Waltham 18s Model 1877...Hunter..anyone have an extra?...or...should I attempt to make an arbor?..thanks...Tony c

Here is a picture

Tony,

Looks like maybe a mainspring has let go to do that, are the train wheel teeth damaged anywhere?

I've made both new arbours and pivot inserts to effect repairs on this type of damage.

Changing the whole arm with or without jewels will mean shifting the pallet stones, so my personal choices would be to re-pivot first, and make an arbour second - simply because getting the old arbour out could damage the arm - and I'm a tad lazy .

Re-pivoting is a perfectly acceptable repair done properly, and was how many of the 'old boys' did it anyway.
I dare say some of the 'purists' will 'poo poo' the notion, but then they ain't doing the repair.

I like to keep as much of the original bits in a watch as possible - and it's a reversible repair!
Depends really whether you can get bits anyway!

Bear in mind too, that a secondhand pallet assembly will most likely have pivots that are worn to some degree or have been sized to fit the movement they came out of, therefore when polished, may be too sloppy for the jewels / pivot holes in your watch and useless anyway - but you could get lucky and find one with pivots that are too big to start with.

Just my 2 penn'orth!

John

So...if I repivot..I need a drill bit a hair smaller than the original pivot size??...how do you set this all up in a lathe?....If I make another arbor...I'll need to remove the old one...is this one riveted like a balance staff?

Tony,

I've no idea what kit you have there, but for these jobs, I mount the arbour in a collet chuck to run true (no 'wobble'), then clean up the broken pivot by taking a Very Light shave straight across the end - just sufficient to remove the broken stub, followed by countersinking the centre - this gets the drill kicked off centred from the start.

Be careful with this, because if you end up with a 'pip' in the depression, they're murder to get rid of without re-dressing the arbour end, and if you do that, it will shorten it and increase the end float of the staff between the jewels/pivot holes - you'll then need to make a new staff!.

I use 'spear point' drill bits because generally they run truer and more to size than a spiral fluted drill which tend to 'ovalise' the hole being bored or, go off centre.

The drill can actually be any diameter you want as long as it's Bigger than the broken pivot, yet leaves enough meat in the arbour walls to take a new pivot without splitting it.
A pivot exactly the same size as the one being replaced, would be too weak as there would be no shoulder machined at its base - only the walls of the hole would support it.

I usually drill as deep as the pivot is exposed, but it can be a tad shorter.
You also need to cut the pivot longer than that needed, to allow trimming to size after it's fitted.

For the pivots, I use blued steel pivot wire of a diameter a tad bigger than the hole to be drilled, so best match the wire to a drill before you start the job, and for this, a digital calliper is good kit for sizing up.

Centre the wire and take a shave off it to clean it up true, and cut a bevel on the end - this helps it to enter the hole drilled in the arbour - then it's a case of taking small cuts off the surface of the wire until it almost fits the hole in the arbour - just keep test fitting the arbour to it, and part it off slightly longer than you need.

I use a staking kit to then gently tap the new pivot into place and rely on a friction fit to hold it.
Some folks also use either cyanoacrylate or a 'Loctite' type agent to bond the pin, but I'm not keen on glues to be honest, and if you take care machining you won't need it anyway.

If you do use a bonding agent, press the pin Very Slowly into the arbour, and be very careful Not to split it, because the hydraulic pressure build up behind the pivot will be enormous whilst excess goop escapes - file a very small flat on the side of the pin to allow it to escape!.

With the pin in place, you'll then need to size it to the jewel or pivot hole, which is why it's necessary to fit a pin bigger than needed - you've then got some meat to play with!

If the pivot hole isn't jewelled (just a brass hole), it's best to true any wear out of this first with a reamer and burnish with a polished broach - or bush it if too badly worn - just as you would with a clock!.
It's vital this is attended to before finishing the pivot, because you will be sizing the pivot to the finished size of that hole!

Mount the pallet arm assembly back into the collet running true, then turn the pivot almost to size so that it's a snug fit in the jewel /hole, (be careful with jewels) then polish and burnish - that operation should remove sufficient material to give a nice working clearance in the hole - but Don't go for a snug 'Engineering fit', it will be too tight!.
Again, be careful near the arbour end, you only need to cut the pivot shoulder to blend into this face, and not cut into the face itself.

If you use a double ended pivot file and burnisher to finish, they have a polished safety edge which is used against faces that need protection.

Get it right, and you'll have a clean shoulder on the pivot which will be an all but invisible repair.
All that remains will be to trim the end of the pivot to length for the hole and polish.

Sounds a horrendous operation, but actually quite an interesting excercise, and with some pivots - especially on pinions, this may be your only option for a repair - especially with English Lever, Verge and early Swiss watches where mass production methods never applied!!

The staff on your pallet arm looks to be a press fit, so it should just knock out (I'm sure the Waltham experts will put us right on that though).
If so, it'll be quicker to turn a new staff following the process above than pivotting, but be wary of busting the arm or chipping the jewels getting the old staff out!
That's a judgement call only you can make.

I have the advantage of a binoccular microscope and compound crosslide on my lathe etc, but gravers are fine with practice - I'm just not masochistic enough to perfect the art

BTW, if that broken pivot worked in a jewel, make sure it's not chipped!

Sorry about the length of the reply, hope you find it useful!

Have fun!

John.

PS.

I have exactly the same job to do on a Benson English Lever, I may get around to taking photo's whilst doing it!
J.W.

Thank you for the detailed process for the fix...I don't have a set of pivot drills...nor do I have anything fancy for a tailstock on my lathe...so I'll probably attempt to make my first staff....I'll see what happens when I attempt to remove the old Pallet Arbor...then go from there...again...Thanks...Tony

Hi Tony,

Great description of re-pivoting from John. Myself I would just go ahead and make a whole new one, they are easy to make, large in comparison to a balance staff and are uncomplicated in shape, just remember to add the slight taper to the upper section to hold the pallet on (you can measure this), which I would do last.

Hi Chris and John....can I assume at this point that this arbor is rivited much like a balance staff?.....and installed much like a rivited staff...if so...why the taper?...

These are normally a screw in type or a taper from what I can see it looks like your is press fit on the taper, no rivit as you would find on a staff and hence a lot easier to make, drive it out and you will see.

Of course the easy way is to ask Brian C ! bet he has one

Thanks for the comments Chris, always a tad daunting writing up a repair like that with so many Real experts looking in!

Tony, pivot drills are quite cheap and easy to get hold of as a rule, either via the 'bay' or supply houses.
You can always make drills from pivot wire anyway, as they're quite easy to do - you'd need to get into practice shaping, sharpening and hardening the points anyway - which is most of the battle!

It wouldn't be the first time I've used a pivot drill held in a pin chuck by hand though, and with care works ok!

The taper that Chris mentioned is to ensure the walls in the bore of the pallet arm grip the staff, there's a chance it would work loose otherwise.
I'm not familiar with Waltham staffs at all, so can't really comment with any authority here.

Best regards

John

John,
Your instructions on repivoting are excellent. The only thing that I would add is to use Bergeon blued wire. I would not use any of the wire from India for any sort of lathe work. I have not had good luck with it. The Bergeon is more money, but well worth it.

Thank you Scott, your comments are certainly appreciated.

I would agree totally with your comments regarding quality of wire too, some of the stuff on the market now is absolute rubbish.
Considering we used to live in one of the best steelmaking centres of the world (Sheffield), it's galling to see so much crud being foisted onto buyers now!

Most of that stuff I've encountered though, is through routine engineering projects rather than any watch materials, but I've no doubt the poor quality goes across the board.

I was fortunate enough to aquire all my pivot wire amongst the tools and stock bought from the estate of a watchmaker who'd been in the busines for near on 65 years, and it's very good stuff indeed.

I think when comparing cost to quantity when bought in from somewhere like Bergeon, it's quite economical when you consider how little of it the average repairer would actually get through.

Bit like good watch oil, little bottles cost a lot, but they go an awful long way.

Best regards

John.

Be sure to drive out the arbor from the small side of the the taper if it's friction fit. You can use your staking set to do this without distorting anything ~ select a hole stump that's a close fit without binding to support the pallet while gently tapping out the arbor. Don't drive in to far just line up the jewels with the escape wheel teeth. Be sure it's friction fit before starting because some are threaded as mentioned above.

George...thanks for the "heads-up"...I have not got back to this particular movement yet...I'll get back to this post for an update when I do...right now ...I'm in the middle of trying to "save",,,a few Waltham 18s hairsprings.....Thanks...Tony c