restoring a cam on an 1860 hammer

[M. De Land]

This is one repair I have not made and am in need of . The bolt finger is really chewing up the soft hammer cam steel . My thinking is to either TiG weld and reshape or drill through and thread a lug stud then file to cam shape and angle, harden and set threads with loc-tite.. I think the threaded stud may be the way to go as it would give some cam angle adjustment on the thread rotation . Any thoughts ?
I got the pin pulled out of my finger rebuild and am slowly getting back to work.

 

[45D]

Your bolt spring is probably quite heavy which is the biggest contributor to "cam whittling". If the bolt arm is sliding off the side ( instead of falling off the front like it's supposed to) it really accelerates the destruction of the cam.
If needed, I grind the cam flat and mark the center. Drill a mounting hole and fashion a new cam using round stock in a drill motor and a belt sander.
It's easier if you make it "proud" on both sides and dress with it mounted. I press mine in with a vice. If you need to adjust by "clocking", you can punch it out about half way and turn it with a pair of pliers and press back in.

To keep that from happening, obviously take care of the spring tension ( 4 pounds is plenty) along with putting a negative angle on the cam "bearing surface" and an opposite angle on the bolt arm surface ( that rides the cam during cycling). That will keep the arm "engaged " with the cam ( and next to the hammer) and not allow it to slide to the side. That will maintain your bolt timing.

Mike

 

[M. De Land]

Your bolt spring is probably quite heavy which is the biggest contributor to "cam whittling". If the bolt arm is sliding off the side ( instead of falling off the front like it's supposed to) it really accelerates the destruction of the cam.
If needed, I grind the cam flat and mark the center. Drill a mounting hole and fashion a new cam using round stock in a drill motor and a belt sander.
It's easier if you make it "proud" on both sides and dress with it mounted. I press mine in with a vice. If you need to adjust by "clocking", you can punch it out about half way and turn it with a pair of pliers and press back in.

To keep that from happening, obviously take care of the spring tension ( 4 pounds is plenty) along with putting a negative angle on the cam "bearing surface" and an opposite angle on the bolt arm surface ( that rides the cam during cycling). That will keep the arm "engaged " with the cam ( and next to the hammer) and not allow it to slide to the side. That will maintain your bolt timing.

Mike

Thanks for the come back, thats what I'll do. I'm wondering how hard the new cam should be made as the hammer steel seems to soft for the job. Guess I'll try some O-1 hardened although I do have some fatigue proof steel I make firing pins from that is about half hard.

 

[Phil Coffins]

You could make and fit the cam then case hardened the whole hammer. That will give good wear and pretty colors to the finished part.

 

[45D]

The nice thing about putting the angles on the two parts is that it makes for a large bearing surface for both. That way, with a little grease they'll put up with each other!!

ASM did that with their's (that's where I got that) and it works great!! Keeps the bolt next to the hammer and away from the "edge" of the cam.

Mike

 

[M. De Land]

You could make and fit the cam then case hardened the whole hammer. That will give good wear and pretty colors to the finished part.

 

[M. De Land]

Good idea but as O-1 is oil hardened I think I'll use mild steel for the stud and case harden the whole deal together. I wonder if the interference fit of the hole to the stud will hold through heat treat (color case ) and water quench?
This gun is going to need a barrel set back, perhaps a new wedge ( this one is deformed/swelled ) and from the looks of the top back side of the bolt notches a hand shortening may be needed although the cam screwing up the bolt timing may be causing this .
I'll end fit the arbor in the set back.
This gun was made in Belgium and the only marking I could make out was a star with a capitol S under it. I checked the cylinder barrel gap and it was .027 so it needs a huge set back. This means a new wedge will need to be made and the forward barrel slots extended.
I center drilled the cam hole an will turn a new one in the lathe., harden , install adjust and get the bolt timing done probably tomorrow then set the barrel up in the lathe and lower the lug height.
Looks like the large set back may cure the short arbor situation also found in this gun.
I already dressed the main spring which had a bunch of file cross cuts and was a third stiffer than needed. The sharp muzzle crown has been cut with a crown tool and chamfered smooth. A bunch of stuff that was never attended to at the factory apparently.

 

[fishmusic]

Your bolt spring is probably quite heavy which is the biggest contributor to "cam whittling". If the bolt arm is sliding off the side ( instead of falling off the front like it's supposed to) it really accelerates the destruction of the cam.
If needed, I grind the cam flat and mark the center. Drill a mounting hole and fashion a new cam using round stock in a drill motor and a belt sander.
It's easier if you make it "proud" on both sides and dress with it mounted. I press mine in with a vice. If you need to adjust by "clocking", you can punch it out about half way and turn it with a pair of pliers and press back in.

To keep that from happening, obviously take care of the spring tension ( 4 pounds is plenty) along with putting a negative angle on the cam "bearing surface" and an opposite angle on the bolt arm surface ( that rides the cam during cycling). That will keep the arm "engaged " with the cam ( and next to the hammer) and not allow it to slide to the side. That will maintain your bolt timing.

Mike

45D,

That's some interesting information. I have a Pietta 1851 Navy which effectively has the same hammer, cam and bolt. I took the hammer out to find that the cam had been damaged and was actually loose in the hammer. I don't have the tools for making a new cam but I will order a new hammer and the lighter bolt spring. Thanks!

 

[45D]

45D,

That's some interesting information. I have a Pietta 1851 Navy which effectively has the same hammer, cam and bolt. I took the hammer out to find that the cam had been damaged and was actually loose in the hammer. I don't have the tools for making a new cam but I will order a new hammer and the lighter bolt spring. Thanks!

Thanks fishmusic!
Is your '51 "new" or rather old? The cams of the last 20 yrs have been part of the hammer machining process rather than a separate part. Either way, your new hammer will have the "built in" cam. A thin washer under the combination spring might be all you need for reducing pressure on the bolt.

Mike

 

[Rich44]

Good idea but as O-1 is oil hardened I think I'll use mild steel for the stud and case harden the whole deal together. I wonder if the interference fit of the hole to the stud will hold through heat treat (color case ) and water quench?

Just do not know why you would do that, O-1 is a great tool steel, Easy to Machine, Harden, and Drawback to what ever you want. You would never wear O-1 out.

 

[M. De Land]

Just do not know why you would do that, O-1 is a great tool steel, Easy to Machine, Harden, and Drawback to what ever you want. You would never wear O-1

I have decided I didn't want to re-case the hammer so will be using the O-1 after all. I was worried the cam of mild steel might move in the hole during heat treat or quench so will use O-1 with an interference fit and some red loctite.

 

[Rich44]

Would draw back to gun metal blue, 52-54rc and it will be the cats meow.

 

[M. De Land]

Just do not know why you would do that, O-1 is a great tool steel, Easy to Machine, Harden, and Drawback to what ever you want. You would never wear O-1 out.

Got back to work on the 60 this AM. Turned a new cam of O-1 in the lathe , filed new cam angle, fit to old, drilled out cam hole, hardened and re-set. The cam protrusion is about .070 and the cam angle taper is from top to bottom. The cam angle is clocked a couple of degree toward the axial hole from what I can see using my own 60 hammer for comparison. The work edge of the new cam was broke with a fine diamond file to remove any sharpness so as not to carve up the bolt finger. I left it full hard not drawing the temper on this particular part as it won't be doing any flexing or have sharp impact to endure.
Next job is barrel set up in lathe to trim lower lug about .023 and end fit arbor.
I'll post some pictures of this stuff as I go for those who may be interested .
I think I will probably need to make a new wedge as well but will see as the build progresses.

 

[Rich44]

Nice job, and yes I am interested in pictures of what you are doing.

 

[William P Sepessy]

M. De Land, include me with interest in more pictures. Nice work on the cam installation and would be equally interested on your method of making a new wedge.

 

[M. De Land]

M. De Land, include me with interest in more pictures. Nice work on the cam installation and would be equally interested on your method of making a new wedge.

I use a mill for making the wedge and will use A-2 tool steel . With as much set back as this barrel will need I will have to lengthen the wedge slots forward in the barrel which may require more wedge width. In the past I have used a file and spotting black to fit these but was thinking it might be a good idea to make a broach for the job. This may be a good time to put the little horizontal mill I picked up some years ago back to work as it gets little use compared to the vertical mill which is more versatile.
The large amount of barrel set back will also necessitate trimming and fitting the arbor end in the well.
I'll check the bore for tight spots as well but am not looking forward to having to lap it level should the need arise. I don't think I have ever come across a revolver before that needed so much help in so many areas.
Another thing I have not done on these and seems like a pretty good idea is to install a cap guard, Any help in showing or describing how to do this would be appreciated.

 

[M. De Land]

Nice job, and yes I am interested in pictures of what you are doing.

I took a couple of shots of the parts I made for my gun as I reassembled it this PM. Mine are the lower in each frame.
The spring is made from a flat coil main spring from a worn out Luftkin tape measure. It is high chrome spring steel and is tough to cut or drill but I've never had one fail. Note the difference in thickness and thus bolt and trigger tension.
The wedge is A-2 and I make them without the keep spring which I have never cared for as it is unnecessary in my opinion. Instead I cut (ball mill) a blind end radial troth a bit larger than the head of the keep screw on the barrel which holds it captive when removing the barrel for cleaning.

 

[45D]

I use a mill for making the wedge and will use A-2 tool steel . With as much set back as this barrel will need I will have to lengthen the wedge slots forward in the barrel which may require more wedge width. In the past I have used a file and spotting black to fit these but was thinking it might be a good idea to make a broach for the job. This may be a good time to put the little horizontal mill I picked up some years ago back to work as it gets little use compared to the vertical mill which is more versatile.
The large amount of barrel set back will also necessitate trimming and fitting the arbor end in the well.
I'll check the bore for tight spots as well but am not looking forward to having to lap it level should the need arise. I don't think I have ever come across a revolver before that needed so much help in so many areas.
Another thing I have not done on these and seems like a pretty good idea is to install a cap guard, Any help in showing or describing how to do this would be appreciated.

I make a "cap post" from a #6 s.s. machine screw shaft. I remove the threads except for about 3 ( drill motor and bench belt sander). Mark for a hole in the hammer slot forward of the boss where the recoil ring is cut. Drill / tap and degrease well. Install the post with red thread-locker. Afterwards, cut height of the post down to top of nipple cone (cut-off wheel). Install hammer and fit post to slot (shaving sides with cut-off wheel). "Finish dress" with file.

 

[M. De Land]

I make a "cap post" from a #6 s.s. machine screw shaft. I remove the threads except for about 3 ( drill motor and bench belt sander). Mark for a hole in the hammer slot forward of the boss where the recoil ring is cut. Drill / tap and degrease well. Install the post with red thread-locker. Afterwards, cut height of the post down to top of nipple cone (cut-off wheel). Install hammer and fit post to slot (shaving sides with cut-off wheel). "Finish dress" with file.

Thanks Mike, appreciate the help, pictures and willingness to share . I've heard of the cap rake but not seen one before. I plugged the nose of my hammer some years ago with a piece of hardened O-1 to stop the cap pull (never really trusted the safe pins on the cylinder anyway) but like to see differing methods to accomplish this. Some folks after changing cones/nipples also relieve the sharp edges of hammer safety pin cut and tell of this greatly relieving cap pull.
Thanks again for the willingness to share good ideas and pictures, it helps every one !
I know when I started to learn how to case color/harden steel it was hard to find good information and had it not been for the writings of Oscar Gaddy and a few others this information would have been largely lost to the general gun community.

 

[M. De Land]

M. De Land, include me with interest in more pictures. Nice work on the cam installation and would be equally interested on your method of making a new wedge.

A bit more on the wedge construction may be of interest to you. The spring on the factory wedge is not only a keep from the stand point of loosing it while cleaning but the tension it self against the top of the wedge slot while in place tends to discourage it loosing and creeping outward.
This is the part I said in the previous post that I had found unnecessary as the ones I make have not, to this point any way, tended to loosen and creep out on there own.