Here's a better short arbor fix.

D

D F Delozier

Inactive
Hello everybody, this will be counted as my first post, but in reality I've made many. I was a member several years ago and just rejoined. So rather than resurrect an old post I'll make this one about the Uberti SAS(short arbor syndrome) I can't take credit for it,I learned it a couple years ago. Some of you may know of it, but judging from some of the older posts about it I've read on here a lot don't, so I'll put it out there. I've done this to my 1985 uberti 3rd model Dragoon. Get on one of several sites that sell Dillon reloading equipment parts and order what's called a locator button or pin, there are a few sizes, find the one closest to your arbors O.D. these button are basicly a flat metal disc with a pin on the back(picture a thumb tack) only thicker. You drill an interference fit hole in the center of your arbor for the pin portion of it, don't worry if you break through to the wedge hole, you'll address that later,the pin part may or may not intrude into the wedge cut out as well,again we'll fix that later. Using the green loctite made for press fit bushing, you'll anchor the button to the end of the arbor(slightly counter sink hole in the end of arbor) this will assure the button gets fully seated against arbor face. Let cure over night,then start working down with files until you get the perfect depth of seating. The button stays with the arbor and doesn't fall off ever, but can be removed by applying heat and twisting it out of the hole. This makes a neat and professional looking repair. Should any of your work break through the wedge hole , simply file it flush in the hole. A drill press works best,but if you're careful a hand drill is fine. You all can thank me later LOL
 
The only problem with this solution is if you break through into the wedge slot you damage the taper in the end of the slot that corresponds to the taper of the wedge and allows the wedge to lock the frame and barrel together without undue force. Most folks are not aware that taper is there but it is and is important. I should state that it is present on original Colts, Uberti, and Piettas but not on ASM and some other clones.
 
The taper of the wedge slot is unaffected by this fix, as long as you are judicious with your filing in the slot, and pay attention to the taper. This is not an undertaking for one that is not mechanically inclined.
 
People also drill through to the wedge slot and tap the hole for a set screw to adjust the wedge fit over time. Works great. The taper isn't an issue.
 
Actually the taper is an issue. With a set screw you have one tiny point bearing on the wedge. While this pressure is centered and is much better than having the wedge contact the inboard edge of the slot only and does provide equal distribution of force it is not as good or secure as 1/4 to 5/16 inch of solid metal in opposing incline planes. The set screw also tends to wear the wedge so it's good that it is adjustable. However with a properly seated arbor and properly fit wedge it is unlikely you will ever wear out a wedge to where it needs adjusting.
 
With Uberti revolvers, there is also an issue with how the wedge contacts the rear of the arbor slot. If that contact is non-existent, wherein the wedge only contacts the barrel lug, the barrel/cylinder gap will depend upon how far the wedge is driven in.

Refer to Mike Brackett http://www.goonsgunworks.com/ for confirmation.

Jim
 
AKexpat said:
With Uberti revolvers, there is also an issue with how the wedge contacts the rear of the arbor slot. If that contact is non-existent, wherein the wedge only contacts the barrel lug, the barrel/cylinder gap will depend upon how far the wedge is driven in.

Refer to Mike Brackett http://www.goonsgunworks.com/ for confirmation.

Jim
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Actually the wedge should never contact the rear of the arbor slot and should bear evenly on both sides of the barrel lug at the rear. The only way the wedge can affect the barrel cylinder gap is if the arbor is short and does not bottom out in the barrel lug. If the arbor bottoms out then the wedge can effectively lock the two assemblies together and as stated not have any effect on b/c gap.
 
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I was fixin to say that, that's also how you know you've got a short arbor, when you tap it in and the cylinder binds, you got S.A.S.
 
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"Short arbor" is not really not the problem the arbor hole is bored to deep to allow for fitting the arbor. how ever you deal with it it needs to be done.
 
The "taper" that Denster refers to is present in some revolvers, not in all revolvers . . even the originals. Full contact of the forward arbor slot and the wedge can and will allow the wedge to "walk" and loosen. Denster and I had a disagreement about this in the past and apparently we still do. And that's OK.
The proper set-up for the wedge to work is simple triangulation. The rear surface of the wedge contacts the rear slot in the barrel assy. ( no contact with the arbor slot). This establishes a wide and parallel "base" with the forward "point" being a contact patch with the forward surface of the arbor slot. This has been verified by my own revolvers as well as many customers and even from a thorough investigation of a '60 Army produced in 1862. The original's arbor was broached without taper and the contact point of the wedge was just inside the entrance of wedge slot (easily verifiable). This is the typical area of contact in most open tops (tapered or not) but it doesn't have to be as long as it's not full contact. Pietta uses or did in the past, a process that looked as if the forward arbor slot surface was ground on both sides leaving the center area as a contact point. The main point in this particular discussion is that vibration has less effect when contact between surfaces are smaller rather than larger.

As far as arbor length correction, I much prefer a single S.S. plug anchored in the arbor hole. I don't like adding anything the end of the arbor which denotes an obvious "repair" and looks less "professional" . . . to me anyway. It also allows for the installation of a 1/4" smooth set screw to act as an adjustable bearing for the wedge. This set-up allows the user to "customize" wedge placement as well as allowing for any wear over time. Thanks noelf2!!

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks
 
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Dragoon and I still disagree on this one singular point. Mind you I'm not saying that his singular point of contact is bad it is not and is much better that simply contacting the inboard edge of the wedge slot. I'm only saying that the opposing tapers is better, more resistant to wear and will not "walk". Everything else Goon does to the open tops is well thought out and worthwhile.
Oh and the center area of the end of the Pietta slot is a 1/4" wide taper that matches the wedge and the admittedly few original Colts I have examined had the taper.
 
Well, I guess there’s more than one way to skin a cat (although the only cat I ever skinned was in veterinary school anatomy lab).
 
Hey Denster, no harm no foul and I appreciate the "well thought out" part. Ultimately, I want to introduce my own version of a Modern Dragoon without a wedge which will alleviate this whole problem! Lol!! I was thinking more on the cartridge side of things but would include a C&B version as well (if there was any interest). It would look just like it does now, just minus the wedge.

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks
 
45 Dragoon said:
Hey Denster, no harm no foul and I appreciate the "well thought out" part. Ultimately, I want to introduce my own version of a Modern Dragoon without a wedge which will alleviate this whole problem! Lol!! I was thinking more on the cartridge side of things but would include a C&B version as well (if there was any interest). It would look just like it does now, just minus the wedge.

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks
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Well??? You just leave us hanging with that???
 
If y'all would stop filling up Goon's time with cap rakes and bolt blocks, he could work on things like 454 Casuul ROAs and wedgeless revolvers!!! :D:D
 
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