Should I make a new arbor?

Discussion in 'Clock Repair' started by bytes2doc, Dec 4, 2018.

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  1. bytes2doc

    bytes2doc Registered User
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    Starting to restore another "trashed" Ansonia.

    Many of the pivots are bad, and all the arbors are somwhat pitted.

    I attempted my first pivot job and it came out great!

    Second one, snap, drill bit broke off in the arbor. Drats!

    Any ideas how to get that drill bit out? Should I just make a new arbor?

    The arbor measures .095, and I have a drill rod .094. Is that close enough?

    Is the wheel and pinion friction fitted? Any trick to removing the wheel from the arbor without damage?

    I assume Locktite for securing the wheel and pinion to the new arbor?



    Barry
     
  2. R. Croswell

    R. Croswell Registered User

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    #2 R. Croswell, Dec 4, 2018
    Last edited: Dec 4, 2018
    It would help to See a picture of the arbor and what is on it. Is there a lantern pinion or cut pinion? Wheels are usually a press fit and there should be no need for loctite if you use the correct size new arbor. You can use a drill press and proper supports to press the arbor out.

    Broken drill........ that's nasty. Probably going to be a fight with poor odds.

    RC
     
  3. wow

    wow Registered User
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    The broken off drill bit is bad. I think I would try to find a donor arbor from another movement or make a new one. Getting that bit out is really nasty.
     
  4. bytes2doc

    bytes2doc Registered User
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    It's a lantern pinion, and I will get out in the shop and snap some pics if and when I can get home from work in a decent hour.
     
  5. Dick Feldman

    Dick Feldman Registered User

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    I sure would not make an arbor from drill rod.
    That is as hard as a drill bit.
    The original was made from much softer material.
    Is it possible to cut back the original arbor and center drill it, past the broken drill bit?
    Maybe you could then add a piece to match the original arbor.
    Best,
    Dick
     
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  6. R&A

    R&A Registered User

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    #6 R&A, Dec 5, 2018
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    Seems like your picking up some bad habits with Locktite Learn to stake things back into place. As far as the drill broken off. How much is broken off. You maybe able to cut it off below the drill and add to it. This all depends on what wheel this has happened to. So what gear is it ?
     
  7. shutterbug

    shutterbug Super Moderator
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    For next time, when drilling be sure to use some cutting oil and pull the bit out often to clean the debris out of the hole. Spade bits are much better for this operation too.
    I agree with R&A's admonition on lock-tite. Although it's being mentioned more and more often as a reliable bonding agent, it is not originally how things were fitted together. It's best to stay with what we know for sure works.
     
  8. R. Croswell

    R. Croswell Registered User

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    Loctite has its place but perhaps not the best of this application. It works best for keeping things in place that aren't under a lot of load. For example, retaining a replacement pivot. There isn't much of any torque or push-pull force on that pivot - it just needs to stay in place. When used to retain a wheel hub on an arbor that may be driving that wheel under considerable torque the demands on the Loctite are much more significant and confidence factor significantly less.

    RC
     
  9. bytes2doc

    bytes2doc Registered User
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    Here are some pics. This is a strike side wheel. As stated, all arbors look like this once I got the rust off.

    2018-12-5 16-32-22.jpg IMG_20181205_163045.jpg IMG_20181205_163124.jpg
     
  10. David S

    David S Registered User
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    Ouch!

    Barry what kind of bit were you using when it broke? i.e HSS or other?

    David
     
  11. bytes2doc

    bytes2doc Registered User
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    I was using a set from Japan. No name on them that I could tell.

    Truth be told, the drill was perfect. I was tapping the new piviot in, but it was no where near the depth I had marked. So what do I do, I hit it harder and the darn thing bent - go figure. Any way, I snapped that bent piviot off and started over. Ground down flat, used a center drill, and started drilling again. All was going well, but about half way through the drill started to wabble and instantly snapped off. There, I confessed! (As I hang my head in shame)
     
  12. wow

    wow Registered User
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    Barry, when you said several of the pivots were bad, did you mean broken off, bent, or just worn? Many times it is possible to cut down the pivots to a smaller size and install bushings with smaller bore and it works fine.
     
  13. bytes2doc

    bytes2doc Registered User
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    All the piviots need to be polished. Some are so bad that after I finished them the diameter was to small, especially for the strike side.
     
  14. gmorse

    gmorse Registered User
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    Hi Barry,

    If you haven't already seen this thread by Jerry Kieffer, it's well worth a look, (as indeed are all his contributions). This technique is a safe and sure way of drilling for pivot replacement; I've used it down to 0.2 mm diameter with no issues or breakages. Trying to drill 'freehand' always carries the risks of drill breakage and conical holes.

    Regards,

    Graham
     
  15. bytes2doc

    bytes2doc Registered User
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    Hi Graham,

    I use the Sherline to repivot. I found that my first two holes were dead on, no problems, and the Sherline really made the task easy.

    My problem came about after I bent the new pivot - hammering too hard as it would not seat to the level I premeasured, only about a third of the way. Maybe the locktite set too quickly?

    Anyway, after snapping that pivot off I started over. So I was actually drilling into a pivot in the arbor. Again, dead on, but something with that configuration guickly went awry.
     
  16. R. Croswell

    R. Croswell Registered User

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    You may have experienced a hydraulic lock. If the pivot was sized for an interference fit any Locktite in the hole would have no way to escape. Liquid will not compress so you would be unable to drive the pivot home regardless of how much you hammered it. If you set your pivots using an interference fit there is no need to use Loctite. If you set pivots with Loctite then they should be snug slip fit and avoid excessive liquid in the hole, and press them home quickly. When I use Loctite for this purpose I push the pivot home using the lathe tail stock which presses it straight in.

    RC
     
  17. Jerry Kieffer

    Jerry Kieffer Registered User
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    Barry
    Sorry, I am late on this, but have been busy and it may not apply unless you were using a HSS drill. (Not Carbide)

    My most complicated method is to spot weld a piece of rod to the end of the drill and pull it out, but we will leave that for another day.

    My most common method is to drill out the drill using a drill designed to drill out broken taps such as the "Armor Drill" shown in the following link.

    Drill Out And Remove Broken Taps With The Armor Mill And Armor Drill Tools

    In the sample link, the smallest drill is a 5/64" that should work for your needs, but smaller diameters are harder to find and must be purchased when available from whoever.

    In addition, when using this type of drill, lead screw control and a sensitive feed rate is required. Based on your mentioning the Use of a Sherline Lathe, you have most of what is needed. (Can supply similar info for other brands by request) If your using the Lathe as stock without alignment accessories and expensive highly accurate drill chuck, I would suggest the following.

    (1) For feed rate sensitivity and for micro drilling, I use the largest hand wheel provided by Sherline per the first attached photo. The larger red wheel shown in the photo is installed when required for this type work offering far greater feed rate control.

    (2) While no tailstock is perfectly aligned on any brand, the drill chucks are generally the worst culprit. To gain the greatest advantage, I sharpen two points and setup per second photo. The tailstock drill chuck is then rotated until the two points come as close together as possible by rotating the chuck in its taper. At this point, both the tailstock and chuck can off set misalignment as close possible and then marked and returned to that point when a higher degree of accuracy is required.

    If what you broke off was Carbide, I would machine a new arbor.

    Jerry Kieffer

    fullsizeoutput_14a.jpeg fullsizeoutput_2ae.jpeg
     
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