How does one polish a pivot hole on a watch?

[GregG]

I want to start burnishing pivots, and I have a Jacot tool to do it.  The tool was in kind of rough condition when I bought it, so I'm in the process of polishing the parts and oiling pieces so that it runs smoothly.  The parts are all there, they just need some TLC.  The process seems simple enough, so I'm not going to harp too much on it.

That leaves the opposite side of the coin, the pivot holes.  Logic should dictate that if either of these are rough, then you're robbing yourself of amplitude.  How would you polish the inside of a steel/brass pivot hole?  Is that what smoothing broaches are used for?  And how do you know which size broach to use?  What is a typical range of sizes that a watch/pocket watch pivot would be?

[ifibrin]

I don’t think a watch pivot hole in a mainplate or bridge (non-jeweled) is going to get rougher due to wear and tear when it was in use. If there’s any problem at all, these holes in steel or brass are going to become bigger or even oval. Most of the time, wear is going to cause the center of the hole to drift slightly. If that’s the case, you are going to have to re-bush or jewel these holes, and not just broach them… The best way to do this is to locate the true center on a lathe then ream out a hole, to replace with a jewel or bush.

[GregG]

6 minutes ago, ifibrin said:

I don’t think a watch pivot hole in a mainplate or bridge (non-jeweled) is going to get rougher due to wear and tear when it was in use. If there’s any problem at all, these holes in steel or brass are going to become bigger or even oval. Most of the time, wear is going to cause the center of the hole to drift slightly. If that’s the case, you are going to have to re-bush or jewel these holes, and not just broach them… The best way to do this is to locate the true center on a lathe then ream out a hole, to replace with a jewel or bush.

Thanks for the reply.  How do you locate the true center exactly?  I don't have a lathe and do not intend on buying one, but wish to know for my own edification.

[ifibrin]

17 minutes ago, GregG said:

Thanks for the reply.  How do you locate the true center exactly?  I don't have a lathe and do not intend on buying one, but wish to know for my own edification.

If the hole on the bridge is still intact, you can use that hole as a reference point by mounting the bridge onto the mainplate. If the hole on the bridge is the one that is showing wear, it becomes much more tricky. i don’t have a lathe either, but this is what I understand from the posts made in this forum

[Nucejoe]

 How about closing the hole a bit ( peen it) and then broach it to size, saw this done on a classic mumbay special and to my surprise  it didn't seem to eat much amplitude. 

 

[GregG]

 

5 hours ago, Nucejoe said:

 How about closing the hole a bit ( peen it) and then broach it to size, saw this done on a classic mumbay special and to my surprise  it didn't seem to eat much amplitude. 

 

Hi Joe, do you have some more information about it?  What tools to use, how to do it, or a video?

[Nucejoe]

Do you have a staking set, use a punch to tap( with a hammer)  on the hole and close it only a bit. You would want to replace the bush if the hole is too worn. 

Had no luck trying to find a video that shows how its done. 

[Graziano]

1 hour ago, Nucejoe said:

Had no luck trying to find a video that shows how its done. 

Hi Joe, here's a video................

 

 

[GregG]

12 hours ago, Graziano said:

Hi Joe, here's a video................

 

 

I love Kalle Slaap (or however you spell his name)!  Thank you!

[ifibrin]

On 5/26/2022 at 1:56 PM, Graziano said:

Hi Joe, here's a video................

 

 

Kalle is clearly a very talented watchmaker, but I’m not sure if I would ream a hole in a bridge or mainplate free hand, and adjust to size.

[Graziano]

21 hours ago, ifibrin said:

but I’m not sure if I would ream a hole in a bridge or mainplate free hand, and adjust to size.

I suppose in some cases it depends how confident you are check this video out reaming 6309 plate for barrel arbor freehand 

Graziano 

 

[Neverenoughwatches]

34 minutes ago, Graziano said:

I suppose in some cases it depends how confident you are check this video out reaming 6309 plate for barrel arbor freehand 

Graziano 

 

The broaching did look a bit brutal if I'm to be honest . No smoothing broach to follow but a tapered rubber grinding head

[Graziano]

17 hours ago, Neverenoughwatches said:

No smoothing broach

Hi, it is to recieve the jewel so no broaching needed if reaming is done correctly 

Cheers Graziano 

Edited May 30, 2022 by Graziano

[Neverenoughwatches]

4 hours ago, Graziano said:

Hi, it is to recieve the jewel so no broaching needed if reaming is done correctly 

Cheers Graziano 

Thanks Graziano.  Does this rougher surfacel help to grip the jewel ?

[clockboy]

The difficulty with this is to maintain absolute centre and that requires the broach to be absolutely vertical. Achieving it by hand is not easy and no second chances with that repair. Using a reamer with a Seitz jeweling tool or similar would be my option. 

Edited May 30, 2022 by clockboy

[Neverenoughwatches]

1 hour ago, clockboy said:

The difficulty with this is to maintain absolute centre and that requires the broach to be absolutely vertical. Achieving it by hand is not easy and no second chances with that repair. Using a reamer with a Seitz jeweling tool or similar would be my option. 

The repairer did look a little rough with his approach to the reaming. Definitely wasnt being too careful about being perfectly square on with the jewel hole. I think id be wanting to use something more accurate as well. The best end result does require the best possible approach 

[ifibrin]

2 hours ago, clockboy said:

The difficulty with this is to maintain absolute centre and that requires the broach to be absolutely vertical. Achieving it by hand is not easy and no second chances with that repair. Using a reamer with a Seitz jeweling tool or similar would be my option. 

Not only does the broach need to be vertical, but the mainplate/bridge also needs to be absolutely horizontal. Using a reamer with a Seitz jeweling tool is probably fine for most jobs, but some prefer to use a lathe with faceplate to ensure the hole is perpendicular in axis to the reamer just to be extra safe.

[Graziano]

6 hours ago, Neverenoughwatches said:

Thanks Graziano.  Does this rougher surfacel help to grip the jewel ?

Hi, the jewel is friction fitted.  

. 01mm larger than the hole that's been reamed. Here is another video showing how it is done using a jeweling tool. For a Seiko 6139 

Cheers Graziano 

Edited May 30, 2022 by Graziano

[mikepilk]

13 hours ago, Graziano said:

Hi, it is to recieve the jewel so no broaching needed if reaming is done correctly 

Cheers Graziano 

Any idea where you find jewels big enough for barrel arbors ?  Cousins only have Seitz jewels up to 1.1 mm hole size, whereas you typically need about 1.6 mm.

[Graziano]

9 hours ago, mikepilk said:

23 hours ago, Graziano said:

Hi, it is to recieve the jewel so no broaching needed if reaming is done correctly 

Cheers Graziano 

Any idea where you find jewels big enough for barrel arbors ?  Cousins only have Seitz jewels up to 1.1 mm hole size, whereas you typically need about 1.6 mm.

Hi there, vintage time Australia has barrel arbor jewels for Seiko movements here's a link to his ebay listing https://www.ebay.com.au/itm/294949559859?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=w5cxySaTQs-&sssrc=2349624&ssuid=hSD7I6uATTu&var=&widget_ver=artemis&media=Copy if you check his other items for sale there is barrel arbor jewels for many Seiko movements available 

Graziano 

Edited May 31, 2022 by Graziano

[Neverenoughwatches]

20 hours ago, mikepilk said:

Any idea where you find jewels big enough for barrel arbors ?  Cousins only have Seitz jewels up to 1.1 mm hole size, whereas you typically need about 1.6 mm.

I think  Brass bushing would be used for barrel arbors mike

10 hours ago, Graziano said:

Hi there, vintage time Australia has barrel arbor jewels for Seiko movements here's a link to his ebay listing https://www.ebay.com.au/itm/294949559859?mkcid=16&mkevt=1&mkrid=705-154756-20017-0&ssspo=w5cxySaTQs-&sssrc=2349624&ssuid=hSD7I6uATTu&var=&widget_ver=artemis&media=Copy if you check his other items for sale there is barrel arbor jewels for many Seiko movements available 

Graziano 

Wow theyre big jewels, same fit as a bush ?

Edited May 31, 2022 by Neverenoughwatches

[mikepilk]

32 minutes ago, Neverenoughwatches said:

I think  Brass bushing would be used for barrel arbors mike

Wow theyre big jewels, same fit as a bush ?

I know, I want to replace brass with jewels.  Also, Cousins only has brass bushings up to 1mm hole size

Edited May 31, 2022 by mikepilk

[Neverenoughwatches]

34 minutes ago, mikepilk said:

I know, I want to replace brass with jewels.  Also, Cousins only has brass bushings up to 1mm hole size

I'm interested with that idea.

[mikepilk]

Seiko bridges are often badly worn at the arbor, so it would be nice to find jewels with 1.5 - 1.6 mm holes. 

I have pocket watches with jewelled holes for the barrel arbor, maybe there are some old pocket watch jewels that would do the job?

[ifibrin]

2 hours ago, mikepilk said:

Seiko bridges are often badly worn at the arbor, so it would be nice to find jewels with 1.5 - 1.6 mm holes. 

I have pocket watches with jewelled holes for the barrel arbor, maybe there are some old pocket watch jewels that would do the job?

I didn’t realise that barrel arbor jewels were that large… and unavailable. Looks like other than making your own jewel @nickelsilver has shown before, the next best thing is to replace with a brass bushing made on a lathe. You will probably need to optically center the arbor hole anyway in a lathe to ream it, so making a bushing is just an extra step on the lathe.