Trying to understand this “short arbor” on Uberti revolvers

[French Colonial]

More than one, to realize that short arbor is not an imaginary problem. BTW, other makes and models are similarly affected including ASM, FIE etc. Most Piettas are not.

And how about us poor ignorant guys who have Ubertis that shoot great right out of the box.

Of course it could be we are just very lucky (I have one of their 1885 highwalls that also shoots great) or maybe we are just better shots.

 

[45D]

And how about us poor ignorant guys who have Ubertis that shoot great right out of the box.

Of course it could be we are just very lucky (I have one of their 1885 highwalls that also shoots great) or maybe we are just better shots.

Dang!!!! I was with ya till I got to the "1885 highwall" . . .
didn’t know they had an arbor!!!!!

Sure, the revolvers can run fine out of the box ( That just points to genius/ linear design) but they'll run better for longer if built like they were designed (rather than "get it out the door Tony !!!!" ). Lots will depend on care, use and load.

Mike

 

[bpalbee]

Dang!!!! I was with ya till I got to the "1885 highwall" . . .
didn’t know they had an arbor!!!!!

Sure, the revolvers can can run fine out of the box ( That just points to genius/ linear design) but they'll run better for longer if built like they were designed (rather than "get it out the door Tony !!!!" ). Lots will depend on care, use and load.

Mike

I think "running fine" means different things to different people . I'm planning on just dabbing some melted steel on the end of the arbor with ye old TIG matchine and filing away until I'm pleased with the fit. Anybody else doing it that way? I will post pictures as I do it if people are interested. I picked up an older Pietta 1860 with both a loose and short arbor, plus missing barrel locating pins and mashed cylinder safety pins. Should be a fun project.

 

[CaptainKirk]

And how about us poor ignorant guys who have Ubertis that shoot great right out of the box.

Of course it could be we are just very lucky (I have one of their 1885 highwalls that also shoots great) or maybe we are just better shots.

If you have an Uberti that runs great out of the box, I'm happy for you! Nothing to worry about then, in your case. But for those of us with the short arbor issue on one or more of our revolvers, it's irritating to have to fix a gun right out of the box, and worse yet to read in the owner's manual about the 'adjustable wedge'.
No disrespect intended, but have you actually checked your cylinder clearance? Have you tried giving the wedge a good hard smack with a plastic mallet (not a gentle tap) and seeing if your cylinder locks up? Because if it does, you have a short arbor. And it's a very easy fix you can do yourself. If you tried this and you still have .003-.005 clearance, consider playing the lottery this week!

 

[Smokerr]

TIG matchine and filing away until I'm pleased with the fit. Anybody else doing it that way?

First I have read but I guess its one way to do it. 45D has a cure that is solid. I always try not to do something I can't take back.

Tig would a least affect the metal of the arbor with heat I would think.

I just used Shims but 45D has a system that matches exact as needed.

 

[M. De Land]

And how about us poor ignorant guys who have Ubertis that shoot great right out of the box.

Of course it could be we are just very lucky (I have one of their 1885 highwalls that also shoots great) or maybe we are just better shots.

I also have one of their Hi-walls and it's the best rendition of any HW ever made with the redesigned firing pin housed in a removable breech face bushing. It makes a very strong single shot perfectly safe against gas blow by in a failed primer seal.
It takes quite a bit of gunsmithing (Frank De Haas modification) to bring an original HW up to the Uberti re-design gas seal standard. The Uberti breech block does not have the lower half machined out for the original HW firing pin design leaving it much stronger and gas sealed to the rear in the captive bushing housing and shouldered firing pin.
Now how they can go to this very fine modification trouble in the HW and not fix the short arbor situation (easy with a new CAD card) in their open frame guns is a mystery to me! I'm assuming they also are using CNC driven machinery.
It does sound like a lawyer is lurking around there somewhere!

 

[M. De Land]

First I have read but I guess its one way to do it. 45D has a cure that is solid. I always try not to do something I can't take back.

Tig would a least affect the metal of the arbor with heat I would think.

I just used Shims but 45D has a system that matches exact as needed.

Arbors are good steel but not hardened as I have filed them often when fitting new wedges. A TIG or Mig weld on the end won't harm anything and is certainly preferred to drilling and tapping, weakening the slot end especially on the short arbor guns that are very often quite thin at slots end.
I do think fitting a tool steel spacer much easier than cleaning up the end of an arbor weld and possibly having to anneal it.
If anything happens metallurgical-ly it will usually be hardening not softening with MIG or TIG and that can be annealed to eliminate stress risers .
I know of folks that actually TIG weld their barrel liners at the muzzle to get rid of the parting ring, which I believe is bad practice but some do it and seem to get away with the procedure. I guess if they don't scale the barrel liner bore it's all good.

 

[M. De Land]

I think "running fine" means different things to different people . I'm planning on just dabbing some melted steel on the end of the arbor with ye old TIG matchine and filing away until I'm pleased with the fit. Anybody else doing it that way? I will post pictures as I do it if people are interested. I picked up an older Pietta 1860 with both a loose and short arbor, plus missing barrel locating pins and mashed cylinder safety pins. Should be a fun project.

How do you plan on approaching the loose arbor threads ?
Bump up the arbor threads and refit ?
Red loc-tite the threads ?
Soft solder (sweat) the threads in the frame with paste?

 

[bpalbee]

How do you plan on approaching the loose arbor threads ?
Bump up the arbor threads and refit ?
Red loc-tite the threads ?
Soft solder (sweat) the threads in the frame with paste?

I have seen a gunsmith slightly peen the outside diameter of the arbor around the seating surface in order to build up material to torque against as you clock the arbor into position. It appeared the most difficult operation was drilling out the retaining pin through the hammer channel without damaging the frame too badly but the one I watched used a drill press and it turned out okay. I plan to dry fit the arbor until I can torque/clock it satisfactorily within an eighth of a turn (kind of like installing a barrel) and then give it the final torque locate/install new retaining pin. I'm open to ideas, but I prefer staying away from epoxies softer metals. I like steel against steel for durability

 

[M. De Land]

I have seen a gunsmith slightly peen the outside diameter of the arbor around the seating surface in order to build up material to torque against as you clock the arbor into position. It appeared the most difficult operation was drilling out the retaining pin through the hammer channel without damaging the frame too badly but the one I watched used a drill press and it turned out okay. I plan to dry fit the arbor until I can torque/clock it satisfactorily within an eighth of a turn (kind of like installing a barrel) and then give it the final torque locate/install new retaining pin. I'm open to ideas, but I prefer staying away from epoxies softer metals. I like steel against steel for durability

Start with a center drill on the retaining pin to get the hole started straight so it won't wonder on you !
I'd put the arbor in the lathe and bump up the thread ends (major diameter) with a burnishing tool. This will thicken them radially along their length not just at the seating end.
Loose arbors in a steel frames mean sloppy initial thread fit ! The first three threads support 70 percent of the load and should be a loading radially as they thread in not just on the seating collar at the end.
If they are not they stretch and loosen up.

 

[bpalbee]

Start with a center drill on the retaining pin to get the hole started straight so it won't wonder on you !
I'd put the arbor in the lathe and bump up the thread ends (major diameter) with a burnishing tool. This will thicken them radially along their length not just at the seating end.
Loose arbors in a steel frames mean sloppy initial thread fit ! The first three threads support 70 percent of the load and should be a loading radially as they thread in not just on the seating collar at the end.
If they are not they stretch and loosen up.

Thanks for the advice on center drilling the retaining pin and bumping up the thread ends with a burnishing tool. I hadn't heard of that before but it seems like a great way to tighten the fit without losing any strength.

 

[French Colonial]

If you have an Uberti that runs great out of the box, I'm happy for you! Nothing to worry about then, in your case. But for those of us with the short arbor issue on one or more of our revolvers, it's irritating to have to fix a gun right out of the box, and worse yet to read in the owner's manual about the 'adjustable wedge'.
No disrespect intended, but have you actually checked your cylinder clearance? Have you tried giving the wedge a good hard smack with a plastic mallet (not a gentle tap) and seeing if your cylinder locks up? Because if it does, you have a short arbor. And it's a very easy fix you can do yourself. If you tried this and you still have .003-.005 clearance, consider playing the lottery this week!

After giving the wedge a good smack with a rawhide mallet the cylinder gap is .003 using feeler gauges (does anyone still use feeler gauges ) This is on one particular 1851 Navy.
Not really my time frame of interest but after learning my Great Grandfather carried one in the war of northern aggression, I had to have one.

I don't know about 75 yards like Wild Bill, but at 50 yards I will keep them all in the center of a B-29 target. For a 150-year-old USA design from an Italian manufacturer I feel pretty good about that one.

Edit, I should not have said "center of a B-29 target" in the torso all killing shots would have been a more accurate description.

 

[M. De Land]

I have seen a gunsmith slightly peen the outside diameter of the arbor around the seating surface in order to build up material to torque against as you clock the arbor into position. It appeared the most difficult operation was drilling out the retaining pin through the hammer channel without damaging the frame too badly but the one I watched used a drill press and it turned out okay. I plan to dry fit the arbor until I can torque/clock it satisfactorily within an eighth of a turn (kind of like installing a barrel) and then give it the final torque locate/install new retaining pin. I'm open to ideas, but I prefer staying away from epoxies softer metals. I like steel against steel for durability

Well, all the epoxy/ loc-tite or soldier does is hold the threads steel against steel from the back side of thread load after they are mated up and force out the liquid before it solidifies thus removing the slack by filling the back lash slop made when cutting loose fitting threads . The load bearing side is still steel against steel. It probably loads more thread area than does bumping up the thread tops alone.
Years ago I learned about the Ford Motor Co. developing what is know as a ramped V thread which made one side of the V with a different angle (ramp) that radially loaded the male top on the opposite thread as it was advanced. What this did was spread the tension load over more of the thread length thus greatly increasing the tension load strength and stiffening of the threaded joint.
This was found to greatly increase accuracy by dampening barrel oscillation when firing. It spread the tension load over more of the entire thread length instead of the first three carrying 70 percent of the tension load in normal V threads . Harold McFarland (San Andea scientist) developed this method of fitting rifle barrels and proved that it improved accuracy by stiffening as well as strengthening the barrel/action joint, in his experiments.
Probably the only reason it has never been adopted commercially is the time it takes to fit the ramped thread correctly and the fact that a good fit on a normal V thread will work fine without added cost.

 

[Smokey Plainsman]

Growing up I was always told the wedge on a Colt’s could be backseated a hairs breadth once the gun became enfouled with residues from the combustion process of black powder.

Whether that’s true or not remains a mystery. I know the “Arbor Debate” is one that rages on.

 

[M. De Land]

Growing up I was always told the wedge on a Colt’s could be backseated a hairs breadth once the gun became enfouled with residues from the combustion process of black powder.

Whether that’s true or not remains a mystery. I know the “Arbor Debate” is one that rages on.

People being varied as they are will seat their wedges according to their beliefs. Some will pound them in until they smoke and others will seat them with thumb pressure and both will swear theirs is the best method. Truth is both will work and satisfy their owner.

 

[CaptainKirk]

People being varied as they are will seat their wedges according to their beliefs. Some will pound them in until they smoke and others will seat them with thumb pressure and both will swear theirs is the best method. Truth is both will work and satisfy their owner.

Welp, it's not the fact that both methods work (IMHO) but the truth that over time, parts that are not solidly anchored will eventually beat the snot out of each other. If you drag your short arbor gun out once a year for a dozen shots, it probably won't matter and you probably won't do much damage. If you go to the range weekly and run through a tin of 100 caps, it will definitely have an effect on your gun's longevity.

 

[45D]

. . . and is certainly preferred to drilling and tapping, weakening the slot end especially on the short arbor guns that are very often quite thin at slots end.

M. De Land doesn't know what he's talking about here and apparently STILL is lacking in the understanding of the design. I've done exactly this setup for at least 1500 open-top revolvers over the years and there hasn't been one failure. Many of these are Walkers and Dragoons that see full charges of Trip 7 used for hunting as well as long range paper punching.

Smokeless powder is much more punishing than BP and the subs and I've used the same setup ( duh!!!!) on all of them (factory and aftermarket conversions) as well. 23,000 + psi hasn't had any negative effects!!

Mike

 

[45D]

People being varied as they are will seat their wedges according to their beliefs. Some will pound them in until they smoke and others will seat them with thumb pressure and both will swear theirs is the best method. Truth is both will work and satisfy their owner.

Colts ( the original designer and producer of the revolvers being discussed here ) very on instructions don't say anything close to "set the wedge - "finger tight" , " with thumb pressure", "however you feel", "what you think is best" . . . it says to "drive the wedge in" . . . also, doesn't say "drive it in till it's smokin' " .
If one "drives the wedge in " as per instructions there's a good chance it will lock up the cylinder . . . if that's the case, the ARBOR is short !!! The originals had an arbor that "checked" the barrel at a predetermined place and that THAT was the factory design. Apparently, even if you post pictures showing originals with said setup (as well as showing those that apparently have never seen what the end of the arbors looked like) and some even commenting "that's info I can hang my hat on", it apparently "evaporates" a day or two later !!! It's incredible to me that proof means absolutely nothing to some folks but hey, it draws a crowd I guess !!!

One step forward, 8 steps back !!

Mike

 

[45D]

Growing up I was always told the wedge on a Colt’s could be backseated a hairs breadth once the gun became enfouled with residues from the combustion process of black powder.

Whether that’s true or not remains a mystery. I know the “Arbor Debate” is one that rages on.

There's really no "debate" . . . the manufacturers instructions say what to do. Folks "knowing better" than the designers ( because they're "smarter") can ignore the instructions and do as they please. Of course if you bring up the "problem" and the easy fix for it, you're wrong and everybody is an expert and they know best.

Folks just can't believe that engineers in the 1840's could actually know what they were doing.
Amazingly, if you set them up as designed, you don't need "tool steel" wedges that fit up, down, in ,out, no spring needed, blah blah blah (they didn't) . . . Colts design, followed, is basically perfect . . . no need to change.

Mike

 

[M. De Land]

M. De Land doesn't know what he's talking about here and apparently STILL is lacking in the understanding of the design. I've done exactly this setup for at least 1500 open-top revolvers over the years and there hasn't been one failure. Many of these are Walkers and Dragoons that see full charges of Trip 7 used for hunting as well as long range paper punching.

Smokeless powder is much more punishing than BP and the subs and I've used the same setup ( duh!!!!) on all of them (factory and aftermarket conversions) as well. 23,000 + psi hasn't had any negative effects!!

Mike

That's good evidence but I don't care for the weakening effect of drilling , tapping and threading the arbor end ahead of the slot for taking up wedge slop and hence don't use it or advise others to. I prefer a better wedge and fitting it well to a full strength arbor slot personally.
The screw head spacer you use for arbor end fit seems like a reasonably good idea though .
I also like and have employed the action shield on the Walker although adopting what I feel a better purchase.
Haven't yet felt the need for cap rakes on any of the models I own or have worked on for others but it's easy enough to accomplish should it ever reveal an actual need..