You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Replacing the Base Pin for 1860 Army
- Thread starter bear108
- Start date
Bear
It is called the arbor.
It is threaded into the frame to the proper position and orientation which is precise to within about two thousandths and less than half a degree. If it is very far off, the pistol will not go back together.
Then it is pinned in place with a round pin. The pin can be found by looking into the hammer channel at the rear of the frame. If the pistol has been fired a lot, you may have to clean up the hammer channel so you can see the back of the arbor and the pin. To get the arbor to turn out, you must remove the pin. This pin is only about 3/32 of an inch in diameter. If you have a steel frame revolver, the pin is likely softer than the frame and so the drill will want to follow the pin. If the revolver has a brass frame the drill will want to wander off of the pin into the brass. You will almost certainly need a drill press to do this job.
Some folks have said that you can remove this pin with an easy out. But by and large (IMHO) there are two problems with this technique. First of all, an easy out is used for threaded fasteners and the pin is not threaded on 1860 and smaller frames. It is an interference fit. Second, I have not seen an easy out small enough to get into this pin. You might be able to thread it for a number four screw, turn a screw into it and use that to pull out the pin.
Another technique might be to completely drill the pin so the entire pin is sacrificed. Then when the arbor is properly positioned, drill and thread the arbor and hole so as to accept a headless screw.
When you reinstall the new arbor, the dimension from the recoil shield to the hole for the wedge is important. This is so the arbor, barrel and cylinder fit together properly. Also the alignment of the arbor with regard to the wedge hole is pretty critical. The centerline of the wedge hole must be coincident with the centerline of the wedge hole in the barrel, or you will have difficulty getting the wedge to go through.
I have done this operation on a brass frame revolver and can't say I am thrilled with the outcome. It was a junk frame so it did not matter The arbor I installed was not the correct one for the revolver so the barrel never did fit.
I might ask why you are changing out the arbor?
It is called the arbor.
It is threaded into the frame to the proper position and orientation which is precise to within about two thousandths and less than half a degree. If it is very far off, the pistol will not go back together.
Then it is pinned in place with a round pin. The pin can be found by looking into the hammer channel at the rear of the frame. If the pistol has been fired a lot, you may have to clean up the hammer channel so you can see the back of the arbor and the pin. To get the arbor to turn out, you must remove the pin. This pin is only about 3/32 of an inch in diameter. If you have a steel frame revolver, the pin is likely softer than the frame and so the drill will want to follow the pin. If the revolver has a brass frame the drill will want to wander off of the pin into the brass. You will almost certainly need a drill press to do this job.
Some folks have said that you can remove this pin with an easy out. But by and large (IMHO) there are two problems with this technique. First of all, an easy out is used for threaded fasteners and the pin is not threaded on 1860 and smaller frames. It is an interference fit. Second, I have not seen an easy out small enough to get into this pin. You might be able to thread it for a number four screw, turn a screw into it and use that to pull out the pin.
Another technique might be to completely drill the pin so the entire pin is sacrificed. Then when the arbor is properly positioned, drill and thread the arbor and hole so as to accept a headless screw.
When you reinstall the new arbor, the dimension from the recoil shield to the hole for the wedge is important. This is so the arbor, barrel and cylinder fit together properly. Also the alignment of the arbor with regard to the wedge hole is pretty critical. The centerline of the wedge hole must be coincident with the centerline of the wedge hole in the barrel, or you will have difficulty getting the wedge to go through.
I have done this operation on a brass frame revolver and can't say I am thrilled with the outcome. It was a junk frame so it did not matter The arbor I installed was not the correct one for the revolver so the barrel never did fit.
I might ask why you are changing out the arbor?
Ok. I have to ability and the shop to do all that, but it sounds as if it may be more trouble that is worth. My cylinder does not slide on so easily and my wedge seems to be to wide, to fit properly. I guess that my only real opinion is to get out one of the files and start filing some metal down, a little at a time. Thank you so much for the proper way to replace the arbor. At least j learned something new. Thank you.
As to the two symptoms
You said that the cylinder does not slide onto the arbor easily.
1. Once it is on the arbor, does the cylinder turn easily?
If it does, you may need to go to town on the front of the arbor. (Carefully) If you are familiar with shop work, you know how to firgure out where the arbor is interfering with the cylinder.
2. Can you put the revolver together and get it to cycle by cocking the hammer?
3. With the revolver assembled, do you have a gap between the front of the cylinder and the forcing cone of the barrel that measures somewhere between 6 and 12 thousandths of an inch?
4. With the revolver assembled does it line up properly, that is to say, does the chamber line up properly with the barrel and the hammer?
5. Does the revolver lock up nice and tight?
The function of the wedge is to hold the barrel at the right location and to a certain small extent to control the gap between the barrel and the forcing cone. It has always been my assumption/opinion that when you look through the wedge hole with the barrel in place but with the wedge removed, you should see a little of the front of the arbor toward the front of the hole. This allows the wedge to bear against the arbor and press back on the barrel as the wedge is pressed into the revolver. The barrel gap should not tighten up very much because this gap should be set by the arbor bottoming out in the hole in the barrel.
If you have a revolver that never gets very tight or never lines up right, you may have to look at it as a learning experience.
I am sure others will have additional things to say.
You said that the cylinder does not slide onto the arbor easily.
1. Once it is on the arbor, does the cylinder turn easily?
If it does, you may need to go to town on the front of the arbor. (Carefully) If you are familiar with shop work, you know how to firgure out where the arbor is interfering with the cylinder.
2. Can you put the revolver together and get it to cycle by cocking the hammer?
3. With the revolver assembled, do you have a gap between the front of the cylinder and the forcing cone of the barrel that measures somewhere between 6 and 12 thousandths of an inch?
4. With the revolver assembled does it line up properly, that is to say, does the chamber line up properly with the barrel and the hammer?
5. Does the revolver lock up nice and tight?
The function of the wedge is to hold the barrel at the right location and to a certain small extent to control the gap between the barrel and the forcing cone. It has always been my assumption/opinion that when you look through the wedge hole with the barrel in place but with the wedge removed, you should see a little of the front of the arbor toward the front of the hole. This allows the wedge to bear against the arbor and press back on the barrel as the wedge is pressed into the revolver. The barrel gap should not tighten up very much because this gap should be set by the arbor bottoming out in the hole in the barrel.
If you have a revolver that never gets very tight or never lines up right, you may have to look at it as a learning experience.
I am sure others will have additional things to say.
I am not a gunsmith, just have had A LOT of C&Bs. After dressing any burrs or hanups on the arbor, maybe the central through the cylinder could be machined or drilled out a thou or two at a time. I don't mind being corrected if that is a dumb idea. The surface of the arbor is case hardened and might not machine as easily as the cylinder which all see pretty soft.