Smith and Wesson crane design

[IHAVEGAS]

I have screwed up 2 cranes by not reloading gently enough, also, talked to a guy a a match yesterday who has his 929 in for service for the same issue - have seen another guy bust one the same way at a match - and have read about others having the issue on this forum.

 

Couple questions come to mind.

 

Was the crane design established with a harder metal crane which S&W later replaced with a soft metal casting? 

 

For those of you who have replaced the spring loaded crane screw with a solid timed screw, is there a best way to go about doing this? A talented friend has done it by taking the plunger out of the oem crane screw assembly and then fitting a stop behind the plunger, but he said the process was a tedious and time consuming nuisance. 

[revoman]

Maybe you need to change the way you reload especially if you are using moon clips. They should fall in by gravity not shoved in. 

[IHAVEGAS]

1 hour ago, revoman said:

change the way you reload

 

Or switch to Ruger. Regardless, am curious about the design history and the solution some have found to make it more rugged. 

[357454]

As a longtime owner of S&W revolvers I have never had a Yoke break until I was trying to straighten one on a 617. Two of my 627s, have over Fifty Thousand rounds thru each of them, The number one crane related problem I have seen is the Yoke screw coming loose, this can be resolved by a few drops of Loctite. If you close the cylinder with your hand while the barrel is pointed down you should not have problems with the yoke

[IHAVEGAS]

1 hour ago, 357454 said:

As a longtime owner of S&W revolvers I have never had a Yoke break until I was trying to straighten one on a 617. Two of my 627s, have over Fifty Thousand rounds thru each of them, The number one crane related problem I have seen is the Yoke screw coming loose, this can be resolved by a few drops of Loctite. If you close the cylinder with your hand while the barrel is pointed down you should not have problems with the yoke

 

I get that. Seems to be an issue more with the folks who weak hand reload and I don't doubt that many or all could learn to baby the crane in the heat of battle or perhaps be more diligent at keeping the cylinder clean. 

 

Still, I am interested in the original two questions. 

[IHAVEGAS]

Found the older thread I was thinking of.

 

Will likely try the fix noted on the last post, haven't figured out how he shaped the drill bit so nicely. Perhaps just Dremel and stationary stone & patience. 

 

Seems most are tending to blame letting the yoke screw get loose rather than entirely technique. 

 

 

[MikeBurgess]

18 hours ago, IHAVEGAS said:

Found the older thread I was thinking of.

 

Will likely try the fix noted on the last post, haven't figured out how he shaped the drill bit so nicely. Perhaps just Dremel and stationary stone & patience. 

 

Seems most are tending to blame letting the yoke screw get loose rather than entirely technique. 

 

 

easy way to form nice round features like that is a drill and a fine file, I have also used a drill and a dremel, chuck the part up in the drill and with it turning remove the desired material with a file, dremel, stone, or sandpaper as needed to achieve the size and shape you want.

[IHAVEGAS]

2 hours ago, MikeBurgess said:

easy way to form nice round features like that is a drill and a fine file, I have also used a drill and a dremel, chuck the part up in the drill and with it turning remove the desired material with a file, dremel, stone, or sandpaper as needed to achieve the size and shape you want.

 

Thanks!

[Dr. Phil]

You may find some of the old style on Numrich Arms (gunpartscorp). They show them for the older N frames.

They look like the old solid style...

[IHAVEGAS]

14 hours ago, Dr. Phil said:

You may find some of the old style on Numrich Arms (gunpartscorp). They show them for the older N frames.

They look like the old solid style...

 

Interesting. Never heard of that site before. 

 

On that site, I do not see any difference in geometry between older and newer yokes. Not to say that there are not differences in geometry and metal hardness that I do not see.

 

Apparently the old style yoke screw was a solid screw, reduced in diameter near the end but not tapered (can not upload pictures at the moment, but a search for Smith and Wesson Yoke screw pops up several pictures). 

[pskys2]

Midway and Brownells also carry the old style screws.

[rishii]

I don’t know if the old style will work with the newer plunger yoke screw, the old style are smaller, and if I remember correctly the same screw as the flat side plate screw and were easily mixed up, and yes it is a fitted part

 

[IHAVEGAS]

1 hour ago, rishii said:

and yes it is a fitted part

 

I wonder if that was the reason for the change (reduced labor), or if there was a reliability/functional issue? 

[mchapman]

11 minutes ago, IHAVEGAS said:

 

I wonder if that was the reason for the change (reduced labor), or if there was a reliability/functional issue? 

Most definitely, saves the time and effort to fit the screw to the crane.

[robertson]

Use the new style plunger with a piece of drill rod behind it instead of the spring. 

[SteelShooten]

The older cranes had a square slot milled around the post on the crane.   A square nosed screw went into that slot to retain the crane.  It was a stronger design.

 

S&W changed to a V groove and a spring loaded plunger.  As others, I assume this it to avoid the labor of fitting. 

 

The problem with the newer design is that the plunger provides very little bearing surface.   When the crane gets pushed hard, it cams the plunger back (into the screw) until the plunger bottoms out.  You can see the crane protrude from the frame if the cylinder is opened and then slightly pressed forward.  Under those circumstances, there is just the very tip of the plunger holding against the lip of the V groove and while the plunger is hard, the crane is not hard metal.  If the edge of the V groove mushes, the crane can push past the plunger and out of the gun.  This leaves a scar perpendicular to the V groove that I don't know how to fix without replacing the part.

 

People I know who have had that happen sent their gun back to the factory to have it fixed.

 

Knowing of this issue, I took the plunger and spring out of the screw in my 617 and reinstalled the screw with a length of drill-rod to replace the plunger and spring.  

I ground the tip of the drill-rod to a chisel point (approximating the angle of V in the crane) and then fitted it to the gun by reducing the length (grinding the flat end) until became the correct length.   If you put the crane in the gun and look into the hole, I suspect the V is not centered relative to the screw hole.   The chisel point should be slightly better than the conic on the original plunger. 

To finalize the length for the drill rod, I took the cylinder off the crane and installed just the crane so it can swing very easily.  Then I started the screw with new rod and checked for binding as the screw was turned.    Initially it bound the crane before the screw was fully installed so I shortened the rod and tried again. 

 

Fitting the drill rod required patience and it can slightly complicate reassembly, but think it does a good job of avoiding the problem described by the OP.

 

I specifically did this for the 617 because the speedloaders for rimfire require more push than any of my other revolvers.  It seemed like a good precaution because its the only revolver (I shoot several other S&Ws) where I might even be close to driving the crane out of the gun.

 

 

 

 

 

 

[pskys2]

I use the strong hand reload, switching hands, and the only time I've had the crane/cylinder assembly act up is when the screw has loosened up.  Another annoying little habit of the S&W design.  A little 242 takes care of that.  I have occasionally used the weak hand, depending on a COF, but I guess I'm not overly aggressive as I was lucky to never have the issue.

[S&W627shooter]

My complaint about the plunger style screw is that when they get loose and back out a little, it is easy to push the yoke past the screw, but not nearly as easy to push back into place without backing the screw out several more turns.  When you are on the clock, it is not intuitive to loosen the screw more in order to get the cylinder back in place before then tightening it again enough that it won't come out in your hand at the next reload.  I've had to do this with my thumbnail on the clock.  NOT COOL!  

[IHAVEGAS]

Broke another extended firing pin (I am cursed, I must have some sort of an aura that breaks gun parts or something) and saw this on TK Custom's website while shopping for a replacement "S&W, after January 2012, has used all MIM (Metal Injected Molded) internal action parts in all of their revolvers, including their standard production and Performance Center revolvers to reduce manufacturing costs. "

 

I don't know that cranes were changed in 2012 as well, but I thought it interesting. 

[IHAVEGAS]

On 7/1/2020 at 9:37 AM, SteelShooten said:

When the crane gets pushed hard, it cams the plunger back (into the screw) until the plunger bottoms out.  You can see the crane protrude from the frame if the cylinder is opened and then slightly pressed forward.  Under those circumstances, there is just the very tip of the plunger holding against the lip of the V groove and while the plunger is hard, the crane is not hard metal.  If the edge of the V groove mushes, the crane can push past the plunger and out of the gun.  This leaves a scar perpendicular to the V groove that I don't know how to fix without replacing the part.

 

People I know who have had that happen sent their gun back to the factory to have it fixed.

 

Knowing of this issue, I took the plunger and spring out of the screw in my 617 and reinstalled the screw with a length of drill-rod to replace the plunger and spring.  

I ground the tip of the drill-rod to a chisel point (approximating the angle of V in the crane) and then fitted it to the gun by reducing the length (grinding the flat end) until became the correct length.   If you put the crane in the gun and look into the hole, I suspect the V is not centered relative to the screw hole.   The chisel point should be slightly better than the conic on the original plunger. 

To finalize the length for the drill rod, I took the cylinder off the crane and installed just the crane so it can swing very easily.  Then I started the screw with new rod and checked for binding as the screw was turned.    Initially it bound the crane before the screw was fully installed so I shortened the rod and tried again. 

 

Fitting the drill rod required patience and it can slightly complicate reassembly, but think it does a good job of avoiding the problem described by the OP.

 

 

 

Copied this technique, thank you. Actually thanks to all who replied, there is much you can figure out but it is always comforting to copy something that worked. 

 

"If you put the crane in the gun and look into the hole, I suspect the V is not centered relative to the screw hole."

 

Was very surprised how poorly the crane v-groove was centered on the crane screw hole. I assume there is variation in crane dimensions as well as frame dimensions and the tolerances stack up better on some guns than others. In any case, rub marks on a brand new crane just back from s&w indicated only about 1/8" (maximum) contact area between the crane screw plunger and the crane. Fitting a new plunger confirmed that there is minimal contact on my particular gun, remove the plunger & fully install the screw and there is no contact with the crane, install the screw again with a solid plunger that is conical tipped to match the oem plunger and protrudes no more than 1/8" from the end of the screw and the length is right (not dragging on the plunger but within a gnats whisker of dragging). 

Makes me wonder if part of the crane fitting process at the factory is supposed to be matching crane V notch location/dimensions to particular guns. Likely not, hopefully things hold together this time, but what I have looks a long way from robust. 

[pskys2]

1 hour ago, IHAVEGAS said:

 

Copied this technique, thank you. Actually thanks to all who replied, there is much you can figure out but it is always comforting to copy something that worked. 

 

"If you put the crane in the gun and look into the hole, I suspect the V is not centered relative to the screw hole."

 

Was very surprised how poorly the crane v-groove was centered on the crane screw hole. I assume there is variation in crane dimensions as well as frame dimensions and the tolerances stack up better on some guns than others. In any case, rub marks on a brand new crane just back from s&w indicated only about 1/8" (maximum) contact area between the crane screw plunger and the crane. Fitting a new plunger confirmed that there is minimal contact on my particular gun, remove the plunger & fully install the screw and there is no contact with the crane, install the screw again with a solid plunger that is conical tipped to match the oem plunger and protrudes no more than 1/8" from the end of the screw and the length is right (not dragging on the plunger but within a gnats whisker of dragging). 

Makes me wonder if part of the crane fitting process at the factory is supposed to be matching crane V notch location/dimensions to particular guns. Likely not, hopefully things hold together this time, but what I have looks a long way from robust. 

Not matching the crane v to the screw is the reason for the spring plunger.  Most people never take a revolver down, it's lucky to get a wipe down and a bore scrub!  So rub marks on the crane interior would never be noticed.  Side effects of "Mass Production".  The really sad part is one would think something called Performance Center would do some minimum matching?