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    Rory formerly worked as Curator of Horology at the Royal Observatory, Greenwich, where his role included day-to-day management of research and digitization projects, writing, public speaking, conservation, convening conferences, exhibition work, and development of acquisition/disposal and collection care policies. In addition, he has worked as a horological specialist at Bonhams in London, where he cataloged and handled many rare timepieces and built important relationships with collectors, buyers, and sellers. Most recently, Rory has used his talents to share his love of horology at the university level by teaching horological theory, history, and the practical repair and making of clocks and watches at Birmingham City University.

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    Until Rory’s relocation to the United States is complete, he will be working closely with an on-boarding team assembled by the NAWCC Board of Directors to introduce him to the opportunities and challenges before us and to ensure a smooth transition. Rory will be participating in strategic and financial planning immediately, which will allow him to hit the ground running when he arrives in Columbia

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Straightening a bent arbor

woodlawndon

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Discovered this bent arbor on the time side of an Ansonia movement. I presume this damage was done when the mainspring broke. Are there any tricks to straightening? Apply a bit of heat? Slowly in a vise?

314361.jpg
 

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R. Croswell

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That's bad! You can try chucking it is a drill press or lathe pretty close to the lantern pinion and just apply force near the base of the large wheel and bend it back straight. Will be hard to get perfect and the lantern pinion cap may become loosened in the process. If you have a lathe you might consider just making a new arbor and transfer the wheel and pinion.

RC
 
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Bruce Alexander

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T-2 took a real shot there didn't it? I'm thinking that at least one of the pivots must be bent as well. It happened pretty fast. This Gear took the brunt of it but carefully check all of the teeth, pinions and pivots in the train as well.
 
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shutterbug

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Just chucking it in a drill and tightening it might straighten it out. If not, RC's approach will work.
 

harold bain

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Drill a hole in a block of hardwood the same size as the arbor. Push until straight, spinning it to check straightness.
 

MartinM

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I've always operated on the premise that corrective force needs to be applied in exactly the same place as the force that bent the metal, whether it's a bent shaft or a dented fender.
On this one (If I didn't have a lathe), I'd install the aluminum angle plates on my vise, lay the arbor across the open jaws, rotate till the high spot is at the top and try pressing down on the trundle cap.
 

Willie X

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I'm with Mart,
I use a thin oak block with a 'V' notch across the small end and tap it with a small (4 ounce) hammer. The notch is placed over the lantern pinion cap/s. The block is about 1/2" x 5/8"x 3" long. The 'V' notch has a 90 degree included angle and is about 5/16" wide. The notch goes across the 1/2" way.

Don't use any heat!

You can spin the arbor/wheel between your thumb and forefinger and tell when it's straight.

Willie X
 

lpbp

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These can often be straightened using a watch makers punch set find one that just fits the arbor, slide it to the bend, bend slowly to straighten.
 

Rob P.

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Before doing anything, check the gear teeth. Any damage, toss it and find a donor replacement.

If the gear (and pinion) is ok then I'd find/make a set of parallels. Put the arbor in the parallels and into a press. The bend is too severe to try to straighten without heat so touch the bend with a tip of a BIG soldering iron until it's hot. You can try a micro torch if you don't have the BIG (and I mean BIG!) soldering iron. Use a press/punch setup to push down on the arbor to straighten it. A dial indicator will tell you when it's straight again.

Don't be surprised if it breaks. If it does, either replace from a donor or make a new arbor.
 

R&A

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Seriously wow In a lathe with an indicator Or you can send it to me and I'll straighten it for you.
 

Willie X

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I have used most of these methods with decent results. I like to use a hammer and block because it seems to unbend things without getting the dreaded 'S' curve. Even if you have access to a lathe, or good drill press, or the other holders mentioned, I would still use a small hammer and the already described small hardwood block to deliver the force.

There is a very low chance that this arbor will break.

Again, don't use any heat unless you want more problems than you have now ...

Willie X
 

R. Croswell

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I have used most of these methods with decent results. I like to use a hammer and block because it seems to unbend things without getting the dreaded 'S' curve. Even if you have access to a lathe, or good drill press, or the other holders mentioned, I would still use a small hammer and the already described small hardwood block to deliver the force.

There is a very low chance that this arbor will break.

Again, don't use any heat unless you want more problems than you have now ...

Willie X
I agree, no heat. The bend us usually at the pinion cap so that's where you want to apply the straightening force. I like the wood "V" block idea. I would not apply the force to the lantern cap alone because there's not much meat there. If it didn't bust when it got bent it isn't likely to bust when bent back but it still may not run true. A no-lathe option (if the other methods do not bring results) is to remove the wheel and pinion then straighten the arbor with a hammer on an anvil or other flat block of steel, then replace the wheel and pinion after the arbor is checked for truth.

RC
 

bangster

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I rather like Harold's suggestion. Doesn't involve hammering on the arbor or the pinion.
 

RJSoftware

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I find that a simple pair of pliers works best at first. You can set the bend between jaws with arc in center of one jaw. Then squeeze making slow careful correction. Or in this case two pliers, one on each side. The advantage is that you can carefully restore the bend back straight by limiting the correction to the bent portion and not the overall shaft, pinion and gear. After that fine tuning I do in the lathe and that can go as far as using binocular microscope for pivot wobble.
 

shutterbug

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I like that idea, RJ. However, in this case I don't think you can get the pliers in position unless you remove the pinion.
 

RJSoftware

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Hey Shutter. Well yep I did mention using two pliers in this case. But in truth I would probably chuck the straight side in the lathe and then bend the effected side back straight with pliers. Only point that I was trying to make is sometimes an aggressive bend with the pliers in the needed direction beats trying to force the bend straight while spinning in the lathe. On the small pivots that I finally managed not to break the bent ones by bending them back with pliers. But a bent pivot restored is still suspect weak.
RJ
 

woodlawndon

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Thanks folks, some terrific ideas here. I'm going to try it over the next couple of days starting with least aggressive (hole in hardwood) and move up as needed. Will let you know how I make out.
Don
 

gocush

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Wood: please take some photos along the way and post them so we can see the progress as well as results of different methods. Don't be shy of mistakes.

Willie or Others: I'd like to see photos of your V blocks etc. with a wheel/arbor sitting in position and how or where you apply force, as if you were going to straighten the arbor (doesn't have to actually be bent, just set it up as if it were and take a pic.)

Same for other methods (use of vice and angle plates, or lathe). I'd like to SEE how folks approach this since it's not obvious from the written descriptions above.

Thanks.
 

MuseChaser

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I've got a bent center/hands arbor of an unknown bim-bam movement, captive in the front plate by a pressed-on pinion gear and two-lobed cam. The part between the plates is fine; the bend is just in front of the plate. Is there a way to straighten it, using some of the great techniques discussed in this thread a couple years ago, without removing the arbor from the front plate? If I leave the movement assembled, chuck the arbor or place a drilled-out hardwood dowel over it, and just bend slowly and carefully, will that damage the front plate, rear pivot, or related pivot holes?
 

Willie X

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Muse,
Not usually, I do this all the time. Set the movement on a solid surface, or in a suitable vise and use a hardwood block as already described. If it's bent at the plate, get your block right up to the plate. Tap check, tap check, etc.
Note,. some folks think that using a hammer in clock repair is nonsense. But, if you've worked around many machinists, you will know that when the fine adjustments are done the last super fine adjustments are always done with a hammer. For clocks a 4 ounce plastic or brass mallet is indispensable in my shop. Willie X
 
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