Broken pivot

[nickelsilver]

I would suggest, as a former teacher, to concentrate on making nice smooth cylinders first, in unhardened steel (or even brass). Then make nice smooth cylindrical pivots (of any size) with nice square shoulders. Then try hitting a specific diameter for simple cylinders, then specific diameters for pivots. Then do the same with hardened and tempered (blue) steel. I understand making an actual part is more motivating than making "dumb" parts, but you will find that in a few hours you can reliably make those cylinders and pivots. Then making the part will be easy. Then you'll be really motivated to make all sorts of stuff.

 

The image is taken from an article in Horological Times, this shape of graver can really help to avoid undercutting a shoulder when making pivots.

Edited April 13, 2020 by nickelsilver

[nickelsilver]

Then making conical pivots (balance staffs) isn't so intimidating.... it's all lengths and diameters with a curve here and there.

[jdrichard]

well the drive belts for the lathe arrived, i shall start again tomorrow  and post more pictures etc as i go. 

I make my lathe belts from thick leather boot lace


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[jdrichard]

Then making conical pivots (balance staffs) isn't so intimidating.... it's all lengths and diameters with a curve here and there.

I use rounded tip 2mm gravers for the conical part of the pivot.


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[rodabod]

8 hours ago, nickelsilver said:

The image is taken from an article in Horological Times, this shape of graver can really help to avoid undercutting a shoulder when making pivots.

I quite like that idea of the square end. I do occasionally swap between "diamond-up" and "diamond-down", so would need to remember that, I suppose. Must also make the tip sturdier too, which would be handy.

Edited April 13, 2020 by rodabod

[jdrichard]

I quite like that idea of the square end. I do occasionally swap between "diamond-up" and "diamond-down", so would need to remember that, I suppose. Must also make the tip sturdier too, which would be handy.

I use carbide gravers. Less sharpening. I use a 2500 grit diamond plate for the occasional sharpening.


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[nickelsilver]

Transporter, it looks like you need to adjust the play on your Lorch headstock. From the pic it appears that the bearings are way too loose. Most lathes of this type have an adjusting nut at the rear of the spindle, but some older Lorch have a different arrangement. If it's not clear how to do it get a pic of the whole headstock and we can help.

 

 

[transporter]

Well spotted mate, yes in that shot it is loose, I had undone the rod that tightens the collet I do have to gently give it a tap to re seat and away I go again.

But I will put a picture up of the head stock form you to have a look at.

New collets arrived today so I will start turning tomorrow.

[nickelsilver]

Well spotted mate, yes in that shot it is loose, I had undone the rod that tightens the collet I do have to gently give it a tap to re seat and away I go again.
But I will put a picture up of the head stock form you to have a look at.
New collets arrived today so I will start turning tomorrow.

The drawbar won't have any effect on the play in the spindle bearings.

[transporter]

Here’s a picture for you to enlighten me if

you would be so kind mate.

 

[nickelsilver]

That's a really early one, I haven't had my hands on one in probably 20 years, but I know you adjust the play on this by shifting the pulley. Without seeing it completely apart I can't really advise more. 95% or something of other plain bearing watch lathes use a completely different arrangement. But if the play is changing when you tighten the collet there is another issue, most likely that the drawbar isn't original and is touching the rear of the headstock.

 

Edit- Found a thread at WUS on a Lorch 6mm with the similar arrangement. I think with the photos there you can see how it works. The pulley limits the play at the rear of the front bearing. Later designs have double conical bearings front and back, this one has a straight bearing at the rear (Schaublin also used this arrangement on the bronze bearing 70 models).

 

https://forums.watchuseek.com/f6/6mm-lathe-some-questions-595187-2.html

Edited April 17, 2020 by nickelsilver

[transporter]

Ok gents for an update here’s a quick test fit, ok I know the pivots aren’t the best on this one but I’m still learning so please bear with.

So fitted the pallets just to see what the tolerances were like. And they seem fine.

Now having test fitted this particular one, if you can look at the pallets in relation to the escape wheel, would you say the pallets are too high, I’m probably answering my own question but I think they are.

Having rebuilt the movement ( it’s nice and easy ) I had to do a little twisting of the hairspring as it was out of shape a little, now the pallet flicks over like a rocket but the balance is struggling to go,

It will only once maybe twice before coming to a halt. The rest of the train runs free, tested wheel by wheel the two wheels then three wheels and so on.
So I’m wondering if the pallets are two high would this be causing enough drag to stop the balance.

[FLwatchguy73]

It looks to me like your pivot is tapered, that's a no go in the world of watches. The pivots must be perfectly straight otherwise they can drive themselves in and lock. I'm only going by your photos, I'm not able to measure your pivot vs the jewel hole clearance. Also, the length plays a major role. If it's too long it puts pressure on the cap jewel, if it's too short it rides on the shoulder. All of that has already been mentioned above by others though.

[transporter]

Absolutely spot on mate, yes they are slightly tapered on this one, I’ll be making some more next week. As for the length, they are running in a brass plate, so no cap jewels to worry about but I’d like to get the length so the pivot just shows proud of the actual hole.

[rodabod]

Yes, what FLW says. It could potentially be ok if you had cap jewels here, but you don’t. 

[FLwatchguy73]

In regards to how high the lever is riding, yes, it can definitely be an issue. Yours is a jeweled lever type pallet and the jewels are designed to ride on the gear faces of the escape wheel. This is a friction reducing design and you'll be losing that benefit if it's not contacting correctly. Also, the jewels may be shaped a bit differently than the structure they're bonded to, this can cause binding and lock the system up. Am I right in assuming that this is either an English lever with either a fusee or going barrel drive train? Just my own curiosity on that bit of info.

[transporter]

Morning FLW, it’s an English lever going barrel, I’m going to mount the lever onto the old broken staff tomorrow and double check the height of the jewels to the teeth on the escape wheel, the I’ll start to make another staff and see how that turns out

[clockboy]

This pivot can have some end shake as the pallets are large enough to allow for this. However the pivots must be straight otherwise they could bind. The pallet needs fitting and testing on it's own to establish if this is the fault.

[transporter]

Cheers clockboy, when you say the pallet needs to be fitted on its own and tested what tests should I carrying out please? This will help me when I make another one. 
Thanks mate

[clockboy]

It should move freely in all positions and have a little end shake and very little side shake. The side shake if too much will alter the locking and it will never run consistently. These vintage fusee pocket watches are a real challenge because effectively you can not really see what is happening. I have recently returned one that was running but it's performance was poor but it was at least running. 

[transporter]

Clockboy, I suppose it’s all the things I thought it might be but I just needed that extra nudge for confirmation, I shall be making another tomorrow, and will brush up on how to finish the pivots.
I turn them to just shy of the actual thickness then get my pivot file and file them down that bit more, then a dab of oil on the burnisher and start slow and then speed the lathe speed  up.
I haven’t yet been able to get a super shine on my pivots and still wonder what I might be doing wrong.
I don’t have a Jacot tool so everything is done by eye whilst the job is still in the collet.

 

[transporter]

Ahhh that moment when you have the pivot almost at the right size so you go to polish it up so that it glides into the jewel hole and..................

[transporter]

I’ve forgotten what attempt this is now, but was just parting the extra length off the final pivot and it snapped, I think my remaining pivot is a better attempt than the previous.

I cannot though seem to get a really good polished finish on them, I have a burnisher but just can’t seem to get them finished to the required standard.
Oh well, time to start again!!!I

[clockboy]

What I have learn't after many, many failures is that very little pressure and a steady hand is required + a lubricant on the burnisher is a must. I then finally polish with Brasso and some peg wood & then buff with buff stick. I used to use a tailstock jacot support for the pivot like this.

 

 

 

 

 

 

[transporter]

Ahhh now I have the bit in the bottom photo but unfortunately not the rod that attaches it to the tail stock, I also don’t have the bit in the top photo ( piece from Jacot tool ). I’ll be honest I’ve not a clue as to how those two tool bits would look like set up on a lathe, well I suppose I have but that’s besides the point and I should search myself.
I do use 3 in 1 on the burnisher but so far no shiney pivots, I do wrap a piece of 1500 wet and dry over a thin piece of brass sheet and allow the pivot to run up and down the edge but it does eat through the paper in quick time  and I can’t say that it’s doing anything to be honest. 
But I think I’m having abit more success now with the turning, here’s the second one of the day, I believe I’m almost there?????

Constructive criticism and pointers greatly appreciated, I will say the top one looks slightly different as it has a high polish on its surface.