Chime rod question

Discussion in 'Clock Repair' started by bangster, Feb 25, 2012.

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  1. bangster

    bangster Moderator
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    Chime rods have a tapered brass thread. Cast iron chime block has no threads. What's the best procedure for getting the rods seated firmly in the block?
     
  2. bangster

    bangster Moderator
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    Dang it, y'all give me some advice here. Do I need to use a hammer?
     
  3. harold bain

    harold bain Registered User
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    Pictures, Bang, pictures. It would be easy to say pound it in, but might not be right. How (and why) did you get them out in the first place?
     
  4. Dick Feldman

    Dick Feldman Registered User

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    Bang,

    Timesavers shows taps and tap drills for gong bases
    Two sizes.
    For 6.5 mm and 8.0 mm chime rods.
    “For drilling and tapping cast iron gong bases when installing new chime rods.“

    Page 29, Upper Right Corner.

    The last time I was faced with this, I used a tap from my tool box that was close—Was it ¼” X 20?

    Best Regards,

    Dick
     
  5. bangster

    bangster Moderator
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    #5 bangster, Feb 26, 2012
    Last edited: Feb 26, 2012
    Thanks Dick...
    However, these threaded rods came out of these non-threaded holes. Presumably, that was from the factory. Is it necessary now to thread the holes in order to re-seat them? I yam mystified.
     
  6. Mike Phelan

    Mike Phelan Registered User

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    That's weird! Must have been a factory glitch or the swapophiles have got there first.

    I would tap the threads. I always use a smear of copper grease on the threads and use an impact driver to fit them to the block as if they aren't really tight it makes a heck of a difference to the sound.
     
  7. shutterbug

    shutterbug Moderator
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    I can't envision what you have there, Bangs. Conical shape with threads? A pic would sure help here :)
     
  8. moe1942

    moe1942 Registered User

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    Use a screw pitch gage to get TPI and measure diameter. Get the proper tap and thread the block.
     
  9. Thyme

    Thyme Banned

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    Me neither. :?| All the ones I've seen are either/or: either the rod has a threaded end that screws into the block, or the rod is tapered and is inserted directly into a hole in the block.
     
  10. bangster

    bangster Moderator
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    Heere bee pics:

    chime rod threads.jpg chime block close-up.jpg
     
  11. moe1942

    moe1942 Registered User

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    Brass isn't hard enough to self tap. Looks like the last sterp was missed. Tap it with a bottoming tap.
     
  12. bangster

    bangster Moderator
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    A: I know brass ain't hard enough to self tap into cast iron.
    B: These rods were in there tighter'n hell until I took them out.

    C: Go figure.

    These threads look to me like tapered threads, a la pipe threads. Where do I find a bottoming tap for those??
     
  13. Dick Feldman

    Dick Feldman Registered User

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    #13 Dick Feldman, Feb 26, 2012
    Last edited: Feb 26, 2012
    Bang,

    I believe the taps I mentioned at Timesavers are for tapered thread. A bottoming tap may be a bit difficult to find and is probably not necessary with tapered threads.

    I think that 1/4" or 5/16" NC bolt thread is close enough to seat the rods securely. If not those, try 1/8" NPT.

    JMHO,

    Dick
     
  14. kdf

    kdf Registered User

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    I think that these holes can't be tapped now, they are too big (brass holders were in them).
    Seems to me that someone already changed rods, 4th rod is diferent from others...
     
  15. Ed O'Brien

    Ed O'Brien Registered User
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    Agreed. Tapping does not seem to be the solution, since at best one thread could be tapped at the bottom of the hole. Not a perfect solution, but an alternative might be putting JB Weld (epoxy) into the holes then tapping that to accept the rods. Otherwise, could open the holes a little more, tap them then make bushings to oversize the threads on the rods. Regarding the epoxy suggestion, not sure whether this might affect the sound of the rods versus a secure metal to metal contact.
     
  16. bkerr

    bkerr Registered User
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    If the thread is a "standard" thread I'd try a helicoil. You don't have much to loose at this point.

    Maybe a replacement block and rods?
     
  17. moe1942

    moe1942 Registered User

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    On closer look The crest of those threads have been flattened from being forced into the untapped holes so they are trashed for installing in a properly tapped hole. You won't know if the hole is nominal size til you measure it. If it is and just missed the tapping step tap it and put new rods in. They have to fit right and tight...If the thread isn't proprietary it is probably a NPT..I would think that the rods should be in solid contact with the block for proper tone. An attempt to build it up with JB or other material could affect the sound. You can try it then we'll all know for sure.
     
  18. shutterbug

    shutterbug Moderator
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    I'm thinking you're going to need a two step approach. First, redress the threads with a die. You might have to decrease the size if they're really flat. Then you'll probably have to enlarge the holes in the block, make a double threaded insert that will accept the rods and screw into the block. It might be easier and cheaper in the long run to buy a new tuned set of rods and tap the block or just replace the block and rods together. I'm surprised that you got them things out! It must have required some work! The machine that puts them together must have grunted a bit to get them in :)
     
  19. Thyme

    Thyme Banned

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    Good that you posted the photo. Obviously the block is supposed to be threaded, so some alteration was done on it.

    Here's a link to a product made for stripped threads (click here). I have used it and it usually works, depending on the situation. However, as stated, it is essential that the contact has to be good and tight to allow the rod to resonate properly. Probably the best solution would be to find another block that hasn't been compromised (but that may be easier said than done...).
     
  20. bangster

    bangster Moderator
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    Thanks for all the comments & advice so far. My intention is to replace the whole set. The longest one was broken, and an attempted repair had crappy results. Tone like hitting a pie tin with a spoon. Chance of getting a single replacement rod that's in tune with the other three approaches zilch. It's the installation of the new set that I'm concerned about.

    FWIW, I found that inserting a shell of very thin brass into the hole gives the threads something to grab, and they can be tightened down snugly.
     
  21. DianneB

    DianneB Registered User

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    That is along thee line I would have taken - filled the holes with oxy-acetylene and brass rod, drill, and re-tap. Chase the threads on the plugs and it is like brand new. With one dud chime though it is not worth the effort because you still don't end up with a useful assembly unless you can find a single rod and tune it.
     
  22. David S

    David S Registered User
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    Sounds like this post will be closing soon. However I think that the block was designed this way. The brass threads provide lots of compliance for a press fit and the hole doesn't have to be very accurate. We used a similar design at work when we needed to press fit a shaft into an insert. Shaft od was not well controlled so we just threaded the inside of the brass insert and pressed the shaft in distorting the threads. It was one of the most robust press fits we had, manufacturing was happy that they didn't have to control shaft and insert to tradional press fit tolerances.
    David
     
  23. bangster

    bangster Moderator
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    That's encouraging news David, and sounds reasonable. The rods were originally DRIVEN into the unthreaded chime block, the brass threads were deformed and the rod held tight. The rods could be unscrewed, but not screwed back in because the threads were buggered, and there were no corresponding threads for them to grab.

    My little brass shim made up the distance lost when the threads were flattened, gave the buggered threads something to grab, and I could screw the rods back in.

    I need some suggestions here. When I install the new rods, should I (a) just pound them in with a hammer, (b) screw them in with a regular screwdriver as much as possible, then finish off with and impact driver, or (c) shim them to start with, and tighten them in with a regular screwdriver. Or (d) something else.

    Whaddya think??
     
  24. David S

    David S Registered User
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    Bang if the threads have been flattened and displaced you could try using a worn die to see if you can reform them rather than cutting, this may increased the OD enough to get a good press fit. Other than that, as you suggest some shim stock formed into a tight C then press it home. The problem is since the original peaks are gone from the original thread, the press force may be much higher. If you are lucky enough to find a die of the right size and if it cuts then it will form new peaks and you can adjust your shim thickness accordingly (if you need it depending on what the thread od looks like), then press it home.
    David
     
  25. GregS

    GregS Registered User

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    Bang,

    Not sure how badly you want use this block, but, in another life, the company I worked for often re-sleeved hydraulic cylinders. We'd re-bore the cylinder and then make a bushing .0025 oversize of the cylinders ID. Next we'd freeze the "bushing" with dry ice and heat the cylinder to about 450 degrees. Then we'd just drop the "bushing" in the cylinder and press it down until everything cooled off. The frozen "bushing" expanded as it warmed up and the heated cylinder shrank as it cooled down. And nothing would ever get that bushing out again, short of machining it.

    If you went this route you could then simply dress the bushing's hole and tap it with a 6.5 mm tap. If you get the one from Timesavers, please note it's not a tapered tap, so you'll only want to thread enough to be able to screw the rod in about half way by hand and then use an impact driver to bottom out the chime rod and lock it in.

    just my 2 cents worth.
     
  26. Jim Hartog

    Jim Hartog Registered User
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    I read this entire thread and I think I might be alone in my opinion. Your block never was threaded nor meant to be threaded. Those threaded rods you have are not original, they are replacements. Your original rods were unthreaded and went into the block with the tapered constriction in the large clearance hole that you show in your photo. The attached end of the rod goes into the small end of the hole.

    I have done a couple of these. I used 1/8" music/piano wire, filed the tapered constriction on my Shopsmith with a steady rest, hammered the round end of the rod into an oval and that oval was hammered (carefully) into the round 1/8" hole of the cast iron block. Done. Sounds great.

    Is your block reversible, right side up or what?

    Forget the threads.

    Jim
     
  27. bangster

    bangster Moderator
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    The block is not reversible, and I'm pretty sure not replaceable. It's the kind mantel clocks have that attaches to the inside upper back of the case with a single screw. And it has a fifth rod, force-driven into a smaller hole, for the strike. So I'm pretty much stuck with this block.

    Anybody know a place to get tapered (non-threaded) rods, max 10" long?
     
  28. David S

    David S Registered User
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    Bangster I have been keeping up on these threads. Your chime rod attachments sure look like what I have on the Gustav Becker that I am working on. I am still thinking that these are press fits. The shallow counter bore in the chime block would have been a pig to thread. And interestingly all the screwhead slots are aligned parallel on mine which I thought odd, even though they show slightly different thread engagement. See Pic of mine.
    David
    chime rod fastening.jpg
     
  29. Jim Hartog

    Jim Hartog Registered User
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    I stand corrected. Humble pie has a nice flavour (flavor for you Americans according to my spell checker).

    From David S's picture and comments maybe they are just hammered in (press fit) using the tapered threads of the brass to grip the iron.

    Or, you could drill a bigger clearance hole on the other side and still tap the hole without a bottoming tap.

    Jim
     
  30. Thyme

    Thyme Banned

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    I'm assuming that what you are referring to as the fifth rod (which is press fit directly into the block) is shown as the first on the left in your photo, followed by the others that have large bored holes. I can't believe that the block was purposely made this way, with one rod mounted totally differently than the others, so I still think it was altered by someone. I also don't believe that threaded rods were ever meant to be hammered into smooth bores in a block without the block being threaded.
     
  31. David S

    David S Registered User
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    Hi Jim no need for the "humble pie". I think there is a lot in these old clocks that we don't really know for sure. All I do know is that using a threaded portion does alow a lot of compliance for a secure press fit. Yes perhaps it goes against our paradigms of what a "proper" union should be. On this Gustav Becker clock I have no idea if someone has done anything with the chime blocks. I do know that I see solder on one wheel arbor, markings where the mainsprings are mounted and some distorted cams (due to previous removal ??), plus a weird bushing on the inside of one plate. So perhaps someone messed with the chime block..but I dont' think so.
    David
     
  32. Thyme

    Thyme Banned

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    What would be the point of making the mounting of one rod entirely different than the others? No manufacturer would do that unless there were a good reason for doing so. (But apparently there isn't any.) :?|
     
  33. David S

    David S Registered User
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    Thyme I have no idea.. My chime block only has the four "screws" holding the four chime rods...nothing else. I have a few clock repair books as recommended on this site, but haven't seen anything so far on the subject of the chime rod mounting that has been discussed here. Perhaps there will be more input??
    David
     
  34. bangster

    bangster Moderator
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    Fifth rod is on the left. Dunno whether the block is original original. It's original to me, and I gotta live with it.
     

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  35. Thyme

    Thyme Banned

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    The fact that those bored holes are not in a straight line really raises my eyebrows. I just looked in my junk bin and found two old chime blocks. One is for press fit rods (small holes) the other is for threaded rods and has holes that are bored all the way through the block that are threaded about halfway through. I've never seen a block that has a variety of rod mounting styles, nor one with large, partially bored holes that are not threaded.

    My guess is that someone had a hard time removing what was left of the original broken rods and decided to drill them out, ultimately resulting in boring over-sized holes to attempt installation of threaded end rods as a compromise. Unfortunately once those holes were enlarged it makes it impossible to go back to the original type of pressed fit rod, of which only one is still remaining.

    Old, ruined chime blocks make good paperweights... :rolleyes:
     

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