hot and dousing it with water will shrink it. Heat transfer to the frame might be a problem though.

 

[Johnm1]

I’ve tried heat and penetrating oil. I figure I’ll need to get the center pin frozen while leaving the frame at room temperature for the install. Even in 1880 I’m pretty sure the pin was frozen for the installation.

I’ve frozen the entire frame then heated it while applying Kroil hoping to get just a little bit of movement during the thermal changes to allow some of the oil to get inside. But as a press fit it isn’t enough to easily pull it out.

That helps a little for removal but not enough to avoid damaging the center pin. At least the way I’ve been trying to remove the pin.

I think the slide hammer will work for removal though. Either thread the center pin or more likely drill a hole for a cross pin and then use the slide hammer. I have more than enough junk frames to test it on.

 

[Big Bore 44]

Your pics show what could be a crosspin between the arbor and the pivot screw. Check that hole and see if it goes through. Puch the pin out from the other side.

 

[Johnm1]

Your pics show what could be a crosspin between the arbor and the pivot screw. Check that hole and see if it goes through. Puch the pin out from the other side.

That pin is out. Friction and 120 years of corrosion are holding it in place.

 

[Big Bore 44]

Soak in ATF and Acetone mix overnight. Followed by GENTLE twisting back and forth, should break the crud bond.

 

[NIGHTLORD40K]

I like the slide hammer idea.
The only other thought I had was possibly use a broken shell extractor if you could find one that will fit into the base pin.

 

[NIGHTLORD40K]

Or maybe an expanding drywall anchor?

 

[Johnm1]

Soak in ATF and Acetone mix overnight. Followed by GENTLE twisting back and forth, should break the crud bond.

That is my go to penetrant. For this project I used the ATF and Acetone in my sonic cleaner with heat as well as letting it soak for days in that mix. It was never meant to be removed.

Lesson learned - don't use the plastic tray in your sonic cleaner when you use acetone. When your done you don't have a tray anymore.

 

[Johnm1]

Its amazing what one can find on the internet if one keeps searching. I really need to buy the standard catalog of Smith & Wesson. I dont even need the most recent version as my interest is in the older stuff. But I found the following at this website

Smith & Wesson .38 Caliber Revolver Descriptions

This chapter contains minutely detailed descriptions of almost every .38 caliber hand gun manufactured by the Smith & Wesson company until the 1940's.

sportsmansvintagepress.com

"Base pin screwed into body of barrel forming straight round bearing for cylinder strap slotted forward of post cut to receive barrel catch cam and cylinder hook."

Initial attempts to remove the bent one was unsuccessful. But I haven't tried real hard. This is true for at least all of the early double actions. It's likely true for the single actions as well but I haven't confirmed that yet.

 

[a5werkes]

......so, the base pin is screwed in to the barrel support lug area until the slot in the base pin aligns with the slot in the barrel support?

 

[Johnm1]

Apparently. I'll understand it better when I remove mine.

 

[Big Bore 44]

You say there's supposed to be a spring in the slot? If it's snapped off, perhaps a piece is still in the slot acting as a lock key. A small pick or shim may push it out of the slot and allow the quill to turn. Also check for burrs in the slots.

 

[Steve762us]

Apparently. I'll understand it better when I remove mine.

A patent search might reveal some...revealing diagrams...

 

[Johnm1]

A patent search might reveal some...revealing diagrams...

Might. I figure that it’ll unscrew one way or the other. I just haven’t gotten to it other than one initial attempt. I have the bent one to practice on. So no loss if I bugger it up. But in the end I’d like to confirm one way or the other.

 

[Big Bore 44]

Another thing to consider, it just might be a LEFT hand thread. Try turning it the wrong way.