Cable termination at Winding Drum

Discussion in 'Tower, Monumental & Street Clocks' started by SamS, May 17, 2009.

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  1. SamS

    SamS Registered User
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    Feb 16, 2008
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    I am interested in knowing how some of you have terminated weight cables inside of winding drums, particularly as this applies to Howard tower clocks. I have seen a variety of techniques used, most using modern swaged fittings or cable clamps. The remnants of cable inside of our winding drums indicate that the cable may have been simply pulled through the side access hole, a knot tied, then the cable pushed back in.

    Old engineering manuals (Marks, Audels and Machinery Handbook) have a little info mostly referring to the need for 3-4 turns around a wire rope drum to provide enough friction to hold. This indicates that all of the holding power comes from the cable friction, and maybe little to none from the cable termination.

    Any thoughts or comments relating to this would be appreciated, especially information relating to how it was originally done.

    Thanks,
    Sam
     
  2. gvasale

    gvasale Registered User
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    Mar 30, 2005
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    Sam: A simple overhand knot is often found with 5" or so of a free end. Also ran into one where a square nut of the proper size to fit in the access hole had the cable unwound like preparing for a splice and threaded through the nut with stands in and out of the nut several times. That is a real he PITA. Going the simplest way is effective, and I tend to agree that a couple wraps of cable around the drum does help in anchoring it. A full drum is sufficient for a week's run. Overlaping with more cable serves only to lower the weights to allow service. In other words, if you find that from the point where the weights are on a surface which allows you to have the cable without tension, and when wound up to the upper stop will start a second layer of rope on the winding drum, when the clock is in use, don't wind the second layer on just wind on one layer. Better for the cable.

    What's the projected date when it will be running?
     
  3. SamS

    SamS Registered User
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    Feb 16, 2008
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    Hi Greg,

    The Clock is in place and running. My wife and I installed the weights yesterday and today cut holes through the floor (4-1/2 inches of solid wood) for the weights to drop to the next floor and to allow the installation of the full length pendulum (which is now installed and running). The clock will run it's first full night with the 9 ft pendulum tonight.

    Still need to install the motion works. That may have to wait until next fall since gaining access to the top of the tower will take some serious effort (40 ft spirol stair case cut through a 25,000 gallon iron water tank).

    Any one else with confirmation on using a knot to connect the cables?

    Sam
     
  4. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    Since the Howard drum appears to have been designed to allow the end of the cable to be anchored to the drum to prevent the cable from "off-winding" once the weight is in place, I would think that would be undeniably the way it should be done. I have no idea how Howard would have done this, but I have never run into a cable clamp small enough to fit through the access hole in the end wall of the drum. I have always tied a knot to slip inside the drum. Do I actually infer correctly that a suggestion has been made that it is not necessary to anchor the terminal end of the cable inside the drum, and that the cable windings themselves will "grip" the drum sufficiently without anchoring the cable, to allow the cable will remain in place?:eek: I don't think so!

    Doug
     
  5. DanJeffries

    DanJeffries The Tower clock man

    Dec 1, 2008
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    I have several tower clocks in my personal collection and of course they aren't running on excessive weights, but they all came to me originally with cables with knots tied in the end. I owned a ST #16 quarter strike and it had the cables with knots tied and when I ran it I followed the same process. I have a small Howard movement and the cable has the knot in it as well.
    Without going on and on.......in my American and European movements they all use the knot in the cable method, I have not seen a clock with any type of clamp whatsoever.
    I do agree with Doug Sinclair......you need something other than just the first 3-4 windings holding the cable in place. It may hold, but I wouldn't want to be the one underneath the weight if it ever decided to test itself! :eek:
    Good Luck and I look forward to pics!
    Dan
     
  6. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    Sam,

    Check to see if there is a local ordinance with respect to limiting the access of people on the main floor, to any area beneath the clock. It is unlikely that there will be anything pertinent to tower clocks, but there will likely be something covering suspended weights of generic description. The floor beneath tower clock weights has traditionally been protected by a shock cushion consisting of something like a section of 36" diameter poly sewer pipe, 4 feet tall, half filled with gravel. Lots of accidents can happen that might cause a weight to fall. I am sure your insurance company will have something to say about just what sort of coverage you may expect should an accident occur. And you WILL want insurance coverage in the event something happens! Oh! By the way! I really do recommend that you secure the end of the cable inside the drum. If you don't, and there is an accident, even if you have insurance coverage, my bet is that an insurance company (the victim's) will take you to the cleaner's big time! And your insurance coverage will likely be null and void unless you take this simple step!

    Doug S.
     
  7. SamS

    SamS Registered User
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    Feb 16, 2008
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    Based on this last response, I am requesting that the web master remove this thread from the message board. Unfortunatly, I will now need to reconsider posting any pictures of the installed clock, or any future interaction with this message board or the NAWCC.

    This last posting is the most insulting thing that has been said to me in some time. What do you think we are, idiots!

    The NAWCC was supposed to be for hobbiest, for fun and enjoyment, not for threats and liability notices. I'll now have to keep my "business" to myself. Maybe I should simply take the tower clock home, hide it in my basement like you do, and not let anyone see it!

    Of course the cable needs to be connected on the end, and of course the weight and pendulum should not expose persons to danger, and of course the cable, connections, and overall system must be engineering properly, and of course the floors and building must be capable of properly supporting the equipment.
     
  8. Grant Perry

    Grant Perry Registered User

    Jun 5, 2002
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    Good evening,
    I have been following this thread and have found it informative. I would like to leave it "as is" at this time, and would rather not delete the thread as there is good content for future reference. I think that the advice offered is sound and helpful, and I suggest that we take all postings as “opinions”. Whether or not we choose to accept those opinions are up to each individual. When we post a question on the message board we always get a variety of information. We need to use what we feel is helpful and disregard the rest. Mr. Sinclair is extremely knowledgeable in this area and I am sure that any advice he is offering is meant to help and not hinder your project. He is offering advice based on many years of experience.
    I would like to see pictures of the movement and setup as it sounds like a great project.
    Best regards,
    Grant

     
  9. hickorydickorydoc

    hickorydickorydoc Registered User

    May 25, 2007
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    Hi Sam,

    The tower clock that I maintain for my town is not a Howard, but a Stevens, but it, too, has a simple overhand knot in the end of both the time and strike cables. The time cable is 1/4" and the strike cable is 3/8". The hole in the end of each drum is barely large enough to angle the knot into; no way a clamp would fit in, and a clamp left on the outside would interfere turning past the frame. When the weights are all the way down, there is between 1 and 1+1/2 turns left on each drum, so I have been a little nervous about a knot letting go, but that's the way it has been since long before me. If you can keep enough cable so that there are at least few turns on the drum when the weight is all the way down, as suggested before, I would trust the knot plus the friction.

    Mark
     
  10. Bill Ward

    Bill Ward Registered User
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    Jan 8, 2003
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    I think that the advice in the engineering manuals about always having several turns on the drum applies to the use of a capstan, in which the "loose" end is either attached to a counterweight (as in an elevator) or it's pulled tight for lifting, but released for dropping (as in a pile driver). If a steel cable is merely wrapped around the drum, without the payout end being restrained, that loose end will immediately, due to the stiffness of the cable, unwind from the drum. So, with steel cable anyway, that end must be restrained somehow.
    In American wood movement tallcase clocks, the loose line end (which you pull down on to wind the clock) is counterweighted; otherwise the line will slip on the drum.
    I've little practical experience with tower clocks, but in my (limited) rigging experience, I was taught never to trust a knot in steel cable, but to always reinforce it with a clamp or to wrap it with copper or soft iron wire,or to unbraid the cable wires and splice them back together over a large nut or something similar.
    I could relate an amusing but cautionary tale along these lines concerning a shelf over my college dorm room bed supporting stereo equipment, hanging from knotted piano wire, very loud music, and my girlfriend, but it would be way too embarrassing.:eek:
     
  11. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    She was only a friend, so I am certain you were just doing homework, right? ;)
     

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