I recently purchased an Uberti 1860 .44 open top and it’s overall quality, finish, and action is excellent but for the usual short arbor. In this case, it caused the barrel-cylinder gap to close and action to bind if the wedge was even finger tight. The wedge also bottomed against its retaining screw with thumb pressure.
Larson Pettifogger’s Uberti tuning guide includes a good fix of drilling and tapping the end of the arbor for a set screw but the case hardening was so nice on the arbor that I wanted to try a different solution. A loose washer dropped in the arbor recess works fine but I preferred a more permanent repair.
44D (Mike at Goon’s Gun Works) mentioned putting a fitted steel plug in the arbor recess and this seemed like a good option. I measured the thickness of 2 #10 washers and dropped them into the arbor recess and installed the barrel onto the frame. This created a gap at the joint between the barrel and lower frame because the arbor was now effectively “too long”.
I measured the gap between the barrel and frame using feeler gauges and measured the depth of the arbor recess (with washers removed) using a depth micrometer. The hole bottom is slightly rounded and the center is about 0.016 “ deeper than the edge. I subtracted the gap between lower barrel projection and frame from the thickness of the 2 washers to determine the theoretical thickness of the plug to be installed in the arbor recess. This came out to be about 0.075”.
I just measured the diameter of the arbor recess hole with a set of calipers (not the best way but fine for this purpose) and turned a 1/2” mild steel rod to a diameter about 0.003” smaller than the measured diameter of the hole so that it would be slightly loose and removable. I also tapped a 6-32 hole in the center of the spacer to make installation and removal easy. The last 2 actions were done to be sure that an incorrectly sized plug was not stuck in the arbor hole!
I parted of a spacer about .008 too thick to allow final sizing to fit using sandpaper/emery cloth. The bottom of the spacer protrudes in the center to account for the rounded bottom of the hole, however this isn’t really necessary. The gun was assembled several times sanding the spacer in between and measuring gap between barrel and frame, barrel and cylinder, and wedge fit.
When everything was correct, I measured the thickness of the spacer and considered making a slightly larger diameter spacer of same thickness and shape that would be a press fit in the arbor recess. I ultimately decided to just peen the perimeter of the spacer using an automatic center punch, sand face flat again, degrease parts, and use a small amount of Loctite 640 sleeve retaining compound. The part was then able to be tapped into place with a brass rod and hammer. This was secure but would have allowed the plug to be removed by installing a 6-32 screw in the tapped hole (before the Loctite set) if the final fit was incorrect when the gun was assembled.
My plan involved my small Atlas lathe, however many #8 washers are only a few thousandths larger than the arbor hole. You should be able to fashion a tiny arbor from a screw and a couple of nuts, chuck it in a hand drill or drill press and turn it to proper diameter with emery cloth. You could probably also file the washer to size in a vise. I hope this helps someone.
Larson Pettifogger’s Uberti tuning guide includes a good fix of drilling and tapping the end of the arbor for a set screw but the case hardening was so nice on the arbor that I wanted to try a different solution. A loose washer dropped in the arbor recess works fine but I preferred a more permanent repair.
44D (Mike at Goon’s Gun Works) mentioned putting a fitted steel plug in the arbor recess and this seemed like a good option. I measured the thickness of 2 #10 washers and dropped them into the arbor recess and installed the barrel onto the frame. This created a gap at the joint between the barrel and lower frame because the arbor was now effectively “too long”.
I measured the gap between the barrel and frame using feeler gauges and measured the depth of the arbor recess (with washers removed) using a depth micrometer. The hole bottom is slightly rounded and the center is about 0.016 “ deeper than the edge. I subtracted the gap between lower barrel projection and frame from the thickness of the 2 washers to determine the theoretical thickness of the plug to be installed in the arbor recess. This came out to be about 0.075”.
I just measured the diameter of the arbor recess hole with a set of calipers (not the best way but fine for this purpose) and turned a 1/2” mild steel rod to a diameter about 0.003” smaller than the measured diameter of the hole so that it would be slightly loose and removable. I also tapped a 6-32 hole in the center of the spacer to make installation and removal easy. The last 2 actions were done to be sure that an incorrectly sized plug was not stuck in the arbor hole!
I parted of a spacer about .008 too thick to allow final sizing to fit using sandpaper/emery cloth. The bottom of the spacer protrudes in the center to account for the rounded bottom of the hole, however this isn’t really necessary. The gun was assembled several times sanding the spacer in between and measuring gap between barrel and frame, barrel and cylinder, and wedge fit.
When everything was correct, I measured the thickness of the spacer and considered making a slightly larger diameter spacer of same thickness and shape that would be a press fit in the arbor recess. I ultimately decided to just peen the perimeter of the spacer using an automatic center punch, sand face flat again, degrease parts, and use a small amount of Loctite 640 sleeve retaining compound. The part was then able to be tapped into place with a brass rod and hammer. This was secure but would have allowed the plug to be removed by installing a 6-32 screw in the tapped hole (before the Loctite set) if the final fit was incorrect when the gun was assembled.
My plan involved my small Atlas lathe, however many #8 washers are only a few thousandths larger than the arbor hole. You should be able to fashion a tiny arbor from a screw and a couple of nuts, chuck it in a hand drill or drill press and turn it to proper diameter with emery cloth. You could probably also file the washer to size in a vise. I hope this helps someone.
( along with everything else!!)
