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Uberti deceiving arbor fit

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J

Jshorter

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I’ve shot some hot loads through my Walker on a few different occasions and now my arbor has a very slight wiggle. I’m not sure if it was like this before or not. I was actually trying to fix the short arbor issue when I discovered the wiggle.

I was previously aware of the Uberti arbor issues, and when I checked mine it seemed to be fit correctly. To my surprise the frame/barrel matched perfect, so I kept on shooting.

I later learned that although the frame/barrel fit up nicely the arbor was still short. This is because the Uberti arbor is slightly tapered, and as you slide the arbor into the hole it stops as the taper gets too big. This makes you think the arbor is bottomed out when in reality it’s too thick and stops before it goes all the way to the bottom of the arbor hole, thus still leaving a gap. This allows the stretching motion on the arbor and will ruin them eventually.

To find out how short the arbor was I got close by measuring the depth of the arbor hole and then measuring how far the barrel slides onto the arbor and subtracting. Then I installed my shim.

Thickness at the end of the arbor—.500
IMG_3419.jpeg


Thickness where the barrel stops—.528
IMG_3420.jpeg


More pictures showing how the tapered arbor increases in thickness causing a false “bottoming out”
IMG_3421.jpeg
IMG_3423.jpeg



Anyways, I hope this revolver isn’t ruined and I’ll continue to shoot and monitor the arbor for stretch/looseness. If you have an Uberti walker I suggest checking the arbor via measurements and not the frame/barrel fit up method as that may be deceiving.
 
Last edited:
Yes, Uberti arbors are all short but it's a pretty easy fix. There are several threads on this forum where I explain how I make my spacer for the correction . . . multiple shims will fail especially in a Walker.

I'm sure you can find a how-to on how to tighten the arbor here as well ( I'm sure I put pictures as well).
How to torque them back in place so you'll never have to worry about it again.

Mike
 
Last edited:
45D said:
Yes, Uberti arbors are all short but it's a pretty easy fix. There are several threads on this forum where I explain how I make my spacer for the correction . . . multiple shims will fail especially in a Walker.

I'm sure you can find a how-to on how to tighten the arbor here as well ( im surei put picturesas well).
How to torque them back in place so you'll never have to worry about it again.

Mike
Click to expand...
I have just one shim I made of lead. I’m hoping that will help. Not sure how easy it would be to tighten the arbor but I’ll have to look into that.
 
I know this is a complex aspect/subject, but I think lead is going to keep on crushing and I would think come up around the sides of the narrow post.

Technically all metals will flow depending on force involved but Lead would be the last material I would use.

I am still trying to wrap my mind around all the aspects of this, but I miss the idea that its the taper at issue. I am not saying this is true and am still working on the mental model of what is going on.

If I am tracking this right, then its yes the frame initially engages fine, but as the wedge is set, the frame bends to the barrel area so its warping (or being warped).

I set the shims so that there was no gap on the lower frame where the pins index the two major parts and still had .003 or so of gap at the forcing cone and cylinder.

The shim is sort of the determiner, it goes through and sets a bit past the lip but not all all the way through. Takes a light tap out and I do a light tap to set when putting in.
 
Last edited:
Jshorter said:
I’ve shot some hot loads through my Walker on a few different occasions and now my arbor has a very slight wiggle. I’m not sure if it was like this before or not. I was actually trying to fix the short arbor issue when I discovered the wiggle.

I was previously aware of the Uberti arbor issues, and when I checked mine it seemed to be fit correctly. To my surprise the frame/barrel matched perfect, so I kept on shooting.

I later learned that although the frame/barrel fit up nicely the arbor was still short. This is because the Uberti arbor is slightly tapered, and as you slide the arbor into the hole it stops as the taper gets too big. This makes you think the arbor is bottomed out when in reality it’s too thick and stops before it goes all the way to the bottom of the arbor hole, thus still leaving a gap. This allows the stretching motion on the arbor and will ruin them eventually.

To find out how short the arbor was I got close by measuring the depth of the arbor hole and then measuring how far the barrel slides onto the arbor and subtracting. Then I installed my shim.

Thickness at the end of the arbor—.500
View attachment 324850

Thickness where the barrel stops—.528
View attachment 324851

More pictures showing how the tapered arbor increases in thickness causing a false “bottoming out”
View attachment 324852View attachment 324853


Anyways, I hope this revolver isn’t ruined and I’ll continue to shoot and monitor the arbor for stretch/looseness. If you have an Uberti walker I suggest checking the arbor via measurements and not the frame/barrel fit up method as that may be deceiving.
Click to expand...
Have you checked the ID of the well to see if the taper is reciprocal ? If it is and fit up to to the arbor taper then it actually does have a bottom radially. I still put a solid plug in mine which had an end gap of .093 if I remember correctly.
I wouldn't worry to much about some slight lateral play in the arbor thread as long as the barrel cylinder gap is not increasing or gap forms in the lower lug fit to the frame, it just means frame/arbor threads were not fit up ( compression mated) as well as they could be but the lock pin (if it has one) in the thread will keep it from backing out and the thread probably will not stretch (elongate) any . Still, any arbor thread lateral play would bug me as well.
I've not yet had to tighten an arbor thread in a steel frame so would have to investigate the best method of doing this. My guess would be to bump up the major thread diameter a bit on the male and refit with some heavy grease into compression. It could be done with loc-tite I suppose or soft solder paste and some heat also.
What does the wedge look like after the heavy loads? I'm told they batter up faster than other open frame guns and was also the case with originals that were supposedly arbor end fit from the factory.
This wedge battering I will be investigating as well with my new Uberti Walker as I plan on shooting it with heavy loads regularly and probably will have to make a new hardened tool steel wedge for it after some hard use. The new wedges have worked really well in the guns I have made and fit them to so far but time and use will tell the tail.
I've not yet made one for a Walker so it should be interesting to do. The one shown is for a 60. I don't use spring clips to retain them on mine but rather a blind end trough that butts against the keep screw. They're made of A-2 tool steel hardened to about Rockwell C-60 or so according the the hardening data.
 

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Last edited:
M. De Land said:
Have you checked the ID of the well to see if the taper is reciprocal ? If it is and fit up to to the arbor taper then it actually does have a bottom radially. I still put a solid plug in mine which had an end gap of .093 if I remember correctly.
I wouldn't worry to much about some slight lateral play in the arbor thread as long as the barrel cylinder gap is not increasing or gap forms in the lower lug fit to the frame, it just means frame/arbor threads were not fit up ( compression mated) as well as they could be but the lock pin (if it has one) in the thread will keep it from backing out and the thread probably will not stretch (elongate) any . Still, any arbor thread lateral play would bug me as well.
I've not yet had to tighten an arbor thread in a steel frame so would have to investigate the best method of doing this. My guess would be to bump up the major thread diameter a bit on the male and refit with some heavy grease into compression. It could be done with loc-tite I suppose or soft solder paste and some heat also.
What does the wedge look like after the heavy loads? I'm told they batter up faster than other open frame guns and was also the case with originals that were supposedly arbor end fit from the factory.
This wedge battering I will be investigating as well with my new Uberti Walker as I plan on shooting it with heavy loads regularly and probably will have to make a new hardened tool steel wedge for it after some hard use. The new wedges have worked really well in the guns I have made and fit them to so far but time and use will tell the tail.
I've not yet made one for a Walker so it should be interesting to do. The one shown is for a 60. I don't use spring clips to retain them on mine but rather a blind end trough that butts against the keep screw. They're made of A-2 tool steel hardened to about Rockwell C-60 or so according the the hardening data.
Click to expand...
I haven’t thought about checking ID, and I’m not sure what would be a good way to do that. I do know that the arbor is short either way and doesn’t reach all the way to the bottom of the arbor hole based on the measurements I took.

From what I see my wedge looks fine. Just the bluing rubbed off but I haven’t shot it a ton.
 
Jshorter said:
Yeah lead maybe not the best. I may pull it and make another from something harder.
Click to expand...
You may want to use @45D ‘s method to correct the short arbor, he has posted the procedure a number of times, though I can’t find it at the moment. I’ve done it on a few Ubertis and it was quick and painless. A pan head screw, a drill and some epoxy.
 
Smokerr said:
I know this is a complex aspect/subject, but I think lead is going to keep on crushing and I would think come up around the sides of the narrow post.

Technically all metals will flow depending on force involved but Lead would be the last material I would use.

I am still trying to wrap my mind around all the aspects of this, but I miss the idea that its the taper at issue. I am not saying this is true and am still working on the mental model of what is going on.

If I am tracking this right, then its yes the frame initially engages fine, but as the wedge is set, the frame bends to the barrel area so its warping (or being warped).

I set the shims so that there was no gap on the lower frame where the pins index the two major parts and still had .003 or so of gap at the forcing cone and cylinder.

The shim is sort of the determiner, it goes through and sets a bit past the lip but not all all the way through. Takes a light tap out and I do a light tap to set when putting in.
Click to expand...
Yes initially the frame would engage fine and everything looked good, but I’m not worried as much about warping or bending the frame in to close the cylinder gap. I’m more worried about the long term consequences of shooting hot loads with a short arbor.
 
SDSmlf said:
You may want to use @45D ‘s method to correct the short arbor, he has posted the procedure a number of times, though I can’t find it at the moment. I’ve done it on a few Ubertis and it was quick and painless. A pan head screw, a drill and some epoxy.
Click to expand...
I read some posts on here before about fixing short arbor issues. I’ll see if I can find it.
 
Jshorter said:
I haven’t thought about checking ID, and I’m not sure what would be a good way to do that. I do know that the arbor is short either way and doesn’t reach all the way to the bottom of the arbor hole based on the measurements I took.

From what I see my wedge looks fine. Just the bluing rubbed off but I haven’t shot it a ton.
Click to expand...
Don't bother checking the ID the taper is not reciprical. The taper on the arbor was just Uberti's quick fix for the short arbor. Also one of the reasons it is often hard to get the barrel off of a new or recent Uberti because it has been forced onto the taper by the wedge. Stays that way for awhile until the arbor hole gets wallowed out. Then you still have the short arbor.
 
denster said:
Don't bother checking the ID the taper is not reciprical. The taper on the arbor was just Uberti's quick fix for the short arbor. Also one of the reasons it is often hard to get the barrel off of a new or recent Uberti because it has been forced onto the taper by the wedge. Stays that way for awhile until the arbor hole gets wallowed out. Then you still have the short arbor.
Click to expand...
Yep, removing the barrel after shooting is usually pretty difficult, and it gets harder the more you shoot.
 
Thanks for the post. I was not aware of the tapered arbor, but it is there, about .020" over the section that fits into the barrel portion. It was tight when new but quickly loosened up. I addressed the short arbor pretty quick using a couple of steel washers soldered together and polished down to the proper thickness. .088" shim thickness worked for me giving me an endshake of .004" It is pretty tight and ends up in the same place each time the gun is reassembled using moderate hits to install the wedge. I did not affix the shim permanently to the arbor as I like the idea of being able to easily change it should the need arise. Plenty of ways to do this. This is what worked for me.
 
M. De Land said:
Have you checked the ID of the well to see if the taper is reciprocal ? If it is and fit up to to the arbor taper then it actually does have a bottom radially. I still put a solid plug in mine which had an end gap of .093 if I remember correctly.
I wouldn't worry to much about some slight lateral play in the arbor thread as long as the barrel cylinder gap is not increasing or gap forms in the lower lug fit to the frame, it just means frame/arbor threads were not fit up ( compression mated) as well as they could be but the lock pin (if it has one) in the thread will keep it from backing out and the thread probably will not stretch (elongate) any . Still, any arbor thread lateral play would bug me as well.
I've not yet had to tighten an arbor thread in a steel frame so would have to investigate the best method of doing this. My guess would be to bump up the major thread diameter a bit on the male and refit with some heavy grease into compression. It could be done with loc-tite I suppose or soft solder paste and some heat also.
What does the wedge look like after the heavy loads? I'm told they batter up faster than other open frame guns and was also the case with originals that were supposedly arbor end fit from the factory.
This wedge battering I will be investigating as well with my new Uberti Walker as I plan on shooting it with heavy loads regularly and probably will have to make a new hardened tool steel wedge for it after some hard use. The new wedges have worked really well in the guns I have made and fit them to so far but time and use will tell the tail.
I've not yet made one for a Walker so it should be interesting to do. The one shown is for a 60. I don't use spring clips to retain them on mine but rather a blind end trough that butts against the keep screw. They're made of A-2 tool steel hardened to about Rockwell C-60 or so according the the hardening data.
Click to expand...
With the arbor issue addressed and firmly seating the wedge I haven't noticed anything taking any wear other than the bolt notches on the cylinder. I use 44 G of FFFg and have shot it quite a bit.
 

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