Electric balance staff remover.

[watchweasol]

That’s usually the case with vintage tools, it’s getting replacement parts etc, some times ok some times scrap you take your chance on eBay, especially if the seller is not forthcoming in answering questions.

[luiazazrambo]

On 4/6/2025 at 10:07 PM, Neverenoughwatches said:

One of the reasons I didn't buy it, the seller couldn't tell me how the grinding disk fitted,  It made me unsure if I could get any more.  It was cheap though,  for a rare tool,  about £100.

The disc is hold by a single screw, found an ebay seller who sells them as a pack of 3, so I quickly bought a pack, they are no special disks, but the diameter and thickness matters as far as I can see it now. 

[Neverenoughwatches]

1 minute ago, luiazazrambo said:

The disc is hold by a single screw, found an ebay seller who sells them as a pack of 3, so I quickly bought a pack, they are no special disks, but the diameter and thickness matters as far as I can see it now. 

That's interesting, thank you.

[luiazazrambo]

By the way they come up very rarely I was hunting one for the last two years and even the cosmetically and/or mechanically bad looking ones do sell around and above £300, a good one is about the double. There is one for sale at the moment on eBay and a tape holds it together for 400 euros. (I dont like to paste an eBay link into watchrepairtalk as the link wont work after the listing is closed.) 

[Neverenoughwatches]

6 minutes ago, luiazazrambo said:

By the way they come up very rarely I was hunting one for the last two years and even the cosmetically and/or mechanically bad looking ones do sell around and above £300, a good one is about the double. There is one for sale at the moment on eBay and a tape holds it together for 400 euros. (I dont like to paste an eBay link into watchrepairtalk as the link wont work after the listing is closed.) 

I know I missed out badly on the one I let drift, I'll find the thread I made about it.

[luiazazrambo]

Meanwhile I learnt that you can buy disks with the correct outside diameter with the correct hole from aliexpress but they are a little bit thicker... I dont know what does the little bit thicker means from the practical point of view, like are they still usable or do you need to tweak something to make them work?

[Neverenoughwatches]

This is the thread ! lol

[luiazazrambo]

Here there is another video from a Hungarian watchmaker:

https://photos.app.goo.gl/4y1t7MmjcopZUHeM6

I hopefully will be able to record something similar soon. I am excited. Balance staff replacement one of the thing i must learn. Then the lathe.. both are very scary things.

Edited April 8 by luiazazrambo

[luiazazrambo]

and a pic from the same watchmaker after the wheel removal:

[Neverenoughwatches]

6 hours ago, luiazazrambo said:

Here there is another video from a Hungarian watchmaker:

https://photos.app.goo.gl/4y1t7MmjcopZUHeM6

I hopefully will be able to record something similar soon. I am excited. Balance staff replacement one of the thing i must learn. Then the lathe.. both are very scary things.

They're only scary if you let them be.  

[luiazazrambo]

The docs I promised:

https://drive.google.com/drive/folders/1MTQV60zWhV5h0SP5OdnusZZx5E24HhTs?usp=drive_link

[luiazazrambo]

Update: The dimensions of the original grinding disc: 

Hole diameter: 4mm Outside diameter: 24mm Thickness ~ 0.49 mm

I have received 3 discs advertised on eBay as Molfres disks but they are not original just borrowed from a rotary set or ordered from aliexpress (I can see that the hole is drilled by somebody not in the factory), also they are thicker than the original about ~0.65 mm which does matter unless you cut trough the retaining plate with the thicker disk. I went out to the garage and I checked two of my rotary sets bought from Lidl - brand name: Parkside and found a red set with ~ 0.65 thickness and a black set with ~ 0.52 mm thickness. Both sets have smaller hole diameter than the required 4mm so I drilled a 4 mm hole into a black one.

From left to right: eBay ~ 0.65mm, original (broken) ~0.49mm, red set from rotary tool (identical to the one got from eBay) ~0.65mm, black set from rotary tool ~0.52mm.

 

I simply drilled a 4mm hole with my bench drill into one of the black ones installed it and went for the first step of my first attempt of balance staff replacement.

The black disk installed:

 

So this FEF 190 was in my cabinet and was waiting for me as this movement is the Holy Grail of my 100 challenge, it cannot be complete without a balance staff replacement.

I quote from the manual: "The balance staff will be sufficiently ground when its projecting portion measures 0.02-0.03 mm. If it is not the case adjust the retaining plate to the correct position."

As you can see on the pics I went a bit too deep the balance wheel should not be touched.

The grinding operation can be done in matter of seconds, however as a new disk was installed i adjusted the retaining plate a number of times and turned the adjusting screw too much at the end.

I used the riveting tool came with the grinding tool to drive the staff out of the balance, unfortunately the smallest one is broken.

 

Edited April 12 by luiazazrambo

[luiazazrambo]

HS is flat and concentric as far as I can tell and the watch is running. I only know the vague theory as how to poise the balance wheel the only thing I did is to put the balance wheel back into place checking the side and end shake plus with the help of my blower I checked if it is running true, on top of that under my microscope I checked if the balance wheel can stop in many position around 360 and it could. Amplitude is low around 220, I cannot remember of the state of the MS and its arbor, the movement was waiting for me for almost a year. I am eager to call this job done, but I cannot leave it like this so I am going to take it apart once again.

 

[Neverenoughwatches]

Can you do a little drawing of how the disk cuts across the staff please. 

[mbwatch]

Based on the video clip, it looks like pivot end of the balance staff must be pressed into the edge of the rotating disc, progressively ground away completely rather than cut. And with the ability to rotate the balance to grind off the hub if its diameter is greater than the thickness of the disc? I was puzzling over the "sunburst finish" left on the balance arms but realize that is from slight finger rotation of the balance while it is chucked in.

 

This is a really neat tool - incredible how fast it is. I'm about to begin learning to cut off a staff on the lathe.

Edited Sunday at 12:53 PM by mbwatch

[Neverenoughwatches]

18 minutes ago, mbwatch said:

And with the ability to rotate the balance to grind off the hub if its diameter is greater

Is this not hollow grinding the hub with the possibility of cutting into the wheel hole ?

[mbwatch]

17 hours ago, luiazazrambo said:

quote from the manual: "The balance staff will be sufficiently ground when its projecting portion measures 0.02-0.03 mm. If it is not the case adjust the retaining plate to the correct position."

Sounds like there is an adjustable stop that is supposed to prevent it.

[Neverenoughwatches]

What I was meaning if the hub has a large diameter, to grind it all off might catch the wheel hole. The full hub maybe does not have to be removed for the staff to come free, just up to the outside edge of the hole. It's an unusual method, very different from cutting it off with a graver.

[luiazazrambo]

Maybe pics are better to explain, but if you read the manual I scanned above it becomes all clear. Its not a lengthy text as you only need to read the English part. You grind off the entire length of the balance staff till the arms by gently pressing it to the rotating disk while slowly turning the collet, to adjust the machine you move the retaining plate closer or further away from the disk. As the disk wears out you slowly need to move the retaining plate towards the disk by the means of turning the adjusting screw. The machine is correctly set I quote again: "The balance staff will be sufficiently ground when its projecting portion measures 0.02-0.03 mm. If it is not the case adjust the retaining plate to the correct position." This 0.02-0.03 mm wafer can be ignored / easily removed. I went too close with my final adjustment and marked the wheel but it should not happen cannot happen if the machine is correctly set.

[Neverenoughwatches]

It's possible to see how the grinding wheel could cut into the balance wheel when trying to take all of the hub off

[luiazazrambo]