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Short Arbor "fix" ??

Discussion in 'Blackpowder' started by unknwn, Mar 18, 2013.

  1. unknwn

    unknwn Well-Known Member

    I had my LGS special order an '72 Open-top .44 Special 4-3/4" Uberti for me and it was available for my inspection over this weekend,
    Surprise of surprises- the gun was suffering the short arbor syndrome.
    Since my LGS wouldn't be open on Mondays I took it upon myself to contact Cimmaron's customer service to explain my findings and ask about my options.
    The representative informed me that there is a modification/fix that they use to overcome the "short arbor" .
    An oversize wedge (wider) is substituted for the factory supplied part. I asked how I could get my hands on this "fix" , and was informed that the gun would really have to be sent back to Cimmaron.
    I'm unable to figure out how this wider wedge is capable of overcoming the problem and hoped that someone here could explain whether I would be getting a suitably repaired cartridge firing gun back -or- is it just a "feel good" substitution that will require the Pettifogger "button" fix afterall?
    Last edited: Mar 18, 2013
  2. tomykay12

    tomykay12 Active Member

    I'm certainly no x-spurt, but seems to me you still would have a 3 legged stool with a short leg. There are more elegant solutions, but I fixed my
    1851, bought from a fine member here, by gluing two #6 brass washers on the end of the arbor then dressing down to perfect length. One could also drop a shim into the arbor bore. Nothing fancy, but it works, and now my wedgie does not bind up the cylinder if inserted firmly. tk
  3. BCRider

    BCRider Well-Known Member

    Like you I prefer to fix the proper problem.

    I recently got a Uberti 1860 that has the same issue. I got through shooting this past weekend by folding over some aluminium pop can metal to make a shim. But I think I'm going to slice off and dress up a short length of steel and soft solder it to the end of the arbor then dress it to fit with a file.

    The test I read of for sizing it is to put the barrel onto the pin so the barrel is sideways. Then while pushing the arbor firmly into the hole rotate and see how the heel of the barrel meets the contact point on the frame. Ideally you'd want to feel a slight touch if pushing down and no touch if pulling up on the barrel for two successive tries. This way you know that the inevitable play in the pin to bore fit is averaging out and life should be good.

    Of course if in doubt err on the side of leaving the button a hair long. Then try assembling the gun and check the cylinder gap. If it's bigger than you want dress the button down a shade more so the interference when pulling down when testing is a little firmer.

    Keep in mind that under no circumstance do you want the barrel heel to contact the frame when you're pulling up on the barrel during this test. If it does then you'll be putting bending stress on the arbor when the wedge is pushed in. It's fine to play with sizing the button, and thus the cylinder gap, within the limits of the slop between barrel and arbor. But that's where it stops.

    Does that seem clear enough?

    For soldering steel to steel plain solder is fine for something which is basically just some "glue" and won't be under any load. The trick is to clean both surfaces well and have them totally degreased.

    I found some liquid brush on soldering flux at one of my hardware stores that works a HUGE amount better than the lousy white paste that shows up commonly in the hardware sections. It's called S-39 and it was made in Holland. Or if you can still locate any of the old school Kester soldering paste that works fantastic for steel to steel as well even with the new lead free solders.

    And hey, if it gets down to it there's always the option of making your own new wedge if you can run a file and hacksaw. It doesn't need to be hardened steel. Although if you have an old file with worn teeth kicking around you could temper it back with a propane torch to a bright blue temper colour which would be soft enough to cut and file but still hard enough to be the sort of toughness you want for a wedge.

    For the spring you should be able to tap the one out of the undersize thread and between the saw and some small files you should be able to file out a groove with the dovetail on the one end to fit the spring into.
  4. TheRodDoc

    TheRodDoc Well-Known Member

    I would say that Cimmaron is removing metal from the forcing cone face at back of barrel and also from the barrel lug face.
    This lets the barrel slide back on the arbor. They would remove enough metal so that the end of the arbor bottoms in the hole in barrel.
    Then the gun would need that wider wedge.
  5. unknwn

    unknwn Well-Known Member

    If that is so I am all for it. This particular gun has the best wood to metal fit of any Italian gun I've handled to date ( not perfect mind you, but a far cry better than all the others combined!).
    The Cimmaron rep. mentioned that -some- guns have come past them with this problem and that is why they were able to come up with thier "fix" (oversize wedge). He initially didn't entertain my "idea" that the gun was problematic, only after being questioned about my familiarity with open-top guns. After my reply that I have almost a dozen open-top reproduction guns and that I wasn't about to use the gun (-or- complete the sale?) unless the repair gets performed...
    Now my next hurdle will be to convince the LGS that they must repackage the gun and send it back to the Cimmaron company for thier particular brand of "magic".
    I hope that the folks at the LGS will let me handle the gun again so that I can record some measurements to determine the extent (if any) of changes made to the gun while it is in the repair facility.
    I've also got to wonder what the situation will be if I ever find the need to replace the "over-sizeD wedge"? I did ask him where I would be able to find that specialised part because I'd never found any listing or reference for it at the parts supply houses VTI, Dixie, or Taylor's.
    He just asked me to "hold" a minute while he went to check with someone and when he came back on the line he said that "I have one of the -wider wedges- in my hand" and that "the gun will have to be sent back to us..." . Not particularly forthcoming with additional information, but, willing to get the gun fixxed (I hope, I hope) to complete the transaction I'd guess.
  6. J-Bar

    J-Bar Well-Known Member

  7. woodnbow

    woodnbow Well-Known Member


    I'd shim the arbor. Permanent fix.
  8. J-Bar

    J-Bar Well-Known Member

  9. Noz

    Noz Well-Known Member

    Me, too.
  10. BCRider

    BCRider Well-Known Member

    All this talk of shimming got me off my keester last night. I shimmed two of my open tops and now they fit up properly and the wedge locks sharply in place without closing the cylinder gap and jamming the cylinder. Although I may have gotten a little too greedy. I estimate that the cylinder gap is a somewhat close .005 to .006. We'll have to see if I can keep it clean enough during a day of shooting to not get sticky.

    I've got two 1851's that need a button as well. But in their case the cylinder gaps are grossly oversize at around .025. That means that the heel of the barrel or frame needs a little metal to be removed as well to let the barrel set back a little. And THEN I can fit the nose button. So I think those two are going to sit a while until the metal shop is back up and running and I can do the work with the milling machine.

    I ended up making the buttons out of some 3/8 steel rod hacked out of the non threaded shank of a bolt I had kicking around. The nose of the arbor was lightly filed clean and the buttons soldered in place as I suggested in the previous post. Works great!

    Now all I need to do with my pair of 1860's is pop out the short front blades and soft solder in a couple of taller ones which I can then trim down to fix my aiming.
  11. tomykay12

    tomykay12 Active Member

    A fitted arbor....

    Sure makes the wedge lock up nicely, dosen't it? I can understand why Uberti leaves them short; each gun is probly a little different and it would take too much handwork to fit. Seems like they could make and adjuster of sorts threaded into the end of the arbor. Maybe they also figger most of these things hang on a wall or nestle in a sock drawer for life. Whatever, glad it is an easy fix, tk
  12. woodnbow

    woodnbow Well-Known Member

    Agree with Tommy. A simple allen set screw in the end of the arbor, adjusted and loctited in place would do the trick...
  13. BCRider

    BCRider Well-Known Member

    The ends of my two arbors that I did were sitting right at about 0.10 "thick". I thought about drilling and tapping for a set screw but that's not a lot of threading to withstand the shock of shooting. Besides, I'm still operating with fairly primitive shop settings as I'm still in the midst of the shop renos. So the fancy stuff is still packed away. On the other hand the vise, hacksaw, some files and the propane torch were handy.... :D

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